U.S. patent application number 11/934262 was filed with the patent office on 2008-04-17 for controller based call control for atm svc signaling.
This patent application is currently assigned to AT&T LABS, INC.. Invention is credited to Philip CUNETTO, James M. DOHERTY, Chien-Chun LU, Timothy Paul SCHROEDER.
Application Number | 20080089345 11/934262 |
Document ID | / |
Family ID | 26918204 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080089345 |
Kind Code |
A1 |
CUNETTO; Philip ; et
al. |
April 17, 2008 |
CONTROLLER BASED CALL CONTROL FOR ATM SVC SIGNALING
Abstract
A method for controlling circuit switched communications using
switched virtual circuit (SVC) signaling includes receiving, at a
service controller over a signaling channel from an originating end
system, a connection setup signal requesting a switched virtual
circuit connection. A proxy setup signal enabling setup of the
switched virtual circuit connection in response to the connection
setup signal is sent over a proxy signaling channel separate from
the signaling channel.
Inventors: |
CUNETTO; Philip; (Austin,
TX) ; DOHERTY; James M.; (Georgetown, TX) ;
LU; Chien-Chun; (Austin, TX) ; SCHROEDER; Timothy
Paul; (Austin, TX) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
AT&T LABS, INC.
Austin
TX
78759
|
Family ID: |
26918204 |
Appl. No.: |
11/934262 |
Filed: |
November 2, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
09923351 |
Aug 8, 2001 |
7307993 |
|
|
11934262 |
Nov 2, 2007 |
|
|
|
60223862 |
Aug 8, 2000 |
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Current U.S.
Class: |
370/396 |
Current CPC
Class: |
H04L 2012/563 20130101;
H04Q 11/0478 20130101 |
Class at
Publication: |
370/396 |
International
Class: |
H04L 12/28 20060101
H04L012/28 |
Claims
1. A method for controlling circuit switched communications using
switched virtual circuit (SVC) signaling, the method comprising:
receiving, at a service controller over a signaling channel from an
originating end system, a connection setup signal requesting a
switched virtual circuit connection; and sending, over a proxy
signaling channel separate from the signaling channel, a proxy
setup signal enabling setup of the switched virtual circuit
connection in response to the connection setup signal.
2. The method according to claim 1, wherein the connection setup
signal is routed from the originating end system to the service
controller through a switch.
3. The method according to claim 2, wherein the switch comprises an
asynchronous transfer mode switch.
4. The method according to claim 2, wherein the switch comprises an
edge switch.
5. The method according to claim 1, wherein the switched virtual
circuit connection includes a connection through the switch.
6. The method according to claim 1, wherein the end system
comprises an addressable communications device provided with a
terminating communications address.
7. The method according to claim 1, wherein the signaling channel
comprises a permanent virtual circuit (PVC) connection.
8. The method according to claim 1, wherein the signaling channel
comprises a dynamically established signaling channel.
9. The method according to claim 1, wherein the signaling channel
comprises a multiplexed virtual channel.
10. The method according to claim 1, further comprising:
determining at least one service feature authorized for the
originating end system based on which the proxy setup signal
enabling setup of the switched virtual circuit is sent.
11. The method according to claim 1, further comprising:
determining at least one service feature authorized for a
terminating end system, based on which the proxy setup signal
enabling setup of the switched virtual circuit is sent.
12. A service controller for controlling circuit switched
communications using switched virtual circuit (SVC) signaling, the
service controller comprising: a receiver that receives, over a
signaling channel from an originating end system, a connection
setup signal requesting a switched virtual circuit connection; and
a sender that sends, over a proxy signaling channel separate from
the signaling channel, a proxy setup signal enabling setup of the
switched virtual circuit connection in response to the connection
setup signal.
13. The service controller according to claim 12, wherein the
service controller communicates with a switched virtual circuit
server to check features authorized for the originating end
system.
14. The service controller according to claim 12, wherein the
service controller communicates with a switched virtual circuit
server to check features authorized for a terminating end
system.
15. The service controller according to claim 12, wherein the
originating end system comprises an asynchronous transfer mode
switched virtual circuit signaling device.
16. The service controller according to claim 12, wherein the
connection setup signal comprises user to network interface (UNI)
signaling.
17. The service controller according to claim 12, wherein the proxy
setup signal comprises switched virtual circuit (SVC) connection
protocol compliant signaling.
18. The service controller according to claim 12, wherein the
service controller is configured to receive connection setup
signals from a plurality of originating end systems.
19. The service controller according to claim 12, wherein the
service controller is configured to send proxy setup signals to a
plurality of switches.
20. A computer readable medium that stores a computer program for
controlling circuit switched communications using switched virtual
circuit (SVC) signaling, the computer readable medium comprising: a
receiving code segment that receives, at a service controller over
a signaling channel from an originating end system, a connection
setup signal requesting a switched virtual circuit connection; and
a sending code segment that sends, over a proxy signaling channel
separate from the signaling channel, a proxy setup signal enabling
setup of the switched virtual circuit connection in response to the
connection setup signal.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
pending U.S. patent application Ser. No. 09/923,351, filed on Aug.
8, 2001, which claims the benefit of U.S. Provisional Patent
Application No. 60/223,862, filed Aug. 8, 2000, entitled
"Controller-Based Call Control for ATM SVC Signaling", in the names
of CUNETTO et al., the disclosures of which are expressly
incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to telecommunications. More
particularly, the present invention relates to service signaling
being processed in a controller adjunct to a switch.
