IS-IS Server Configuration

To configure the IS-IS server, start in config-frr-isis mode and run the server vrf <name> command, where <name> is the name of a Virtual Routing and Forwarding instance or default for the default route table:

tnsr(config)# route dynamic isis
tnsr(config-frr-isis)# server vrf default
tnsr(config-isis)#

This changes into config-isis mode which contains the following commands:

admin-group-send-zero:

Allow sending default admin group 0.

advertise-high-metrics:

Advertise a high metric value on all interfaces to discourage use of this router by peers.

The default value varies by metric type. The value is 63 for narrow metrics, 16777215 for wide metrics, and 62 for transition metrics.

See also

RFC 3277

advertise-passive-only:

Instructs the daemon to only advertise prefixes for passive interfaces, not active interfaces.

area-password <options>:

Configures authentication for IS-IS level 1.

authenticate-snp send-only:

Send authenticated PDUs, do not check inbound.

authenticate-snp validate:

Send authenticated PDUs, check inbound.

clear <password>:

Sets a clear-text password, 1-254 characters in length.

md5 <password>:

Sets an MD5 hash password, which is a 32 character hexadecimal string.

area-tag <name>:

Mandatory unique name identifying this IS-IS server instance. The same name must be configured on interfaces associated with this server.

asla-legacy-flag:

Set legacy flag in LSP ASLA Sub-TLV.

attached-bit-receive-ignore:

Ignore the attached bit on received LSP for inter-area traffic. When set, this router will not create a default route to the neighbor even if one is advertised by the neighbor.

default-information originate (ipv4|ipv6) (level-1|level-2) (always|metric <metric>|route-map <route-map>):

Configures distribution of a default route to the specified level.

always:

Always advertise default route, even when there is no default route in the table.

metric <metric>:

Sets a metric value for the default route. The default value is 0 (use default).

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.

route-map <route-map>:

Use a route map to control distribution.

disable-attached-bit-send:

Do not set attached bit in inter-area LSP messages transmitted to L1 routers when acting as a level-1-2 router.

disable-dynamic-hostname:

Disable dynamic hostname exchange between neighbors.

When this is unset, IS-IS status output can replace the System ID of neighbors with hostnames in certain contexts to make identifying peers easier, similar to DNS resolution.

See also

The show route dynamic isis hostname command displays the current system ID to hostname mappings. See Hostname to System ID Mappings for details.

domain-password <options>:

Configures authentication for IS-IS level 2.

authenticate-snp send-only:

Send authenticated PDUs, do not check inbound.

authenticate-snp validate:

Send authenticated PDUs, check inbound.

clear <password>:

Sets a clear-text password, 1-254 characters in length.

md5 <password>:

Sets an MD5 hash password, which is a 32 character hexadecimal string.

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

Configures loop-free alternate (LFA) fast-reroute behavior. This allows IS-IS to pre-determine alternate paths to a destination so that traffic can take those backup paths if preferred paths fail.

disable-load-sharing:

Disable load-share across multiple backups.

priority-limit (critical|high|medium):

Minimum priority to consider for LFA backup calculation.

tiebreaker (downstream|lowest-backup-metric|node-protecting) index <index>:

Tie-breaker for multiple LFA backups.

  • downstream: Downstream node as the backup path.

  • lowest-backup-metric: Node with the lowest total metric as the backup path.

  • node-protecting: Node protecting the backup path.

  • index <index>: Numeric priority. Smaller value is higher priority.

    Value must be in the range 1..255.

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

Configures the IS-IS Level for this router.

level-1:

Level 1 only.

level-1-2:

Levels 1 and 2. (Default)

level-2:

Level 2 only.

log-adjacency-changes:

Log changes to adjacencies for this IS-IS server.

log-pdu-drops:

Log dropped PDUs for this IS-IS server.

lsp mtu <mtu>:

Configures the maximum LSP size in bytes.

This value must be in the range 128-4352, default: 1497.

lsp timers (level-1|level-2) (gen-interval|max-lifetime|refresh-interval) <seconds>:

Configures LSP timers for a given level.

gen-interval <seconds>:

The minimum interval between generation of LSPs, in seconds.

This value must be in the range 1-120, default: 30.

This value must be less than the value of refresh-interval.

max-lifetime <seconds>:

The maximum lifetime for an LSP, in seconds.

This value must be in the range 350-65535, default: 1200.

This value must be greater than or equal to the value of refresh-interval plus 300 seconds.

refresh-interval <seconds>:

The interval between refresh of LSPs, in seconds.

This value must be in the range 1-65535, default: 900.

metric-style (narrow|transition|wide):

Configures the style of TLVs and range of metric values supported by this server.

narrow:

Narrow IS-IS TLV style used by older IS-IS implementations which follow ISO/IEC 10589. Narrow metric values can rage between 0-63 with a total of 1023 for a path.

Use this style when inter-operating with legacy IS-IS routers.

transition:

Both wide and narrow IS-IS metric styles.

wide:

Modern TLV style capable of carrying wider IS-IS metric values in the range 0-16777215. This is the default style

net <address>:

Network Entity Title (NET). Unique identifier which acts as a router ID for this server. Must follow the format of an OSI NSAP address.

See also

See Network Entity Title (NET) for more information including how to form a complete NET value.

purge-originator:

RFC 6232 purge originator identification.

redistribute (ipv4|ipv6) (bgp|connected|kernel|ospf) (level-1|level-2) (metric <metric>|route-map <route-map>):

Enables redistribution of routes from another source to the specified level.

Available route sources are listed in Dynamic Routing Protocol Lists.

metric <metric>:

Metric for redistributed routes.

Value must be in the range 0..16777215, default: 0 (use default).

route-map <route-map>:

Apply the given route map to the redistributed route advertisements.

set-overload-bit:

Sets the overload bit in LSP messages which indicates to peers that this router is overloaded and they should avoid this router.

set-overload-bit-on-startup <value>:

Duration of time after startup, in seconds, during which this router sets the overload bit.

This behavior helps to avoid problematic routing while services on this router are initialized at boot time.

spf backoff-delay <option>:

Configures parameters for Shortest Path First (SPF) algorithm backoff delay (RFC 8405).

enable:

Enable SPF backoff delay.

holddown <holddown>:

Time with no received events before IGP considered stable, in milliseconds.

This value must be in the range 0-60000, default: 10000.

This value must be larger than the time-to-learn delay.

init-delay <init-delay>:

Delay used while in QUIET state, in milliseconds.

This value must be in the range 0-60000, default: 50.

long-delay <long-delay>:

Delay used while in LONG_WAIT state, in milliseconds.

This value must be in the range 0-60000, default: 5000.

This value must be greater than or equal to the short-delay value.

short-delay <short-delay>:

Delay used while in SHORT_WAIT state, in milliseconds.

This value must be in the range 0-60000. default: 200.

This value must be greater than or equal to the init-delay value.

time-to-learn <time-to-learn>:

Maximum time needed to learn all events for a single failure, in milliseconds.

This value must be in the range 0-60000, default: 500.

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

Interval between Shortest Path First algorithm executions.

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

spf prefix-priority (critical|high|medium) <access-list>:

Shortest Path First algorithm prefix priority.

critical:

Critical priority

high:

High priority

medium:

Medium priority

<access-list>:

Access list to match.