U.S. patent application number 14/576112 was filed with the patent office on 2016-06-23 for network controller having predictable analytics and failure avoidance in packet-optical networks.
The applicant listed for this patent is Juniper Networks, Inc.. Invention is credited to Gert Grammel, Hans-Juergen W. Schmidtke.
Application Number | 20160182146 14/576112 |
Document ID | / |
Family ID | 55023892 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160182146 |
Kind Code |
A1 |
Schmidtke; Hans-Juergen W. ;
et al. |
June 23, 2016 |
NETWORK CONTROLLER HAVING PREDICTABLE ANALYTICS AND FAILURE
AVOIDANCE IN PACKET-OPTICAL NETWORKS
Abstract
Techniques for providing closed-loop control and predictive
analytics in packet-optical networks are described. For example, an
integrated, centralized controller provides tightly-integrated,
closed-loop control over switching and routing services and the
underling optical transport system of a communication network. In
one implementation, the controller includes an analytics engine
that applies predictable analytics to real-time status information
received from a monitoring subsystem distributed throughout the
underlying optical transport system. Responsive to the status
information, the analytics engine applies rules to adaptively and
proactively identify current or predicted topology-changing events
and, responsive to those events, maps reroutes packet flows through
a routing/switching network and control and, based on any updated
bandwidth requirements due to topology changes, dynamically adjusts
allocation and utilization of the optical spectrum and wavelengths
within the underlying optical transport system.
Inventors: |
Schmidtke; Hans-Juergen W.;
(Mountain View, CA) ; Grammel; Gert; (Ditzingen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Juniper Networks, Inc. |
Sunnyvale |
CA |
US |
|
|
Family ID: |
55023892 |
Appl. No.: |
14/576112 |
Filed: |
December 18, 2014 |
Current U.S.
Class: |
398/2 |
Current CPC
Class: |
H04Q 11/0062 20130101;
H04J 14/0283 20130101; H04Q 11/0066 20130101; H04L 69/324 20130101;
H04J 14/0223 20130101; H04J 14/0268 20130101; H04Q 2011/0081
20130101; H04L 45/42 20130101; H04L 69/325 20130101; H04B 10/038
20130101; H04J 14/0257 20130101; H04L 45/02 20130101; H04J 14/021
20130101; H04L 45/28 20130101; H04L 45/62 20130101 |
International
Class: |
H04B 10/038 20060101
H04B010/038 |
Claims
1. A method comprising: receiving, with an integrated network
controller, state information from optical components of an optical
transport system having a plurality of interconnected
packet-optical transport devices; applying, with an analytics
engine, a set of rules to identify a failure of any of the optical
components; computing, with a path computation element of the
controller and in response to identifying the failure, at least one
updated path through a routing and switching network having a
plurality of interconnected layer three (L3) routing components and
layer two (L2) switching components for communicating packet-based
network traffic; communicating, with a software defined network
(SDN) control module of the controller, updated routing information
to the routing components to control packet flows through the
routing and switching network in accordance with the updated path;
and responsive to the updated routing information, configuring,
with a routing wavelength and spectrum assignment control module of
the controller, the packet-optical transport devices to operate at
particular wavelengths based upon bandwidth requirements for the
network traffic at each of the routing components.
2. The method of claim 1, wherein identifying a failure of any of
the optical components comprises applying, with the analytics
engine, the set of rules to determine a likelihood of a future
failure of any of the optical components.
3. The method of claim 2, wherein identifying the failure comprises
identifying the failure in response to determining that the
likelihood of failure for an individual one of the optical
components exceeds a threshold specified by the set of rules.
4. The method of claim 1, further comprising identifying the
failure in response to determining that a combined likelihood of
failure for a plurality of the optical components along a common
path through a network exceeds a threshold.
5. The method of claim 2, wherein the state information includes
one or more of power consumption, current draw, voltage levels or
operating temperature for the optical components of the optical
transport network.
6. The method of claim 1, wherein the packet-optical transport
devices comprises any of Re-configurable Optical Add Drop
Multiplexers (ROADMs), Photonic Cross Connects (PXCs), optical
cross-connects (OXCs), Dense Wavelength Division Multiplexing
equipment (DWDMs), amplifiers, transponders, and Optical
Termination Terminals (OTTs).
7. The method of claim 1, wherein configuring, with a routing
wavelength and spectrum assignment control module of the
controller, the packet-optical transport devices to operate at
particular wavelengths comprises: determining, for each of a
plurality of packet-optical transport devices interconnected to
form an optical transport system, a respective channel group size
specifying a number of optical channels to reserve for each of the
packet-optical transport devices from a total number of optical
channels supported by the optical transport system, wherein the
respective channel group size for each of the packet-optical
transport devices is determined based on a bandwidth requirement
for the respective packet-optical transport device; reserving, in
accordance with the determined channel group sizes, a set of
optical channels for each of the packet-optical transport devices
from an optical spectrum supported by the packet-optical transport
devices, each of the reserved optical channels having an
unspecified wavelength within the optical spectrum, each of the
sets of optical channels associated with a different portion of the
optical spectrum and having an spectral range that is based on the
channel group size determined for the respective packet-optical
transport device; and for each of the packet-optical transport
devices, assigning a respective wavelength from the optical
spectrum to one or more of the optical channels of the set of
optical channels reserved for the packet-optical transport device
to balance network traffic level associated with the packet-optical
transport device around a center of the portion of the optical
spectrum associated with the set of optical channels reserved for
the packet-optical transport device.
8. The method of claim 7, wherein assigning a respective wavelength
from the optical spectrum to one or more of the optical channels of
the set of optical channels reserved for the packet-optical
transport device comprises, for each of the packet-optical
transport devices: determining a center of the portion of the
optical spectrum reserved for the respective packet-optical
transport device; determining the number of optical channels in the
respective optical channels reserved for the packet-optical
transport device to which to assign a respective wavelength to
provide bandwidth that exceeds the bandwidth requirement associated
with the respective packet-optical transport device; and assigning,
for each of the packet-optical transport devices, respective
wavelength to the number of optical channels to balance the traffic
flows around the center of the respective portion of the optical
spectrum reserved for the packet-optical transport device.
9. The method of claim 1, wherein bandwidth requirement for each of
the packet-optical transport devices is based on current bandwidth
utilization for the respective packet-optical transport device.
10. The method of claim 1, wherein bandwidth requirement for each
of the packet-optical transport devices is based on a predicted
bandwidth utilization for the respective packet-optical transport
device.
11. An integrated network controller comprising: a message
processor that receives state information from optical components
of an optical transport system having a plurality of interconnected
packet-optical transport devices; an analytics engine that applies
a set of rules to identify a failure of any of the optical
components; a path computation element that, responsive to the
identified failure, computes at least one updated path for the
network traffic through a routing and switching network having a
plurality of interconnected layer three (L3) routing components and
layer two (L2) switching components for communicating packet-based
network traffic; a software defined networking (SDN) control module
that communicates updated routing information to the routing
components of the routing and switching network to control packet
flows through the routing and switching network in accordance with
the updated path; and a routing wavelength and spectrum assignment
control module that, in response to the updated routing
information, configures each of a plurality of packet-optical
transport devices to operate at particular wavelengths based on
bandwidth requirements for the network traffic for optically
transporting the network traffic between the routing and switching
components.
12. The integrated controller of claim 11, wherein the analytics
engine identifies the failure by applying the set of rules to
determine a likelihood of a future failure of any of the optical
components.
13. The integrated controller of claim 12, wherein the analytics
engine identifies the failure in response to determining that the
likelihood of failure for an individual one of the optical
components exceeds a threshold specified by the set of rules.
14. The integrated controller of claim 11, the analytics engine
identifies the failure in response to determining that a combined
likelihood of failure for a plurality of the optical components
along a common path through a network exceeds a threshold.
15. The integrated controller of claim 11, wherein the state
information includes one or more of power consumption, current
draw, voltage levels or operating temperature for the optical
components of the optical transport network.
16. The integrated controller of claim 11, wherein the
packet-optical transport devices comprises any of Re-configurable
Optical Add Drop Multiplexers (ROADMs), Photonic Cross Connects
(PXCs), optical cross-connects (OXCs), Dense Wavelength Division
Multiplexing equipment (DWDMs), amplifiers, transponders, and
Optical Termination Terminals (OTTs).
17. The integrated controller of claim 11, wherein the routing
wavelength and spectrum assignment control module of the controller
configures the packet-optical transport devices to operate at
particular wavelengths by: determining, for each of a plurality of
packet-optical transport devices interconnected to form an optical
transport system, a respective channel group size specifying a
number of optical channels to reserve for each of the
packet-optical transport devices from a total number of optical
channels supported by the optical transport system, wherein the
respective channel group size for each of the packet-optical
transport devices is determined based on a bandwidth requirement
for the respective packet-optical transport device; reserving, in
accordance with the determined channel group sizes, a set of
optical channels for each of the packet-optical transport devices
from an optical spectrum supported by the packet-optical transport
devices, each of the reserved optical channels having an
unspecified wavelength within the optical spectrum, each of the
sets of optical channels associated with a different portion of the
optical spectrum and having an spectral range that is based on the
channel group size determined for the respective packet-optical
transport device; and for each of the packet-optical transport
devices, assigning a respective wavelength from the optical
spectrum to one or more of the optical channels of the set of
optical channels reserved for the packet-optical transport device
to balance network traffic level associated with the packet-optical
transport device around a center of the portion of the optical
spectrum associated with the set of optical channels reserved for
the packet-optical transport device.
18. The integrated controller of claim 17, wherein the wavelength
and spectrum assignment module is configured to: determine a center
of the portion of the optical spectrum reserved for the respective
packet-optical transport device; determine the number of optical
channels in the respective optical channels reserved for the
packet-optical transport device to which to assign a respective
wavelength to provide bandwidth that exceeds the bandwidth
requirement associated with the respective packet-optical transport
device; and assign, for each of the packet-optical transport
devices, respective wavelength to the number of optical channels to
balance the traffic flows around the center of the respective
portion of the optical spectrum reserved for the packet-optical
transport device.
