IS-IS is configured to support both IPv4 and IPv6 routing.Which statement is true?
A.
Separate IPv4 and IPv6 hellos will be sent.
B.
IPv6 will have a separate link-state database.
C.
IS-IS v6 support must be enabled under protocols isis.
D.
IS-IS sends IPv6 topology information as new TLVs in existing LSPs.
I think answer is D
http://tools.ietf.org/html/draft-ietf-isis-ipv6-07
IS-IS is an extendible intra-domain routing protocol. Each router in the routing domain issues an LSP that contains information pertaining to that router. The LSP contains typed variable length data often referred to as TLVs (type-length-values). We extend the protocol with 2 new TLVs to carry information required to perform IPv6 routing.
In [RFC1195] a method is described to route both OSI and IPv4. We utilize this same method with some minor changes to allow for IPv6.
To do so we must define 2 new TLVs, namely “IPv6 Reachability” and “IPv6 Interface Address” and a new IPv6 protocol identifier. In our new TLVs we utilize the extended metrics and up/down semantics of [RFC2784].