IS-IS Link-State Packets

Level 1 and Level 2 LSPs are similar in format even though each type of packet carries information for different levels of the IS-IS routing hierarchy. This section reviews the generic LSP packet format and identifies differences between Level 1 and Level 2 LSPs. It also looks at the TLVs associated with each type of LSP.

Link-State Packet Format

As noted in Chapter 3, all IS-IS packets have a header to which TLV fields are appended (refer to Figure 3-2). A complete layout of the LSP format, including the header and the TLV sections, is shown in Figure 5-4.

Figure 5-4. LSP format.

The PDU types for Level 1 and Level 2 LSPs ...

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