[0004] 2. Acronyms
[0005] The written description provided herein contains acronyms
which refer to various network services, components and techniques,
as well as features relating to the present invention. Although
some of these acronyms are known, use of these acronyms is not
strictly standardized in the art. For purposes of the written
description herein, the acronyms are defined as follows:
Advanced Intelligent Network (AIN)
Asymmetric Digital Subscriber Line (ADSL)
Asynchronous Transfer Mode (ATM)
Broadband Services Network (BBSN)
Customer Premise Equipment (CPE)
Digital Subscriber Line (DSL)
FTTC (Fiber To The Curb)
Integrated Services Digital Network (ISDN)
Internet Protocol (IP)
Inter Network Interface (INI)
Interworking Function (IWF)
ISDN User Part (ISUP)
Lightweight Directory Access Protocol (LDAP)
Local Area Network (LAN)
Operations, Administration, & Maintenance (OA&M)
Permanent Virtual Circuit (PVC)
Personal Computer (PC)
Public Switched Telephone Network (PSTN)
Private Network to Network Interface (PNNI)
Proxy Signaling Agent (PSA)
Quality of Service (QoS)
Signaling System 7 (SS7)
Switched Virtual Circuit (SVC)
User to Network Interface (UNI)
Virtual Channel Identifier (VCI)
Virtual Network (VN)
Virtual Path (VP)
Virtual Path Identifier (VPI)
Virtual Path Connection Identifier (VPCI)
[0006] 3. Discussion of Background Information
[0007] High bandwidth ATM systems are in many cases replacing
narrowband systems. As part of the migration to high bandwidth
technologies, the efficient implementation of middleware services
such as session management, messaging, directory, accounting,
security, nomadicity, and database access are becoming problematic.
In most ATM implementations, service related tasks are handled by
transport layer systems using call models and triggers applied
directly to transport layer devices, hindering the use and
management of high bandwidth services.
[0008] A call model provides a template for the flow of service
logic. Service definitions that do not fit the pre-defined flow are
difficult, if not impossible, to implement in an intelligent
network layer as is needed by broadband networks due in large part
to the limited functionality of call models utilizing only
triggers. To overcome some of the call model limitations, service
nodes have arisen to provide services that do not fit current call
models. But service nodes also have limitations when applied to
broadband networks.
[0009] Alternative designs which entail signaling to a transport
element, and then have the transport element "trigger" or signal to
a network element for policy management decisions have enabled more
service functionality; however, triggering is very costly due to
additional software development costs and low functioning
standardization. Moreover, such standardization typically requires
additional signaling schemes between transport elements and network
elements and modification of the flow of processing in the
transport elements. The result being that transport elements
eventually become a bottleneck in the deployment of new services
because they must be updated with the new protocols and "call
model" modifications as each new service is rolled out. In such an
environment, the likelihood increases that switches from different
vendors do not implement the same call model or protocol options
and additional costs are incurred to handle different
interfaces.
[0010] Because of the growing network demands of broadband
networks, a new approach is needed that is of relatively low cost
and more flexible than today's call model and trigger systems. An
approach that separates service control from transport elements and
allows service signaling directed to broadband network control
elements would help satisfy these needs.
[0011] An example where a new approach to handling service
signaling is needed is in the implementation of the Internet
Protocol (IP). In various forms of IP traffic, service signaling,
policy implementation, and data transport are handled together, and
typically by the same device such as a router or firewall.
Processing solely in the transport device complicates implementing
a secure network over a wide geographic area since policy data must
be coordinated across a large number of devices. Due to this
scalability issue, a further need exists to separate the service
signaling from data in IP data packets so that policy requests may
be more centrally processed.
[0012] Another example where a new approach to handling service
signaling is needed is in the implementation of Virtual Networks
(VNs). A VN includes a group of service users that have specific
policies and customized network behavior associated with the group.
The policies and behaviors can relate to performance and Quality of
Service (QoS) guarantees, routing procedures, addressing, billing,
privacy, and to which network services the user has access.
Additionally, since issues regarding network resources in a shared
use mode versus dedicated use mode are not essential to the concept
of a VN, a VN provider may choose any number of ways to implement a
VN capability. Due to the diversity of services a VN provider may
implement, a need for a new service signal processing architecture
exists to efficiently accommodate VN services.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The present invention is further described in the detailed
description which follows, with reference to the noted plurality of
drawings by way of non-limiting examples of exemplary embodiments
of the present invention, in which like reference numerals
represent similar parts throughout the several views of the
drawings, and wherein:
[0014] FIG. 1 shows an exemplary architecture of a system that
processes service signaling in a controller separate from a
switching element, according to an aspect of the present
invention;
[0015] FIG. 2 shows an exemplary architecture including originating
and terminating end systems, originating and terminating edge
switches, and originating and terminating service controllers,
according to an aspect of the present invention;
[0016] FIG. 3 is a call flow diagram showing an exemplary SVC call
establishment, according to an aspect of the present invention;
[0017] FIG. 4 shows an exemplary service signaling topology using
multiple homing of switches to service controllers, according to an
aspect of the present invention;
[0018] FIG. 5 shows an exemplary service signaling topology in
which a single service controller controls multiple switches,
according to an aspect of the present invention; and
[0019] FIG. 6 shows an exemplary signaling channel configuration,
according to an aspect of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0020] The particulars shown herein are by way of example and for
purposes of illustrative discussion of the embodiments of the
present invention only and are presented in the cause of providing
what is believed to be the most useful and readily understood
description of the principles and conceptual aspects of the present
invention. In this regard, no attempt is made to show structural
details of the present invention in more detail than is necessary
for the fundamental understanding of the present invention, the
description taken with the drawings making apparent to those
skilled in the art how the several forms of the present invention
may be embodied in practice.
