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Re: [lisp] IPv6 UDP checksum issue

Dino Farinacci <dino@cisco.com> Wed, 29 July 2009 12:02 UTC

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From: Dino Farinacci <dino@cisco.com>
To: Marshall Eubanks <tme@americafree.tv>
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Subject: Re: [lisp] IPv6 UDP checksum issue
Date: Wed, 29 Jul 2009 05:02:51 -0700
References: <F3FC18FF-E085-47E9-8376-2C4DA00D9F03@americafree.tv>
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> This is a reminder that  draft-fairhurst-6man-tsvwg-udptt and
>
> http://tools.ietf.org/html/draft-eubanks-chimento-6man-00
>
> are still open and will be discussed at the 6man meeting Wednesday.
>
> Basically, one prescribes no checksum for the "outer" packet in
> IPv6 encapsulations, the other a fixed checksum per flow. My
> understanding is that this matter is relevant to LISP.
>
> If you are interested, please try to attend as a decision may be  
> made soon.

Sorry, I have a conflict right now. But here is the position of one  
LISP implementor and a coauthor of the LISP specifications:

 From a practical perspective, we prefer that a LISP encapsulator (ITR  
and PTR) not incurred additional work when encapsulating packets. The  
main LISP spec indicates:

(1) The UDP checksum in the outer header MUST be set to 0 by an  
encapsulator.
(2) The decapsulator MUST ignore the UDP checksum.

We stand by this text and see no reason to change it.

There are no practical reasons to use outer header UDP checksums  
regardless of the 4 combinations of packet types (v4-in-v4, v6-in-v6,  
v6-in-v4, or v4-or-v6) being forwarded by LISP routers.

Dino


>
> Regards
> Marshall
> _______________________________________________
> lisp mailing list
> lisp@ietf.org
> https://www.ietf.org/mailman/listinfo/lisp

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