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Configuring L1/L2 Routers

To configure a switch to operate as a L1/L2 IS-IS router, do the following:

  1. Prepare the IP interfaces that will support level 1 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 an L1/L2 router using the following command:
    configure isis area area_name is-type level [1 | 2 | both-1-and-2]
    Specify both-1-and-2 for the level option using the following command:
    Note

    Note

    When no other L2 processes are defined on the router, the default IS type level is L1/L2, and this command can be omitted.
  4. Add an IS-IS area level-1 address to the router using the following command:
    configure isis area area_name add area-address area_address
  5. 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
  6. Add IS-IS-eligible interfaces to the area 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.
  7. If your topology requires interfaces to operate at a specific topology level, configure the appropriate interfaces with the following command:
    configure isis [vlan all | {vlan} vlan_name] circuit-type level [1 | 2 | both-1-and-2]
  8. The default IS-IS system ID is the switch MAC address. If you want to change the default IS-IS system ID, use the following command:
    configure isis area area_name system-id [automatic | system_id]
    Note

    Note

    Although the IS-IS protocols manage IP routing, they use the Connectionless Network Protocol (CLNP) for IS-IS communications between routers. The IS-IS system ID is required to identify the router in the AS.
  9. Enable the IS-IS router using the following command:
    enable isis {area area_name}
Published March 2020prev | next

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