Configuring a Basic IS-IS Network

Last Updated: October 22, 2011

This module describes the tasks to configure and monitor a basic Intermediate System-to-Intermediate System (IS-IS) network. The IS-IS process and adjacency formation are also explained. IS-IS is link-state protocol that allows the network designer to organize the network into a group of flooding domains. Often deployed as the Interior Gateway Protocol (IGP) for an ISP network backbone, IS-IS is capable of handling large topologies and large numbers of routing changes.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Configuring a Basic IS-IS Network

  • Before performing the tasks in this module, you should be familiar with the concepts described in the "Integrated IS-IS Routing Protocol Overview" module.
  • You should know your network design and how you want traffic to flow through it before configuring IS-IS. Define areas, prepare an addressing plan for the routers (including defining the NETs), and determine the interfaces that will run Integrated IS-IS. To facilitate verification, a matrix of adjacencies should be prepared before you configure your routers, showing what neighbors should be expected in the adjacencies table. For more information on verifying IS-IS configuration and formed adjacencies, see the Monitoring IS-IS.

Information About the IS-IS Routing Protocol

IS-IS Process and Adjacencies

IS-IS requires some configuration on both the router and the interface. An IS-IS process is created when you enable IS-IS on a router and define a specific tag to identify that routing process. Interfaces configured with a specific tag will be part of the corresponding router process. More than one IS-IS process can run on a router for Connectionless Network Service (CLNS), but only one IS-IS process can run for IP.

Small IS-IS networks are built as a single area that includes all the routers in the network. As the network grows larger, it is usually reorganized into a backbone area made up of the connected set of all Level 2 routers from all areas. The areas are connected to local areas. Within a local area, routers know how to reach all system IDs. Between areas, routers know how to reach the backbone, and the backbone routers know how to reach other areas.

Routers establish Level 1 adjacencies to perform routing within a local area (intra-area routing). Routers establish Level 2 adjacencies to perform routing between Level 1 areas (inter-area routing).

If the network administrator does not specify Level 1 or Level 2 routing for the routing process being configured, the default routing behavior for the routing process will be Level 1-2.

If Level 2 routing is configured on any process, additional processes are automatically configured as Level 1, with the exception of previously configured Level 2 process, which will remain Level 2. You can have only one Level-2 process. You can configure the Level-2 process to perform Level-1 routing at the same time. If Level-2 routing is not desired for a router instance, use the is-type command in router configuration mode to remove the Level-2 capability. You can also use the is-type command to configure a different router instance as a Level-2 router.

Some networks use legacy equipment that supports only Level 1 routing. These devices are typically organized into many small areas that cannot be aggregated due to performance limitations. Cisco routers are used to interconnect each area to the Level 2 backbone.

Network entity titles (NETs) define the area addresses and the system ID of the router.

PDU Packet Types in IS-IS Routing

The OSI stack defines a unit of data as a protocol data unit (PDU). A frame therefore is regarded by OSI as a data-link PDU, and a packet is regarded as a network PDU. There are four types of PDU packets, and each type can be Level 1 or Level 2:

  • LSP--Link-state PDU. Used to distribute link-state information.
  • IIH PDU--For IS-IS this is called the IS-IS Hello PDU. Used to establish and maintain adjacencies.

Note
On point-to-point links, IIH PDUs will be the same for Level 1 and Level 2. Both Level-1 and Level-2 IIH use the same type of PDU, but they carry different circuit types.
  • PSNP--Partial sequence numbers protocol data unit (PDU). Used to acknowledge and request link-state information.
  • CSNP--Complete sequence number protocol data unit (PDU). Used to distribute the complete link-state database of a router.

IS-IS LSPs include specific information about the router's attachments. The following information is included in multiple TLV fields in the main body of the LSP:

  • The links to neighbor router intermediate systems (ISs), including the metrics of those interfaces
  • The links to the neighbor end systems (ESs)

You can shut down IS-IS (placing it in an administrative down state) to make changes to the IS-IS protocol configuration, without losing your configuration parameters. You can shut down IS-IS at the interface level or at the global IS-IS process level. If the router was rebooted when the protocol was turned off, the protocol would be expected to come back up in the disabled state. When the protocol is set to the administrative down state, network administrators are allowed to administratively turn off the operation of the IS-IS protocol without losing the protocol configuration, to make a series of changes to the protocol configuration without having the operation of the protocol transition through intermediate--and perhaps undesirable--states, and to then reenable the protocol at a suitable time.