19. The integrated controller of claim 11, wherein bandwidth
requirement for each of the packet-optical transport devices is
based on current bandwidth utilization for the respective
packet-optical transport device.
20. The integrated controller of claim 11, wherein bandwidth
requirement for each of the packet-optical transport devices is
based on a predicted bandwidth utilization for the respective
packet-optical transport device.
Description
TECHNICAL FIELD
[0001] The disclosure relates to computer networks and, more
particularly, to optical networks.
BACKGROUND
[0002] Modern communication networks continue to grow at a rapid
pace in both geographical size (e.g., sites, racks, physical ports,
interconnects) and traffic volume (i.e., bandwidth requirements).
Moreover, communication networks are increasingly required to
support diverse types of traffic and higher-agility traffic
patterns.
[0003] To support these requirements, communication networks, such
as carrier networks, access networks, core networks, and the like,
utilize underlying optical transport systems for transporting,
multiplexing and switching communications through high-speed
optical fiber links. Many optical transport systems are migrating
toward utilizing entirely packet-based communications. That is,
optical transport systems for large-scale networks are
transitioning to packet-optimized optical transport networks,
referred to as Packet Optical Transport.
[0004] Packet-Optical Transport represents a convergence of
converging time-division multiplexing (TDM) and wave-division
multiplexing (WDM) technologies. As such, large-scale
packet-optical transport systems utilize a variety of components
including Re-configurable Optical Add Drop Multiplexers (ROADMs),
Photonic Cross Connects (PXCs), optical cross-connects (OXCs),
Dense Wavelength Division Multiplexing equipment (DWDMs),
amplifiers, transponders, Optical Termination Terminals (OTTs) and
other equipment.
SUMMARY
[0005] This disclosure describes techniques for providing
closed-loop control and predictive analytics in packet-optical
networks. For example, a network element, such as a centralized
controller, provides tightly-integrated, closed-loop control over
switching and routing services (e.g., IP/MPLS) and the underling
optical transport system of a communication network.
[0006] In one example implementation described herein, the
controller includes an analytics engine that applies predictable
analytics to real-time status information received from a
monitoring subsystem distributed throughout the underlying optical
transport system. Responsive to the status information, the
analytics engine applies a rule-based of policies and may
adaptively and proactively reroute communications within the
network. For example, the controller may provide integrated control
of routing and switching components to reroute packet flows within
the network with control components of the underlying optical
transport network with respect to transport of packet data through
the optical links and other equipment. The controller may, for
example, provide integrated control over allocation or utilization
of optical spectrum and wavelengths within the optical transport
system underlying the routing and switching services.
[0007] In one example, a method for wavelength and spectrum
assignment comprise determining, for each a plurality of
packet-optical transport devices interconnected to form an optical
transport system, a respective channel group size specifying a
number of optical channels to reserve for each of the
packet-optical transport devices from a total number of optical
channels for the optical transport system, wherein the respective
channel group size for each of the packet-optical transport devices
is determined based on a bandwidth requirement for the respective
packet-optical transport device. The method further comprises
reserving, in accordance with the each of the determined channel
group sizes, a set of optical channels for each of the
packet-optical transport devices from an optical spectrum supported
by the packet-optical transport devices, each of the reserved
optical channels having an unassigned wavelength, and each of the
sets of optical channels being associated with a different portion
of the optical spectrum and having an spectral range that is based
on the channel group size determined for the respective
packet-optical transport device. The method further comprises, for
each of the packet-optical transport devices, assigning a
respective wavelength from the optical spectrum to one or more of
the optical channels of the set of optical channels reserved for
the packet-optical transport device to balance network traffic
associated with the packet-optical transport device around a center
of the portion of the optical spectrum associated with the set of
optical channels reserved for the packet-optical transport device.
In additional examples, a network controller includes at least one
processor configured to perform the above described method.
[0008] In another example, an integrated controller for controlling
both the routing and switching network and the underlying optical
transport system is described. A system may comprising a routing
and switching network having a plurality of interconnected layer
three (L3) routing components and layer two (L2) switching
components for communicating packet-based network traffic, and a
plurality of packet-optical transport devices interconnected to
form an optical transport system and coupled to the routing and
switching system for optically transporting the network traffic
between the routing and switching components. A controller may
comprise a path computation element to compute paths for the
network traffic through the routing and switching network, a
software defined networking control module to communicate updated
routing information to the routing components of the routing and
switching network to control packet flows through the routing and
switching network in accordance with the computed paths, and a
routing wavelength and spectrum assignment control module to that
configures the packet-optical transport devices to operate at
particular wavelengths in response to the updated routing
information and bandwidth requirements for the network traffic.
[0009] In another example, a method comprises receiving, with an
integrated network controller, state information from a routing and
switching network having a plurality of interconnected layer three
(L3) routing components and layer two (L2) switching components for
communicating packet-based network traffic. The example method
includes computing, with a path computation element of the
controller, a plurality of paths for layer three (L3) packets
through the routing components, and communicating, with a software
defined network (SDN) control module of the controller, updated
routing information to the routing components to control packet
flows through the routing and switching network in accordance with
the computed paths. The example method further includes
configuring, with a routing wavelength and spectrum assignment
control module of the controller, the packet-optical transport
devices to operate at particular wavelengths in response to the
computed paths and bandwidth requirements for the network traffic
at the routers along the paths.
[0010] In another example, an integrated network controller
comprises a path computation element that computes paths for the
network traffic through a routing and switching network having a
plurality of interconnected layer three (L3) routing components and
layer two (L2) switching components for communicating packet-based
network traffic; a software defined networking (SDN) control module
that communicates updated routing information to the routing
components of the routing and switching network to control packet
flows through the routing and switching network in accordance with
the computed paths; and a routing wavelength and spectrum
assignment control module that configures each of a plurality of
packet-optical transport devices an optical transport system to
operate at particular wavelengths in response to the updated
routing information and bandwidth requirements for the network
traffic for optically transporting the network traffic between the
routing and switching components.
[0011] In additional examples, integrated network controller is
described having predictable analytics and failure avoidance in
packet-optical networks. An integrated network controller may
comprise: a message processor that receives state information from
optical components of an optical transport system having a
plurality of interconnected packet-optical transport devices; an
analytics engine that applies a set of rules to identify a failure
of any of the optical components; a path computation element that,
responsive to the identified failure, computes at least one updated
path for the network traffic through a routing and switching
network having a plurality of interconnected layer three (L3)
routing components and layer two (L2) switching components for
communicating packet-based network traffic; a software defined
networking (SDN) control module that communicates updated routing
information to the routing components of the routing and switching
network to control packet flows through the routing and switching
network in accordance with the updated path; and a routing
wavelength and spectrum assignment control module that, in response
to the updated routing information, configures each of a plurality
of packet-optical transport devices to operate at particular
wavelengths based on bandwidth requirements for the network traffic
for optically transporting the network traffic between the routing
and switching components.
[0012] An example method comprises: receiving, with an integrated
network controller, state information from optical components of an
optical transport system having a plurality of interconnected
packet-optical transport devices; applying, with an analytics
engine, a set of rules to identify a failure of any of the optical
components; computing, with a path computation element of the
controller and in response to identifying the failure, at least one
updated path through a routing and switching network having a
plurality of interconnected layer three (L3) routing components and
layer two (L2) switching components for communicating packet-based
network traffic; communicating, with a software defined network
(SDN) control module of the controller, updated routing information
to the routing components to control packet flows through the
routing and switching network in accordance with the updated path;
and responsive to the updated routing information, configuring,
with a routing wavelength and spectrum assignment control module of
the controller, the packet-optical transport devices to operate at
particular wavelengths based upon bandwidth requirements for the
network traffic at each of the routing components.
[0013] The details of one or more examples are set forth in the
accompanying drawings and the description below.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a block diagram illustrating an example network in
which one or more network devices employ the techniques of this
disclosure.
[0015] FIG. 2 is a block diagram illustrating an example network in
which a controller provides integrated control over allocation or
utilization of the optical spectrum and wavelengths utilized by
packet-optical transport devices in accordance with techniques
described herein.
[0016] FIG. 3 is a flow diagram illustrating example operation of a
centralized controller when allocating channels for nodes in a ring
topology and assigning wavelengths to the channels in the
respective nodes in accordance with the techniques described
herein.
[0017] FIG. 4 is a graph illustrating example wavelength assignment
in an optical transport system having N packet-optical transport
devices.
[0018] FIG. 5 is a block diagram illustrating an example
centralized controller network device that operates in accordance
with the techniques of this disclosure.
[0019] FIG. 6, for example is a graph that illustrates an example
expected relationship between current draw over time by an optical
amplifier and a probability of failure.
[0020] FIG. 7 is a block diagram illustrating an example
centralized controller 300 that operates in accordance with the
techniques of this disclosure.
DETAILED DESCRIPTION
[0021] FIG. 1 is a block diagram illustrating an example system 10
in which a network 12 includes one or more network devices that
employ the techniques of this disclosure. In this example, network
12 includes a routing/switching system 15 in which network elements
14A-14D ("network elements 14") control switching and routing of
packet flows. Examples of network elements 14 include layer three
(L3) routers and layer two (L2) switches that collective provide
routing/switching system 14.
[0022] Network elements 14 of routing/switching system 15 typically
provide L2/L3 traffic forwarding services, such as traffic
engineering via Multi-Protocol Label Switching traffic-engineered
(MPLS-TE) label switched paths (LSP), Virtual Local Area Network
(VLANs) and the like. Network elements 14 may communicate and
control traffic flows using a variety of traffic engineering
protocols, such as the Label Distribution Protocol (LDP) and the
Resource Reservation Protocol with Traffic Engineering extensions
(RSVP-TE). In some aspects, network elements 14 may be IP routers
that implement MPLS techniques and operate as label switching
routers (LSRs).
