Re: [tsvwg] draft-ietf-udp-options issues from IETF 104

[Joe Touch <[e-mail]>]

On 2019-07-12 09:16, Tom Herbert wrote: 

...

>> Neither TCP nor UDP require their payloads to end on a word boundary. So transport checksums already need to deal with up to 3 bytes of "cleanup".
> Per RFC768, a zero byte is appended if the UDP data length is odd.

That's in the description of how the checksum calculation works; there's
no requirement to make the payload of actual even length. 

Padding with a single zero byte is equivalent to dealing with the
"cleanup" (which for IP checksum, is only ever 1 byte anyway). 

>> Given that, why force the front alignment? At most it only doubles that cleanup, which ought to be nominal anyway.
> 
> It's a straightforward application of sending clause the robustness
> principle. Other IP protocols ensure checksum and headers aligned so
> this protocol should too in order to maximize robustness.

That's not the robustness principle. That's ossification. 

Joe