How to Create Monitor and Make Changes to a Basic IS-IS Network

Enabling IS-IS as an IP Routing Protocol on the Router

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    router isis [area-tag]

4.    net network-entity-title

5.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
router isis [area-tag]


Example:

Router(config)# router isis

 

Assigns a tag to an IS-IS process. Enters router configuration mode.

  • Configure tags to identify multiple IS-IS processes by giving a meaningful name for each routing process. If the tag is not specified, a null tag (0) is assumed and the process is referenced with a null tag. The tag name must be unique among all IP router processes for the router.
 
Step 4
net network-entity-title


Example:

Router(config-router)# net 49.0001.0000.0000.000b.00

 

Configures the NET on the router.

  • The NET identifies the router for IS-IS.
 
Step 5
end


Example:

Router(config-router)# end

 

Exits router configuration mode and returns to privileged EXEC mode.

 

Enabling IS-IS as an IP Routing Protocol on the Interface

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary]

5.    ip router isis [area - tag]

6.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
interface type number


Example:

Router(config)# interface Gigabitethernet 4/0/0

 

Enters interface configuration mode.

 
Step 4
ip address ip-address mask [secondary]


Example:

Router(config-if)# ip address 172.16.1.27 255.255.255.0

 

Sets the primary IP address on the interface.

 
Step 5
ip router isis [area - tag]


Example:

Router(config-if)# ip router isis company1

 

Enables IS-IS on the interfaces that are to use IS-IS to distribute their IP information (and additionally that might be used to establish IS-IS adjacencies).

Note    If there is more than one IS-IS process on the router, repeat the ip router isis command for each interface, specifying an area tag for each interface to associate each interface with the specific process to which it belongs.
 
Step 6
end


Example:

Router(config-if)# end

 

Exits interface configuration mode and returns to privileged EXEC mode.

 

Monitoring IS-IS

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    isis display delimiter [return count | character count]

4.    exit

5.    show ip protocols

6.    show clns is area-tag neighbors [type number] [detail]

7.    show clns interface [type number]

8.    show clns area-tag neighbors [type number] [area] [detail]

9.    show clns area-tag traffic

10.    show ip route [ip-address [mask]] [longer-prefixes| protocol [process-id] | list [access-list-number | access-list-name] | static download]

11.    show isis [process-tag] database [level-1] [level-2] [l1] [l2] [detail] [lspid]

12.    show isis database verbose

13.    show isis lsp-log

14.    show isis [area-tag] [ipv6 | *] spf-log

15.    show isis [process-tag] [ipv6 | *] topology

16.    show isis [area-tag] neighbors[detail]


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
isis display delimiter [return count | character count]


Example:

Router(config)# isis display delimiter return 15

 

Makes output from multiarea displays easier to read by specifying the delimiter to use to separate displays of information.

 
Step 4
exit


Example:

Router(config)# exit

 

Returns to privileged EXEC mode.

 
Step 5
show ip protocols


Example:

Router# show ip protocols

 

Displays the parameters and current state of the active routing protocol process.

  • You can use this command to learn what protocols are active, what interfaces they are active on, what networks they are routing for, and other parameters that relate to the routing protocols.
 
Step 6
show clns is area-tag neighbors [type number] [detail]


Example:

Router# show clns is tag3 neighbors detail

 

Displays IS-IS information for IS-IS router adjacencies.

 
Step 7
show clns interface [type number]


Example:

Router# show clns interface

 

List the CLNS-specific information about each interface.

 
Step 8
show clns area-tag neighbors [type number] [area] [detail]


Example:

Router# show clns area3 neighbors

 

Displays both ES and IS neighbors.

  • The show clns neighbor command output verifies that the right adjacencies have established. A matrix of adjacencies should be prepared before you configure your routers, showing what neighbors should be expected in the adjacencies table, to facilitate verification.
 
Step 9
show clns area-tag traffic


Example:

Router# show clns area3 traffic

 

Displays traffic statistics.

