Configuring L2 Routers

To configure a switch to operate as a level 2 IS-IS router, do the following:

  1. Prepare the IP interfaces that will support level 2 IS-IS routing as follows:
    1. Add an IPv4 or IPv6 address.
    2. Enable IP or IPv6 forwarding.
  2. Create the IS-IS routing process, which is also called an area, using the following command:
    create isis area area_name
  3. Configure the routing process to serve as a L2-only router using the following command:
    configure isis area area_name is-type level [1 | 2 | both-1-and-2]

    Specify 2 for the level option.

  4. Add an IS-IS area level-2 address to the router using the following command:
    configure isis area area_name add area-address area_address
  5. Add IS-IS-eligible interfaces to level 2 using the following command:
    configure isis add [vlan all | {vlan} vlan_name] area area_name {ipv4 | ipv6}
    An IS-IS-eligible interface is one that already has the appropriate IP address type (IPv4 or IPv6) address assigned to it.
  6. Add an IS-IS system ID to the router using the following command:
    configure isis area area_name system-id [automatic | system_id]
    Use the automatic option to assign the switch MAC address to the IS-IS system ID. The default option is automatic, so you can also enter the command without options to select the switch MAC address.
  7. Enable the ISIS router using the following command:
    enable isis {area area_name}
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