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

[Joe Touch <[e-mail]>]

> On Jul 11, 2019, at 7:14 PM, Tom Herbert <[e-mail]> wrote:
> 
> Not sure I follow here - so there are only a few variants that seem viable:
> 
> 1.- at the front of the surplus space
> 2.- at the front of the surplus space after alignment NOPs
> 3.- at the end of the surplus space
> 4.- at the end of the surplus space with alignment
> 
> AFAICT, there’s no real help in requiring OCS be aligned (it can be designed to tolerate any alignment), which means we don’t need #2 or #4.
> 
> #2 gives greatest probability of working with existing implementation of checksum offload.

A few questions on that:
- Can we deal with a small amount of “cleanup” operations after the offload?
- if so can that allow arbitrary byte start? 
- or at least16-bit instead of 32-bit alignment? 

Keep in mind that regardless of where we start, we shouldn’t need aligned ends, so there’s always some “cleanup” with such support anyway.

I.e., why can’t we start at the 32-bit alignment and just add the rest and adjust later, rather than pad?

Joe