[0023] As further shown in FIG. 1, network 12 includes an
underlying optical transport system 16 for transporting,
multiplexing and switching packet-based communications through
high-speed optical fiber links. In the example of FIG. 1A,
packet-optical communication devices 18A-18D (collectively,
"packet-optical transport devices 18") are interconnected via
optical links 20 and control transmission of optical signals
carrying packet data along the links. In this way, optical
transport system provides a physical layer that physically
interconnects network elements 14 of routing/switching layer
15.
[0024] Packet-optical transport devices 18 may be, for example,
Re-configurable Optical Add-Drop Multiplexers (ROADMs), Photonic
Cross Connects (PCXs), Dense Wavelength Division Multiplexing
(DWDMs) or other devices that transmit, switch and/or multiplex
optical signals. Moreover, as shown in FIG. 1, optical transport
system 16 typically includes a number of other components 23, such
as amplifiers, transponders, Optical Transport Terminals (OTTs),
repeaters and other equipment for controlling transmission of
optical packet data along optical links 20. For simplicity, FIG. 1
illustrates only a few optical components 23, although large
optical transport systems may have significant numbers of such
devices that influence optical transmissions. Although described
with respect to only optical links 20, optical transport system 16
may include other types of physical links as well, such as Ethernet
PHY, Synchronous Optical Networking (SONET)/Synchronous Digital
Hierarchy (SDH), Optical Transport Networks (OTN) switches, Lambda,
or other Layer 2 data links that include packet transport
capability.
[0025] In some example, network 12 may be a service provider
network or metro carrier network that provides packet-based network
services for subscriber devices (not shown). Example subscriber
devices may be, for example, any of personal computers, laptop
computers or other types of computing device associated with
subscribers. Subscriber devices may comprise, for example, mobile
telephones, laptop or desktop computers having, e.g., a 3G, 4G or
5G wireless card, wireless-capable netbooks, video game devices,
pagers, smart phones, personal data assistants (PDAs) or the like.
Subscriber devices may run a variety of software applications, such
as word processing and other office support software, web browsing
software, software to support voice calls, video games,
videoconferencing, and email, among others.
[0026] In the example of FIG. 1, network 12 further includes a
controller 22 that provides tightly-integrated, closed-loop control
over both routing/switching system 15 and underling optical
transport system 16. As further described below, controller 22
receives real-time status information 25 from monitoring agents
distributed and installed within packet-optical transport devices
18 and optical components 23 of underlying optical transport system
16. Responsive to the status information, an analytics engine
within controller 22 applies a rule-based of policies and may
adaptively and proactively reroute communications within the
network.
[0027] In one example implementation, controller 22 provides
integrated control over both network elements 14 and packet-optical
transport devices 18 of underlying optical transport network 16
with respect to transport of packet data through the optical links
and other equipment. For example, controller 22 may not only
control path selection and traffic engineering operations of
routing/switching system 15 but may also, as described in detail
below, provide integrated control over allocation or utilization of
the optical spectrum and wavelengths utilized by each
packet-optical transport device 18 within optical transport system
16 that underlie the network elements of routing/switching system
15.
[0028] As further described below, in some example embodiments,
controller 22 applies real-time, predictable analytics to state
information (e.g., congestion levels) received from routing and
switching components of network 15 as well as state information
(e.g., current draw, power levels, operating temperature) from
packet-optical transport devices and other optical components of
underling optical transport system 16. Controller 22 applies
analytics to identify topology-changing events, including current
events and predicted future events. Responsive to identifying or
otherwise predicting such events, controller 22 applies integrated,
real-time control over both routing/switching system 15 and optical
transport system 16.
[0029] Application of analytics within integrated controller 22 may
be advantageous for many reasons, and may be particularly
beneficial in large networks that have become increasingly more
complex, virtualized and distributed. For example, as further
described, the closed-loop, tightly integrated control architecture
of controller 22 may provide more efficient, predictable network
behavior in complex networking environments involving the interplay
of multiple, layered systems. This disclosure describes techniques
for the verification of the network state, the prediction of
traffic demands, the prediction of failure or outages in networks,
and a closed-loop controller that provides integrated controller
over both routing/switching system 15 and optical transport system
16.
[0030] FIG. 2 is a block diagram illustrating an example network
system 40 in which controller 42 provides integrated control over
allocation or utilization of the optical spectrum and wavelengths
utilized by each packet-optical transport devices 44A-44H
(collectively, "44") of an underlying optical transport system in
accordance with techniques described herein. In this way, FIG. 2
may be viewed as a more detailed example of FIG. 1 in which
controller 42 represents controller 22 and packet-optical transport
devices 44 represent a ring topology for packet-optical transport
devices 18 of FIG. 1.
[0031] As shown in the example of FIG. 2, network system 40
includes a collection of packet-optical transport devices 44
arranged to form an optical transport system 46 having a ring
topology. As shown in FIG. 1, routers 48A, 48B operate to provide
packet-based network access services for customer networks 13A,
13B, respectively. In this example, optical transport system 46
operates to provide fast packet-based transport of communications
between customer networks 13, 15, respectively. Each customer
network 13, 15 may comprise a private network and may include local
area networks (LANs) or wide area networks (WANs) that comprise a
plurality of subscriber devices. Although described with respect to
customer networks, optical transport system 46 may be used to
provide optical connectivity between any type of packet-based
network, such as public networks, core networks, access networks
and the like.
[0032] FIG. 2 illustrates two bi-directional flows 50A, 50B that
ingress and egress at packet-optical transport devices 44A, 44E.
Flow 50A is referred to as a primary flow in that the flow
represents an allocation of wavelength and spectral bandwidth for
carrying optical communications around optical transport 46 between
packet-optical devices 44A and 44E via intermediate packet-optical
transport devices 44B, 44C and 44D. Flow 50B is referred to as a
backup flow in that the flow represents an allocation of wavelength
and spectral bandwidth that is reserved for carrying optical
communications around optical transport 46 between packet-optical
transport devices 44A and 44E in the event primary flow 50A cannot
be utilized. As shown, back flow 50B represents reserved
wavelengths and spectral bandwidth for carrying optical
communications around optical transport 46 between packet-optical
transport devices 44A and 44E via intermediate packet-optical
devices 44F, 44G and 44H.
[0033] As described herein, controller 42 implements real-time
control over packet-optical devices 44 to provide fine-grain
control over allocation and utilization of the optical spectrum and
bandwidth within optical transport system 46. The techniques
described herein provide high-speed, highly-scalable wavelength and
spectrum assignment highly suited for implementation within
centralized controller 42. Controller 42 may, for example, include
an analytics engine that applies rules to quickly and efficiently
determine wavelength and spectrum assignment at each of
packet-optical devices 44. As such, the techniques offer
predictable and reproducible behavior that is robust from network
and flow changes. Moreover, the techniques are particularly well
suited in a closed-loop arrangement where centralized controller 42
continuously controls wavelength and spectrum assignment by
applying analytics to status information 52 (e.g., status
information 25 of FIG. 1) from monitoring agents distributed and
installed within packet-optical transport devices 44 and optical
components of optical transport system 46.
[0034] In general, the techniques described herein as implemented
by controller 42 for wavelength and spectrum assignment may
systematically suppress or otherwise avoid adverse optical effects
that may otherwise be experienced by optical communication channels
between packet-optical devices 44. That is, there are many physical
effects that that can destroy or otherwise degrade these optical
communication channels, and the techniques applied by controller 42
for allocating portions of the spectrum and assigning wavelengths
may avoid or suppress such effects. Example effects include Four
Wave Mixing (FWM) and Self-Phase Modulation (SPM) that can lead to
optical signal degradation and can also impair neighbored channels.
Other physical non-linear optical effects that may be avoided or
mitigated by the techniques described herein include, an intra-band
Raman effect that pumps the "red" channels in the spectrum by the
"blue" channels. The attribute "red" refers to channels that are of
longer wavelength than the "blue" channels. The "blue" channels
serve as pump source for the "red" channel signals. If the "blue"
channels fall away, e.g. due to a fiber cut, equipment outage, the
red will not be pumped as much anymore and might not meet a
receiver window required by optical components of transport system
46.
[0035] In general, controller 42 dynamically controls wavelength
and spectrum assignment to suppress or generally avoid optical
effects that can degrade communication performance. For example, as
described in further detail below, controller 42 provides
closed-loop control over dynamic partitioning of the spectral range
of optical transport system into channel groups and assigned of the
groups to respective packet-optical transport devices 44. Moreover,
controller 42 controls assigns of individual wavelengths within
each channel group so as to balance channel utilization within the
channel group and also to optimize the spectral separation of the
channels within the channel group.
[0036] FIG. 3 is a flow diagram illustrating example operation of a
centralized controller (e.g., controller 22 of FIG. 1 or controller
42 of FIG. 2) when allocating channels for nodes in a ring topology
and assigning wavelengths to the channels in the respective nodes
in accordance with the techniques described herein. For purposes of
example, FIG. 3 is described with respect to controller 42 of FIG.
2. Moreover, as further described below including by reference to
FIG. 7, controller 42 is packet-aware, i.e., aware of packet data
units including layer three (L3) routing information, and
continuously applies the techniques described herein to map
higher-level network service requirements into underlying, physical
resources of optical transport system 46.
[0037] In general, the flow diagram of FIG. 3 represents a
closed-loop control process during which controller 22 monitors and
optimizes wavelength allocation among packet-optical transport
devices 44 based on monitored status information 52 received from
optical transport 46 and routing/switching elements, such as
routers 48A, 48B. Controller 42 may, for example, continuously
execute the control-loop illustrated in FIG. 3 to control
wavelength allocation within the optical transport system 46. As
additional examples, controller 42 may execute the control-loop
control so as to reallocate wavelength assignment in response to
actual or predicted events.
[0038] As illustrated in the example of FIG. 3, controller 42
initially learns, discovers or otherwise is configured with
information specifying the topology of optical transport system 46
as well as the optical capabilities of the system (101). For
example, controller 42 may be configured with or otherwise
determine the total spectral range supported by packet-optical
transport devices 44, a maximum number of optical channels that can
be utilize by optical transport system 46, a maximum number of
devices 44 and a minimum spectral distance.
