Configuring L1/L2 Routers

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

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.
Create the IS-IS routing process, which is also called an area, using the following command:
create isis area area_name
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
When no other L2 processes are defined on the router, the default IS type level is L1/L2, and this command can be omitted.
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
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
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.
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]
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
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.
Enable the IS-IS router using the following command:
enable isis {area area_name}