[0021] According to an aspect of the present invention there is
provided a system for processing ATM SVC signaling which includes
an ATM switch connected to an end system, a controller, a signaling
channel, and a proxy signaling channel. The ATM switch receives an
ATM SVC connection request from the end system. The controller
connected to the ATM switch controls the processing of the ATM SVC
connection request. The signaling channel terminates at the end
system and at the controller with the signaling channel being
routed through the ATM switch. The ATM switch receives signaling,
associated with the request, over the signaling channel and the ATM
switch forwards the signaling to the controller via the signaling
channel. The proxy signaling channel terminates at the controller
and at the ATM switch. The controller communicates proxy signals
over the proxy signaling channel to instruct the switch to set up
an SVC connection in response to the request received over the
signaling channel.
[0022] In another aspect of the invention, the signaling channel
may be a PVC. The system may, additionally, contain a policy
database communicating with the controller, the policy database
storing policy information that is queried by the controller in
response to the ATM SVC connection request. In yet another aspect,
the ATM SVC connection may carry UNI signaling. Further, the end
system may be an ATM SVC signaling device. Moreover, the proxy
signal may be SVC connection protocol compliant signaling. In
another aspect of the invention, a second controller may become
connected with the ATM switch when the controller becomes
unavailable. In yet another aspect of the invention, the ATM switch
may further be multiple switches, each ATM switch being connected
to the controller. Further, the system may intercept IP packets and
retrieves IP signaling for processing by the controller to support
Internet Protocol in another aspect of the invention. The system
may further include an IWF gateway that converts non-system
signaling into ATM signaling. Furthermore, the system may have a
second controller that becomes connected with the ATM switch when
the controller becomes unavailable.
[0023] According to an alternate embodiment, the processing of ATM
SVC signaling includes receiving by a first controller a first
connection setup signal from a first end system, the first
connection setup signal being routed through a first ATM switch.
The method also includes sending a first proxy signal to the first
ATM switch in order to set up an SVC connection across an ATM
network in response to the received first connection setup
signal.
[0024] The process may further include checking a policy by the
first controller in response to the received first connection setup
signal and determining whether to grant a connection request.
Furthermore, the process may include sending a second proxy signal
from a second ATM switch to a second controller, and sending a
second connection setup signal from the second controller to a
second end system through the second switch. Moreover, the process
may further include receiving by the second controller a first
connection connect signal from the second end system; the
connection connect signal being routed through the second ATM
switch. The process may also include sending a third proxy signal
from the second controller to the second ATM switch. The process,
moreover, may include sending a second connection connect signal
from the second ATM switch to the first ATM switch and sending a
fourth proxy signal from the first ATM switch to the first
controller. The process, further, may include sending a third
connection connect signal from the first controller to the first
end system, the third connection connect signal being routed
through the first ATM switch.
[0025] In another aspect of the invention, the process may further
include receiving via a PVC the first connection connect signal.
The first proxy signal may be SVC connection protocol compliant
signaling. The process, moreover, may include intercepting IP
packets and retrieving IP signaling for processing by the first
controller to support the Internet Protocol. The process,
furthermore, may include converting non-system signaling into ATM
signaling.
[0026] The present invention relates to processing of service
signaling. Service signaling is defined as any signaling that
represents a request for a network service. The network service may
be a service at any "level"--a transport service or a higher layer
service (e.g., end user or content service). Service signaling
originates from service subscribing entities, such as end users,
enterprise networks, or peer networks. Peer networks are considered
service subscribing entities because, by virtue of interconnecting
with them, a service signaling subnetwork grants the peer networks
the right to place service requests into the service signaling
subnetwork. By this definition, subscribers (individuals and
enterprises) and peer networks use service signaling to request
services, and a telecommunications carrier network uses service
signaling to request services in peer networks or in third party
networks (networks from which services are obtained that are not
implemented by the telecommunications carrier, or networks through
which a connection must be completed).
[0027] Service signaling is subject to authorization and other
service policy checks before granting the requested service,
because service signaling represents a request for a network
service. In general, the policy checks entail a combination of the
subscriber's service features and limits, and access rights and
limits. These policies may be applied in the context of a virtual
network where features and limits are determined not just by the
subscribers involved but by the virtual networks to which the
subscribers belongs.
[0028] According to the present invention, all service signaling
travels to a network element when the service signaling is
processed. By signaling to a network element, policy management can
be applied, user profiles accessed to determine disposition of the
request, and all similar functions can be performed before any
actions are taken to set up connections or dedicate network
resources to the user request. And if this approach is taken for
all access types, the problems of insistent transport element
behavior in handling the user's service request are avoided.
[0029] The following description is primarily in terms of a
specific form of service signaling: requests for asynchronous
transfer mode (ATM) switched virtual circuit (SVC) connections.
Although the description is provided with respect to a specific
type of service signaling for the sake of explanation, it is
recognized that the present invention applies to any kind of
service signaling. Thus, the present invention is not intended to
be limited to ATM SVC requests.
[0030] The present invention also relates to control signaling.
Control signaling includes any form of signaling, typically within
the network, that controls one network element from another network
element. Control signaling is not considered a service invocation;
it is the signaling required to implement distributed control of
network element functions.
[0031] UNI Proxy is an example of a control protocol. Another
example is a protocol between an information service implemented in
a session controller and a content server. In general, network
resources such as content servers, bridging devices, etc., provide
control signaling interfaces to service controllers that implement
services in accordance with instructions received from these
network resources.
