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

[Joe Touch <[e-mail]>]

On 2019-07-18 08:35, Tom Herbert wrote:

> ...
> 
> A single bit in the option type to indicate that the option can be
> skipped if unrecognized should be sufficient.
> 
> Tom

That bit has two meanings: 

- for legacy receivers, it's simply ignored for legacy data 

- for option-aware, if the flag is set, what does it mean? 
  - it should never mean drop the legacy data, otherwise an
options-aware endpoint can't decide to act as legacy 
  - it could mean drop non-legacy data 

Right now, the onus is on the receiver to decide what to do with the
data. The info is passed to the user - NOT decided by UDP. 

I.e., cuurrently: 

- unknown options are ignored by both legacy and option-aware endpoints 
- UDP processing skips over all such options 
- users can decide/negotiate what to do with those options on a per
endpoint basis 

Note: the first time you send something, if you want a response to help
you know what the endpoint will do, you need to set "ignore" anyway,
which is what the default does. Otherwise you won't get a response and
won't know why (the packet could have been dropped). 

So this only makes sense for negotiated soft-state anyway, at which
point the user can either configure the endpoint UDP socket to drop if
unknown or accept. 

Why would we NOT give the user this choice?

Joe