[0039] In the example where each of packet-optical transport
devices 44 is a tunable or tunable and directionless ROADM,
controller 42 operates to distribute the desired maximum channels
so as to have at least a minimum spectral distance throughout the
total spectrum size. For example, optical transport system 46 may
comprises a ring of eight ROADMs supporting a total spectrum of the
size of at least 4800 GHz, and a controller 42 may control
wavelength allocation so as to maintain at least a minimum spectral
separation between channels of 50 GHz or 100 GHz in this example.
In many environments, the minimum spectral separate may be
specified to account for penalties and signal bandwidth.
[0040] When implementing the closed-loop control process of FIG. 2
to assign optical communication channels and allocate wavelength
assignments for each of packet-optical transport devices 4,
controller 42 utilizes status information 52 from routers 48 to
partition the spectral range to reserve groups (blocks) of
sequential optical channels the packet-optical transport devices
based on traffic demands reported by higher-level routing/switching
elements, such as routers 48A and 48B in the example of FIG. 2.
State information 52 from routers 48A, 48B provides an indication
of current bandwidth consumption based on current traffic flows,
e.g., traffic flows 50A, 50B in the example of FIG. 2, and/or may
provide an indicator of layer three (L3) congestion at each of the
routers.
[0041] In particular, controller 42 initially determines the number
of optical channels for each of packet-optical transport devices 44
based on the current bandwidth consumption reported by high-level
routers 48 (102). In this way, controller 42 determines the number
of optical channels, i.e., the group size, for each packet-optical
transport device based on current traffic flows experienced by the
respective packet-optical transport device. As other examples,
controller 42 may assign the number of optical channels to each
packet-optical transport device based on historical, current or
predicted levels of bandwidth, or combinations thereof, at each
respective packet-optical transport device 44. In this way,
controller 42 determines the number of channels to reserve for each
packet-optical transport device 44 from the overall number of
maximum channels supported by optical transport system 46 on a
pro-rata (i.e., weighted) basis based on demand for bandwidth at
each of the packet-optical transport devices. As further described
below, the terms optical communication channel and wavelength are
used differently in that an optical communication channel is a
logical construct representing a "unit" of the maximum number of
optical communication channel that can be allocated within the
spectral range supported by optical transport system 46 and, in
particular, may or may not have an assigned wavelength. In
contrast, a wavelength represents a specific location within the
spectrum at which an optical communication may be assigned for
communication.
[0042] After determining the number of optical channels to reserve
for each packet-optical transport device 44 from the maximum number
of channels, controller 42 assigns a specific set of channels (also
referred to as a "channel group") to each respective packet-optical
transport device until all of the maximum number of channels are
reserved (104).
[0043] As a simple example, controller 42 may determine that
optical transport system 46 supports a maximum of forty channels to
be allocated equally to the eight packet-optical transport devices
55 such that each packet-optical transport device is to be
allocated five channels. As further described below, controller 42
may designate the forty communication channels with identifiers
1-40 and may assign optical communications channels 1-5 to
packet-optical transport device 44A, channels 6-10 to
packet-optical transport device 44B, and so forth. In some
examples, the groups of channels assigned to packet-optical
transport device 44 may not be in sequential order, and the
channels within a given channel group may not necessarily be
adjacent in the spectral domain.
[0044] After controller 42 assigns a specific set of optical
communication channels to each packet-optical transport device 44,
controller 42 assigns the wavelengths to one or more optical
communication channels within each of the groups (106). That is,
for each packet-optical device 44, controller 22 assigns individual
wavelengths to the communication channel that are to be utilized by
the respective device, either for carrying primary flows or backup
flows. Any remaining optical communication channels of a channel
group may not necessarily be assigned respective wavelengths. That
is, in any of the channel groups, some of the optical communication
channels may be assigned respective wavelengths for primary or
backup data communications (e.g., current packet flows 50A, 50B)
while other channels of the groups may remain unutilized without
wavelength assignment. Moreover, for any given channel group,
controller 22 assigns the necessary wavelengths in that group to
establish to balance the utilized communication channel across the
portion of the spectrum associated with the channel group. In other
words, for any given channel group, controller 42 may assign the
wavelengths needed by that channel group in a manner that in
general balances the network traffic level around a center of the
spectral region associated with that channel group. In other words,
controller 42 controls allocation of wavelengths for a given
channel group so as to equally distribute network traffic
throughout the spectral region associated with the group and to
balance traffic around a "center of gravity" of a given
packet-optical transport device, where the "center of gravity" can
be viewed as the center communication channel within the set of
communication channels associated with a given packet-optical
transport device 44.
[0045] For example, if for a given channel group only a single
wavelength is to be assigned, the wavelength is assigned so as to
position the first channel in the middle of the group of channels.
For channel groups having an odd number of wavelengths to assign,
the remaining wavelengths are sequentially allocated around the
center wavelength so as to maintain the balance of network traffic
around the center channel within the channel group and to optimize
the spectral separation of the channels within the channel group.
For channel groups having an even number of wavelengths to assign,
pairs of wavelengths are assigned equidistant around the center
wavelength of the portion of the spectrum designated for the
channel group.
[0046] To illustrate, FIG. 4 is a graph illustrating example
wavelength assignment in an optical transport system having N
packet-optical transport devices ("nodes"). In this example,
NODE.sub.1, NODE.sub.2 and NODE.sub.3 are allocated channel groups
having three communication channels, NODE.sub.4 is allocated a
channel group having four communication channels and NODE.sub.N is
allocated a channel group having nine communication channels. For
NODE.sub.1, only a single wavelength is assigned and, therefore, is
assigned in the spectral portion associated with NODE.sub.1. For
NODE.sub.2, two wavelengths are assigned of the three optical
communication channels of the group. As such, the controller
assigns a pair of wavelengths equidistant from the center
wavelength of the spectral portion associated with NODE.sub.1,
thereby maintaining a balanced "weighting" with that portion of the
spectrum. Similarly, for NODE.sub.3, two wavelengths are assigned
of the three optical communication channels of the group. For
NODE.sub.4, the controller has a reserved a channel group having
four optical channels and has assigned wavelengths to only two of
the optical channels. In this example, a pair of wavelengths have
been assigned to the first and last channel of the four channels of
the group. Alternatively, the pair of wavelengths could have been
assigned to the second and third optical channels and a weighted
balance around the center wavelength of the spectral portion
associated with NODE.sub.4 would still have been maintained. For
NODE.sub.N, the controller has reserved a channel group having nine
optical communication channels and assigned wavelengths to the
first, third, fifth, seventh and ninth communication channels,
which indicates that NODE.sub.N may be experiencing, or is
predicted to experience, particularly heavy traffic flows relative
to the other nodes. In this way, as illustrated in FIG. 4, the
controller maintains balanced, intra-node distribution of assigned
wavelengths yet maintains a minimum, threshold spectral separation
between all individual optical communications channels for the
packet-optical transport devices.
[0047] Returning to the flowchart of FIG. 3, once controller 42 has
assigned the wavelengths to the communication channels, controller
42 outputs commands to packet-optical transport devices 44 to
configure the wavelengths utilized by each of the optical
interfaces of the devices (107).
[0048] After configuring packet-optical transport devices 44,
controller 42 monitors state information 52 reported by or
otherwise received from routers 48 and underlying components of
optical transport system 46. More specifically, controller 42
monitors state information 52, such as current network traffic
levels, power consumption, current draw, and the like, and applies
analytics to identify or predict topology-changing events (108).
For example, controller 42 may apply analytics to state information
52 to determine that one or more packet-optical transport devices
44 requires additional bandwidth. As another example, controller 42
may determine that, based on state information 52, one or more
optical components of optical transport system 46 is likely to or
has already failed and, as a result, traffic is to be routed around
the component, thereby increasing the traffic load on certain
packet-optical transport devices 44 while decreasing the traffic
load on others.
[0049] Responsive to such events, controller 42 first determines
whether the existing channel groups as previously allocated by the
controller are sufficient to handle the new bandwidth requirements
of each of packet-optical transport devices 44 (110). That is, for
any affected channel groups needing additional bandwidth,
controller 42 determines whether a sufficient number of
communication channels having unassigned wavelengths exist in the
groups. If so, controller 42 applies the process described above
(e.g., step 106 of FIG. 3) to assign one or more additional
wavelengths (112). At this time, controller 42 may reassign all of
the wavelengths in the affected channel groups and the
corresponding packet-optical transport devices according to the
process described above so as to maintain balanced wavelength
distribution throughout the channel groups.
[0050] If, however, controller 42 determines that there are an
insufficient number of open communication channels in the affected
communication groups (e.g., all communication channels of the group
have been assigned wavelengths), controller 42 may first determine
whether an incremental update to the channel group configuration
and wavelength assignment can be performed by at least temporarily
reassigning one or more unused communication channels from other
groups to the affected channel group (114). If so, controller 42
reassigns one or more communication channels from one or more other
channel groups to the channel groups need more bandwidth (116). At
this time, controller 42 applies the process described above (e.g.,
step 106 of FIG. 3) to newly assign all of the wavelengths in the
channel group having the increased number of communication channels
to maintain balanced wavelength distribution throughout the channel
group, and configures the corresponding packet-optical transport
device to begin forwarding optical communications in according to
the assigned wavelengths.
[0051] In some situations controller 42 may determine that an
incremental update to the channel configuration groups and
wavelength assignment is not appropriate (NO of 114). For example,
controller 42 may determine that there are no other open channels
in other packet-optical transport devices 44. In some examples,
such as events that would require significant changes to the
current channel group and wavelength assignments, controller 42 may
determine that it is more appropriate to re-initiate the
closed-loop control process so as to entirely recalculate the
channel communication groups and wavelength assignments (NO of
114). If so, controller 42 repeats the closed-loop process
described above, taking into account the detected topology-changing
events.
