Re: [tsvwg] design assumptions - draft-ietf-udp-options

[<[e-mail]>]

Hi Joe,

IMO, the core requirements are #1, #2, #3, #4, and #7. 

#7 should be mandatory feature. 

5#, 6#, and #8 are nice-to-have. I would even prefer if those are covered in a separate specification. For example, I'm not sure whether FRAG will be useful and how it can interacts with IP fragmentation.  

Cheers,
Med

> -----Message d'origine-----
> De : tsvwg [mailto:[e-mail]] De la part de Joe Touch
> Envoyé : mercredi 17 juillet 2019 02:31
> À : tsvwg
> Objet : [tsvwg] design assumptions - draft-ietf-udp-options
> 
> Getting back to the core design assumptions:
> 
> 1- support options
> 2- allow at least some options to be silently ignored by legacy receivers
> (to enable ‘“optionally enhanced” exchanges)
> 3- allow at least some options to be required
> 4- allow the options themselves to be protected
> 5- support for fragmentation/reassembly
> 6- support for MTU discovery
> 7- support (optional?) middlebox checksum/payload length bug traversal
> 8- support LITE, i.e., where some of the payload is not covered by at
> least some checksum processing
> 
> AFAICT:
> 
> #7 requires a CCO-like sum, but it MUST he calculated AFTER all other
> options are populated (it depends on the value of ALL other options and
> surplus data)
> 
> #8 can depend on everything except CCO (it doesn’t need to protect CCO),
> but it depends on the value of all other options and needs to be computed
> next-to-last (or last if CCO isn’t present)
> 
> And we need a way to know:
> 	- for #7, whether CCO is included or not used (at user’s peril, but
> to allow for transmitters to avoid work)
> 	- for #8, when to end the options (either a length field OR a EOL
> flag)
> 
> Are there any other design requirements?
> 
> Joe
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