Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4582bis-10.txt
Tom Kristensen <2mkristensen@gmail.com> Fri, 14 February 2014 23:24 UTC
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References: <20131104104454.10115.16900.idtracker@ietfa.amsl.com> <52777C07.1080403@cisco.com> <52934193.5050304@ericsson.com> <CEFAC2B1.1A751%eckelcu@cisco.com> <CAFHv=r8WN4Nj6ZDHdSNeK194peHWdOZxpJhwePyvpaETgY8-hg@mail.gmail.com> <CF23D77E.1F021%eckelcu@cisco.com>
Date: Sat, 15 Feb 2014 00:24:34 +0100
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From: Tom Kristensen <2mkristensen@gmail.com>
To: "Charles Eckel (eckelcu)" <eckelcu@cisco.com>
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Cc: "bfcpbis@ietf.org" <bfcpbis@ietf.org>, Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com>, "Tom Kristensen (tomkrist)" <tomkrist@cisco.com>
Subject: Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4582bis-10.txt
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Thanks, a bit hasty there. Fixed now, time to submit just-in-time. -- Tom On 14 February 2014 23:28, Charles Eckel (eckelcu) <eckelcu@cisco.com>wrote: > Editorial nits inline in case you have not submitted yet. > > From: Tom Kristensen <2mkristensen@gmail.com> > Date: Friday, February 14, 2014 1:38 PM > To: Charles Eckel <eckelcu@cisco.com> > Cc: Gonzalo Camarillo <Gonzalo.Camarillo@ericsson.com>, Tom Kristensen < > tomkrist@cisco.com>, "bfcpbis@ietf.org" <bfcpbis@ietf.org> > Subject: Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4582bis-10.txt > > On 14 January 2014 20:03, Charles Eckel (eckelcu) <eckelcu@cisco.com>wrote: > >> Hi Gonzalo, >> >> I was looking through the archives and did not see any response to you >> comments. Sorry for the delay. Please see inline. >> >> On 11/25/13 4:24 AM, "Gonzalo Camarillo" <Gonzalo.Camarillo@ericsson.com> >> wrote: >> >> >Hi Tom, >> > >> >thanks for keeping the draft alive. I have had q quick look at Section 6 >> >and I have a few comments. >> > >> >http://tools.ietf.org/html/draft-ietf-bfcpbis-rfc4582bis-10#section-6 >> > >> >The first paragraph of Section 6 states that an entity can choose TCP or >> >UDP depending on the environment. Lately, the IESG is asking authors to >> >be a bit more explicit about operational issues. So, I think we should >> >add a few sentences explaining (briefly) who makes that decision. Is it >> >the implementation that first tries TCP and, if it does not work, it >> >falls back to UDP? Or do we expect administrators to configure this >> >depending on the environment? We can describe several potential >> >different deployment scenarios as well. >> >> In practice I have typically seen this configured as either use TCP first >> and fallback to UDP or vice versa. Depending on the product and >> environment, the choose of defaulting to TCP vs. UDP is made. The text in >> Appendix B describes the challenges with using TCP in some environments. >> In such environments, UDP would be typically be configured as the default. > > > I have added an informational note in Section 6, it reads as follows: > > "Informational note: In practice products is configured to try one > > > In practice, products are ... > > transport initially and use the other one as a fallback. > Whether > TCP or UDP is chosen as underlying transport depends on type of > product and the nature of the environment it is deployed, here the > > > deployed. Here ... > > considerations in Appendix B is an important input."' > > > ... Appendix B are important to consider. > > > >> >The second paragraph of Section 6.2 explains that the floor control >> >server is considered present and available upon receiving a HelloAck >> >message. We should also explain the circumstances in which the service >> >is considered to have become unavailable (e.g., ICMP messages or >> >timeouts) >> > > The ICMP behaviour is defined in 6.2.2. Also, the behaviour when timers > fire are described in Section 8. > > > are described -> is described > > Cheers, > Charles > > > >The following is the last sentence of the 3rd paragraph of Section 6.2: >> > >> >> Concordantly, messages sent by the floor >> >> control server that are not transaction-completing (e.g., >> FloorStatus >> >> announcements as part of a FloorQuery subscription) are server- >> >> initiated transactions that require acknowledgement messages from >> the >> >> floor participant and chair entities to which they were sent. >> > >> > >> >I do not think the term "transaction-completing" have been defined in >> >the document. We should use a different term or, even better, explain >> >explicitly what we mean. Also, I do not understand the point the >> >sentence is intended to make. We should rephrase. >> >> How about: >> Concordantly, messages sent by the floor control server that initiate new >> transactions (e.g., FloorStatus announcements as part of a FloorQuery >> subscription) require acknowledgement messages from the floor participant >> and chair entities to which they were sent >> > > A better explanation and we avoid introducing a term > (transaction-completing), that is not defined or even needed. > > >The 4th paragraph of Section 6.2 talks about the "Unable to parse" >> >message in the context of unreliable transports. Why don't we use that >> >with TCP as well? Is it because of backward compatibility issues? If so, >> >we should add a clarifying note. >> >> RFC 4582 stated the following, "If a BFCP entity (a client or a floor >> control server) receives data from TCP that cannot be parsed, the entity >> MUST close the TCP connection, and the connection SHOULD be >> reestablished." >> As there is no concept of a connection with UDP, we decided to handle by >> defining the new error code. >> > > Right. And there's no need for an explanation of that rationale in the > draft I assume. > > >The following sentence appears in the first paragraph of page 41: >> > >> >> The subsequent changes in state for >> >> the request are new transactions whose Transaction ID is determined >> >> by the floor control server and whose receipt by the client >> >> participant shall be acknowledged with a FloorRequestStatusAck >> >> message. >> > >> >Instead of "shall be", we should write "MUST be" if this behavior has >> >not been normatively defined anywhere else, or "is" if the behavior has >> >been normatively defined somewhere else. >> >> The normative language for this situation is in section 10.1.3, "When >> communicating over an unreliable transport and upon receiving a >> FloorRequestStatus message from a floor control server, the >> participant MUST respond with a FloorRequestStatusAck message within >> the transaction failure window to complete the transaction." >> I think replacing "shall be" with "is" is fine. >> > > Yes, fixed to avoid "confusion" as normative statements are provided for > this elsewhere. > > >> >The following paragraph appears later in Section 6.2: >> > >> >> If a client wishes to end its BFCP connection with a floor control >> >> server, it is RECOMMENDED that the client send a Goodbye message to >> >> dissociate itself from any allocated resources. If a floor control >> >> server wishes to end its BFCP connection with a client (e.g., the >> >> Focus of the conference informs the floor control server that the >> >> client has been kicked out from the conference), it is RECOMMENDED >> >> that the floor control server send a Goodbye message towards the >> >> client. >> > >> >Why is it RECOMMENDED (i.e., SHOULD level) instead of REQUIRED (i.e., >> >MUST level)? This comment is also somewhat related to my first comment >> >above about BFCP entities considering other entities gone. Have we >> >defined at which point can they forget their state information? This >> >also relates to the last paragraph of Section 6.2.2 that talks about >> >using STUN connectivity checks for this. We should probably talk about >> >all this somewhere. >> >> I cannot think of good reason for not sending a Goodbye. It may be that >> the Goodbye fails, and I think there may be existing implementations that >> do not send the Goodbye, but from a protocol perspective MUST/REQUIRED >> strength seems appropriate. >> > > I agree. I'm not quite sure, but it might be that the SHOULD level stems > from earlier versions where Goodbye also was an option specified for TCP in > a common section. Will change to REQUIRED in that paragraph. > > >The following paragraph appears in Section 6.2.3: >> > >> >> When a BFCP implementation receives a BFCP message fragment, it MUST >> >> buffer the fragment until it has received the entire BFCP message. >> >> The state machine should handle the BFCP message only after all the >> >> fragments for the message have been received. >> > >> >However, the paragraph after that seems to contradict the "MUST" above >> >because it allows receivers to discard incomplete buffers. >> >> I think it needs to read as follows, "When a BFCP implementation receives >> a BFCP message fragment, it MUST buffer the fragment until either it has >> received the entire BFCP message, or until the Response Retransmission >> Timer expires." >> There is also a "must" that should be changed to "MUST" in the paragraph >> describing the retransmission timer. > > > Yes, fixed accordingly. > > -- Tom > > -- > # Cisco | http://www.cisco.com/telepresence/ > ## tomkrist@cisco.com | http://www.tandberg.com > ### | http://folk.uio.no/tomkri/ > > -- # Cisco | http://www.cisco.com/telepresence/ ## tomkrist@cisco.com | http://www.tandberg.com ### | http://folk.uio.no/tomkri/
- [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4582b… internet-drafts
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Tom Kristensen
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Gonzalo Camarillo
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Charles Eckel (eckelcu)
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Tom Kristensen
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Charles Eckel (eckelcu)
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Tom Kristensen
- Re: [bfcpbis] I-D Action: draft-ietf-bfcpbis-rfc4… Gonzalo Camarillo