prefix-export-limit (Protocols IS-IS)
Syntax
prefix-export-limit number;
Hierarchy Level
[edit logical-systems logical-system-name protocols isis level level-number], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols isis level level-number], [edit protocols isis level level-number], [edit routing-instances routing-instance-name protocols isis level level-number]
Description
Configure a limit to the number of prefixes exported into IS-IS.
By default, there is no limit to the number of prefixes that
can be exported into IS-IS. To configure a limit to the number of
prefixes that can be exported into IS-IS, include the prefix-export-limit statement. The prefix-export-limit statement protects
the rest of the network from a malicious policy by applying a threshold
filter for exported routes.
The number of prefixes depends on the size of your network. Good design advice is to set it to double the total number of IS-IS Level 1 and Level 2 routing devices in your network.
If the number of prefixes exported into IS-IS exceeds the configured
limit, the overload bit is set and the overload state is reached.
When other routers detect that this bit is set, they do not use this
routing device for transit traffic, but they do use it for packets
destined to the overloaded routing device’s directly connected
networks and IP prefixes. The overload state can be cleared by using
the clear isis overload command.
The show isis overview command displays the prefix export limit when it is configured.
Options
number—Prefix limit.
Range: 0 through 4,294,967,295 (232 – 1)
Default: None
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced before Junos OS Release 7.4.