Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)

Fernando Gont <fgont@si6networks.com> Tue, 03 September 2019 15:57 UTC

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To: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>, Joe Touch <touch@strayalpha.com>, Alissa Cooper <alissa@cooperw.in>
Cc: Joel Halpern <joel.halpern@ericsson.com>, "draft-ietf-intarea-frag-fragile@ietf.org" <draft-ietf-intarea-frag-fragile@ietf.org>, "int-area@ietf.org" <int-area@ietf.org>, The IESG <iesg@ietf.org>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
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From: Fernando Gont <fgont@si6networks.com>
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Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
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On 3/9/19 18:41, Templin (US), Fred L wrote:
> 
> 
>> -----Original Message-----
>> From: Fernando Gont [mailto:fgont@si6networks.com]
>> Sent: Tuesday, September 03, 2019 7:50 AM
>> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>om>; Joe Touch <touch@strayalpha.com>om>; Alissa Cooper <alissa@cooperw.in>
>> Cc: Joel Halpern <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; int-area@ietf.org; The IESG <iesg@ietf.org>rg>;
>> intarea-chairs@ietf.org
>> Subject: Re: [Int-area] Alissa Cooper's No Objection on draft-ietf-intarea-frag-fragile-16: (with COMMENT)
>>
>> On 3/9/19 17:33, Templin (US), Fred L wrote:
>>> Why was this section taken out:
>>>
>>>> 1.1.  IP-in-IP Tunnels
>>>>
>>>>    This document acknowledges that in some cases, packets must be
>>>>    fragmented within IP-in-IP tunnels [I-D.ietf-intarea-tunnels].
>>>>    Therefore, this document makes no additional recommendations
>>>>    regarding IP-in-IP tunnels.
>>>
>>> Tunnels always inflate the size of packets to the point that they may exceed
>>> the path MTU even if the original packet is no larger than the path MTU. And,
>>> for IPv6 the only guarantee is 1280. Therefore, in order to robustly support
>>> the minimum IPv6 MTU tunnels MUST employ fragmentation.
>>
>> Isn't that an oxymoron? If fragmentation is fragile, if you need
>> something robust, you need to rely on something else....
> 
> IPv6 fragmentation is not fragile - only IPv4 fragmentation is fragile.

* RFC7872.
* https://blog.apnic.net/2017/08/22/dealing-ipv6-fragmentation-dns/

These seems pretty fragile to me. YMMV, though.

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
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