U.S. patent application number 11/084217 was filed with the patent office on 2006-01-19 for switching device interfaces.
Invention is credited to Monalisa Agrawal, Moni Matthew, Hamayun Mujeeb, Bill Rubino, Ayikudy Srikanth.
Application Number | 20060013248 11/084217 |
Document ID | / |
Family ID | 34632696 |
Filed Date | 2006-01-19 |
United States Patent
Application |
20060013248 |
Kind Code |
A1 |
Mujeeb; Hamayun ; et
al. |
January 19, 2006 |
Switching device interfaces
Abstract
A device is switched from a first physical interface on the
device to a second physical interface on the device based on
information in an interface redundancy group. The information in
the interface redundancy group identifies the first physical
interface as a primary interface for the device and the second
physical interface as a secondary interface for the device.
Inventors: |
Mujeeb; Hamayun; (Billerica,
MA) ; Agrawal; Monalisa; (Norwood, MA) ;
Srikanth; Ayikudy; (Reading, MA) ; Matthew; Moni;
(Sharon, MA) ; Rubino; Bill; (Chelmsford,
MA) |
Correspondence
Address: |
DOCKET CLERK
P.O. DRAWER 800889
DALLAS
TX
75380
US
|
Family ID: |
34632696 |
Appl. No.: |
11/084217 |
Filed: |
March 18, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09374460 |
Aug 13, 1999 |
6906998 |
|
|
11084217 |
Mar 18, 2005 |
|
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Current U.S.
Class: |
370/463 |
Current CPC
Class: |
H04L 2012/5627 20130101;
H04L 49/3009 20130101; H04Q 3/0025 20130101; H04L 49/552 20130101;
H04L 69/40 20130101 |
Class at
Publication: |
370/463 |
International
Class: |
H04L 12/66 20060101
H04L012/66 |
Claims
1-94. (canceled)
95. A method of switching between physical interfaces on a device,
the method comprising the steps of: detecting an event at a first
physical interface on the device; switching, in response to the
event, from the first physical interface to a second physical
interface on the device based on information in an interface
redundancy group; wherein the information in the interface
redundancy group identifies the first physical interface as a
primary interface for the device and the second physical interface
as a secondary interface for the device.
96. The method of claim 95, wherein the event comprises a failure
of the first physical interface.
97. The method of claim 96, wherein the first physical interface is
associated with a driver and a signaling stack, and the failure of
the first physical interface comprises a failure of one of the
driver or the signaling stack.
98. The method of claim 97, further comprising monitoring the
driver and the signaling stack in order to detect a failure of one
of the driver or the signaling stack.
99. The method of claim 95, wherein the event comprises receipt of
a slot failure at the first physical interface.
100. The method of claim 95, wherein the first and second physical
interfaces comprise asynchronous transfer mode (ATM) physical
interfaces.
101. The method of claim 95, further comprising the steps of:
monitoring availability of the first physical interface; and
switching from the second physical interface to the first physical
interface once the first physical interface becomes available.
102. The method of claim 101, wherein the switching is performed
automatically in response to the first physical interface becoming
available.
103. A method of preferentially switching between prioritized
physical interfaces on a single device, the method comprising the
steps of: designating a first physical interface on the device as a
high priority physical interface; monitoring availability of the
high priority physical interface; and switching from a second
physical interface on the device to the high priority physical
interface once the high priority physical interface becomes
available.
104. The method of claim 103, wherein the switching is performed
automatically in response to the high priority physical interface
becoming available.
105. The method of claim 103, further comprising the steps of:
designating a the second physical interface on the device as a
moderate priority physical interface; monitoring availability of
the moderate priority physical interface; and switching from a
third physical interface on the device to either the high priority
physical interface once the high priority physical interface
becomes available or the moderate priority physical interface once
the moderate priority physical interface becomes available.
106. The method of claim 103, wherein the first and second physical
interfaces comprise asynchronous transfer mode (ATM) physical
interfaces.
107. The method of claim 103, wherein the first physical interface
is defined as the primary interface for the device.
