IS-IS Interface Configuration

IS-IS must use one or more interfaces to announce itself to neighbors and receive announcements from neighbors. At least one interface must be configured and active in order to locate neighbors and form an adjacency.

Warning

Due to the fact that IS-IS operates at L2, active IS-IS interfaces must be able to carry L2 information. Currently this is limited to Ethernet interfaces as well as GRE interfaces in Transparent Ethernet Bridging (TEB) mode.

To configure an interface for use with IS-IS, start in config-frr-isis mode and run the interface <name> command to enter config-isis-if mode:

tnsr(config)# route dynamic isis
tnsr(config-frr-isis)# interface CCLINK
tnsr(config-isis)#

config-isis-if mode contains the following commands:

area-tag <name>:

Name used when defining an IS-IS server instance.

circuit-type (level-1|level-1-2|level-2):

Configures the IS-IS Level for this interface.

level-1:

Level 1 only.

level-1-2:

Levels 1 and 2.

level-2:

Level 2 only.

Warning

The level of an interface must not conflict with level defined on the server. For example, if the server is defined as level 1 only, an interface cannot be level 2 only.

disable-three-way-handshake:

Disable three-way handshake (RFC 5303) when forming adjacencies across point-to-point interfaces.

hello (level-1|level-2) interval <interval>:

Hold time between hello PDUs.

This value must be in the range 1-600, default: 3.

hello (level-1|level-2) multiplier <multiplier>:

Multiplier for hello interval.

This value must be in the range 2-100, default: 10.

hello padding (always|disabled|during-adjacency-formation):

Controls padding of Hello PDUs. When padding is enabled, the size of the PDU packet is equal to the interface MTU.

always:

All hello packets are padded.

disabled:

No hello packets are padded.

during-adjacency-formation:

Hello packets are padded during adjacency formation only.

ipv4:

Enable IS-IS for IPv4 routing on this interface.

Warning

At least one of ipv4 or ipv6 must be set.

ipv6:

Enable IS-IS for IPv6 routing on this interface.

Warning

At least one of ipv4 or ipv6 must be set.

(level-1|level-2) csnp-interval <csnp-interval>:

Complete Sequence Number PDU generation interval.

This value must be in the range 1-600, default: 10.

(level-1|level-2) fast-reroute lfa <options>:

Configures loop-free alternate (LFA) fast-reroute behavior for this interface.

enable:

Enable LFA computation (Default: disabled).

exclude-interface <interface>:

Excludes an interface from LFA computation.

(level-1|level-2) metric <metric>:

Default metric for this interface. The default value is 10.

This value must be in the range 0-16777215 if the metric-type on the server is wide or transitional.

This value must be in the range 0-63 if the metric-type on the server is narrow.

(level-1|level-2) priority <priority>:

Priority of this router for Designated Router (DR) election at the given level.

This value must be in the range 0-127, default: 64.

(level-1|level-2) psnp-interval <psnp-interval>:

Partial Sequence Number PDU generation interval.

This value must be in the range 1-120, default: 2.

passive:

Marks this interface as passive. IS-IS does not advertise for neighbors on, or receive routes through, passive interfaces. IS-IS will advertise the networks on passive interfaces as reachable through this router.

Note

Loopback interfaces are always passive as they cannot be directly connected to any peer. Loopback interfaces cannot have the passive attribute unset.

password (clear|md5) <password>:

Authentication password for this interface.

point-to-point:

Defines this interface as a point-to-point connection to a neighbor. When unset, the interface is treated as broadcast (default).

Note

This must be set when configuring IS-IS on TEB GRE tunnel interfaces.