Re: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile

"Templin (US), Fred L" <Fred.L.Templin@boeing.com> Fri, 06 September 2019 16:46 UTC

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From: "Templin (US), Fred L" <Fred.L.Templin@boeing.com>
To: Ole Troan <otroan@employees.org>
CC: Joe Touch <touch@strayalpha.com>, Ron Bonica <rbonica=40juniper.net@dmarc.ietf.org>, "int-area@ietf.org" <int-area@ietf.org>, IESG <iesg@ietf.org>, Joel Halpern <joel.halpern@ericsson.com>, "draft-ietf-intarea-frag-fragile@ietf.org" <draft-ietf-intarea-frag-fragile@ietf.org>, Suresh Krishnan <suresh@kaloom.com>, "intarea-chairs@ietf.org" <intarea-chairs@ietf.org>
Thread-Topic: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile
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Date: Fri, 6 Sep 2019 16:46:03 +0000
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Subject: Re: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile
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Ole,

> -----Original Message-----
> From: Ole Troan [mailto:otroan@employees.org]
> Sent: Friday, September 06, 2019 9:35 AM
> To: Templin (US), Fred L <Fred.L.Templin@boeing.com>
> Cc: Joe Touch <touch@strayalpha.com>om>; Ron Bonica <rbonica=40juniper.net@dmarc.ietf.org>rg>; int-area@ietf.org; IESG
> <iesg@ietf.org>rg>; Joel Halpern <joel.halpern@ericsson.com>om>; draft-ietf-intarea-frag-fragile@ietf.org; Suresh Krishnan
> <suresh@kaloom.com>om>; intarea-chairs@ietf.org
> Subject: Re: [Int-area] Discussion about Section 6.1 in draft-ietf-intarea-frag-fragile
> 
> >>>>> And of course encapsulation can also exacerbate the problem
> >>>>> by increasing packet size.
> >
> > All this means is that the fragmentation layer needs to take into account the
> > size of the outer encapsulation layers that will be added and make sure its
> > fragments do not exceed 1280 bytes *after* encapsulation. So, e.g., if the
> > encapsulation layer adds an IPv6 header and a UDP header the fragmentation
> > layer should not produce fragments larger than 1280 - 40 - 8 = 1232. If the
> > fragmentation layer does not know the size of the outer encapsulations to
> > be added, it can overestimate and set a safe smaller value (e.g., 1024).
> 
> Yes, absolutely. But I don't think we are talking about IP fragmentation any more.

No - it is simply RFC8200-standard IPv6 fragmentation - not something else.

Fred

> Cheers,
> Ole