MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels
First Published: March 18, 2002
Last Updated: May 4, 2009
The MPLS Traffic Engineering—Configurable Path Calculation Metric for Tunnels feature enables the user to control the metric used in path calculation for traffic engineering (TE) tunnels on a per-tunnel basis. Certain tunnels are used to carry voice traffic, which requires low delay, and other tunnels are used to carry data. A TE link metric can be used to represent link delay and configure tunnels that carry voice traffic for path calculation and configure tunnels that carry data to use the Interior Gateway Protocol (IGP) metric for path calculation.
Finding Feature Information
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 for MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
•Prerequisites for MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•Restrictions for MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•Information About MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•How to Configure MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•Configuration Examples for Configuring a Path Calculation Metric for Tunnels
•Additional References
•Feature Information for MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
Prerequisites for MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
Before you configure tunnel path calculation metrics, your network must support the following Cisco IOS XE features:
•Multiprotocol Label Switching (MPLS) traffic engineering tunnels
•IP Cisco Express Forwarding
•Open Shortest Path First (OSPF) or Intermediate System-to-Intermediate System (IS-IS)
Restrictions for MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•Unless explicitly configured, the TE link metric for a given link is the IGP link metric. When the TE link metric is used to represent a link property that is different from cost/distance, you must configure every network link that can be used for TE tunnels with a TE link metric that represents that property by using the mpls traffic-eng administrative-weight command. Failure to do so might cause tunnels to use unexpected paths.
•MPLS traffic engineering supports only a single IGP process/instance. Multiple IGP processes/instances are not supported and MPLS traffic engineering should not be configured in more than one IGP process/instance.
Information About MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels Overview
•MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels Benefits
MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels Overview
When MPLS TE is configured in a network, the IGP floods two metrics for every link: the normal IGP (OSPF or IS-IS) link metric and a TE link metric. The IGP uses the IGP link metric in the normal way to compute routes for destination networks.
You can specify that the path calculation for a given tunnel be based on either of the following:
•IGP link metrics.
•TE link metrics, which you can configure so that they represent the needs of a particular application. For example, the TE link metrics can be configured to represent link transmission delay.
MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels Benefits
When TE tunnels are used to carry two types of traffic, the Configurable Path Calculation Metric for Tunnels feature allows you to tailor tunnel path selection to the requirements of each type of traffic.
For example, suppose certain tunnels are to carry voice traffic (which requires low delay) and other tunnels are to carry data. In this situation, you can use the TE link metric to represent link delay and do the following:
•Configure tunnels that carry voice to use the TE link metric set to represent link delay for path calculation.
•Configure tunnels that carry data to use the IGP metric for path calculation.
How to Configure MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
•Configuring a Platform to Support Traffic Engineering Tunnels (required)
•Configuring the IGP (IS-IS or OSPF) for MPLS Traffic Engineering, page 4 (required)
•Configuring Traffic Engineering Link Metrics (required)
•Configuring an MPLS Traffic Engineering Tunnel (required)
•Configuring the Metric Type for Tunnel Path Calculation (required)
•Verifying the Tunnel Path Metric Configuration (optional)
Configuring a Platform to Support Traffic Engineering Tunnels
SUMMARY STEPS
1. enable
2. configure terminal
3. ip cef distributed
4. mpls traffic-eng tunnels
5. exit
DETAILED STEPS
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Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
ip cef distributed
Router(config)# ip cef distributed |
Enables distributed Cisco Express Forwarding operation. |
Step 4 |
mpls traffic-eng tunnels
Router(config)# mpls traffic-eng tunnels |
Enables the MPLS traffic engineering tunnel feature on a device. |
Step 5 |
exit
Router(config)# exit |
Exits global configuration mode and returns to privileged EXEC mode. |
Configuring IS-IS for MPLS Traffic Engineering
Note MPLS traffic engineering supports only a single IGP process/instance. Multiple IGP processes/instances are not supported and MPLS traffic engineering should not be configured in more than one IGP process/instance.