[0052] The following sections describe in further detail example
implementations of the closed-loop communication channels and
wavelength assignment operation performed by a controller, such as
controllers 22, 42, in accordance with the techniques described
herein. Table 1 lists notations and definitions that are used
throughout the following sections.
TABLE-US-00001 TABLE 1 Notation Description Maximum number of
wavelength channels N.sub.max Maximum number of Nodes Nodes.sub.max
Node identifier Node.sub.i Total traffic between Node.sub.i and
Node.sub.j T.sub.ij [Gb/s] Flow between Node.sub.i and Node.sub.j
with attributes A F.sub.ij.sup.a [Gb/s] Lamda between Node.sub.i
and Node.sub.j at wavelength K, Lamda.sub.i, j, k, l, s port L, and
shape S Total number of channels from node I to node J .sup.Tij
C-band of total spectral width C [THz] Spectral bandwidth of a
single channel c [THz] Spectral distance between channels d [THz]
Maximum channel number of DWDM system Ch.sub.max Group of channel
added/dropped at Node.sub.i Ch.sub.i Total number of channels
added/dropped at Site I #Ch.sub.i Minimum channel at Node.sub.i
Ch.sub.i, .sub.min Maximum channel at Node.sub.i Ch.sub.i, .sub.max
Minimum assigned wavelength at Node.sub.i n.sub.i, .sub.min Maximum
assigned wavelength at Node.sub.i n.sub.i, .sub.max Bandwidth of a
channel with spectrum S B.sub.s [GHz] Group of Reserved Channels at
Node.sub.i R.sub.i
[0053] Using this nomenclature, a relationship can be defined
between the total spectral width C and the spectral distance
between channels d as:
Ch.sub.max=C/d,
where Ch.sub.max is the maximum number of channels with a constant
or uniform spectrum.
[0054] The spectral bandwidth c for each, single channel can be
represented as:
C/c>Ch.sub.max.
Some optical transport systems may be implemented to allow for the
least amount of penalties across packet-optical devices due to
filter effects (e.g., bandwidth narrowing).
[0055] Moreover, the closed-loop control process of FIG. 3 can
represented as assigning one or more wavelengths from every node
N_i with i=1, . . . , N_max, wherein each node represents a
respective one of packet-optical transport devices 44.
[0056] As discussed above, the number of optical channels, i.e.,
the channel group size, may be determined for each node in a
weighted manner based on current or predicted traffic flows.
According to these expressions, in one example implementation, for
each node N_i, the total number of allocated channels #Ch.sub.i for
that node N_i may be determined based on a sum of all the flows
from that node N_i to the nearest edge side N_e in relation to the
sum of all flows from all the nodes and multiplied by the maximum
number of channels Ch_max. That is, the number of optical channels,
i.e., the channel group size, for each respective node may be
determined by the formula:
# Chi i = Roundup ( Bandwith required at Node i .SIGMA. x = 1 j
Bandwith required at Node x * Ch max ) . ##EQU00001##
The bandwidth requirements for a given flow may be selected as the
maximum value of a given flow over a configurable time period. The
shortest average time of configurable may, in some implementations,
be limited to a defined response time of the controller, i.e., the
time typically required by the controller to recompute and reassign
channel group assignments and wavelengths.
[0057] Reservation of channel groups R_i at each node N_i may be
expressed as a set of channel identifiers, which each channel group
represented by a unique channel group identifier. In one example,
the controller logically arranges the channel groups in a sorted
order based on total number of channels within each group. In some
examples, the controller arranges the channel groups in declining
order such that the channel group having the largest number of
channels is first in the order. In this example, the controller may
allocate the largest channel group to the red portion of the
optical spectrum, the second largest group adjacent to the first
and so on. This ordering of the groups may, for example, allow the
controller to help ensure that in case of a node or link failure
survival for this channel group is guaranteed. This survival of a
wavelength signal depends on many factors including but not limited
to response time of the amplifier power control, the power and
distribution of the wavelengths in the signal spectrum (as
wavelength-signals pump wavelength signals via the "in-band"
Raman-effect, the receiver windows and other effects specific to
the DWDM optical system. An example is the allocation of a band
with a lot of traffic into the "middle" of a spectrum to guarantee
the lowest potential influence of the Raman intra-band effect. A
variety of numbering schemes for individual channel numbers can be
used, such as the standardized channel numbering scheme proposed in
ITU-T G.694.1: "SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL
SYSTEMS AND NETWORKS," International Telecommunication Union (ITU),
2012, incorporated herein by reference, or any numbering scheme
with declining wavelength or increasing optical frequency.
[0058] Using this nomenclature, example implementation of
wavelength assignment within each channel group may be expressed
according to the following equations. For example, the center of
gravity (CG) of given channel group R_i may be calculated as:
C G = Rounddown ( Ch i , max - Ch i , min 2 ) , ##EQU00002##
[0059] where Ch.sub.i, max and Ch.sub.i, min are the highest and
lowest unique identifier, respectively, for the channels in the
channel group assigned to the node. In general, the controller may
apply techniques that consistently rounds up or down.
[0060] Within any given channel group, the separation distance (SD)
in terms of a number of channels separating the wavelengths to be
assigned in that channel group may be calculated as:
S D = Rounddown ( Ch x , max - Ch x , min k + 1 ) ,
##EQU00003##
where k equals the number of channels in the group that will have
an assigned wavelength in the given node. Like the center of
gravity formula, the controller may round up or down so long as the
controller rounds the function consistently.
[0061] For a channel group R_i, associated with a respective node
N_i, systematic wavelength assignment to the channels in the group
in a manner that maintains a balance around the center of gravity
CG may be expressed as an optimization of:
F ( n i , j ) = 1 .English Pound. Ch i .SIGMA. k = n i , min n i ,
max n i , k , ##EQU00004##
such that:
F ( n i , j ) - Ch i , max + Ch i , min 2 .about. 0 ,
##EQU00005##
where n.sub.i,j represents the wavelength to be selected at
wavelength j at site i. In situation where there are multiple
solutions to this model, the controller may determine which
solution to select by maximizing the separation distance between
the channels within the channel group, as described above.
[0062] Moreover, several example scenarios are now described to
illustrate the closed-loop channel group allocation and wavelength
assignment control process.
Example 1
[0063] In a first example scenario, consider an example network in
which the optical transport system has eight packet-optical
transport devices (referred to as Node.sub.1-Node.sub.8 where
Nodes.sub.max=8). For purposes of this example, consider the
following assumptions: [0064] maximum number of optical
communication channels is 80 (N.sub.max=80), [0065] total bandwidth
B per optical channel is 100 Gb/s, [0066] determined demand
(current or predicted) for bandwidth for Node.sub.1,
Node.sub.2,
[0067] Node.sub.4, Node.sub.5, Node.sub.6, and Node.sub.8 is 10
Gb/s per node, [0068] initial demand for bandwidth for Node.sub.3
and Node.sub.7 is 20 Gb/s per node, and [0069] Node.sub.1 is the
only edge packet-optical transport device 44 such that Node.sub.1
is the sole entrance and exit point, and [0070] No channel(s) will
be reserved as backup flows.
[0071] Table 2 illustrates an example resultant traffic matrix T_ij
with i=1 . . . 8 and j=1 . . . 8., where i represents the sending
node and j represents the receiving node. In Table 2, units are
shown in Gigabits per seconds.
TABLE-US-00002 TABLE 2 Total express Total at site Total Node local
(counter- express at T_ij 1 2 3 4 5 6 7 8 add clock) site
(clockwise) 1 10 10 20 10 10 10 20 10 10 0 90 2 10 0 0 0 0 0 0 0 10
10 70 3 20 0 0 0 0 0 0 0 20 20 60 4 10 0 0 0 0 0 0 0 10 40 50 5 10
0 0 0 0 0 0 0 10 50 40 6 10 0 0 0 0 0 0 0 10 60 20 7 20 0 0 0 0 0 0
0 20 70 10 8 10 0 0 0 0 0 0 0 10 90 0 Total 100 10 20 10 10 10 20
10 100
[0072] In this example, the controller applies the closed-loop
channel allocation and wavelength techniques described herein first
determine the total number of optical channels to reserve for each
node, the results of which are shown in the column 3 of Table 3.
Next, the controller assigns the channel groups to each node,
resulting in the channel groups listed in column 4 of Table 3.
[0073] Since in this example, only one of the 100 Gb/s optical
channels need be utilized per node without any backup flows being
reserved, controller 42 assigns the wavelength to the middle
channel in each group of channels. Taking Node.sub.3 as an example,
the maximum channel (Ch.sub.x,max) assigned to Node.sub.3 is
channel 16 and the minimum channel (Ch.sub.x,max) assigned to
Node.sub.3 is channel 1. The center of gravity for the channel
group is determined as described above to be channel 8. In this
way, the controller assigns wavelengths are for each node
Node.sub.x as shown in the fifth column of Table 3.
TABLE-US-00003 TABLE 3 Initial Wavelength Bandwidth # Channels
Channels Assigned to Node.sub.i Requirement Reserved Assigned
(R.sub.i) Channel(s) 1 10 Gb/s 8 R.sub.1 = 33-40 36 2 10 Gb/s 8
R.sub.2 = 41-48 44 3 20 Gb/s 16 R.sub.3 = 1-16 8 4 10 Gb/s 8
R.sub.4 = 49-56 52 5 10 Gb/s 8 R.sub.5 = 57-64 60 6 10 Gb/s 8
R.sub.6 = 65-72 68 7 20 Gb/s 16 R.sub.7 = 17-32 24 8 10 Gb/s 8
R.sub.8 = 73-80 76
Example 2
[0074] In a second example scenario, assume the same network
configuration as the prior example but that network traffic has
grown in a linear fashion for all eight nodes (to ten times the
original bandwidth requirements). Thus, for purposes of this
example, consider the following assumptions: [0075] maximum number
of optical communication channels is 80 (N.sub.max=80), [0076]
total bandwidth B per optical channel is 100 Gb/s, [0077]
determined demand (current or predicted) for bandwidth for
Node.sub.1, Node.sub.2, Node.sub.4, Node.sub.5, Node.sub.6, and
Node.sub.8 is 100 Gb/s per node, [0078] determined demand (current
or predicted) for bandwidth for Node.sub.3 and Node.sub.7 is 200
Gb/s per node, and [0079] Node.sub.1 is the only edge
packet-optical transport device 44 such that Node.sub.1 is the sole
entrance and exit point, and [0080] No channel(s) will be reserved
as backup flows.
