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Cecil,
ipv6ip is one of the manual tunnels, this mode is the one which uses less overhead (that’s the key) the other is tunnel mode gre, which adds reliability capabilities. This is pretty much a “regular” tunnel, you need to specify both endpoints.
Ipv6 6to4 is a “dynamic” tunnel; here you do not have to configure the remote endpoint since the software of the routers is able to figure out the destination IPv4 address from the IPv6 address. The IPv6 addresses in this case use a special format for this case. When you use 6to4 you are required to design your overlay IPv6 address space accordingly.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/ ipv6_c/sa_tunv6.htm#wp1037465
Best Regards, Roberto
—–Original Message—– From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Cecil Jackson Sent: Tuesday, June 27, 2006 4:19 PM To: ‘Cisco certification’ Subject: IPV6 tunnels
How would a question have to be worded around the question of creating create an IPV6 tunnel using either tunnel mode ipv6ip or tunnel mode ipv6ip 6to4?

RACK03R6(config-if)#tunnel mode ipv6ip RACK03R6(config-if)# RACK03R6(config-if)#tunnel mode ipv6ip ? 6to4 IPv6 automatic tunnelling using 6to4 auto-tunnel IPv6 automatic tunnelling using IPv4 compatible addresses isatap IPv6 automatic tunnelling using ISATAP
RACK03R6(config-if)#tunnel mode ipv6ip
Thanks
Cecil