SUMMARY STEPS
1. enable
2. configure terminal
3. router isis
4. mpls traffic-eng {level-1 | level-2}
5. mpls traffic-eng {level-1 | level-2}
6. mpls traffic-eng router-id interface-name
7. metric-style wide
8. exit
9. exit
DETAILED STEPS
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|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
router isis
Router(config)# router isis |
Enables IS-IS routing, specifies an IS-IS process for IP, and enters router configuration. |
Step 4 |
mpls traffic-eng {level-1 | level-2}
Router(config-router)# mpls traffic-eng level-1 |
Configures a router running IS-IS so that it floods MPLS TE link information into the indicated IS-IS level. •This commands turns on MPLS TE for IS-IS level 1. |
Step 5 |
mpls traffic-eng {level-1 | level-2}
Router(config-router)# mpls traffic-eng level-2 |
Configures a router running IS-IS so that it floods MPLS TE link information into the indicated IS-IS level. •This command turns on MPLS TE for IS-IS level 2. |
Step 6 |
mpls traffic-eng router-id interface-name
Router(config-router)# mpls traffic-eng router-id loopback0 |
Specifies that the TE router identifier for the node is the IP address associated with a given interface. •This command specifies the IP address of loopback0 as the TE router ID. |
Step 7 |
metric-style wide
Router(config-router)# metric-style wide |
Configures a router to generate and accept only new-style type, length, value objects (TLVs). |
Step 8 |
exit
Router(config-router)# exit |
Exits router configuration mode and returns to global configuration mode. |
Step 9 |
exit
Router(config)# exit |
Exits global configuration mode and returns to privileged EXEC mode. |
Configuring OSPF for MPLS Traffic Engineering
Note MPLS traffic engineering supports only a single IGP process/instance. Multiple IGP processes/instances are not supported and MPLS traffic engineering should not be configured in more than one IGP process/instance.
SUMMARY STEPS
1. enable
2. configure terminal
3. router ospf process-id]
4. mpls traffic-eng area number
5. mpls traffic-eng router-id interface-name
6. exit
7. exit
DETAILED STEPS
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Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
router ospf process-id
Router(config)# router ospf 100 |
Configures an OSPF routing process for IP and enters router configuration mode. •The process-id argument is an internally used identification parameter for an OSPF routing process. It is locally assigned and can be any positive integer. Assign a unique value for each OSPF routing process. |
Step 4 |
mpls traffic-eng area number
Router(config-router)# mpls traffic-eng area 0 |
Configures a router running OSPF MPLS so that it floods traffic engineering for the indicated OSPF area. •The number argument specifies the OSPF area on which MPLS TE is enabled. |
Step 5 |
mpls traffic-eng router-id interface-name
Router(config-router)# mpls traffic-eng router-id loopback0 |
Specifies that the TE router identifier for the node is the IP address associated with a given interface. •The interface-name argument specifies the IP address of loopback0 as the TE router ID. |
Step 6 |
exit
Router(config-router)# exit |
Exits router configuration mode and returns to global configuration mode. |
Step 7 |
exit
Router(config)# exit |
Exits global configuration mode and returns to privileged EXEC mode. |
Configuring Traffic Engineering Link Metrics
Unless explicitly configured, the TE link metric is the IGP link metric.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type slot/subslot/port[.subinterface-number]
4. mpls traffic-eng administrative-weight weight
5. exit
6. exit
DETAILED STEPS
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|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type slot/subslot/port[.subinterface-number]
Router(config)# interface pos2/0/0 |
Configures an interface type and enters interface configuration mode. •The type argument is the type of interface to be configured. •The slot argument is the chassis slot number. Refer to the appropriate hardware manual for slot information. For SIPs, refer to the platform-specific SPA hardware installation guide or the corresponding "Identifying Slots and Subslots for SIPs and SPAs" topic in the platform-specific SPA software configuration guide. •The /subslot keyword and argument pair is the secondary slot number on a SIP where a SPA is installed. The slash (/) is required. Refer to the platform-specific SPA hardware installation guide and the corresponding "Specifying the Interface Address on a SPA" topic in the platform-specific SPA software configuration guide for subslot information. •The /port keyword and argument pair is the port or interface number. The slash (/) is required. Refer to the appropriate hardware manual for port information. For SPAs, refer to the corresponding "Specifying the Interface Address on a SPA" topics in the platform-specific SPA software configuration guide •The .subinterface-number keyword and argument pair is the subinterface number in the range 1 to 4294967293. The number that precedes the period (.) must match the number to which this subinterface belongs. |