[0081] Table 4 illustrates an example resultant traffic matrix T_ij
with i=1 . . . 8 and j=1 . . . 8. for this example.
TABLE-US-00004 TABLE 4 Total express Total at site Total Node local
(counter- express at T_ij 1 2 3 4 5 6 7 8 add clock) site
(clockwise) 1 100 100 200 100 100 100 200 100 100 0 900 2 100 0 0 0
0 0 0 0 100 100 700 3 200 0 0 0 0 0 0 0 200 200 600 4 100 0 0 0 0 0
0 0 100 400 500 5 100 0 0 0 0 0 0 0 100 500 400 6 100 0 0 0 0 0 0 0
100 600 200 7 200 0 0 0 0 0 0 0 200 700 100 8 100 0 0 0 0 0 0 0 100
900 0 Total 1000 100 200 100 100 100 200 100 1000
[0082] Due to the linear growth for all nodes in this example, the
relative bandwidth between the nodes is the same as the prior
example. Thus, the number of channels reserved per node and the
specific group of channels assigned to each node does not change.
Since the total bandwidth per channel is 100 Gb/s, Node.sub.1,
Node.sub.2, Node.sub.4, Node.sub.5, Node.sub.6, and Node.sub.8 can
still accommodate the entire bandwidth via a single optical
communication channel. However, Node.sub.3 and Node.sub.7 cannot
accommodate the entire bandwidth in a single optical communication
channel because the total bandwidth used by Node.sub.3 and
Node.sub.7 exceeds the capacity of a single optical communication
channel. As such, when implementing the control process described
herein, the controller updates that allocation and wavelength
scheme for the network to assign additional wavelengths to
communication channels reserved for Node.sub.3 and Node.sub.7.
[0083] For example, the controller may assign maintain the initial
wavelengths assigned to Node.sub.3 and Node.sub.7 so as to minimize
disruption and of communication flows. As such, the controller may
assign not one but two additional wavelengths within the channel
groups associated with Node.sub.3 and Node.sub.7, thereby
maintaining a balance around the initial wavelengths already
assigned within the group. As such, for Node.sub.3, the controller
may assign wavelengths to communication channel 4 and communication
channel 12 around the initial communication channel 8 currently in
use. Other examples exist for Node.sub.3, such as communication
channels 3, 13 or 2, 14, which differ only is spectral spacing. The
controller may be programmed to select the particular pair of
wavelengths to assign based on the boundaries and optical link
control qualities of the individual packet-optical transport
system. The controller similarly assigns an additional pair of
wavelengths within the channel group allocated to Node.sub.7, such
as communication channels 20, 28 around the initial communication
channel 24 currently in use. Results of this example are reflected
in Table 5.
TABLE-US-00005 Initial Wavelength Bandwidth # Channels Channels
Assigned to Node.sub.i Requirement Reserved Assigned (R.sub.i)
Channel(s) 1 100 Gb/s 8 R.sub.1 = 33-40 36 2 100 Gb/s 8 R.sub.2 =
41-48 44 3 200 Gb/s 16 R.sub.3 = 1-16 4, 8, 12 4 100 Gb/s 8 R.sub.4
= 49-56 52 5 100 Gb/s 8 R.sub.5 = 57-64 60 6 100 Gb/s 8 R.sub.6 =
65-72 68 7 200 Gb/s 16 R.sub.7 = 17-32 20, 24, 28 8 100 Gb/s 8
R.sub.8 = 73-80 76
[0084] Alternatively, when assigning additional wavelengths to
Node.sub.3 and Node.sub.7, the controller may elect to rebalance
the wavelengths with the respective communication channels. For
example, since only two wavelengths are required by Node.sub.3 and
Node.sub.7 in this example, the controller may eliminate use of the
wavelength positioned at the center of gravity within each channel
group and assign the wavelengths in a balanced manner. For example,
for Node.sub.3, the controller may assign wavelengths to
communication channel 4 and communication channel 12 and remove the
initial wavelength assignment to communication channel 8, thereby
maintaining balanced wavelength assignment within the group yet
increasing spectral separation. In selecting between the two
approaches, the controller may maintain at least a threshold amount
of excess bandwidth (e.g., at least 20% or at least 10 GB/s, etc.)
relative to the determined bandwidth requirements for the Node. In
this example, since both Node.sub.3 and Node.sub.7 have, or are
predicted to have, bandwidth requirements of 100 Gb/s, which
matches the bandwidth capacity of a single optical communication
channel, the controller may elect to allocate three wavelengths
within the channel group, as described above.
[0085] This example illustrates another advantage of the integrated
controller described herein, such as the controller further
described below with respect to FIG. 7. As the overall control
system has network-services awareness, the controller can act to
roll-over the traffic from one wavelength to another while the
initial wavelength can be moved. This allows a re-setting of the
wavelength assignment within the optical transport network while
not interrupting the packet-based traffic flow through the
routing/switching network at all. The control architecture
described herein having packet-awareness and closed loop control
over the optical transport system in combination with analytics can
flawlessly and efficiently deliver a Make-before-break (MBB)
solution in this manner.
Example 3
[0086] In a third example scenario, assume the same network
configuration as the prior examples but that network traffic has
now grown in a non-linear fashion for all eight nodes from the
state presented in example. Thus, for purposes of this example,
consider the following assumptions: [0087] maximum number of
optical communication channels is 80 (N.sub.max=80), [0088] total
bandwidth B per optical channel is 100 Gb/s, [0089] determined
demand (current or predicted) for bandwidth for Node.sub.1,
Node.sub.4, Node.sub.5, and Node.sub.8 is 100 Gb/s per node, [0090]
determined demand (current or predicted) for bandwidth for
Node.sub.2 and Node.sub.6, is 1700 Gb/s per node, [0091] determined
demand (current or predicted) for bandwidth for Node.sub.3 and
Node.sub.7, is 1700 Gb/s per node, and [0092] Node.sub.1 is the
only edge packet-optical transport device 44 such that Node.sub.1
is the sole entrance and exit point, and [0093] No channel(s) will
be reserved as backup flows.
[0094] Table 4 illustrates an example resultant traffic matrix T_ij
with i=1 . . . 8 and j=1 . . . 8. for this example. Columns shown
the accumulative bandwidth requirements around the ring have been
dropped for simplicity.
TABLE-US-00006 Total Node local T_ij 1 2 3 4 5 6 7 8 add 1 100 200
1700 100 100 200 1700 100 4000 2 200 0 0 0 0 0 0 0 200 3 1700 0 0 0
0 0 0 0 1700 4 100 0 0 0 0 0 0 0 100 5 100 0 0 0 0 0 0 0 100 6 200
0 0 0 0 0 0 0 200 7 1700 0 0 0 0 0 0 0 1700 8 100 0 0 0 0 0 0 0 100
Total 4200 200 1700 100 100 200 1700 100 4000
[0095] Responsive to detecting the non-linear changes to bandwidth
requirements, the controller determines that the current allocation
of communication channels is insufficient to support the bandwidth
requirements for at least Node.sub.3 and Node.sub.7. As such, the
controller determines whether an incremental update to the channel
group configuration and wavelength assignment can be performed by
at least temporarily reassigning one or more unused communication
channels from other groups to the affected channel group (see block
114 of FIG. 3).
[0096] In this way, the controller may elect to allocate bandwidth
from a packet-optical transport device (node) with excess capacity
to an over-extended packet-optical transport device (i.e., where
demand for bandwidth exceeds capacity (e.g., Node.sub.3 and
Node.sub.7)). An incremental update may be beneficial, in that the
controller may be able to allocate bandwidth without reprogramming
the entire packet-optical transport system. For example, in an
incremental update, the controller may identify any candidate nodes
with open or unused channels, i.e., currently without wavelength
assignment, that can be re-assigned to the over-extended node.
Controller 42 may select which candidate node to re-allocate
bandwidth from based on which node has the most open channels 24,
which candidate node has the least network traffic, which candidate
node has experienced the least growth in bandwidth demand, or other
factors.
[0097] In this example scenario, the controller may determine that
Node.sub.1, Node.sub.4, Node.sub.5, and Node.sub.8 are candidate
nodes for re-assigning communication channels because each are tied
for having the most number of unused channels (seven) and each
currently have the lowest bandwidth requirements (100 Gb/s). In
some examples, controller 42 may re-assign a subset of the needed
channels from each of the candidate nodes, thereby minimizing any
future impact on any given node.
[0098] Alternatively, the controller may determine that an
incremental update to the channel configuration groups and
wavelength assignment is not appropriate (see NO branch of block
114 of FIG. 3). For example, the controller may be programmed
configuration data specifying a maximum threshold number of
communication channels to reassign without re-initiate the
closed-loop control process so as to entirely recalculate the
channel communication groups and wavelength assignments. Assuming,
for purposes of example, the threshold number is configured to one
(1), the controller in this example would determine that at least
two communication channels (one for each of Node.sub.3 and
Node.sub.7) are needed and, therefore, bypass the incremental
update and instead perform a new channel group allocation and
wavelength assignment for all nodes.
[0099] FIG. 5 illustrates a portion of a network 200 in which
controller 202 provides integrated control packet-optical transport
devices 204A, 204B of an underlying optical transport system in
accordance with techniques described herein. FIG. 5 may be viewed
as detailed portion of the examples of FIG. 1 or FIG. 2, and
controller 202 may represents controllers 22, 42 described
above.
