LNS Configuration Prerequisites

Before you begin configuring the router as an LNS, perform the following steps:

  1. Create a virtual router.
    host1(config)#virtual-router west
  2. Assign a router ID IP address, such as that for a loopback interface, to the virtual router. This address must be reachable by the L2TP peer.
    host1:west(config)#ip router-id

    Caution: You must explicitly assign a router ID to a virtual router rather than using a dynamically assigned router ID. A fixed ID is required because every time the ID changes, L2TP must disconnect all existing tunnels and sessions that use the old ID. If you use a dynamically assigned router ID, the value can change without warning, leading to failure of all L2TP tunnels and sessions. Also, the router could dynamically assign a router ID that is not reachable by the L2TP peer, causing a complete failure of L2TP. You must set the router ID even if you specified a source address in the domain map or a local address in the host profile.

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