Step 4 |
mpls traffic-eng administrative-weight weight
Router(config-if)# mpls traffic-eng administrative-weight 20 |
Overrides the IGP administrative weight (cost) of the link. •The weight argument is the cost of the link. |
Step 5 |
exit
Router(config-if)# exit |
Exits interface configuration mode and returns to global configuration mode. |
Step 6 |
exit
Router(config)# exit |
Exits global configuration mode and returns to privileged EXEC mode. |
Configuring an MPLS Traffic Engineering Tunnel
This tunnel has two path setup options: a preferred explicit path and a backup dynamic path.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface tunnel number
4. ip unnumbered type number
5. tunnel destination ip-address
6. tunnel mode mpls traffic-eng
7. tunnel mpls traffic-eng bandwidth bandwidth
8. tunnel mpls traffic-eng path-option number {dynamic | explicit {name path-name
| id path-number}} [lockdown]
9. exit
10. exit
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface tunnel number
Router(config)# interface Tunnel0 |
Configures an interface type and enters interface configuration mode. •The number argument is the number of the tunnel. |
Step 4 |
ip unnumbered type number
Router(config-if)# ip unnumbered loopback0 |
Enables IP processing on an interface without assigning an explicit IP address to the interface. •The type and number arguments name the type and number of another interface on which the router has an assigned IP address. It cannot be another unnumbered interface. •An MPLS traffic engineering tunnel interface should be unnumbered because it represents a unidirectional link. |
Step 5 |
tunnel destination ip-address
Router(config-if)# tunnel destination 192.168.4.4 |
Specifies the destination for a tunnel interface. •The ip-address argument must be the MPLS traffic engineering router ID of the destination device. |
Step 6 |
tunnel mode mpls traffic-eng
Router(config-if)# tunnel mode mpls traffic-eng |
Sets the tunnel encapsulation mode to MPLS traffic engineering. |
Step 7 |
tunnel mpls traffic-eng bandwidth bandwidth
Router(config-if)# tunnel mpls traffic-eng bandwidth 250 |
Configures the bandwidth for the MPLS traffic engineering tunnel. •The bandwidth argument is a number in kilobits per second that is set aside for the MPLS traffic engineering tunnel. Range is from 1 to 4294967295. Note If automatic bandwidth is configured for the tunnel, use the tunnel mpls traffic-eng bandwidth command to configure the initial tunnel bandwidth, which is adjusted by the autobandwidth mechanism. |
Step 8 |
tunnel mpls traffic-eng path-option number {dynamic | explicit {name path-name | identifier path-number}} [lockdown]
Router(config-if)# tunnel mpls traffic-eng path-option 10 explicit identifier 321 |
Configures the tunnel to use a named IP explicit path or a path dynamically calculated from the traffic engineering topology database. •The number argument is the preference for this path option. When you configure multiple path options, lower numbered options are preferred. Valid values are from 1 to 1000. •The dynamic keyword indicates that the path of the label switched path (LSP) is dynamically calculated. •The explicit keyword indicates that the path of the LSP is an IP explicit path. •The name path-name keyword and argument are the path name of the IP explicit path that the tunnel uses with this option. •The identifier path-number keyword and argument pair names the path number of the IP explicit path that the tunnel uses with this option. The range is from 1 to 65535. •The lockdown keyword specifies that The LSP cannot be reoptimized. Note A dynamic path is used if an explicit path is currently unavailable. |
Step 9 |
exit
Router(config-if)# exit |
Exits interface configuration mode and returns to global configuration mode. |
Step 10 |
exit
Router(config)# exit |
Exits global configuration mode and returns to privileged EXEC mode. |
Configuring the Metric Type for Tunnel Path Calculation
Unless explicitly configured, the TE link metric type is used for tunnel path calculation. Two commands are provided for controlling the metric type to be used: an interface configuration command that specifies the metric type to be used for a particular TE tunnel and a global configuration command that specifies the metric type to be used for TE tunnels for which a metric type has not been specified by the interface configuration command.