[0032] Referring now to FIG. 1, an embodiment of the invention is
described. An end system (e.g., PC, workstation, LAN device, phone,
etc.) 12 has a signaling channel 14 to a service controller 13
(also referred to as a session controller), via a switch 11, such
as an ATM switch. The service controller 13 processes all service
signaling received from the end system 12 and also includes a proxy
signaling channel 16 connected to the ATM switch 11. In one
embodiment, the signaling channel 14 is "nailed up". That is, the
signaling channel may be a permanent virtual circuit (PVC)
connection.
[0033] An exemplary ATM switch 11 is the MainStreetXpress 36170
Multiservices Platform available from Alcatel of France. An
exemplary session controller 13 operates on a Sun Netra Server
available from Sun Microsystems, Inc., of Palo Alto, Calif.
[0034] When the end system 12 has requested an ATM SVC connection,
the service controller 13 establishes the circuit 15 by signaling
to the switch 11 over proxy signaling channel 16. That is,
according to the present invention even though the end system 12
has the capability to signal, the signaling stream is redirected to
the controller 13, which proxy signals for the end system 12.
Placing signal processing in a component 13 separate from the
switching element 11, allows the network provider to apply policy
to the connection handling in the adjacent controller 13.
[0035] Additional advantages of the present invention include the
timely evolution of services and transport capabilities due to
independent upgrade capability, causing upgrades to become less
costly. Additionally, costs lessen for service level Operations,
Administration, and Management (OA&M) because fewer network
elements and fewer network element types must have service level
OA&M interfaces. Moreover, service functions can ride the
dropping price/performance ratio of computing platforms because the
components in the system can be non-proprietary and the same
service can be provided to all subscribers, regardless of access
type. Furthermore, nomadic users can access their services and
profiles no matter where or how they access the network.
[0036] Unlike the narrowband intelligent network design, the
switching and access elements generally do not invoke triggers or
functions from the service signaling subnetwork. Rather, the user's
signaling travels directly to the service controller 13 via a
nailed up signaling channel 14 through the access nodes and
switches 11, or via a dynamically established signaling channel
14.
[0037] The signaling protocol used depends on which network service
the user is invoking. The service controller 13 acts on the service
request accessing the user profile, applying policy management,
etc. and then signals the switching components 11 to establish the
connections required by the service. If the service controller 13,
due to a policy management decision, for example, rejects the
service request, the end-system 12 is notified and no connection
control commands are issued by the service signal controller 13 to
the switching element 11. The policy profile may be stored in the
service controller 13 or alternatively may be stored in a separate
database (not shown) that can be accessed by multiple service
controllers 13.
[0038] In native ATM signaling protocols such as UNI 3.1/4.0, a
virtual channel on the subscriber's physical interface is
configured as the logical signaling channel for the protocol.
Additional protocols like an n-way multi-channel connection
protocol may be assigned a dedicated signaling virtual channel from
the space of reserved virtual channels, or the protocols may be
multiplexed with other protocols on existing signaling virtual
channel. In the latter case, a protocol discriminator byte already
defined in message headers could be used to differentiate
multiplexed protocols. Thus, the signaling subnetwork is designed
to work with both multiplexed and dedicated signaling virtual
channels.
[0039] In native ATM services, services are characterized by the
signaling mechanism and transport encapsulation. The International
Telecommunications Union (ITU) and the ATM Forum have defined a
native ATM service signaling mechanism that uses a dedicated
virtual channel between an end system 12 and the network for the
signaling channel 14. Thus, it is preferred to employ the defined
service signaling mechanism for ATM SVC services. More
specifically, to support standard end systems 12 and standard end
system software that use ATM UNI signaling, the end systems 12
should use VP=0/VC=5 as the signaling channel. The present
invention is also flexible enough, however, to handle signaling
channels for additional service protocols. Similarly, even for ATM
SVC requests, alternate channels could be employed if desired.
[0040] In one embodiment of the invention, the service controller
13 processes UNI 3.1/4.0 signaling for the ATM SVC service. As
shown in FIG. 2, UNI signals are sent transparently from the user's
end system 12 through the user's edge switch 11 to the service
controller 13 that terminates the signaling protocol. After policy
management, address translation, and other such service signaling
functions are applied, the service controller 13 signals via the
proxy signaling channel 16 using, for example UNI proxy 4.0, to
establish the requested and authorized SVC 15. As described above,
UNI from the end system 12 is terminated in the service controller
13, not the edge switch 11 that the end system 12 is physically
homed on.
[0041] In UNI signaling on an SVC setup request from the
originating end system 12 to a terminating end system 26, not only
is the originating end system 12 originating UNI signaling proxied
for, but so is the end system's 26 terminating UNI signaling
(assuming the terminating end system 26 is an SVC service
subscriber on the network). Although terminating end system's 26
signaling is not required to be proxied for, proxying terminating
signaling is preferred. For example, in the case of a connection to
an end system in an adjoining network that can be reached via
alternate egress points, proxying terminating signaling allows
instantiating terminal signal agents in the appropriate service
controller, regardless of the selected egress point.
[0042] As additional service interfaces are provided by the
network, other signaling protocols from the end system 12 will be
handled in the same manner. The service controller 13, for example,
will terminate the service signaling protocol, and, just as in the
UNI case, session policy management is applied and the service
controller 13 instructs the switch 11 to set up the necessary
connections. Because a session may entail connections that do not
traverse the originating edge switch 11, the session controller 13
has the ability to signal, via a network internal control protocol,
to other session controllers 22 to set up connections between end
systems 12, 26.
