Configuring L2 Routers

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

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.
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 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.
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 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.
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.
Enable the ISIS router using the following command:
enable isis {area area_name}