Summary
A routing protocol essentially assembles and organizes addressing information according to location within a network. IS-IS was originally designed for routing in ISO CLNS environments where the Layer 3 protocol is CNLP and the network layer addresses are described as NSAPs. Adapting IS-IS to carry IP information didn't eliminate NSAP addressing altogether because of the strong links within the protocol basis. Therefore, using IS-IS on IP routers requires node-based NSAPs to be defined in addition to the link-based IP addresses on the interfaces.
This chapter attempts to demystify NSAP addressing by explaining why it is still featured in Integrated IS-IS, even for IP-only routing, and by discussing the NSAP addressing architecture. The ...
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