108. An apparatus which preferentially switches between prioritized
physical interfaces, the apparatus comprising: plural physical
interfaces; and a processor which executes instructions to:
designate a first physical interface on the apparatus as a high
priority physical interface; monitor availability of the high
priority physical interface; and switch from a second physical
interface on the device to the high priority physical interface
once the high priority physical interface becomes available.
109. The apparatus of claim 108, wherein the switch is performed
automatically in response to the high priority physical interface
becoming available.
110. The apparatus of claim 108, wherein the processor further
executes instructions to: designate the second physical interface
on the device as a moderate priority physical interface; monitor
availability of the moderate priority physical interface; and
switch from a third physical interface on the device to either the
high priority physical interface once the high priority physical
interface becomes available or the moderate priority physical
interface once the moderate priority physical interface becomes
available.
111. The apparatus of claim 108, wherein the first and second
physical interfaces comprise asynchronous transfer mode (ATM)
physical interfaces.
112. The apparatus of claim 108, wherein the first physical
interface is defined as the primary interface for the device.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to interfaces on a network
device.
[0002] Network devices have physical interfaces that are subject to
failure. When such an interface fails, a network device can be
cut-off from the network. This is particularly problematic in the
case of a router, where failure of a single physical interface can
make a whole branch of the network inaccessible to other
devices.
SUMMARY OF THE INVENTION
[0003] In one aspect of the invention, a device is switched from a
first physical interface on the device (for example, a failed
interface) to a second physical interface on the device based on
information in an interface redundancy group. The information in
the interface redundancy group identifies the first physical
interface as a primary interface for the device and the second
physical interface as a secondary interface for the device.
[0004] The foregoing aspect of the invention may include one or
more of the following features/functions.
[0005] The interface redundancy group may include information
defining the primary interface for the device and one or more
secondary interfaces for the device. An event may be detected at
the first physical interface, and switching may be performed in
response to the event. The event may comprise a failure of the
first physical interface. The first physical interface may be
associated with a driver and a signaling stack, and the failure of
the first physical interface may comprise a failure of the driver
and/or the signaling stack. The driver and the signaling stack may
be monitored in order to detect failures therein. The event may
comprise receipt of a slot failure at the first physical
interface.
[0006] Prior to switching, the second physical interface may
operate in a passive mode during which the second physical
interface is dormant. Prior to switching, the second physical
interface may operate in an active mode during which the second
physical interface is communicating over a network. The first
physical interface may support one or more network layer
interfaces. Following switching, the second physical interface may
support the one or more network layer interfaces formerly supported
by the first physical interface. The first and second physical
interfaces may comprise asynchronous transfer mode ("ATM") physical
interfaces. The first and second physical interfaces may be
resident on a single network router.
[0007] Following switching, the second physical-interface may
assume responsibilities of the first physical interface. These
responsibilities may include routing and/or bridging functions.
Following switching, the second physical interface may be
configured in a same manner as the first physical interface was
configured prior to switching. The device may include a third
physical interface, and the interface redundancy group may identify
the third physical interface as a tertiary interface. The device
may be switched from the second physical interface to the third
physical interface in response to an event. Following switching,
the third physical interface may assume responsibilities of the
first and second physical interfaces. These responsibilities may
include routing and/or bridging functions.
[0008] In another aspect, physical interfaces on a single device
are switched by designating a physical interface on the device as a
high priority physical interface, and determining if the high
priority physical interface is available. The device is switched
from a lower priority physical interface to the high priority
physical interface when the high priority physical interface is
available.
[0009] The foregoing aspect of the invention may include one or
more of the following features/functions. Switching may be
performed automatically in response to the high priority interface
being available. The high priority physical interface may be
monitored to determine if the high priority physical interface is
available.
[0010] In another aspect, a device is switched from a first ATM
physical interface on the device to a second ATM physical interface
on the device based on information in an interface redundancy
group. The information in the interface redundancy group identifies
the first ATM physical interface as a primary interface for the
device and the second ATM physical interface as a secondary
interface for the device. ATM network layer interfaces are
established over the second physical interface that correspond to
ATM network layer interfaces that were established over the first
ATM physical interface prior to switching.
[0011] This brief summary has been provided so that the nature of
the invention can be understood quickly. A detailed description of
illustrative embodiments of the invention is set forth below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 shows a network system, which includes a router
having switchable physical interfaces.
