Specifying the Egress LER

The egress LER is the router from which packets exit the MPLS domain in this LSP.

Each LSP requires one and only one egress LER. After the LSP is successfully established, the address of the egress LER is installed as an internal host route on the ingress LER, allowing the ingress LER to direct BGP next-hop traffic into the LSP. The destination address does not necessarily have to be the final node in the primary path specified for the LSP. When the final node in the path differs from the destination address, the hop between the final node in the path and the egress LER is treated as a loose hop.

To specify 10.100.1.1 as the address of the egress LER for LSP tunnel1, complete the following steps.

  1. Enable the device for configuration.
    device# configure
  2. Enable the MPLS router.
    device(config)# router mpls
  3. Enable the specified label switched path (LSP).
    device(config-router-mpls)# lsp tunnel1
    In this example, the specified LSP is tunnel1.
  4. Specify node as the address of the egress LER for a LSP.
    device(config-router-mpls-lsp)# to 10.100.1.1
    In this example, address 10.100.1.1 is configured as the address of the egress LER for LSP tunnel1.

Example

The following example shows how to specify 10.100.1.1 as the address of the egress LER for LSP tunnel1.

device# configure 
device(config)# router mpls
device(config-router-mpls)# lsp tunnel1
device(config-router-mpls-lsp)# to 10.100.1.1
Note

Note

When IS-IS is used as the IGP, the egress LER advertises the tunnel destination must be in Extended IP Reachability TLV 135 in order for the LSP to be properly mapped by CSPF. To ensure that this happens, connect to the egress LER and enable IS-IS on the interface which has the IP address of the tunnel destination. When none of the interfaces on the egress LER has the IP address of the tunnel destination (for example, when the tunnel destination address is the egress LER‘s router ID) rather than an interface address -- to manually set the router ID, then the tunnel destination address must be included in Traffic Engineering router ID TLV 134 in the LSP originated by the egress LER. This is accomplished by setting the egress LER‘s traffic engineering policy to IS-IS with the traffic engineering isis level command