To monitor IS-IS for stability once it has been deployed across your network, enter the show clns traffic command to check the following important statistics: high numbers of SPFs, checksum errors, and retransmissions. To troubleshoot IS-IS behavior, you can use the output from the show clns traffic command to check for the following indicators:

  • The number of link-state PDUs (LSPs) can help you determine the stability of the IS-IS network. The number of LSPs should never be zero. However, an LSP count that keeps increasing over a short time period indicates a network issue.
  • LSP retransmissions should stay low. A later execution of the show clns traffic command that shows an increase in LSP retransmissions, as compared to an earlier execution of the command, can indicate instability or traffic problems.
  • To check for partial route calculations (PRCs), enter the show clns traffic command. PRCs are flooded when a change that does not affect topology is reported through an LSP; typical examples include the addition or removal of a prefix or metric changes for external or passive interfaces. A PRC update queue that remains full or increases to the maximum value for long periods of time indicates network instability.
  • LSP checksum errors indicate a problem.
  • The update queue should not stay full and should not drop much.
 
Step 10
show ip route [ip-address [mask]] [longer-prefixes| protocol [process-id] | list [access-list-number | access-list-name] | static download]


Example:

Router# show ip route 172.16.0.21

 

Displays the current state of the routing table.

 
Step 11
show isis [process-tag] database [level-1] [level-2] [l1] [l2] [detail] [lspid]


Example:

Router# show isis database detail

 

Displays additional information about the IS-IS database.

  • Displays the link-state database for Level-1 and Level-2, the contents for each LSP, and the link-state protocol PDU identifier.
 
Step 12
show isis database verbose


Example:

Router# show isis database verbose

 

Displays additional information about the IS-IS database such as the sequence number, checksum, and holdtime for LSPs.

 
Step 13
show isis lsp-log


Example:

Router# show isis lsp-log

 

Displays a log of LSPs including time of occurrence, count, interface, and the event that triggered the LSP.

 
Step 14
show isis [area-tag] [ipv6 | *] spf-log


Example:

Router# show isis spf-log

 

Displays how often and why the router has run a full shortest path first (SPF) calculation.

  • If the router continues to run SPF without ceasing, there might be an issue regarding a change in the network (intra-area). The cause for the continued SPF calculations could be an interconnecting link that is transitioning up/down/up/down or a metric change. It is normal for the SPF calculation to run a few times when a network change occurs, but then it should cease.
 
Step 15
show isis [process-tag] [ipv6 | *] topology


Example:

Router# show isis topology

 

Displays a list of all connected routers in all areas.

 
Step 16
show isis [area-tag] neighbors[detail]


Example:

Router# show isis neighbors detail

 

Displays IS-IS adjacency information.

  • The show isis neighbor detailcommand output verifies that the right adjacencies have established. A matrix of adjacencies should be prepared before you configure your routers, showing what neighbors should be expected in the adjacencies table, to facilitate verification.
 

Examples

When the show isis neighbors command is entered with the detail keyword, the output provides information on the IS-IS adjacencies that have formed. 

Router1# show isis neighbors detail
System Id      Type Interface IP Address      State Holdtime Circuit Id
Router2         L2   GE1/0/0   10.1.1.0        UP   255      Circuit3.01          
  Area Address(es): 32
  SNPA: aabb.cc00.2001      
  State Changed: 00:00:14
  LAN Priority: 64
  Format: Phase V

Troubleshooting Tips

You can use the following two system debugging commands to check your IS-IS IPv4 implementation.

  • If adjacencies are not coming up properly, use the debug isis adj-packets command.
  • To display a log of significant events during an IS-IS SPF calculation, use the debug isis spf-events command.

Shutting Down IS-IS in Interface Mode

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    isis protocol shutdown

5.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
interface type number


Example:

Router(config)# interface Gigabitethernet 0/0/0

 

Configures an interface and enters interface configuration mode.

 
Step 4
isis protocol shutdown


Example:

Router(config-if)# isis protocol shutdown

 

Disables the IS-IS protocol so that it cannot form adjacencies on a specified interface and places the IP address of the interface into the LSP that is generated by the router.

 
Step 5
end


Example:

Router(config-if)# end

 

Exits interface configuration mode and returns to privileged EXEC mode.