[0013] FIG. 2 shows virtual circuits supported by the physical
interfaces on the router.
[0014] FIG. 3 is a flow diagram showing a process for switching a
physical interface on the router in "passive" mode.
[0015] FIG. 4 shows an alternative connection of the virtual
circuits to the physical interfaces on the router.
[0016] FIG. 5 is a flow diagram showing a process for switching a
physical interface on the router in "active" mode.
[0017] FIG. 6 shows the configuration of the virtual circuits after
the switching performed in FIG. 5.
[0018] FIG. 7 is a flow diagram showing a process for switching a
physical interface on the router based on priority.
[0019] FIG. 8 shows a router having three physical interfaces and
redundancy groups therefor.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring to FIG. 1, a network system 10 is shown. Network
system 10 includes router 12, switches 14 and 16, workstations 18,
20 and 22, and network 24.
[0021] Network 24 is an asynchronous transfer mode ("ATM") wide
area network ("WAN"). ATM is a connection-oriented protocol,
meaning that connections are established between devices before
data and/or communications can be transmitted between the devices.
The network layer interface comprises virtual circuits, over which
data packets (in ATM parlance, "cells") are transmitted among
devices coupled to network 24, such as router 12 and switches 14
and 16. Virtual circuits can be established by protocols such as
ELANs (Emulated Local Area Networks) on network 24.
[0022] Switches 14 and 16 interface workstations 20 and 22,
respectively, to network 24. Each switch 14 and 16 is an electronic
device that routes cells between network 24 and a corresponding
workstation. Workstations 18, 20 and 22 are personal computers
("PCs") or other devices that are capable of receiving cells from
network 24, processing cells, and transmitting cells to network
24.
[0023] Router 12 is a computer or other device that transmits
packets/cells among workstations 18, 20 and 22 via network 24. For
example, router 12 receives cells/packets from workstation 18 and,
based on information in those cells/packets, routes the
cells/packets to either workstation 20 or 22 (through an
intervening switch and other hardware on network 24).
[0024] ATM physical interfaces 26a and 26b are ports provided on
router 12 for interfacing to network 24. Although only two such
interfaces are shown, any number may be provided. In system 10 of
FIG. 1, one of the interfaces (e.g., 26a) is designated as the
primary interface for router 12 and the other (e.g., 26b) is
designated as the secondary (or backup) interface. When the primary
physical interface 26a fails, the secondary physical interface. 26b
is switched in to take its place. A process to accomplish this is
described below.
[0025] Physical interfaces 26a and 26b are comprised of wires
terminating in connectors, such as an OC-3/OC-12 connector, which
mate to corresponding receptacles on router 12. One or more network
layer interfaces are established by router 12 over each physical
interface 26a and 26b for communication to, and over, network 24.
ATM line drivers 30a and 30b transmit cells over corresponding
physical interfaces 26a and 26b.
[0026] Included in router 12 are a processor 34 and a memory 36
connected by bus 38 (see view 40). Memory 36 stores routing engines
42a and 42b, interface switching code 44, and signaling stacks 46a
and 46b. Processor 34 executes instructions in this code to cause
router 12 to perform the functions described below. Memory 36 also
stores interface redundancy group information 48 (described
below).
[0027] Signaling stacks 46a and 46b are blocks of code, associated
with corresponding physical interfaces 26a and 26b, for
establishing virtual connections for the network layer interfaces
over the physical interfaces. As noted, one or more network layer
interfaces may be configured over a single ATM physical interface
26a and 26b.
[0028] Routing engine 42a routes cells over physical interface 26a
and routing engine 42b routes cells over physical interface 26b.
Routing engines 42a and 42b examine destination information in the
cells and route the cells over appropriate interfaces. Examples of
routing engines that may be used are "ARE" (ATM Routing Engine) and
the 5782 Centillion Multiprotocol Engine.
[0029] Interface redundancy group information 48 defines which
physical interface is the primary interface (e.g., 26a) and which
is the secondary interface (e.g., 26b). This information may be
input manually at router 12 via configuration software such as Site
Managers or Bay Command Consoles ("BCC"). This software is used by
network administrators to configure network devices. Alternatively,
interface redundancy group information 48 may be downloaded from a
remote location such as network 24 or workstation 18 or set via
interface switching code 44.