[0043] According to an embodiment of the present invention, proxy
signaling is UNI 4.0, as described above with reference to FIG. 2.
UNI 4.0 proxy signaling 28 is full proxy signaling. Thus, all UNI
messages flow to the service controller 13, not just a selected
subset. Proxy signaling occurs between the service controller 13
and a software function controlling the UNI in the edge switch 11.
This allows the edge switch to forward signaling to a well known
VCI/VP rather than acting on the signaling request.
[0044] UNI 4.0 has specified a form of proxy signaling in which a
proxy signaling agent (PSA) can UNI signal for the end system 12.
The proxy signaling agent function is one of the functions of the
service controller 13. By definition, proxy signaling implies that
when an edge switch 11 has a UNI message destined for an end system
12 on a particular port and Virtual Path (VP), the edge switch 11
sends that message on the signaling channel 14 instead, with an
identifier of the original port and VP. Similarly, when a UNI
message is received on the interface 14 marked with a particular
port and VP, the switch 11 treats that message as though it was
received from the end system 12 on that port and VP. The port and
VP identifier are encoded using a virtual path connection
identifier (VPCI) information element in UNI setup and call
proceeding messages, in conjunction with a table, stored in the
switch 11 and service controller 13, that relates VPCI values to
port and VP identifier values.
[0045] Proxy signaling as defined in UNI 4.0 is sufficient as a
control signaling protocol between the edge switch 11 and the
service controller 13. As edge switches are built larger, however,
the standard eight bit port identifiers may be too small to support
all of the proxied ports. Thus, the standard can be modified or
multiple proxy interfaces to a single switch can be used.
[0046] According to another embodiment, PNNI or AINI is used as a
protocol rather than UNI, for example when signaling to another
network occurs. In this embodiment, there is a need for tunneling
and proxy signaling for PNNI or AINI on connection requests coming
into the network. PNNI and AIM are service protocols that are used
in requesting a network service and are also terminated in the
service controller.
[0047] Referring again to FIG. 2, an example is described in which
data originates in end system 26 and is routed through switch 25
and switch 11 and ultimately terminated at end system 12, which in
this example is an edge device of another network. When routing
connection requests to an adjoining network, PNNI or AINI proxy
data can be used. PNNI or AINI control signals are tunneled from
controller 22 via switching 25, 11 and terminated at the service
controller 13. PNNI or AINI proxy control signals are then
transferred between the service controller 13 and the edge device
12.
[0048] In this example, a control entity is instantiated in the
service controller 13 of the egress edge switch 11 for this
connection. The receipt of the proxied setup message in the service
controller 13 can serve as the control signal that causes the
instantiation. In the case when the connecting network is a UNI
network, PNNI control information is transferred between edge
switch 25 and edge switch 11. As in the embodiment described above,
UNI proxy information is communicated between service controller 22
and edge switch 25 and UNI 3.1/4.0 is communicated between end
system 26 and service controller 22 through edge switch 25.
[0049] FIG. 3 shows an exemplary call flow for an SVC call
establishment. Initially, an SVC call is initiated by a calling
party (SVC service customer) 12 sending a UNI 3.1/4.0 setup request
to the service controller 13 via the edge switch 11 at step 51. The
SVC service controller 13 then applies policy checks for both the
calling and called party ends of the call at step 52. In general,
the policy checks could entail a combination of the subscribers'
service features and limits, and access rights and limits.
[0050] Once the policy checks have affirmed the connection is to
continue, the SVC service controller 13 then sends a UNI 4.0 proxy
setup request to the ATM edge switch 11 in step 53. The ATM edge
switch 11 then sends a call proceeding signal to the SVC service
controller 13 with an allocated VPI A/VCI B setting in step 54. The
ATM edge switch 11 then sends a PNNI setup signal to an ATM core
switch 524 in step 55.
[0051] The core switch 524 is a switch that is not directly
connected to an end system 12 and functions primarily as an
intermediary switch between edge switches. The core switch 524 is
different from an edge switch 11, which is a switch that is
connected to an end system 12.
[0052] After the core switch 524 receives the setup signal, the SVC
service controller 13 then sends a call proceeding signal
containing VPI A/VCI B call information to the calling end system
12 in step 56. The ATM core switch 524 then sends a PNNI setup
signal to the edge switch 25 in step 57. The edge switch 25 then
sends a proxy setup signal to the SVC service controller 22
providing VPI C, VCI D information in step 58. The SVC service
controller 22 then sends a setup signal to the called party (SVC
service customer) 26 with VPI C, VCI D signaling information in
step 59.
[0053] When the setup signal has been processed by the called party
26, the called party 26 sends a connect signal to the SVC service
controller 22 in step 510. The SVC service controller 22 then sends
a connect acknowledgment to the called party 26 in step 511. The
SVC service controller 22 then sends a connect signal to the edge
switch 25 in step 512, and the edge switch 25 responds with a
connect acknowledgment to the SVC service controller 22 in step
513.
[0054] Subsequently, the edge switch 25 sends a connect signal to
the core switch 524 in step 514. The core switch 524 then sends a
connect signal to the edge switch 11 in step 515. In response, the
edge switch 11 sends a connect signal along the proxy interface to
the SVC service controller 13 in step 516. The SVC service
controller 13 then replies with a connect acknowledgment in step
517. The SVC service controller 13 then sends a connect signal to
the calling party in step 518. Finally, the calling party 12 sends
a connect acknowledgment to the SVC service controller 13 in step
519 and the SVC is established. Once an SVC calling party has
established an SVC to the called party, SVC data flows can be
communicated between the two parties.
