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The MPLS Traffic Engineering (TE)--IP Explicit Address Exclusion feature provides a means to exclude a link or node from the path for Multiprotocol Label Switching (MPLS) TE label switched path (LSP).
The feature is enabled through the ip explicit-path command that allows you to create an IP explicit path and enter a configuration submode for specifying the path. The feature adds to the submode commands the exclude-address command for specifying addresses to exclude from the path.
If the excluded address for an MPLS TE LSP identifies a flooded link, the constraint-based shortest path first (CSPF) routing algorithm does not consider that link when computing paths for the LSP. If the excluded address specifies a flooded MPLS TE router ID, the CSPF routing algorithm does not allow paths for the LSP to traverse the node identified by the router ID.
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.
Your network must support the following Cisco IOS features in order to support IP explicit address exclusion:
MPLS TE will accept an IP explicit path comprised of either all excluded addresses configured by the exclude-address command or all included addresses configured by the next-addresscommand, but not a combination of both.
MPLS is an Internet Engineering Task Force (IETF)-specified framework that provides for the efficient designation, routing, forwarding, and switching of traffic flows through the network.
Traffic engineering (TE) is the process of adjusting bandwidth allocations to ensure that enough is left for high-priority traffic.
In MPLS TE, the upstream router creates a network tunnel for a particular traffic stream, then fixes the bandwidth available for that tunnel.
Cisco Express Forwarding is an advanced, Layer 3 switching technology inside a router. It defines the fastest method by which a Cisco router forwards packets from ingress to egress interfaces. The ip cef command enables Cisco Express Forwarding globally, and the ip route-cache cefcommand enables Cisco Express Forwarding on an interface.
Command or Action | Purpose | |||
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Example: Router> enable |
Enables privileged EXEC mode.
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Example: Router# configure terminal |
Enters global configuration mode. |
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Example: Router(config)# interface tunnel11 |
Configures an interface type and enters interface configuration mode. |
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Example: Router(config-if)# ip unnumbered loopback0 |
Assigns the tunnel interface an IP address.
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Example: Router(config-if)# tunnel destination 10.11.11.11 |
Specifies the destination for a tunnel.
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Example: Router(config-if)# tunnel mode mpls traffic-eng |
Sets the tunnel encapsulation mode to MPLS traffic engineering. |
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Example: Router(config-if)# tunnel mpls traffic-eng bandwidth 100 |
Configures the bandwidth for the MPLS traffic engineering tunnel. |
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Example: Router(config-if)# tunnel mpls traffic-eng path-option 2 dynamic |
Configures the tunnel to use a named IP explicit path or a path dynamically calculated from the traffic engineering topology database.
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Example: Router(config-if)# exit |
Exits from interface configuration mode. |
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Example: Router# show mpls traffic eng tunnels |
Shows information about tunnels, including the current tunnel path if a tunnel is operational.
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The following example shows how to configure an MPLS TE tunnel with two path options: a preferred explicit path with an excluded address and a backup dynamic path.
Configure the IP explicit path named OmitR12, which excludes the router with router ID 10.12.12.12:
ip explicit-path name OmitR12 exclude-address 10.12.12.12 Explicit Path name OmitR12: 1: exclude-address 10.12.12.12 exit
To verify the configuration of the explicit path, use the show ip explicit-path command.
show ip explicit-paths name OmitR12 PATH OmitR12 (loose source route, path complete, generation 3) 1: exclude-address 10.12.12.12
Note |
You must know the router IDs for LSRs (nodes) in the network; in this example, that 10.12.12.12 is a router ID. Otherwise, it will not be apparent whether the specified address is the IP address of a link or a router ID. |
The following example configures Tunnel11 with its two options, where the preferred path option is the IP explicit path OmitR2:
interface tunne l11 ip unnumbered loopback0 tunnel destination 10.11.11.11 tunnel mode mpls traffic-eng tunnel mpls traffic-eng path-option 1 explicit name OmitR12 tunnel mpls traffic-eng path-option 2 dynamic
Note |
There are additional commands for configuring properties for TE tunnels such as bandwidth and priority. For descriptions of those commands, refer to the Cisco IOS IP Switching Services Configuration Guide . |
Related Topic |
Document Title |
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MPLS commands |
Cisco IOS Multiprotocol Label Switching Command Reference |
Standard |
Title |
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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. |
-- |
MIB |
MIBs Link |
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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 IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFC |
Title |
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No new or modified RFCs are supported by this release. |
-- |
Description |
Link |
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The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
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 MPLS Traffic Engineering (TE)--IP Explicit Address Exclusion |
Feature Name |
Releases |
Feature Configuration Information |
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MPLS Traffic Engineering (TE)--IP Explicit Address Exclusion |
12.0(14)ST 12.2(4)T 12.2(4)T2 12.2(14)S 12.0(32)S 12.2(28)SB |
The MPLS Traffic Engineering (TE)--IP Explicit Address Exclusion feature provides a means to exclude a link or node from the path for Multiprotocol Label Switching (MPLS) TE label switched path (LSP). The following command was introduced by this feature: exclude-address. In 12.0(14)ST, this feature was introduced. In 12.2(4)T, this feature was integrated into Release 12.2(4)T. In 12.2(4)T2, this feature was integrated into Release 12.2(4)T2. In 12.2(14)S, this feature was integrated into Release 12.2(14)S. In 12.0(32)S, this feature was integrated into Release 12.0(32)S. In 12.2(28)SB, this feature was integrated into Release 12.2(28)SB. |
CEF --Cisco express forwarding. A means for accelerating the forwarding of packets within a router, by storing route lookup information in several data structures instead of in a route cache.
IP explicit path --A list of IP addresses, each representing a node or link in the explicit path.
link --Network communications channel consisting of a circuit or transmission path and all related equipment between a sender and a receiver. Sometimes referred to as a line or a transmission link.
MPLS --Multiprotocol Label Switching. Switching method that forwards IP traffic using a label. This label instructs the routers and the switches in the network where to forward the packets based on preestablished IP routing information.
node --Endpoint of a network connection or a junction common to two or more lines in a network. Nodes can be interconnected by links, and serve as control points in the network.
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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.