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Routing & Switching · Intermediate

Link-State PDU (LSP)

The IS-IS packet that carries a router's link-state information, analogous to an OSPF LSA.

Definition

Each router generates one LSP (possibly fragmented) per level describing adjacencies and reachable prefixes as TLVs. LSPs have a sequence number and remaining lifetime that counts down from 1200 seconds by default, and are refreshed every 15 minutes. LSPs are flooded throughout the level.

Example

show isis database detail

Exam tip

In IS-IS context, LSP means link-state PDU, not an MPLS label switched path.

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