[0030] Interface redundancy group information 48 includes
user-defined redundancy groups. These redundancy groups assign
priority to the interfaces. In the case of a two-interface router,
such as router 12, there are two possible groups. For example,
physical interface 26a is configured as the primary interface and
physical interface 26b is configured as the secondary interface.
The routing engine for each interface is configured to know the
role of the interface in each redundancy group. Representative code
to configure routing engines is provided in the Appendix.
[0031] In routers with more than two physical interfaces, interface
redundancy groups become more complicated. Table 1 shows an example
of redundancy groups for a router having four physical interfaces
"Interface 1", "Interface 2", "Interface 3" and "Interface 4" (not
shown). TABLE-US-00001 TABLE 1 Redundancy Primary Secondary
Tertiary Group Interface Interface Interface 1 Interface 1
Interface 2 Interface 3 2 Interface 2 Interface 1 Interface 3 3
Interface 4 Interface 3 --
For example, in redundancy group "1", "Interface 1" acts as the
primary interface; "Interface 2" acts as the secondary (first
backup) interface and is used if. "Interface 1" fails; and
"Interface 3" acts as the tertiary (or second backup) interface and
is used if both "Interfaces 1" and "Interface 2" fail.
[0032] Detecting physical interface failure and switching from a
primary to a secondary physical interface (or from a secondary to a
tertiary physical interface, etc.) is performed by interface
switching code 44. The operation of interface switching code 44
differs depending upon whether the secondary interface is in
passive mode or active mode.
Passive Mode
[0033] In passive mode, prior to switching, the secondary interface
is dormant. That is, the secondary interface is not
driving/receiving signals to/from network 24. Passive mode may be
set as the default mode of router 12 using Site Manager.RTM. or
BCC.RTM..
[0034] Referring to FIG. 2, a graphical representation of passive
mode is shown. In FIG. 2, physical interface 26a is configured as
the primary interface and physical interface 26b is configured as
the secondary interface in passive mode. This configuration is set
in interface redundancy group information 48. In FIG. 2, lines 54a
to 54h represent connections maintained by primary physical
interface 26a and lines 56a to 56h represent connections that are
maintained by secondary physical interface 26b after secondary
interface 26b-takes over the role of primary interface 26b.
[0035] Referring to FIG. 3, an interface switching process 56 is
shown. Interface switching process 56 is performed by interface
switching code 44 to switch from primary physical interface 26a to
secondary physical interface 26b. Process 56 monitors 58 primary
physical interface 26a, including both driver 30a and signaling
stack 46a, for specific "events". These events can include, but are
not limited to, receipt of a slot reset at primary physical
interface 26a and/or a failure of primary physical interface 26a,
such as a failure of driver 30a and/or signaling stack 46a.
[0036] In response to detecting 60 one of the foregoing events,
process 56 switches 62 from primary physical interface 26a to
secondary physical interface 26b (in accordance with interface
redundancy group information 48). Switching 62 is performed by
enabling driver 30b for secondary physical interface 26b. Following
switching, secondary interface 26b establishes 63 the network layer
interfaces to network 24 (in this example, ELANs 52a to 52h), and
assumes the responsibilities (including routing and bridging
services) of primary interface 26b. Switching between interfaces is
performed as quickly as possible, e.g., within thirty seconds of
failure or reset.
[0037] With driver 30b enabled, in 64, signaling stack 46b
transmits cells over secondary physical interface 26b to ELANs 52a
to 52h. Primary physical interface 26a can be repaired while
secondary physical interface 26b performs its functions.
Active Mode
[0038] In active mode, prior to switching, the secondary physical
interface 26b is already communicating over the network. Following
failure of the primary physical interface 26a, the secondary
interface 26b assumes the responsibilities of the primary interface
26a. In particular, upon switching, code in the signaling stack
establishes the network layer interfaces (e.g., over ELANs) of the
primary interface 26a, and assumes the routing and bridging
functions of the primary interface 26a.