[0055] In order to simplify the above example, virtual calling and
called party addresses placed in the setup message have not been
considered. In such a scenario, the SVC service controller 13 on
the calling side applies a policy based upon virtual addresses. To
initiate the proxy setup, the controller 13 queries an address
translation device and replaces the virtual addresses with physical
addresses. On the called side, the SVC service controller 22
replaces the physical addresses with their corresponding virtual
addresses and forwards the setup signal to the called party 26.
[0056] The present invention supports variations in routing of
signaling for purposes such as load balancing across service
providing systems, and routing to alternate service providing
elements when primaries are out of service due to planned
maintenance outages, unscheduled outages, or the like. FIG. 4 shows
a service signaling topology where edge switch 33(a) and edge
switch 33(d) are single-homed via connection 32(a) and connection
32(f) to service controller 31(a) and service controller 31(c),
respectively. Edge switch 33(b) and edge switch 33(c) are
dual-homed via connection 32(b), connection 32(c), connection
32(d), and connection 32(e), to service controller 31(a), service
controller 31(b), and service controller 31(c), respectively.
[0057] In order to build an acceptable level of fault tolerance,
the failure of a single service controller will result in minimal
service unavailability. Single link failures are recovered at the
access layer in a way that is transparent to the signaling stream,
and so do not require fault tolerance mechanisms in the service
signaling architecture.
[0058] In the case of failure of an edge switch's service
controller, the edge switch is reconfigured to establish new
virtual channel cut-throughs from the signaling channels to the
physical interface to an alternate service controller. All switches
served by the failed controller do not have to be reconfigured to
the same alternate service controller. By using multiple
alternates, no one service controller sees a significant load
increase due to a failure. When the failed controller comes back
online, the original virtual circuit cut-throughs can be
re-established.
[0059] In the event a service controller needs to be taken off-line
or malfunctions, an automatic switch over procedure can be
implemented using one or more surviving service controllers. These
remaining service controllers can be used to sense the failure of
the non-functioning service controller and to reconfigure signaling
channels in switches using a virtual switch interface. Failure of a
service controller is automatically detected and recovery
procedures are invoked automatically, even including the
coordination of other network components. Similarly, restoration to
the pre-failure configuration automatically occurs in a coordinated
fashion including controlling when automatic restoration takes
place.
[0060] When the alternate virtual circuit cut-throughs are
established to the alternate service controller, the edge switch is
unable to resynchronize the signaling channel because sequence
numbers of signaling protocol data units are not available at the
alternate controller. As a result, the edge switch restarts the
signaling links with the alternate controller. Because
resynchronization does not succeed, the edge switch tears down any
SVCs set up by the failed signaling channel to protect the
resources from being held in a busy state indefinitely due to loss
of signaling messages.
[0061] Loss of SVCs occurs no matter how quickly the alternate
virtual circuit cut-throughs are established. The length of that
delay affects how soon the user can reestablish new SVCs. This same
behavior occurs when the failed service controller is restored.
[0062] Ultimately, it is desirable to avoid the loss of established
SVCs on a service controller switch-over. To avoid the loss of an
SVC, a level of coordination occurs between transport elements and
services layer to allow some sharing of call state information and
possibly resource allocation information.
[0063] FIG. 5 shows a topology where multiple edge switches 43(a),
43(b), 43(c) are controlled by a single service controller 41. This
topology allows centralized modifications at a single service
controller 41 to affect the operations of multiple switches. Links
42(a), 42(b), 42(c) represent the connectivity between the edge
switches 43(a), 43(b), 43(c) and the service controller 41.
[0064] To bring user-to-network signaling directly to a service
controller, it is advantageous to adopt a convention on the routing
of signaling channels and the treatment of these channels in
intervening switches. The present invention handles UNI signaling
for the ATM SVCs and also signaling channels for additional service
protocols that will appear in the future. With reference to FIG. 6,
an embodiment that accounts for all of these service signaling
protocols is described.
[0065] In the example shown in FIG. 6, the service controller 66
serves a group of edge switches 63(a), 63(b). In turn, each edge
switch terminates a number of user-to-network interfaces, each of
which supports one or more logical signaling channels. To support
standard end systems 61(a), 61(b), 61(c), 61(f) and associated
standard end system software that use ATM UNI signaling, the end
systems 61(a), 61(b), 61(c), 61(f) use VP=0/VC=5 as the signaling
channel into ports 62(a), 62(b), 62(c), 62(g) of switch 63(a) and
switch 63(b). As described above, that UNI protocol sent on the
signaling channel is terminated in the network controller 66, not
the switch 63(a), 63(b).
[0066] On each port 62(a), 62(b), 62(c), 62(g) with a UNI signaling
channel, channel VP=0/VC=5 is "nailed up" in the switch 63(a),
63(b) to a controller port 64(a), 64(b). Each controller port
64(a), 64(b) is connected to the network controller 66. The "nailed
up" connection of course passes transparently through the ATM
switch 63(a), 63(b). That is, the switch 63(a), 63(b) performs no
inspection of the data on this channel.
[0067] The switch 63(a), 63(b), however, maps VP=0/VC=5 to
VP=x/VP=y for the controller ports 64(a), 64(b). In this
embodiment, x is associated uniquely to each ATM switch 63(a),
63(b), and y is associated uniquely to each port 62(a), 62(b),
62(c), 62(g) on that switch 63(a), 63(b). These associations are
network configuration data. The network controller 66 can then
identify the switch 63(a), 63(b) and each port 62(a), 62(b), 62(c),
62(g) on the switch 63(a), 63(b) associated to each signaling
channel by the VP/VC of the cells received.
