[core] Review of draft-dijk-core-groupcomm-bis-03
Jim Schaad <ietf@augustcellars.com> Fri, 20 March 2020 15:44 UTC
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From: Jim Schaad <ietf@augustcellars.com>
To: draft-dijk-core-groupcomm-bis@ietf.org
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Date: Fri, 20 Mar 2020 08:43:33 -0700
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Subject: [core] Review of draft-dijk-core-groupcomm-bis-03
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I need still need to review your response to my last review. This is a clean review from scratch without reference to my prior one. Jim * General - Feel free to ignore this, but I far prefer positive rather than negative protocol requirements. Thus in section 2.3.5 - "MUST respond to this request and not suppress it". Negative statements are difficult to test, did you cover every single condition? * Section 2.1, para 3 - are application groups only those which provide the resources or do they also include those which use the resources? It is not clear from the text which is true. * Section 2.1, para 4 - does this mean that a group of CoAP servers which are not in a multicast URI (i.e. not a Group URI) then they cannot be part of an application group? This could be a scoping issue where the problem is that for me Group Communication does not necessarily equal Multicast Communication. Think in terms of pub-sub as an alternate backbone. Another alternative for this is Anycast where you send a message and you don't know which server it is going to but they are still treated as a group. If the issue is scoping then expand some discussion about this in the introduction. * Section 2.1, para 5 - I think I understand what you are trying to say here, however based on the definition of a CoAP group a security group would likely include endpoints which are not in a CoAP group. This makes the one-to-one concept a bit difficult to grok. * Section 2.1, para 5 - If application groups are really designed to be non-intersecting, that needs to be part of the definition of an application group in the previous paragraphs. I would be surprised if a resource could not be part of two different application groups so I think this is an incorrect statement. * Section 2.1, para 6 - If I read the definitions correctly, then this requires that each of the first two items could be empty. That is a message sent by a client endpoint does not have either an application group or a CoAP group. The target it is sending the message to has those properties however. * Section 2.1, Figure 2 - I think it would be reasonable to place "Cli2" into security group 2 as well to show that clients can be in multiple security groups. * Section 2 - you need to put a qualifier for "Group" on all of the title fields and probably on every usage in the document. I think you need to create a new term to cover the "This is more than one" group * Section 2.2.4 para 2 - the last clause appears to be a repeat * Section 2.2.4 - does not cover application group maintenance * Section 2.3.4 - In the bullet that says requests are non-confirmable, I think it would be reasonable to say that a server SHOULD treat a confirmable request as if it where non-confirmable. * Section 2.3.4 - last bullet - I don't know how IPv6 multicast works, but does this mean that a CoAP group may want to advertise itself at different scopes so that a client can work its way up from interface-local to organization-local? Looks like a pointer to 2..1 w/ a sentence would be useful here. * Section 2.3.5 - para - I am not sure that you can use the same token for both the multicast and the unicast observe request. It is going to make a difference in terms of the sending port that is used by the client. Otherwise there is the potential that you could get messed up on the code which deals with token cancelations in the event that the unicast server does not honor the observe request. * Section 5.2.1 s/paralizing/paralyzing/ * Section 5..3 - s/Group OSCORE prevents to effectively mount/ ???? I don't know what this means s/Group OSCORE prevents to make any/ ???