[0100] In the example of FIG. 5, controller 202 provides
centralized, closed-loop control and management of routers 206A,
206B, and packet-optical transport devices 204A, 204B of the
underlying packet-optical transport system. Controller 202
continuously controls wavelength and spectrum assignment within
packet-optical transport devices by applying analytics to status
information 210 from monitoring agents distributed and installed
within routers 206 as well as packet-optical transport devices 204
and optical components 208 of the underlying optical transport
system.
[0101] As described herein, controller 202 processes status
information 210 with an internal analytics engine and, using
higher-level topology information, responds to the status
information to map packets into network 200 including routers 206
and transport resources associated with packet-optical transport
devices 204. For example, in one example implementation, controller
210 provides closed-loop environment having a real-time analytical
engine that predicts outages based on status information 210. The
analytics engine may predicts events and, for events for which a
likelihood of occurrence that exceeds defined thresholds,
reconfigures the router and switching (L3/L2) devices and/or
reconfigures the spectral allocation and wavelength assignments of
the underlying analog optical transport devices. In this way,
controller 202 may combine features of advanced L3/L2 software
defined networking (SDN) controller with an analog control
architecture for controlling the underlying analog optical
transport system, where the real-time control for both of these
systems is driven by predictable analytics. As such, the analytical
engine of controller 202 is responsive to real-time status
information 210 and allows controller 202 to optimize the routing,
wavelength and spectrum assignment (RWSA) implemented by the
combination of the routing/switching system and the underlying
optical transport system.
[0102] For example, packet-optical devices 204A, 204B typically
include advanced optical transmit and receive interfaces having
multiple components, any of which may be monitored by an internal
monitoring agent that determines and communicates respective status
information 210B, 210F to controller 202. Packet-optical devices
204A, 204B typically may, for example, include optical mixers,
optical multiplexers, optical amplifiers and other components that
communicate optical signals, any of which may be monitored by
internal monitoring agents of the packet-optical devices that
determine and communicate respective status information 210B, 210F
to controller 202. Moreover, in the example of FIG. 5, optical
transport system of FIG. 5 includes a plurality of optical
components 208A-208C for transmission of optical packet data along
an optical link between packet optical devices 204A, 204B. Example
optical components 208 include amplifiers, transponders, OTTs,
repeaters and other equipment. Each of optical components 208A-208C
provide respective status information 210C, 201D and 210 E.
[0103] Further, routers 206A, 206B may include advanced optical
transmit and receive interfaces having multiple components for
converting between digital and optical packet data. For example,
routers 206A, 206B may have optical transmitters having lasers,
local oscillators, optical modulators, optical mixers, amplifiers,
modems and other components. Routers 206A, 206B may similarly have
optical receivers having timing recovery units, equalizers, analog
to digital converters and other components. Any of these components
of routers 206A, 206B may be monitored by internal monitoring
agents that determine and communicate respective status information
210A, 210G to controller 202.
[0104] In one example, one or more of status information 210A-210G
take the form of communications that convey operating parameters of
one or more components, such as power consumption, current draw,
voltage levels, operating temperature and other parameters measured
from electrical or optical components within the respective
devices. Analytical device-specific agents may be used to predict
the outage based on measurements of the behavior of an individual
device, and these agents can be associated/adapted to their special
properties.
[0105] The analytical engine of controller 202 applies rules based
on either the current measurements or based on a time-series of
current and past measurements and computes probabilities of
failures or other compromising events based on the operating
conditions measured at the various components, thereby predicting
future outages or compromised states associated with network
resources within network 200. Based on the analytics, a path
computation module of controller 200 high-level traffic engineering
and topology information associated with the routing and switching
system (e.g, routers 206 in this example) to proactively redirect
traffic in the event one or more components are likely to fail or
otherwise result in a topology-changing event.
[0106] In one example, status information 210C, 210D and 210E
respective convey current power consumption of amplifiers within
optical components 208A, 208B and 208C, respectively. Controller
202 may poll monitoring agents within optical components 208 and
request status information 210, or the monitoring agents may send
the status information periodically or upon determining that an
operating parameter is approaching a configured trigger within an
operating range. In any event, the analytics engine within
controller 202 applies rules that specify triggers for proactively
changing the topology of network 200.
[0107] FIG. 6, for example is a graph that illustrates an example
expected relationship between current draw over time by an optical
amplifier and a probability of failure. As illustrated, it may be
expected that current draw 220 for a given model of amplifier
increases (e.g., linearly) over time so as to maintain a constant
transmit power. Moreover, a trigger 224 may be defined as an
indicator that the expected operating life of the amplifier is
within a threshold probability 222 of failure. As such, the
analytics engine of controller 202 may be configured with a rule
that implements the example expected relationship illustrated in
FIG. 6. That is, an administrator may create, for example, a rule
that triggers a topology changing action in the event current draw
from an underlying optical component 208 exceeds trigger 222.
Responsive to detecting that such a condition exists, the path
computation element of controller 202 may proactively reroute
traffic around the link that has been predicted to fail.
[0108] The example described and illustrated works not only for
optical amplifiers, but any laser-based amplification or just
laser-based signaling component e.g. local oscillator,
laser-signal, optical pre- and post-amplifiers, optical booster,
semiconductor optical amplifier (SOA) and similar optical
components.
[0109] As another example, an agent may signal the status of the
device solely based on its age. This may gain be beneficial as
optical devices undergo commoditization and simplification for
capital/expenditure (CapEx) reasons and, as such, life-time
specifications for optical components may be fairly limited.
[0110] Moreover, in some examples measurement of the functional
parameters described above may be combined with the reported age of
a device. Prediction for failure for devices that operating at
maximum of specification may be defined within the rules to have a
much lower device life-time than devices not consistently operated
at its maximum specification. For example, based on the measurable
environmental conditions such as temperature and humidity, the
impact of mechanical vibrations with respect to life-time of the
device can be predicted by the analytical engine.
[0111] In another example, any of the monitoring agents may locally
apply rules, such as the example rule discussed above, to operating
parameters of the local electronic components. In this example, any
of status information 210A-210G may take the form of communications
that convey results of the rules. For example, any of status
information 210 may convey results of one or more locally applied
rules, such as: (1) STATUS OK indicating that all parameters are
below trigger points, (2) FAILURE PENDING indicating that a
corresponding rule resulted in a threshold be triggered, and (3)
FAILED indicating that a component has actually failed. The status
information (2) FAILURE PENDING might, in some example, include a
prediction of when the outage of the component may be expected to
occur, an indicator that the determined probability of an outage is
exceeding a pre-configurable threshold or even the determined
probability itself.
[0112] In some examples, controller 202 may apply complex rules
that are based on status information received from multiple
underlying components. For example, rules may be defined based on
an overall probability of failure for multiple devices or
components associated with the same optical link or
routing/switching location. As one example, controller 202 may
apply a complex rule to status information 210C-210E as all of the
respective optical components 208A-208C are associated with a
common optical link between packet-optical transport devices 204A,
204B. Although none of optical components 208 may individually
trigger the rule discussed above so as to cause a topology change,
a second rule may be defined to trigger a topology change in the
event that any two or more of the optical components are experience
current draw above a second, lower threshold 226. Other complex
rules may easily be defined that combine thresholds and different
operating parameters, such as current draw and operating
temperature, from any combination of optical components of the
underlying packet-optical transport system. Moreover, any of the
rules may trigger topology changing actions within controller 202,
including path selection and control by controller 202 of the
routing/switching components and/or wavelength and spectrum
assignment within packet-optical transport devices. In this way,
controller 202 provides centralized, closed-loop control and
management of both systems, including routers 206A, 206B of the
routing/switching system and packet-optical transport devices 204A,
204B of the underlying packet-optical transport system.
[0113] FIG. 7 is a block diagram illustrating an example
centralized controller 300 that operates in accordance with the
techniques of this disclosure. Controller 300 may be implemented as
a separate physical device or virtual device and for example, and
may represent an example instance of controllers 22, 42, 202
described herein.
[0114] Controller 300 includes a control unit 302 coupled to one or
more network interfaces 304 to exchange packets with other network
devices by links 306. Control unit 302 include one or more
processors (not shown in FIG. 7) that execute software
instructions, such as those used to define a software or computer
program, stored to a computer-readable storage medium, such as
non-transitory computer-readable mediums including a storage device
(e.g., a disk drive, or an optical drive) or a memory (such as
Flash memory or random access memory (RAM)) or any other type of
volatile or non-volatile memory, that stores instructions to cause
the one or more processors to perform the techniques described
herein. Alternatively or additionally, control unit 302 may
comprise dedicated hardware, such as one or more integrated
circuits, one or more Application Specific Integrated Circuits
(ASICs), one or more Application Specific Special Processors
(ASSPs), one or more Field Programmable Gate Arrays (FPGAs), or any
combination of one or more of the foregoing examples of dedicated
hardware, for performing the techniques described herein.
[0115] As described herein, controller 300 includes both an RWSA
(Routing Wavelength and Spectrum Assignment) control module 324 and
an SDN control module 325 that cooperate to provide integrated
closed-loop control over both routing/switching system and an
underling optical transport system within a network. In the example
of FIG. 1, control unit 302 provides an operating environment for
path computation element 310, topology discover module 312, message
processor 320, analytics engine 322, RWSA control module 324, SDN
control module 325 and network services application 326. In one
example, these modules may be implemented as one or more processes
within control unit 302 or may execute on one or more virtual
machines of one or more servers communicatively coupled to
controller 300. That is, while generally illustrated and described
as executing on a single controller 300, aspects of these modules
may be delegated to other computing devices in a distributed
manner.
[0116] Message processor 320 receives real-time status information
from monitoring agents distributed and installed within
packet-optical transport devices and optical components of
underlying optical transport system. Message processor 320
processes the status information and updates network state database
332. Responsive to the status information, analytics engine 322
applies rule-based of policies 334 and outputs messages to RWSA
control module 324 and SDN control module 325, thereby adaptively
and proactively reroute communications within the network.
