Configuring the IS level and circuit level
Follow these guidelines when you configure the IS level for routers in only one area:
Configure the IS level of all routers as Level-1 or Level-2 rather than different levels because the routers do not need to maintain two identical LSDBs.
Configure the IS level as Level-2 on all routers in an IP network for good scalability.
For an interface of a Level-1 or Level-2 router, the circuit level can only be Level-1 or Level-2. For an interface of a Level-1-2 router, the default circuit level is Level-1-2. If the router only needs to form Level-1 or Level-2 neighbor relationships, configure the circuit level for its interfaces as Level-1 or Level-2. This will limit neighbor relationship establishment.
To configure the IS level and circuit level:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter IS-IS view. | isis [ process-id ] [ vpn-instance vpn-instance-name ] | N/A |
3. Specify the IS level. | is-level { level-1 | level-1-2 | level-2 } | By default, the IS level is Level-1-2. |
4. Return to system view. | quit | N/A |
5. Enter interface view. | interface interface-type interface-number | N/A |
6. Specify the circuit level. | isis circuit-level [ level-1 | level-1-2 | level-2 ] | By default, an interface can establish either the Level-1 or Level-2 adjacency. |