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level (IS-IS Interfaces)

 

Syntax

Hierarchy Level

Release Information

Statement introduced before Junos OS Release 7.4.

Statement introduced in Junos OS Release 9.0 for EX Series switches.

Description

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.

Options

level-numberThe IS-IS level number, which can be 1 or 2. The default is for the device to operate as both a Level 1 and 2 device.
hello-authentication-key passwordConfigure an authentication key (password) for hello packets. Neighboring routing devices use the password to verify the authenticity of packets sent from an interface. For the key to work, you also must include the hello-authentication-type statement. 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. The authentication password can be up to 255 characters. Characters can include any ASCII strings. If you include spaces, enclose all characters in quotation marks (“ ”).
hello-authentication-key-chain key-chain-nameApply an authentication keychain to the IS-IS interface. The authentication keychain name key-chain-name can be up to 126 characters. Characters can include any ASCII strings. If you include spaces, enclose all characters in quotation marks (“ ”).
hello-authentication-type (md5 | simple)Enable authentication on an interface for hello packets. If you enable authentication on hello packets, you must specify a password by including the hello-authentication-key statement. You can configure authentication for a given IS-IS level on an interface. On a point-to-point link, if you enable hello authentication for both IS-IS levels, the password configured for Level 1 is used for both levels.
Caution

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.

hello-interval secondsModify the frequency with which the routing device sends hello packets out of an interface, in seconds. Routing devices send hello packets at a fixed interval on all interfaces to establish and maintain neighbor relationships. This interval is advertised in the hello interval field in the hello packet. You can send out hello packets in subsecond intervals. To send out hello packets every 333 milliseconds, set the hold-time value to 1.

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).

Note

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.

ipv4-multicast-metric metricSpecify the IPv4 multicast topology metric value for the level. The value for metric can range from 0 through 16,777,215.
ipv6-multicast-metric metricSpecify the IPv6 alternate multicast topology metric value for the level. The value for metric can range from 0 through 16,777,215.
ipv6-unicast-metric metricSpecify the IPv6 unicast topology metric value for the level. The IS-IS interface metrics for the IPv4 topology can be configured independently of the IPv6 metrics. The value for metric can range from 0 through 16,777,215.
priority numberConfigure the interface’s priority for becoming the designated router. The interface with the highest priority value becomes that level’s designated router. The priority value is meaningful only on a multiaccess network. It has no meaning on a point-to-point interface.

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.

srv6-adjacency-segment Configure the SRv6 adjacency segment options.
protected | unprotectedEnable or disable TI-LFA backup protection.
locatorSpecify the address to which the end-x-sid function is assigned. Ensure that the locator address and interface address belong to the same prefix to avoid unexpected network behavior.
end-x-sid sidSpecify the function for the SRv6 adjacency.
flavorSpecify the behavior of the end-x-sid function such as penultimate segment pop (psp), ultimate segment pop (usp) or ultimate segment decapsulation (usd).
te-metric metricSet the metric value used by traffic engineering for information injected into the traffic engineering database. The value of the traffic engineering metric does not affect normal IS-IS forwarding. When traffic engineering is enabled on the routing device, you can use this statement to configure an IS-IS metric that is used exclusively for traffic engineering. The value for metric can range from 1 through 16,777,215. The default is the value of the IGP metric.

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.