Note If you do not enter either of the path selection metrics commands, the traffic engineering (TE) metric is used.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface tunnel number
4. tunnel mpls traffic-eng path-selection metric {igp | te}
5. exit
6. mpls traffic-eng path-selection metric {igp | te}
7. exit
DETAILED STEPS
|
|
|
Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface tunnel number
Router(config)# interface Tunnel0 |
Configures an interface type and enters interface configuration mode. •The number argument is the number of the tunnel. |
Step 4 |
tunnel mpls traffic-eng path-selection metric {igp | te}
Router(config-if)# tunnel mpls traffic-eng path-selection metric igp |
Specifies the metric type to use for path calculation for a tunnel. •The igp keyword specifies the use of the Interior Gateway Protocol (IGP) metric. •The te keyword specifies the use of the traffic engineering (TE) metric. This is the default. |
Step 5 |
exit
Router(config-if)# exit |
Exits interface configuration mode and returns to global configuration mode. |
Step 6 |
mpls traffic-eng path-selection metric {igp | te}
Router(config)# mpls traffic-eng path-selection metric igp |
Specifies the metric type to use if a metric type was not explicitly configured for a given tunnel. •The igp keyword specifies the use of the Interior Gateway Protocol (IGP) metric. •The te keyword specifies the use of the traffic engineering (TE) metric. This is the default. |
Step 7 |
exit
Router(config)# exit |
Exits global configuration mode and returns to privileged EXEC mode. |
Verifying the Tunnel Path Metric Configuration
SUMMARY STEPS
1. enable
2. show mpls traffic-eng topology
3. show mpls traffic-eng tunnels
4. exit
DETAILED STEPS
Step 1 enable
Use this command to enable privileged EXEC mode. Enter your password if prompted. For example:
Step 2 show mpls traffic-eng topology
Use the show mpls traffic-eng topology command, which displays TE and IGP metrics for each link, to verify that link metrics have been correctly configured for a network. For example:
Router# show mpls traffic-eng topology
My_System_id: 1440.0000.0044.00 (isis level-1)
IGP Id: 0090.0000.0009.00, MPLS TE Id:192.168.9.9 Router Node (isis level-1)
link[0 ]:Nbr IGP Id: 0090.0000.0009.03, gen:7
frag_id 0, Intf Address:10.0.0.99
TE metric:100, IGP metric:48, attribute_flags:0x0 !!Note TE and IGP metrics
physical_bw: 10000 (kbps), max_reservable_bw_global: 0 (kbps)
max_reservable_bw_sub: 0 (kbps)
link[1 ]:Nbr IGP Id: 0055.0000.0055.00, gen:7
frag_id 0, Intf Address:10.205.0.9, Nbr Intf Address:10.205.0.55
TE metric:120, IGP metric:10, attribute_flags:0x0 !!Note TE and IGP metrics
physical_bw: 155000 (kbps), max_reservable_bw_global: 500000 (kbps)
max_reservable_bw_sub: 0 (kbps)
Step 3 show mpls traffic-eng tunnels
Use the show mpls traffic-eng tunnels command, which displays the link metric used for tunnel path calculation, to verify that the desired link metrics are being used for each tunnel. For example:
Router# show mpls traffic-eng tunnels
Name: te3640-17-c_t221 (Tunnel22) Destination: 192.168.100.22
Admin: up Oper: up Path: valid Signalling: connected
path option 1, type dynamic (Basis for Setup, path weight 10)
Bandwidth: 400 kps (Global) Priority: 1 1 Affinity: 0x0/0xFFFF
Metric Type: IGP !!Note metric type
AutoRoute: enabled LockDown: disabled Loadshare: 0 bw-based
auto-bw: disabled(0/115) 0 Bandwidth Requested: 0
Name: te3640-17-c_t222 (Tunnel33) Destination: 192.168.100.22
Admin: up Oper: up Path: valid Signalling: connected
path option 1, type dynamic (Basis for Setup, path weight 10)
Bandwidth: 200 kbps (Global) Priority: 1 1 Affinity: 0x0/0xFFFF
Metric Type: TE !!Note metric type
AutoRoute: enabled LockDown: disabled Loadshare: 0 bw-based
auto-bw: disabled(0/115) 0 Bandwidth Requested: 0
Step 4 exit
Use this command to return to user EXEC mode. For example:
Configuration Examples for Configuring a Path Calculation Metric for Tunnels
•Example: Configuring Link Type and Metrics for Tunnel Path Selection
Example: Configuring Link Type and Metrics for Tunnel Path Selection
