Re: [core] Chair's review of draft-ietf-core-hop-limit-02.txt
<mohamed.boucadair@orange.com> Tue, 26 February 2019 13:28 UTC
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From: mohamed.boucadair@orange.com
To: Klaus Hartke <hartke@projectcool.de>
CC: Carsten Bormann <cabo@tzi.org>, core <core@ietf.org>, "draft-ietf-core-hop-limit@ietf.org" <draft-ietf-core-hop-limit@ietf.org>
Thread-Topic: [core] Chair's review of draft-ietf-core-hop-limit-02.txt
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Date: Tue, 26 Feb 2019 13:28:18 +0000
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Subject: Re: [core] Chair's review of draft-ietf-core-hop-limit-02.txt
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Hi Klaus, Agree. The reasoning is straightforward for error codes. For the few cacheable success codes, we maintained the same wording because a change of the hop-limit is seen as a hint of a topology change and thus as a trigger to check the forwarding path. The conditions are as follows: * The forwarding path is changed between the proxy and the server (e.g., adding new proxies to the path). Such path may not be loop-free. * The client is informed out of band to increase the initial hop limit to accommodate the increase of hops. Cheers, Med > -----Message d'origine----- > De : Klaus Hartke [mailto:hartke@projectcool.de] > Envoyé : mardi 26 février 2019 12:19 > À : BOUCADAIR Mohamed TGI/OLN > Cc : Carsten Bormann; core; draft-ietf-core-hop-limit@ietf.org > Objet : Re: [core] Chair's review of draft-ietf-core-hop-limit-02.txt > > Mohamed Boucadair wrote: > > Carsten Bormann wrote: > > > 2. I don't understand the rule about using cached copies. As a > > > general observation, rules like this should not simply be stated > > > without a rationale why they are the way they are. > > I assume you're referring to this rule: > > A CoAP proxy which understands the Hop-Limit option MUST NOT use a > stored response unless the value of the Hop-Limit option in the > presented request is less than or equal to the value of the Hop-Limit > option in the request used to obtain the stored response. > > (This matches the language in [1].) > > Let's say proxy receives a request and has a matching Hop Limit > Reached error response in its cache. If the hop limit in the request > is equal to the hop limit in the request for the stored response, then > the stored error response can be returned. If the hop limit is less, > then the stored error response can also be returned. (If 6 hops are > not enough to reach the server, then 3 hops are also not enough.) If > the hop limit is greater, then the stored error response cannot be > returned. (The server might not be reachable in 6 hops, but it might > be reachable in 7 hops.) (This assumes that the number of hops to > reach a server doesn't change. If it changes, then a stored error > response might be served incorrectly until its max-age expires.) > > I have to admit that I never checked if this also makes sense for > stored responses that are not a Hop Limit Reached error response... > > Klaus > > [1] https://tools.ietf.org/html/rfc7252#section-5.6
- [core] Chair's review of draft-ietf-core-hop-limi… Carsten Bormann
- Re: [core] Chair's review of draft-ietf-core-hop-… mohamed.boucadair
- Re: [core] Chair's review of draft-ietf-core-hop-… Jim Schaad
- Re: [core] Chair's review of draft-ietf-core-hop-… Carsten Bormann
- Re: [core] Chair's review of draft-ietf-core-hop-… mohamed.boucadair
- Re: [core] Chair's review of draft-ietf-core-hop-… Klaus Hartke
- Re: [core] Chair's review of draft-ietf-core-hop-… mohamed.boucadair