[0068] Any application of service policy or user profile access,
however, should be based on the calling party number in the SETUP
message. That is, because the present invention supports nomadic
users, the switch and switch port from which the SETUP was sent
does not identify the user sending this request.
[0069] The present invention also operates in a digital subscriber
line (DSL) environment. In such an environment, a digital subscribe
line access multiplexer (DSLAM) 67 may be employed. When the DSLAM
67 is used with end systems 61(d), 61(e) signaling UNI to it 67,
the UNI ports are configured such that VP=0/VC=5 is used on the
DSLAM's link to the edge switch 63(b). This setting is also used
for any other type of access or gateway device that signals UNI to
the service signaling controller 66.
[0070] Because the DSLAM 67 terminates a subscriber's signaling,
the signaling channel from the subscriber's end system 61(d), 61(e)
is not cut-through the DSLAM 67. However, the signaling channel
from the DSLAM 67 to the service controller 66 is configured in a
manner similar to described above. That is, the signaling channel
runs from the DSLAM in a cut-through fashion through the edge
switch 63(b) and terminates on the service controller 66. In cases
when an intermediate access node is not involved in signaling, such
as FTTC or switched-based ADSL, the signaling originates from the
end system itself.
[0071] Once the DSLAM 67 connects to the edge switch 63(b), the
remaining connections are setup, as described above, between the
switch 63(b) and the network controller 66. More specifically,
within each switch, the user-side signaling channels for each DSLAM
are virtual circuit-switched on to a common physical interface to
the service controller 66, with each separate signaling channel
occupying its own dedicated VP/VC on that physical interface. This
is done for each edge switch 63(a), 63(b) within the service
controller's domain. In this case, the service controller 66 sees a
dedicated virtual signaling channel for each DSLAM 67 (in FIG. 6,
only a single DSLAM). Within the service controller 66, the triplet
(physical port, VP, VC) can be uniquely associated with a specific
DSLAM user-side port. Also as described above the called party
number is used to identify the service requestor.
[0072] The following signaling scenario illustrates the placement
of an ATM SVC call between two DSLAM terminated subscribers.
Initially, the subscriber's application in the originating terminal
signals UNI to the network. The DSLAM terminates that signaling,
and in response, signals UNI to the edge switch. That is, the DSLAM
propagates the calling party number in the setup message received
from the subscriber to the Setup message sent to the edge switch.
In this process, the DSLAM applies connection admission control to
decide if sufficient DSLAM resources and link bandwidth are
available to allow the connection. However, beyond that
availability check, the DSLAM performs no other SVC service
processing.
[0073] Next, the UNI signaling from the DSLAM is passed
transparently to the session controller. The subscriber is
identified by the calling party number field in the received
address associated to the port on which the original setup message
was received. At this point service policy is applied, the caller's
user profile is accessed, and it is decided whether to allow the
service request.
[0074] Assuming the service request is granted, the session
controller proxy signals to the edge switch to set up the desired
connection. Subsequently, the setup proceeds normally in the
transport network. In other words, the edge switch uses PNNI
signaling to create a source route for the SVC, and then the edge
switch and the subsequent switches in the path use PNNI to signal
the setup of the SVC.
[0075] At the terminating edge switch, the UNI signaling destined
for the DSLAM is proxied to the service controller. In this case,
no service processing is required because it was performed at the
originating service controller. The service controller uses UNI to
signal to the DSLAM transparently through the edge switch and the
SVC setup completes normally.
[0076] The present invention also provides IP-based service
signaling interception allowing an IP end system to invoke ATM
services. That is, the IP end system can use the ATM services to
transport IP packets over an ATM network and communicate with a
distant IP network server or IP network element.
[0077] The invention's particular IP-over-ATM implementation
creates a service signaling subnetwork within the IP-over-ATM
network that carries intercepted service signaling from IP packets
to service controllers. In one embodiment, the interception of IP
service signals occurs at the edge of the service signaling
subnetwork. Once retrieved, IP service signals are routed to a
destination service controller that translates IP service signals
into proxy signals that a network switch can process. The IP packet
is then packaged and handled by the ATM network in a way similar to
that intended by the IP service signals of the original IP
packet.
[0078] In cases where IP service signals are not retrievable or are
not mapped to ATM services, the IP packets associated with the IP
service signals may still be routed through the ATM network.
Alternatively, the IP packets may be directed away from the ATM
network to a traditional IP network. The present invention's
ability to separate service signaling from at least some IP
transmissions allows ATM SVC services to be employed.
[0079] In an IP-over-ATM system, SVC service requests can be
invoked by an IP service signal to set up an SVC that is used as an
IP layer 2 link, to connect to an IP router, to connect to an IP
authentication server, or to connect to another like device. Once
the SVC is set up, IP packets can be packaged and transmitted over
an ATM system.
[0080] Moreover, in IP-over-ATM transport, the ATM connections can
be established by the service controller initiating a proxy
connection setup. In the case of IP class of service flow, the
controller can provide the end-system with a label for use data
packets, or download packet processing rules to the classifying
router at the edge or both to provide the appropriate class of IP
transport.
[0081] By combining IP and ATM technologies, IP and ATM
functionality can be reused to keep capital and operations cost
down. For example, explicitly signaled IP services and native ATM
services are quite similar in their signaling operation with regard
to policy checking, and hence, reuse of policy servers and policy
checking mechanisms and protocols can result in cost savings.