[0117] More specifically, response to applications of policies 334
by analytics engine 322, SDN control module 325 may invoke path
computation element 310 to compute one or more new paths through a
network. SDN control module 325 configures routers and/or switches
within the network to adaptively and proactively reroutes
communications within the network in accordance with the computed
paths. SDN control module 325 may implement, for instance, a Path
Computation Element Communication Protocol (PCEP) or a
software-defined networking (SDN) protocol, such as the OpenFlow
protocol, to provide and direct the nodes to install forwarding
information to their respective data planes. Additional details
regarding OpenFlow are found in "OpenFlow Switch Specification
version 1.1.0", OpenFlow Consortium, February 2011, which is
incorporated by reference herein. Additional details regarding PCEP
may be found in "Path Computation Element (PCE) Communication
Protocol (PCEP)," Network Working Group, Request for Comment 5440,
March 2009, the entire contents of each of which being incorporated
by reference herein. In addition, or alternatively, SDN control
module 325 may configure forwarding tables within routers by other
interface types, such as a Simple Network Management Protocol
(SNMP) interface, path computation element protocol (PCEP)
interface, a Device Management Interface (DMI), a CLI, Interface to
the Routing System (IRS), or any other node configuration
interface.
[0118] In addition to the higher-level control provided by SDN
control module 324, RWSA control module 324 cooperatively and
responsively updates routing wavelength and spectrum assignments
(RWSA) based on any traffic flow changes engineered by path
computation element 310. That is, based on any updated changes to
current and/or predicted traffic flow due to SDN control module
324, RWSA control module 324 controls and rebalances wavelength and
spectrum assignment of the underlying packet-optical transport
system.
[0119] TE discovery module 312 represents one or more routing
protocol process that maintains TE database 330. For example, TE
discover module 312 may execute a routing protocol to receive
routing protocol advertisements, such as Open Shortest Path First
(OSPF) or Intermediate System-to-Intermediate System (IS-IS) link
state advertisements (LSAs) or Border Gateway Protocol (BGP) UPDATE
messages. In some instances, topology indication module 64 may
alternatively, or additionally, execute a topology discovery
mechanism such as an interface for an Application-Layer Traffic
Optimization (ALTO) service.
[0120] Traffic engineering (TE) database 330 stores topology
information, received by topology discovery module 312, for a
network that constitutes a path computation domain for controller
300. TED 330 may include one or more link-state databases (LSDBs),
where link and node data is received in routing protocol
advertisements, received from a topology server, and/or discovered
by link-layer entities such as an overlay controller and then
provided to topology discover module 312. In some instances, an
operator may configure traffic engineering or other topology
information within TED 72 via a client interface.
[0121] Network services applications 326 represent one or more
processes that provide services to clients of a service provider
network. Network services applications 326 may provide, for
instance, include Voice-over-IP (VoIP), Video-on-Demand (VOD), bulk
transport, walled/open garden, IP Mobility Subsystem (IMS) and
other mobility services, and Internet services to clients of the
service provider network. Networks services applications 326 may
require services provided by controller 300, such as node
management, session management, and policy enforcement. Each of
network services applications 326 may include client interface,
such as a command line interface (CLI), graphical user interface
(GUI) or application programming interface (API), by which one or
more client applications request high-level network services.
[0122] The control architecture in FIG. 7 may be applied to address
other very severe challenges in networks. For example, the
architecture may help overcome challenges with the availability of
devices and the health of the network connections, as described,
but also help overcome some of the restrictions induced by the
optical transport network itself. One of restrictions that may be
overcome is rolling-over wavelengths, that might be blocking, by
way of the controller architecture. The system may help overcome
limitation due to the optical filter structure, DWDM bandwidth
limitation in one path or physical limitation of the ROADM and PXC
architecture. The underlying transport infrastructure may become,
at least to some extent, virtualized for the end-to-end path.
[0123] For example, in general, fixed ROADM's are ROADM's with a
pre-defined and fixed wavelength for a dedicated port. In tunable
ROADM's, on the other side for a given port, any wavelength can be
set, provided it is not already allocated. The system proposed
herein including controller 300 and the RWSA control module 324 and
analytics engine 322, as depicted in FIG. 7, may deliver a seamless
and tunable solution for the network services (L2/L3 service
applied to packet flows). A network service (e.g. L2/L3VPN) between
two points may be mapped into the fixed ROADM infrastructure and
automatically, depending on the demands and service attributes,
adjusted. As such, the systems described herein do not merely
virtualize the transport layer of the network but rather enhance
the capabilities due to a higher-level view of the controller. In
this way, a stand-alone physical fixed ROADM a virtual tunable
ROADM is created from the underlying, stand-alone physical fixed
ROADM system using the integrated controller. The example also
applies for a fixed PXC and a tunable PXC.
[0124] As another example, instead of a single optical transport
(e.g, DWDM) system, there may be several DWDM systems deployed that
are connected to one or more routing/switching systems, all of
which are monitored and controlled in accordance with the
techniques described herein. The controller is able to place
network service demands optimally into the transport networks. This
results, from a network service perspective, in a seamless
end-to-end network. The system creates out of two physical DWDM
systems, a single virtualized one underlying optical transport
network that is centrally managed, e.g., with respect to routing
wavelength and spectrum assignment, based on current or predicted
demand for higher level (L7-L2) services. The controller may
optimize load balancing between the DWDM networks, availability and
reliability considerations by ideal packet flow placement and ideal
wavelength placements into the underlying optical transport
infrastructure.
[0125] As another example, a ROADM or PXC might be fully or
partially eliminated and replaced by routers/switches that are
directly connected with a DWDM transport system. ROADM's would not
physically exist but the system as such could steer the network
traffic in a way that is equivalent to a virtual tunable &
directionless ROADM or PXC. Also a ROADM and point-to-point DWDM
system might be deployed physically at the same location but some
of the DWDM wavelength might be terminated directly at the router
w/o the ROADM. Also for this example the system could steer the
network traffic in a way that is equivalent to a virtual tunable
& directionless ROADM or PXC.
[0126] As another example, an optical transport system may
physically include a single OTT or ROADM filter structure but
include multiple, different line systems with different
amplification systems. This physically divided network, e.g., two
different optical amplifier chains, may utilize the same DWDM
system, i.e., because the filter systems are the same. This type of
network may also be virtualized by the control architecture
described herein into a single logical optical transport system to
which closed-loop control can be applied. For such a system, the
controller may optimize load balancing between the underlying
optical transport DWDM networks and availability and reliability
considerations by selecting and configuring ideal packet flow
placement within the routing/switching system and ideal wavelength
placements within the underlying optical transport system.
[0127] As another example, in Ingress Policy-determined multi-layer
routing, packet flows are combined at the edge and LSP's are
formed. A path is setup throughout the network for each LSP and
used to transport packets mapped to that LSP. This architecture has
several challenges. First, as the underlying transport network
capacities and redundancy is typically not known, path setup may
not be optimal. Second, as the bandwidth of the ingress flows can
change widely, the initially setup path many no longer be optimal
due to blocking effects. Third, as the ingress flows attributes
change, the routing of the network may need to change, e.g. the
need for specific resiliency, latency might be changing as well.
The integrated described herein (e.g., controller 300 in FIG. 7) is
able to determine the packaging of the flows into LSP to fit the
ingress demands to the routing perfectly, inclusive of all the
network resources. In summary for every specific network service
class, with its own policy, attributes, the virtualized environment
controlled by the controller can be optimized. This results into a
virtual "slicing" of the network.
[0128] As another example, a best effort High Speed Internet (HSI)
traffic flow might be connected with best effort not-protected
underlying transport equipment. Network policy and shaping that is
known to the controller can then place the network service by
assigning only one wavelength with no redundancy.
[0129] As another example, a network service with high resiliency,
guaranteed bandwidth requirements may need to be placed. The
controller described herein may automatically build multiple
redundancies on the transport layers (e.g. creating several
redundant wavelengths) and on the router & switched layer (e.g.
port redundancy), and is able to analyze the availability
prediction and match it with the network service requirements.
[0130] The techniques described in this disclosure may be
implemented, at least in part, in hardware, software, firmware or
any combination thereof. For example, various aspects of the
described techniques may be implemented within one or more
processors, including one or more microprocessors, digital signal
processors (DSPs), application specific integrated circuits
(ASICs), field programmable gate arrays (FPGAs), or any other
equivalent integrated or discrete logic circuitry, as well as any
combinations of such components. The term "processor" or
"processing circuitry" may generally refer to any of the foregoing
logic circuitry, alone or in combination with other logic
circuitry, or any other equivalent circuitry. A control unit
comprising hardware may also perform one or more of the techniques
of this disclosure.
[0131] Such hardware, software, and firmware may be implemented
within the same device or within separate devices to support the
various operations and functions described in this disclosure. In
addition, any of the described units, modules or components may be
implemented together or separately as discrete but interoperable
logic devices. Depiction of different features as modules or units
is intended to highlight different functional aspects and does not
necessarily imply that such modules or units must be realized by
separate hardware or software components. Rather, functionality
associated with one or more modules or units may be performed by
separate hardware or software components, or integrated within
common or separate hardware or software components.
[0132] The techniques described in this disclosure may also be
embodied or encoded in a computer-readable medium, such as a
computer-readable storage medium, containing instructions.
Instructions embedded or encoded in a computer-readable medium may
cause a programmable processor, or other processor, to perform the
method, e.g., when the instructions are executed. Computer-readable
media may include non-transitory computer-readable storage media
and transient communication media. Computer readable storage media,
which is tangible and non-transitory, may include random access
memory (RAM), read only memory (ROM), programmable read only memory
(PROM), erasable programmable read only memory (EPROM),
electronically erasable programmable read only memory (EEPROM),
flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette,
magnetic media, optical media, or other computer-readable storage
media. It should be understood that the term "computer-readable
storage media" refers to physical storage media, and not signals,
carrier waves, or other transient media.
[0133] Various embodiments of the invention have been described.
These and other embodiments are within the scope of the following
claims.
* * * * *