Which two tunneling techniques support IPv6 multicasting? (Choose two.)

A.
6to4

B.
6over4

C.
ISATAP

D.
6PE

E.
GRE

Explanation:
When IPv6 multicast is supported (over a 6to4 tunnel), an IPv6 multicast routing protocol must be
used
Restrictions for Implementing IPv6 Multicast
IPv6 multicast for Cisco IOS software uses MLD version 2. This version of MLD is fully backwardcompatible with MLD version 1 (described in RFC 2710). Hosts that support only MLD version 1
will interoperate with a router running MLD version 2. Mixed LANs with both MLD version 1 and
MLD version 2 hosts are likewise supported.
IPv6 multicast is supported only over IPv4 tunnels in Cisco IOS Release 12.3(2)T, Cisco IOS
Release 12.2
(18)S, and Cisco IOS Release 12.0(26)S.
When the bidirectional (bidir) range is used in a network, all routers in that network must be able to
understand the bidirectional range in the bootstrap message (BSM).
IPv6 multicast routing is disabled by default when the ipv6 unicast-routing command is configured.
On Cisco Catalyst 6500 and Cisco 7600 series routers, the ipv6 multicast-routing also must be
enabled in order to use IPv6 unicast routing

http://www.cisco.com/web/about/ac123/ac147/ac174/ac197/about_cisco_ipj_archive_article09186
a00800c830a.html
http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-multicast.html

https://supportforums.cisco.com/thread/183386