The section illustrates how to configure the link metric type to be used for tunnel path selection, and how to configure the link metrics themselves. The configuration commands included focus on specifying the metric type for path calculation and assigning metrics to links. Additional commands are required to fully configure the example scenario: for example, the IGP commands for traffic engineering and the link interface commands for enabling traffic engineering and specifying available bandwidth.
The examples in this section support the simple network technology shown in Figure 1.
Figure 1 Network Topology
In Figure 1:
•Tunnel1 and Tunnel2 run from R1 (headend) to R4 (tailend).
•Tunnel3 runs from R1 to R5.
•Path calculation for Tunnel1 and Tunnel3 should use a metric that represents link delay because these tunnels carry voice traffic.
•Path calculation for Tunnel2 should use IGP metrics because MPLS TE carries data traffic with no delay requirement.
Configuration fragments follow for each of the routers that illustrate the configuration relating to link metrics and their use in tunnel path calculation. TE metrics that represent link delay must be configured for the network links on each of the routers, and the three tunnels must be configured on R1.
These configuration fragments force Tunnel1 to take path R1-R3-R4, Tunnel2 to take path R1-R2-R4, and Tunnel3 to take path R1-R3-R4-R5 (assuming the links have sufficient bandwidth to accommodate the tunnels).
R1 Configuration
The following example shows how to configure the tunnel headend (R1) for Tunnel1, Tunnel2, and Tunnel3 in Figure 1:
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
interface Tunnel1 !Tunnel1 uses TE metric (default)
tunnel destination 192.168.4.4 255.255.255.0
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 dynamic
interface Tunnel2 !Tunnel2 uses IGP metric
tunnel destination 192.168.4.4 255.255.255.0
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 dynamic
tunnel mpls traffic-eng path-selection-metric igp !Use IGP cost for path selection.
interface Tunnel3 !Tunnel3 uses TE metric (default)
tunnel destination 192.168.5.5 255.255.255.0
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng bandwidth 1000
tunnel mpls traffic-eng path-option 1 dynamic
R2 Configuration
The following example shows how to configure R2 in Figure 1:
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 40 !TE metric different from IGP metric
R3 Configuration
The following example shows how to configure R3 in Figure 1:
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 5 !TE metric different from IGP metric
R4 Configuration
The following example shows how to configure R4 in Figure 1:
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 5 !TE metric different from IGP metric
R5 Configuration
The following example shows how to configure R5 in Figure 1:
mpls traffic-eng administrative-weight 15 !TE metric different from IGP metric
mpls traffic-eng administrative-weight 5 !TE metric different from IGP metric
Additional References
Related Documents
Standards
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No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
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MIBs
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No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. |
To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs |
RFCs
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No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified. |
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Technical Assistance
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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 MPLS Traffic Engineering—Configurable Path Calculation Metrics for Tunnels
Table 1 lists the features in this module and provides links to specific configuration information
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 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.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at 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. (1005R)
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
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