GRE IPV6 Confusion!

[lowfell]

I need some clarity on this type of GRE  configuration

Configuration of R3:
!
interface Tunnel34
 no ip address
 ipv6 address 2026::34:1/122
 ipv6 enable
 ipv6 ospf 6 area 34
 tunnel source Serial0/0/0.34
 tunnel destination 10.1.1.10
 tunnel mode ipv6

@@@@@@@@@@@@@@@

1. What type of tunnel is this? is it plain old tunnel, and in that case is  in that case is is still necessary to have

tunnel mode ipv6 ?

2. Is it an ipv6 tunnel and the tunnel mode needs to be #tunnel mode ipv6 ? 

3. Is it always mandatory to have a tunnel mode ?

4. what is the difference between #tunnel mode gre ipv6  

& #tunnel mode ipv6 ?

Thanks in Advance

[Philip D'Ath]

It is tunnelling IPv6 over IPv4.

[Philip D'Ath]

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-3s/ir-xe-3s-book/ip6-man-tunls-xe.pdf

[lowfell]

It is tunnelling IPv6 over IPv4

So in this instance is it mandatory to have #tunnel mode ipv6 ?

[Philip D'Ath]

It has to match the remote end - and it has to be a type that tunnels IPv6.

So you could use a different IPv6 tunnel mode - but you must have one.

[lowfell]

So if its                                                 R1#tunnel mode ipv6

then the other side has to be               R2#tunnel mode ipv6 ?

Or                                                        R1#tunnel mode gre ipv6

                                                            R2#tunnel mode gre ipv6     or whatever as long as they match? 

[Philip D'Ath · Accepted solution]

Correct.

[lowfell]

Thanks Philip. That's much appreciated.