RE: IPv6 over IPv4 GRE

Hi Chris,

GRE is a typical solution for an IPv6 manual tunnel, as they can carry
protocols other than IPv6, like IS-IS. I have seen documentation that
references the ipv6ip mode as deprecated. Here is a good link on IPv6
tunnels:

http://www.cisco.com/en/US/docs/ios/ipv6/configuration/guide/ip6-tunnel_ps69
22_TSD_Products_Configuration_Guide_Chapter.html#wp1056650

or

www.tinyurl.com/v6tunnels

HTH,

Bob Sinclair CCIE 10427 CCSI 30427
CIERS2 Online Instructor
www.tinyurl.com/ciers2online

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Grammer, Christopher
> Sent: Saturday, August 28, 2010 5:37 PM
> To: Cisco certification
> Subject: IPv6 over IPv4 GRE
>
> All,
>
> I have basic GRE tunnel question.
>
> R3 -- R1 ===GRE=== R2 -- R4
>
>
> Between R3 and R1 is IPv6.
> Between R2 and R4 is IPv6
>
> I am using a manual GRE tunnel between R1 ad R2 which is only
> configured for
> IPv4 1.1.12.0/24
> R1 loopback 1.1.1.1/32
> R2 loopback 1.1.1.2/32
>
> Tunnel12 is IPv6 addressed with with IPv4 source and destination.
>
> RIPng is running between R3 and R1....over the GRE...and between R2 and
> R4.
> Everything works perfect.
>
> tunnel mode is GRE
>
> And I get debug detail:
>
> *Mar 1 00:24:46.215: IP: s=1.1.1.1 (Tunnel12), d=1.1.1.2
> (FastEthernet0/0),
> len 136, sending, proto=47
>
> Notice protocol 47...which I expect.
> I did not expect the tunnel to work without setting the tunnel mode to
> IPv6IP.
>
> I change the tunnel mode IPv6IP
>
> *Mar 1 00:35:47.387: IP: s=1.1.1.1 (Tunnel12), d=1.1.1.2
> (FastEthernet0/0),
> len 1020, sending, proto=41
> Protocol 41 which I expect.
> Ignore the length I was playing with MTU also.
>
> Tunnel mode IPIP doesnt work.
>
> My question is:
> Is it wrong to use GRE encapsulation in this scenario?
> The only difference I see is that the protocol number is different and
> it
> doesnt follow an RFC i suppose.
>
> Thanks for your help in advance,
>
> Chris
>
>
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Received on Sat Aug 28 2010 - 18:07:18 ART