Re: [core] Review Comments on draft-boucadair-core-hop-limit
<mohamed.boucadair@orange.com> Wed, 12 September 2018 08:19 UTC
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From: mohamed.boucadair@orange.com
To: Jim Schaad <ietf@augustcellars.com>, "draft-boucadair-core-hop-limit@ietf.org" <draft-boucadair-core-hop-limit@ietf.org>
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Thread-Topic: Review Comments on draft-boucadair-core-hop-limit
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Date: Wed, 12 Sep 2018 08:19:01 +0000
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Subject: Re: [core] Review Comments on draft-boucadair-core-hop-limit
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Hi Jim, all, Thank you for sharing the comments. Please see inline. Cheers, Med > -----Message d'origine----- > De : Jim Schaad [mailto:ietf@augustcellars.com] > Envoyé : jeudi 23 août 2018 06:19 > À : draft-boucadair-core-hop-limit@ietf.org > Cc : 'core' > Objet : Review Comments on draft-boucadair-core-hop-limit > > Section 3 - para 2 - It would be clearer to me to say that the Hop-Limit > value is between 0 and 255 inclusive rather than talk about the length of > the option because I don't know if that includes all of the option encoding > bytes or not. > [Med] Done in my local copy. > Section 3 - para 4 - Probably does not matter, but the current algorithm > wastes one bit. Check for 0 and then decrement would give one addition > possible field. It would also compress down the size of the encoded option > faster. > > Section 3 - I don't know that you only want to have a proxy information > appearing once. If it appears multiple times then you can easily spot the > loop. No real option one way or the other. > [Med] We had that restrictions for two reasons: - ease correlation between hop count and the information recorded in the body. - maintain a reasonable message size. > Section 3 - Last paragraph - I presume that a border proxy could remove > rather than re-write the option as well. This would be esp. true if for > example it was changing transports. > [Med] Yes, fixed in my local copy. > Section 4.2 - Someplace there needs to be a discussion on why the values of > C, U and N > > I would have expected the values to be > - Critical - no [Med] Agree. > - Unsafe - no - a proxy which does not understand the option should still > forward it on. At worst you will get the same behavior as if the option was > not included. [Med] We set it to "Unsafe - yes" for the DOTS case because the proxies are under the control of the same entity and we wanted to have something reliable. I do agree that for the general CoAP case, we can relax that to "Unsafe - no" > - NoCacheKey - yes - If you get two gets for the same resource with > different hop counts the proxy should still be able to return the currently > cached value. > [Med] Will add some text to explain the rationale for setting the C/U/N values. Thanks. > Section 5 - There is a potential privacy consideration that may need to be > covered. The return value is going to provide an eavesdropper a large > amount of information on the configuration of the network. Is there value > to configuring so that the error but not the trace stack is provided? > > [Med] Good point. There is still a value in returning the error even without the trace as this allows a peer to know why a request failed. Proxies at boundaries are supposed to generate alarms to administrators. We can consider adding the following: - a proxy which is located at the boundary of an administrative domain may be instructed to strip the diagnostic payload or part of it before forwarding 5.06 upstream.
- [core] Review Comments on draft-boucadair-core-ho… Jim Schaad
- Re: [core] Review Comments on draft-boucadair-cor… mohamed.boucadair
- Re: [core] Review Comments on draft-boucadair-cor… Jim Schaad
- Re: [core] Review Comments on draft-boucadair-cor… mohamed.boucadair