[0082] The present invention provides a common architecture for
network based services where there is a service signaling phase,
either IP or ATM signaling, and where the service controller
authorizes the request based on subscriber data, and then uses
service control signaling to establish User-to User or
User-to-Content Server connections, either true ATM connections, or
IP class of service flows.
[0083] The present invention also allows peer networks to invoke
services from the service signaling subnetwork. This is
accomplished by an interworking function (IWF). The peer networks
could be another carrier's broadband network, the PSTN, Voice over
IP networks, etc.
[0084] In cases when interworking is required, it can be protocol
interworking, transport format interworking, or, most commonly,
both. In each scenario, the interworking device may be located on
the customer premises. For example, a home gateway can be employed
that interfaces an analog phone on the customer side and uses
digital signaling and voice encoding from the home gateway to the
network. In other cases, the interworking can be performed at
gateways at the edge of the service signaling subnetwork. For
example, an IWF gateway can be provided that terminates PSTN trunks
and SS7 signaling and translates the signaling into a form the
service signaling subnetwork can process. Another example is an IWF
gateway that converts ISDN PRI D-channel connection signaling from
a peer network to ATM UNI for processing by the service signaling
subnetwork. Interworking legacy service protocols and transport
formats at the edge of the service signaling subnetwork via a
gateway is a very cost effective approach to the design of a
multi-service network with interconnections to various forms of
customer premise equipment (CPE) and peer networks.
[0085] In some cases, the service signaling subnetwork will
interconnect with peer legacy networks where the legacy network has
a very different version of a service than the service signaling
subnetwork. In order to allow a service invocation to span the
service signaling subnetwork and the legacy networks, the service
signaling subnetwork could implement a different version of service
for each interconnected legacy network. Alternatively the service
signaling subnetwork can implement a broadband version of the
service that is invoked with a "native" protocol, the protocol
corresponding to the service signaling subnetwork version of the
service. For example, the native protocol may be an IP protocol or
another network's ATM protocol which can be interworked into the
service signaling subnetwork protocols at an IWF gateway on the
edge of the service signaling subnetwork.
[0086] Where policy data is required at an IWF, the IWF can use the
same data management architecture that the service controllers use.
For example, data can be obtained from directory servers in the
service signaling subnetwork via LDAP interfaces. Depending on the
performance requirements and the amount of data involved, the data
can either be cached at the IWF or retrieved from a policy
database. In either case, the IWF data is administered in
conjunction with other service data in the services network. The
same redundancy and distribution mechanisms which allow the service
controllers to access network data should be used for IWFs. This
integration reduces the cost of policy coordination and allows for
effective service assurance activities because all relevant data is
available in a common directory system.
[0087] The IWF gateway performs the service interworking, address
translation, and related policy management. Depending on the
internetwork interface, information available across that interface
may be relayed in the UNI setup message in appropriate information
elements (or in the free form Broadband Higher Layer information
element). That information can be used for connection policy
management, address translation, and supplementary service
propagation (calling line id, auto-callback, etc). The approach can
also be used for out of band signaling between networks. SS7 ISUP
will be used as an example. SS7 signaling can terminate in the
gateway device and be translated into UNI commands for service
signaling subnetwork processing.
[0088] Although the invention has been described with reference to
several exemplary embodiments, it is understood that the words that
have been used are words of description and illustration, rather
than words of limitation. Changes may be made within the purview of
the appended claims, as presently stated and as amended, without
departing from the scope and spirit of the invention in its
aspects. Although the invention has been described with reference
to particular means, materials and embodiments, the invention is
not intended to be limited to the particulars disclosed; rather,
the invention extends to all functionally equivalent structures,
methods, and uses such as are within the scope of the appended
claims.
[0089] In accordance with various embodiments of the present
invention, the methods described herein are intended for operation
as software programs running on a computer processor. Dedicated
hardware implementations including, but not limited to, application
specific integrated circuits, programmable logic arrays and other
hardware devices can likewise be constructed to implement the
methods described herein. Furthermore, alternative software
implementations including, but not limited to, distributed
processing or component/object distributed processing, parallel
processing, or virtual machine processing can also be constructed
to implement the methods described herein.
[0090] It should also be noted that the software implementations of
the present invention as described herein are optionally stored on
a tangible storage medium, such as: a magnetic medium such as a
disk or tape; a magneto-optical or optical medium such as a disk;
or a solid state medium such as a memory card or other package that
houses one or more read-only (non-volatile) memories, random access
memories, or other re-writable (volatile) memories. A digital file
attachment to E-mail or other self-contained information archive or
set of archives is considered a distribution medium equivalent to a
tangible storage medium. Accordingly, the invention is considered
to include a tangible storage medium or distribution medium, as
listed herein and including art-recognized equivalents and
successor media, in which the software implementations herein are
stored.
[0091] Although the present specification describes components and
functions implemented in the embodiments with reference to
particular standards and protocols, the invention is not limited to
such standards and protocols. Each of the standards for Internet
and other packet-switched network transmission (e.g., TCP/IP,
UDP/IP, HTML, SHTML, DHTML, XML, PPP, FTP, SMTP, MIME); peripheral
control (IrDA; RS232C; USB; ISA; ExCA; PCMCIA), and public
telephone networks (ISDN, ATM, xDSL) represent examples of the
state of the art. Such standards are periodically superseded by
faster or more efficient equivalents having essentially the same
functions. Accordingly, replacement standards and protocols having
the same functions are considered equivalents.
* * * * *