Re: [tsvwg] signaling packet importance [was Re: New Version Notification for draft-herbert-fast]

["[e-mail]" <[e-mail]>]

My concern is that endorsing use of UDP options to signal in-network devices could cause the same reaction as IP HBH options - that they could be seen as unsafe to routers and could cause an over-reaction that causes deliberate blocking or stripping.

As the discussion noted, that’s not currently the case, or at least as best can be determined. I

It’d be useful to avoid creating new reasons that routers would want to interfere. I.e., the question isn’t whether IP options are an alternative - they clearly are the appropriate place for draft-kaippallimalil-tsvwg-media-hdr-wireless and draft-reddy-tsvwg-explcit-signal - it’s whether using UDP options for those purposes could jeapordize them for everyone else.

draft-daiya-tsvwg-udp-options-protocol-number is of a completely different nature; it aims to be part of the transport protocol in chaining the meaning of protocol layers, rather than encoding them all in the destination port of the first exchange. In that regard, it’s more like draft-touch-tcpm-sno (service number option), except that it would require similar ’next protocol’ identifiers at all protocol layers, which is (sadly) not the way current services and protocol stacks work.

Joe

—
Dr. Joe Touch, temporal epistemologist
www.strayalpha.com

> On Aug 12, 2023, at 6:14 PM, C. M. Heard <[e-mail]> wrote:
> 
> On Fri, Aug 11, 2023 at 7:47 PM Joe Touch wrote:
>> Just to be clear:
>>> On Aug 11, 2023, at 2:42 PM, C. M. Heard <[e-mail] <mailto:[e-mail]>> wrote:
>>> I've been pushing the idea to co-opt the per-fragment UDP options used for host-to-network signaling, and I'd like to make some comments about that.
>> 
>> This confuses transport options with network options.
> 
> Not confusion, but rather an explicit proposal to use the per-fragment options as network options instead of transport options. It is put forward to provide potentially workable solutions to the problems that draft-kaippallimalil-tsvwg-media-hdr-wireless and draft-reddy-tsvwg-explcit-signal are intended to solve.
> 
> Granted, an architecturally preferable way to accomplish these objectives would be to use IPv4 Options or IPv6 Hop-by-Hop Options. Indeed, I myself would prefer for IPv4/IPv6 Options to be used if the issues of high discard rates of packets with these options could be solved. There are efforts underway to mitigate the problems for IPv6 Hop-by-Hop Options. Those might bear fruit someday, though the timeline is at best uncertain. But as far as I know, the discard rates for IPv4 Options are equally dismal, and there are no efforts underway to fix that problem. Correction by parties with better knowledge of the facts than mine are invited.
> 
> My take is that the problems that draft-kaippallimalil-tsvwg-media-hdr-wireless and draft-reddy-tsvwg-explcit-signal (and possibly draft-daiya-tsvwg-udp-options-protocol-number as well) could, in principle, be solved by what I see as a modest change of direction to the UDP Options spec. Whether that would work out in practice is much less certain, for the reasons that Tom Herbert has pointed out. IMO it is a judgement call whether the chances are better to get IP Options (in any version) to work within our professional lifetimes. Given that, I don't think it would be right to turn draft-kaippallimalil-tsvwg-media-hdr-wireless and draft-reddy-tsvwg-explcit-signal away without a proper discussion.
> 
> Thanks,
> 
> Mike