Enabling IS-IS on the Interface

IS-IS must be enabled on each interface with an IS-IS adjacency. Not all interfaces on an intermediate system participate in IS-IS routing. Because IS-IS is a link-state routing protocol, routing information is not exchanged unless at least one adjacency is formed. In IS-IS, enabling of the IS-IS protocol on an interface begins the adjacency formation process. Therefore, no routing information is exchanged until IS-IS is enabled on at least one interface.

Use the ip router isis command in interface configuration mode to enable IS-IS on an IPv4 interface

The following example shows how to enable IPv4 IS-IS routing on VLAN 100:

System(rw)->configure
System(rw-config)->interface vlan 100
System(rw-config-intf-vlan.0.100)->ip router isis
System(rw-config-isis)->

Use the ipv6 router isis command in interface configuration mode to enable IS-IS on an IPv6 interface.

The following example shows how to enable IPv6 IS-IS routing on VLAN 100:

System(rw)->configure
System(rw-config)->interface vlan 100
System(rw-config-intf-vlan.0.100)->ipv6 router isis
System(rw-config-isis)->

The IS-IS circuit type for the interface defaults to Level 1 and 2. You can change the IS-IS circuit type for the intermediate system to IS-IS type Level 1 or IS-IS type Level 2.

Use the isis circuit-type command to configure the IS-IS circuit type for the interface.

The cost of using an interface can be configured. The cost of using an interface defaults to 10. Use the isis metric command in interface configuration mode to configure the interface metric.