Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-zero checksums

Joe Touch <touch@isi.edu> Thu, 01 May 2014 21:09 UTC

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Date: Thu, 01 May 2014 14:08:52 -0700
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Subject: Re: [Tofoo] VXLAN (UDP tunnel protocols) and non-zero checksums
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On 5/1/2014 2:00 PM, Tom Herbert wrote:
...
>     Receiver processing is simple:
>
>              - if the checksum is zero, ignore
>
>              - if the checksum is NOT zero, it MUST match
>
> This is true with caveat that an implementation MAY ignore a zero
> checksum, not MUST ignore a zero checksum. This is specified in RFC1122.

It says that the app MAY optionally be able to configure the system to 
pass zero-checksum UDP packets up or discard them.

I.e., a *configuration* MAY decide to accept or drop zero-checksum UDP 
packets; the UDP layer isn't in control of that by itself.

>   VXLAN draft also breaks this by making accepting packets with zero
> checksums a MUST.

That's not "breaking" anything; VXLAN is - to UDP - an application.

Joe