 

Shutting Down IS-IS in Router Mode

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    router isis area-tag

4.    protocol shutdown

5.    end


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
router isis area-tag


Example:

Router(config)# router isis 1

 

Enables the IS-IS routing protocol and specifies an IS-IS process.

  • Enters router configuration mode.
 
Step 4
protocol shutdown


Example:

Router(config-router)# protocol shutdown

 

Prevents IS-IS from forming any adjacency on any interface and clears the IS-IS LSP database, without actually removing the IS-IS configuration.

 
Step 5
end


Example:

Router(config-router)# end

 

Exits router configuration mode and returns to privileged EXEC mode.

 

Configuration Examples for a Basic IS-IS Network

Example Configuring a Basic IS-IS Network

The following example shows how to configure three routers to run IS-IS as an IP routing protocol. The figure below illustrates the sample configuration.

Router A Configuration

router isis
 net 49.0001.0000.0000.000a.00
interface Gigabitethernet 0/0/0
 ip address 10.1.1.1 255.255.255.0
 ip router isis
interface serial 2/0/0
 ip router isis
 ip address 192.168.1.2 255.255.255.0

Router B Configuration

router isis
 net 49.0001.0000.0000.000b.00
interface gigabitethernet 0/0/0
 ip router isis
 ip address 172.17.1.1 255.255.255.0
interface serial2/0/0
 ip router isis
 ip address 192.168.1.1 255.255.255.0
interface serial5/0/0
 ip router isis
 ip address 172.21.1.1 255.255.255.0

Router C Configuration

router isis
 net 49.0001.0000.0000.000c.00
interface gigabitethernet 2/0/0
 ip router isis
 ip address 172.21.1.2 255.255.255.0
interface serial5/0/0
 ip router isis
 ip address 172.22.1.1 255.255.255.0

The show isis topology command displays the following information about how the routers are connected within the IS-IS network: 

RouterB# show isis topology
IS-IS paths to level-1 routers
System Id            Metric     Next-Hop             Interface   SNPA
RouterA              10         RouterA              Se2/0/0     *HDLC*         
RouterB              --
RouterC              10         RouterC              Se5/0/0     *HDLC*         
IS-IS paths to level-2 routers
System Id            Metric     Next-Hop             Interface   SNPA
RouterA              10         RouterA              Se2/0/0     *HDLC*         
RouterB              --
RouterC              10         RouterC              Se5/0/0     *HDLC*

The show isis database command displays following information for the Level 1 and Level 2 LSPs for each router in the IS-IS network. 

RouterB# show isis database
IS-IS Level-1 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
RouterA.00-00         0x00000005   0x1A1D        1063              0/0/0
RouterB.00-00       * 0x00000006   0xD15B        1118              0/0/0
RouterC.00-00         0x00000004   0x3196        1133              1/0/0
IS-IS Level-2 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
RouterA.00-00         0x00000008   0x0BF4        1136              0/0/0
RouterB.00-00       * 0x00000008   0x1701        1137              0/0/0
RouterC.00-00         0x00000004   0x3624        1133              0/0/0

The show ip route command displays information about the interfaces of each router, including their IP addresses and how they are connected to Router B: 

RouterB# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
     172.17.0.0/24 is subnetted, 1 subnets
C       172.17.1.0 is directly connected, gigabitethernet 0/0/0
     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, Serial4/0
     172.21.0.0/24 is subnetted, 1 subnets
C       172.21.1.0 is directly connected, Serial5/0
     172.22.0.0/24 is subnetted, 1 subnets
i L1    172.22.1.0 [115/20] via 172.21.1.2, Serial5/0
     10.0.0.0/24 is subnetted, 1 subnets
i L1    10.1.1.0 [115/20] via 192.168.1.2, Serial2/0
C    192.168.1.0/24 is directly connected, Serial2/0
C    192.168.3.0/24 is directly connected, Serial3/0

The show isis spf-log command displays logs of Level 1 and Level 2 LSPs including time of occurrence, duration, count, and the event that triggered the LSP. 

