Tunneling Technologies: ISATAP Tunnels

Intra-Site automatic Tunnel addressing Protocol (ISATAP) like 6to4 treats underlying IPv4 networks as NBMA cloud.  Making ISATAP tunnels support point to multipoint operation natively and determines destination on a per packet basis.

ISATAP Addressing uses the following format

[64 bit link local or global unicast pefix]:0000:5EFE:[IPv4 address of ISATAP link]

Configuration for the most part is the same except for a different tunnel mode

tunnel-mode ipv6ip isatap

IPv6 address must be derived from EUI-64 addressing in a tunnel interface, the EUI-54 address of a tunnel interface has the lower 32bit address based off the tunnel interfaces source IPv4 address

Router Advertisements are needed for neighbor auto discovery, however when tunnels are enabled this DISABLES Router advertisements.  Enable RAs using the following command:

no ipv6 nd suppress-ra



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