An Alternative Connection Model for the Message Session Relay Protocol (MSRP)
RFC 6135
Note: This ballot was opened for revision 10 and is now closed.
(Gonzalo Camarillo) Yes
(Jari Arkko) No Objection
Comment (2010-12-02 for -)
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A few comments from Ari Keränen's review: 1. Introduction COMEDIA is especially useful when an endpoint is located behind a NAT. The endpoint can use the mechanism to indicate that it will create the media transport connection, in order for the media to traverse the NAT without the usage of relays, without being required to support more complex mechanims (e.g. TCP Candidates with Interactive Connectivity Establishment (ICE) [I-D.ietf-mmusic-ice-tcp]). Instead of "an endpoint" it would be better to say "one of the endpoints" since this does not help if both of the endpoints are behind a NAT. 4.2.1. General An MSRP UA must support the a=setup "active", "actpass" and "passive" s/must/MUST/ An MSRP UA MUST NOT send the "holdconn" attribute, and MUST ignore it if received. What to do when "ignoring" the attribute? Behave as if there was no "setup" attribute at all (i.e., assume COMEDIA isn't supported)? 4.2.2. Attribute usage When the a=setup attribute value is "actpass" or "passive", the IP address and port values in the MSRP URI of the SDP a=path attribute MUST contain the actual address and port values on which the UA can receive a TCP Open request for the MSRP transport connection. What is "TCP Open request" (found multiple times throughout the document)? TCP SYN perhaps? If not, a reference where this is defined would be nice. If an MSRP UA can provide a global IP address that the other endpoint can use as destination for a TCP Open request, the UA MUST use the a=setup "actpass" attribute value in SDP offers. Would SHOULD be sufficient here? For the purpose of stateful firewall traversal, UA might want to use "active" even if it has a global IP address. - the UA has used Session Traversal Utilities for NAT (STUN) [RFC5389] signaling to retrieve NAT address and port through the local port to be used for the eventual transport connection, while also having determined that the NAT is not address restricted. Could use RFC5382 (and 4787) terminology instead of "address restricted". And actually one should use RFC5780 to discover the behavior. 5. Interoperability with connection model defined in RFC 4975 [...] NAT traversal can only be achieved if the MSRP UA supports ICE [I.D.ietf-mmusic-ice-tcp] and the network provides TURN servers, or if the network supports SBC assisted NAT traversal for TCP. While quite often useful, TURN (or even STUN) servers are not always needed for ICE-TCP to work (could just remove that part of the sentence).
(Ron Bonica) No Objection
(Stewart Bryant) No Objection
(Ralph Droms) No Objection
(Lars Eggert) No Objection
Comment (2010-11-30 for -)
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Nit: s/MRSP/MSRP/ in several places in the document. Section 1., paragraph 2: > [RFC4145] defines a connection-oriended media mechanism, COMEDIA, Nit: s/connection-oriended/connection-oriented/ Section 1., paragraph 4: > to support more complex mechanims (e.g. TCP Candidates with Nit: s/mechanims/mechanisms/ Section 9., paragraph 2: > o Changes based on comments from Gonzalo Camrillo. Nit: s/Camrillo./Camarillo./ Section 9., paragraph 8: > Changes from draft-ietf-simple-mscp-acm-02 Nit: s/draft-ietf-simple-mscp-acm-02/draft-ietf-simple-msrp-acm-02/
(Adrian Farrel) No Objection
Comment (2010-12-01 for -)
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Acronyms need to be expanded in the main text on first usage (regardless of their use in the Abstract). --- Section 3 Support of this specification is optional for MSRP user agents in Is that "OPTIONAL"? --- Section 4.2.2 In accordance with [RFC4145], if the a=setup attribute value is "active", the port number value should be 9. s/should/SHOULD/ ?
(Russ Housley) No Objection
(Tim Polk) No Objection
(Peter Saint-Andre) No Objection
(Robert Sparks) No Objection
(Sean Turner) No Objection
Comment (2010-11-30 for -)
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Sec 1: Spell out SDP on first usage. Sec 3: r/optional/OPTIONAL? It's specifying support requirements. Sec 4.2.1: r/An MSRP UA must support the a=setup.../An MSRP UA MUST support the a=setup...