Re: Tunnel mode ipv6 or tunnel mode gre ipv6?

Right, I'm with you now guys. Just went back to basics on GRE and my
protocol and ethertypes.

I noticed on there that the GRE keepalives work by encapsulating an IPv4 GRE
tunnel inside an IPv4 GRE tunnel. That's pretty cool - is there any
theoretical limit on the number of encapsulations that could be made? Or
does it just come down to packet size?
So, just for fun, could you theoretically have a single packet encapsulated
like:
Ethertype: 0x800
IP Header: 47
GRE Pro: 0x800
IP Prot: 41
IPv6 Next Header: 47
GRE Pro: 0x86DD
IPv6 Next Header: 4
IP Prot: 6
TCP Payload

Thanks for clearing that up! :)

2009/11/4 Rick Mur <rmur_at_ipexpert.com.17968701521507777236.send.nyms.net>

> Sorry my mistake, bit strange typo. It's 47 like Mathew said.
>
>
>
>
> --
>
> Regards,
>
> Rick Mur
> CCIE2 #21946 (R&S / Service Provider)
> Sr. Support Engineer  IPexpert, Inc.
> URL: http://www.IPexpert.com
>
> On 4 nov 2009, at 17:49, Divin Mathew John wrote:
>
> GRE is 47 aint it?
>
> On Wed, Nov 4, 2009 at 9:50 PM, Rick Mur <rmur_at_ipexpert.com> wrote:
>
>> The first one is an abbreviation for ipv6ip, which is protocol 41 and is
>> IPv6 traffic encapsulated in a IPv4 packet. ipv6 gre is IPv6 encapsulated
in
>> GRE (+IPv4) and is IP protocol 43.
>>
>> Totally different from each other :-)
>>
>>
>> --
>>
>> Regards,
>>
>> Rick Mur
>> CCIE2 #21946 (R&S / Service Provider)
>> Sr. Support Engineer IPexpert, Inc.
>> URL: http://www.IPexpert.com
>>
>>
>> On 4 nov 2009, at 16:45, groupstudy_at_nyms.net wrote:
>>
>> Sweet - thanks Nathan!
>>>
>>> 2009/11/4 Nathan Richie <
>>> nathanr_at_boice.net.2573395321876976672.send.nyms.net
>>>
>>>>
>>>>
>>> INE has a great blog on the IPv6 tunnels. You are correct concerning the
>>>> overhead, but with the GRE IPv6 tunnel, the packet can carry additional
>>>> data
>>>> such as IS-IS.
>>>>
>>>>
>>>>
>>>>
http://blog.internetworkexpert.com/2009/08/28/ipv6-transition-mechanisms-part
-2-greipv4-tunnels/
>>>>
>>>> Hope this helps....
>>>>
>>>> -----Original Message-----
>>>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
>>>> groupstudy_at_nyms.net
>>>> Sent: Tuesday, November 03, 2009 6:24 PM
>>>> To: ccielab_at_groupstudy.com
>>>> Subject: Tunnel mode ipv6 or tunnel mode gre ipv6?
>>>>
>>>> Hi chaps,
>>>> What's the difference between running "tunnel mode ipv6" and "tunnel
>>>> mode
>>>> gre ipv6"? I'm working on a rented rack so I can't sniff.
>>>>
>>>> Both appear to work as long as each side is running the same mode, but
>>>> not
>>>> intercompatible. Both encapsulate in IPv6 but I don't get the need for
>>>> two
>>>> methods of doing this.
>>>> I guess the easy answer is that the latter encapsulates into GRE before
>>>> encapsulating into IPv6 - if that's the case, then why would anyone use
>>>> that
>>>> option which I assume adds extra size to the headers?
>>>>
>>>> Can't find much on the Cisco site or Google other than this: Static
>>>> tunnel
>>>> interface configured to encapsulate IPv6 or IPv4 packets in IPv6.
>>>>
>>>> Anyone help me out here? What am I missing?
>>>> THANKS!
>>>>
>>>>
>>>> Blogs and organic groups at http://www.ccie.net
>>>>
>>>> _______________________________________________________________________
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>>>
>>>
>>> Blogs and organic groups at http://www.ccie.net
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>>> _______________________________________________________________________
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>>
>>
>> Blogs and organic groups at http://www.ccie.net
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>> _______________________________________________________________________
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>>
>>
>>
>
>
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Received on Thu Nov 05 2009 - 12:00:04 ART