Subject: Re: [core] Opsdir last call review of draft-ietf-core-hop-limit-05

From: Carsten Bormann <[email-masked]>
Date: Wed, 2 Oct 2019 17:47:36 +0200

On Sep 27, 2019, at 14:24, Carsten Bormann <[email-masked]> wrote:
> 
> The other question was why the hop-limit option isn’t made mandatory.  Med has already pointed out that the text of the draft does recommend its use in specific situations (i.e., where proxies are involved).  The transition strategy is somewhat mild, as proxies today don’t know the option, so its interpretation by a receiving instance is elective (i.e., not critical).
> Application domains that do make use of complicated proxying structures (which is not the norm today for CoAP), such as DOTS, might make more stringent requirements.  Generally, we don’t use “updates” for specifications that merely exercise an extension point, so I don’t think hop-limit “updates” RFC 7252, but the “updates” label is in active discussion already anyway.

In the CoRE Virtual Interim we just had (minutes to be posted), we said that the WG wouldn’t have a problem with changing the “are expected to” (implement and default-enable) in Section 1.1 into a stronger MUST.  This would still leave the option for a Proxy operator to turn off the use of the Option, i.e., a receiver cannot rely on actually receiving it.  Let’s wait for the ADs to chime in on that…

Grüße, Carsten