5.5. Essential TLVs

As with essential LSAs, by essential TLVs I mean those that are necessary for the basic functioning of IS-IS in an IP network. Certain TLVs would be essential to IS-IS in a CLNS network, but are not necessary—or relevant—to an IP network, and so are not covered in this book. Also covered here are the TLVs that enable the support of wide metrics. These are not essential to the operation of IS-IS, but are included because wide metrics are covered in this chapter. Many other TLVs are discussed in other chapters, in the context of the IS-IS features and extensions they support.

The essential TLVs are:

  • Area Addresses TLV

  • IS Neighbors TLV

  • Protocols Supported TLV

  • IP Interface Address TLV

  • IP Internal Reachability Information TLV

  • IP External ...

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