RouterB## show isis spf-log
   level 1 SPF log
  When   Duration  Nodes  Count    First trigger LSP   Triggers
00:01:30       0      3      7        RouterB.00-00  PERIODIC NEWADJ NEWLSP TLVT
   level 2 SPF log
  When   Duration  Nodes  Count    First trigger LSP   Triggers
00:01:31       0      3      7        RouterB.00-00  PERIODIC NEWADJ NEWLSP TLVT
Figure 1 IS-IS Routing


Example Shutting Down IS-IS in Interface Mode

The following router output shows that the router has two IS-IS adjacencies:

Router# show clns neighbors
System Id  Interface  SNPA            State  Holdtime  Type      Protocol
first      GE3/1/0    0002.7dd6.1c21  Up     25        L1L2      IS-IS
second     GE3/2/0    0004.6d25.c056  Up     29        L1L2      IS-IS

When the isis protocol shutdown command is entered for GigabitEthernet interface 3/1/0, the IS-IS protocol will be disabled for the specified interface:

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface gigabitethernet3/1/0
Router(config-if)# isis protocol shutdown
Router(config-if)# end

The following router output shows that the adjacency for GigabitEthernet interface 3/1/0 has not formed:

Router# show clns neighbors
System Id  Interface  SNPA            State  Holdtime  Type      Protocol
second     GE3/2/0    0004.6d25.c056  Up     27        L1L2      IS-IS

Example Shutting Down IS-IS in Router Mode

The following router output shows that the router has two IS-IS adjacencies:

Router# show clns neighbors
System Id  Interface  SNPA            State  Holdtime  Type      Protocol
south      GE3/1/0    0002.7dd6.1c21  Up     29        L1L2      IS-IS
north      GE3/2/0    0004.6d25.c056  Up     28        L1L2      IS-IS

The protocol shutdown command is entered so that IS-IS is disabled and no adjacencies will be formed on any interface:

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# router isis area1
Router(config-router)# protocol shutdown
Router(config-router)# end

The following router output now shows that both adjacencies are gone.

Router# show clns neighbors
System Id  Interface  SNPA            State  Holdtime  Type      Protocol

When the no protocol shutdown command is entered, the adjacencies will again be formed on both interfaces:

Router(config)# router isis area1
Router(config-router)# no protocol shutdown
Router(config-router)# end
Router# show clns neighbors
System Id  Interface  SNPA            State  Holdtime  Type      Protocol
south      GE3/1/0    0002.7dd6.1c21  Up     24        L1L2      IS-IS
north      GE3/2/0    0004.6d25.c056  Up     24        L1L2      IS-IS

Where to Go Next

  • To customize IS-IS for your network design, see the "Customizing IS-IS for Your Network Design" module.
  • To customize IS-IS for achieving fast convergence and scalability, see the following modules:
    • "Overview of IS-IS Fast Convergence"
    • "Setting Best Practice Parameters for IS-IS Fast Convergence"
    • "Reducing Failure Detection Times in IS-IS Networks"
    • "Reducing Link Failure and Topology Change Notification Times in IS-IS Networks"
    • "Reducing Alternate-Path Calculation Times in IS-IS Networks"
  • To enhance IS-IS network security, see the "Enhancing Security in an IS-IS Network" module.

Additional References

Related Documents

Related Topic

Document Title

IS-IS commands: complete command syntax, command mode, defaults, command history, usage guidelines, and examples

Cisco IOS IP Routing: ISIS Command Reference

Overview of IS-IS concepts

"Integrated IS-IS Routing Protocol Overview" module

Customizing IS-IS for achieving fast convergence and scalability

"Overview of IS-IS Fast Convergence" module

Cisco IOS master command list, all releases

Cisco IOS Master Command List, All Releases

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

--

MIBs

MIB

MIBs Link

  • CISCO-IETF-IP-FORWARD-MIB
  • CISCO-IETF-IP-MIB

To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFC

Title

RFC 1195

Use of OSI IS-IS for Routing in TCP/IP and Dual Environments

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for Configuring a Basic IS-IS Network

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 1 Feature Information for Configuring a Basic IS-IS Network

Feature Name

Releases

Feature Information

Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters

Cisco IOS XE Release 2.1

The Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters feature allows you to disable the IS-IS protocol at the interface level or at the global IS-IS process level without removing the IS-IS configuration parameters.

This feature was introduced on the Cisco ASR 1000 Series Aggregation Services Routers.

The following commands were modified by this feature: isis protocol shutdown.

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2011 Cisco Systems, Inc. All rights reserved.