level (IS-IS Interfaces)
Statement introduced before Junos OS Release 7.4.
Statement introduced in Junos OS Release 9.0 for EX Series switches.
Configure the IS-IS level. You can configure one instance of Level 1 routing and one instance of Level 2 routing on each interface, and you can configure the two levels differently.
If no authentication is configured for Level 1 on a point-to-point link with both levels enabled, the hello packets are sent without any password, regardless of the Level 2 authentication configurations.
By default, hello authentication is not configured on an interface. However, if IS-IS authentication is configured, the hello packets are authenticated using the IS-IS authentication type and password.
md5— Specifies Message Digest 5 as the packet verification type.
simple—Specifies simple authentication as the packet verification type.
The valid range is from 1 to 20,000 seconds. The default is 3 seconds (for designated intermediate system [DIS] routers), 9 seconds (for non-DIS routers).
When elected as a designated intermediate system [DIS] router on any LAN adjacency, the hello and hold-timer intervals are scaled down by a factor of 3. This means the default values of 9 and 27 seconds of ISIS hello and hold time intervals are scaled down to 3 and 9 seconds for LAN adjacencies. During switchovers, this hello interval is too short to form LAN adjacencies. Therefore, you can configure one of the following solutions:
Set the hello and hold time interval for LAN adjacencies to 30 seconds and 90 seconds respectively on both the DIS and a neighboring router.
Convert the LAN interfaces to point-to-point IS-IS interfaces.
On QFX10000 switches, we strongly recommend that you configure all IS-IS interfaces, including peer interfaces, as point-to-point interfaces. If you do not, you might experience session flaps, that is, IS-IS sessions that go down and then come back up, when IS-IS is configured in virtual routing and forwarding (VRF) instances. When you scale IS-IS in any scenario, you might also experience scaling issues if you do not configure IS-IS interfaces as point-to-point interfaces.
A routing device advertises its priority to become a designated router in its hello packets. On all multiaccess networks, IS-IS uses the advertised priorities to elect a designated router for the network. This routing device is responsible for sending network link-state advertisements, which describe all the routing devices attached to the network. These advertisements are flooded throughout a single area. A routing device’s priority for becoming the designated router is indicated by an arbitrary number from 0 through 127. Routing devices with a higher value are more likely to become the designated router. The default priority value is 64.
The remaining statements are explained separately. See CLI Explorer.
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.