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Hierarchy Level


Modify the maximum size of IS-IS link-state PDUs. IS-IS sends link-state PDUs out of IS-IS enabled interfaces to distribute routing information between the IS-IS nodes. You can configure the maximum lsp size per level or at the global level. If configured at both global and per level, the per level setting takes precedence.


Set the max lsp size to a value less than or equal to the MTU of all the interfaces within the ISIS domain. Otherwise the bigger size LSP will not get flooded to all the nodes in the domain, which might lead to traffic loss and unforeseen events.



Maximum size allocated for IS-IS link-state PDUs.

  • Range: 512 through 9192 bytes

  • Default: 1492 bytes

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 12.1.

Per Level statement introduced in Junos OS Release 23.1