[0039] Referring to FIG. 4, a graphical representation of active
mode is shown. In FIG. 4, physical interface 26a is the primary
interface and physical interface 26b is the secondary interface in
active mode. This configuration is set in interface redundancy
group information 48. Since secondary physical interface 26b is in
active mode, prior to switching, it is providing network layer
services over virtual circuits for ELANs 52e to 52h. Primary
physical interface 26a is supporting ELANs 52a to 52d.
[0040] Referring to FIG. 5, an interface switching process 66 is
shown, that is performed by interface switching code 44 to switch
from primary physical interface 26a to secondary physical interface
26b. Interface switching process 66 monitors 68 primary physical
interface 26a, including both driver 30a and signaling stack 46a,
for specific events. These events are the same as those noted above
for passive mode.
[0041] In response to detecting 70 one of the foregoing events,
process 66 switches 72 from primary physical interface 26a to
secondary physical interface 26b. Switching is performed in the
manner described above; that is, enabling and disabling the drivers
for the appropriate network interfaces.
[0042] Interface switching process 66 establishes 74, over
secondary physical interface 26b, the network layer interfaces (in
this case, ELANs 52a to 52d) of primary physical interface 26a.
Secondary physical interface 26b continues to perform its original
routing and bridging functions over ELANs 52e to 52h. Now, however,
secondary physical interface 26b also performs the routing and
bridging functions formerly performed by primary physical interface
26a over ELANs 52a to 52d.
[0043] With driver 30b enabled, and secondary physical interface
26b switched, in 76, signaling stack 46b transmits cells over
secondary physical interface 26b to all of ELANs 52a to 52h. This
is shown in FIG. 6. Primary physical interface 26a no longer
transmits (hence no lines are shown between this interface and the
ELANs in FIG. 6).
Switching Based on Priority
[0044] ATM physical interfaces may also be assigned relative
priorities and switched on that basis. An option in router. 12 may
be set, e.g., by a user, to trigger automatic switching based on
priority. The priority information upon which switching is based
may be included in interface redundancy group information 48, for
example.
[0045] Referring to FIG. 7, a process 78 is shown that is performed
by interface switching code 44 to switch interfaces based on
priority. Process 78 designates 80 any number of physical
interfaces on a sliding priority scale, from highest priority to
lowest priority. In router 12 (FIG. 2), only two physical
interfaces are shown. For the sake of illustration, therefore,
physical interface 26a is designated 80 as high priority and
physical interface 26b is designated 80 as low priority.
[0046] Once physical interfaces 26a and 26b are designated in terms
of priority, switching between them may be performed. Process 78
monitors 82 high priority physical interface 26a to determine if it
is up and running. If high priority physical interface 26a is
available 84 (i.e., it is not "down"), process 78 switches 86 from
low priority physical interface 26b to high priority physical
interface 26a. As a result, the "best available" interface on
router 12 is used to provide network layer connections over network
24. Process 60 may be incorporated into processes 56 and 66 to
provide further enhanced switching capabilities.
[0047] As noted above, the invention may be used on routers having
more than two physical interfaces. For example, in FIG. 8, router
90 has three physical interfaces 92a, 92b and 92c organized into
two interface redundancy groups 94 and 96. Interfaces 92a and 92c
are in group 94 and interfaces 92b and 92c are in group 96. In this
example, interface 92c is a backup for interfaces 92a and 92b. If
either of interfaces 92a and 92b fail, then interface 92c will
assume the configuration of either (or both of) failed interfaces
92a and 92b.
[0048] Switching in the case of more than two interfaces is
performed in the same way as described in processes 56, 66 and 78,
except that a decision must be made regarding which (lower
priority) interface to switch for the primary interface. This
decision is made based on interface availability and the priority
of the various interfaces.
[0049] The invention is not limited to the specific hardware and
software configurations described herein. For example, the
invention can be used outside the context of ATM WANs, and with
network devices other than routers. In this regard, it is to be
understood that while the invention has been described in
conjunction with the detailed description thereof, the foregoing
description is intended to illustrate, and not to limit, the scope
of the invention. Other aspects, advantages, and modifications are
within the scope of the following claims.
* * * * *