Subject: Re: [bfcpbis] draft-ietf-bfcpbis-rfc4583bis

From: "Charles Eckel (eckelcu)" <[email-masked]>
Date: Fri, 17 Apr 2015 21:42:30 +0000

[adding bfcppbis list]

Hi Christer,

Thanks for your review and comments. In the BFCP usage, the DTLS
connection is dedicated to the BFCP stream it contains. As I understand
it, the complications around DTLS re-establishement discussed in MMUSIC
result from use of a single DTLS connection for multiple RTP and/or SCTP
streams. Those complications do not exist with the BFCP usage, so I think
it is sufficient to continue to reference RFC 5763 and not use the SDP
connection attribute.

Cheers,
Charles (as an individual)

On 4/15/15, 12:29 AM, "Christer Holmberg" <[email-masked]>
wrote:

>Hi,
>
>First, I want to apologize for not providing my review earlier.
>
>As far as the BFCP specifics are concerned, I am ok with the latest
>version of the draft.
>
>However, there is an issue regarding the DTLS considerations (section
>10.5).
>
>The text says:
>
>	"Once a DTLS connection has been established, if the 'active/passive'
>   	status of the endpoints change during a session, a new DTLS
>   	connection MUST be established."
>
>There is currently an ongoing discussion in MMUSIC about when a DTLS
>connection is to be re-established.
>
>The discussion is still ongoing, but the outcome will most likely NOT be
>aligned with the text above.
>
>For example, there has been a suggestion (by myself) to use the SDP
>connection attribute to explicitly indicate that a new DTLS connection
>needs to be established.
>
>
>The draft also says:
>
>	"If the transport parameters or the key fingerprints change, the
>   	endpoints MUST establish a new DTLS connection."
>
>This is related to the earlier issue. There is the discussion about ICE
>"virtual connections", and that a single DTLS connection would apply to
>all ICE candidates associated with
>an m- line. So, even if a candidate changes (read: transport parameter
>changes), it would not automatically trigger a new DTLS connection.
>
>
>The issues above are also holding up the SCTP-SDP draft, so it doesn't
>only affect BFCPbis :)
>
>
>Regards,
>
>Christer
>
>
>-----Original Message-----
>From: Alissa Cooper [mailto:[email-masked]]
>Sent: 8. huhtikuuta 2015 3:07
>To: Charles Eckel (eckelcu)
>Cc: Gonzalo Camarillo; Tom Kristensen (tomkrist);
>[email-masked]; Ben Campbell; Christer
>Holmberg
>Subject: Re: draft-ietf-bfcpbis-rfc4583bis
>
>Adding Christer to this thread.
>
>On Apr 7, 2015, at 12:44 PM, Charles Eckel (eckelcu) <[email-masked]>
>wrote:
>
>> Christer (cc’d) and I discussed some of the changes offlist in Dallas,
>> and he is to come back to the list with comments after Dallas - which
>> is now :)
>> 
>> Cheers,
>> Charles
>> 
>> On 4/7/15, 10:26 AM, "Alissa Cooper" <[email-masked]> wrote:
>> 
>>> Checking in on this — has Christer been prompted to review the latest
>>> rev of draft-ietf-bfcpbis-rfc4583bis?
>>> 
>>> Thanks,
>>> Alissa
>>> 
>>> On Feb 25, 2015, at 9:14 AM, Charles Eckel (eckelcu)
>>> <[email-masked]>
>>> wrote:
>>> 
>>>> Most of the changes I this recent update to rfc4583bis were inspired
>>>> by comments and suggested text provided by Christer. He is in the
>>>> process of reviewing. If all goes well with that, we are ready to
>>>> proceed with proto writeup (Mary) and AD review.
>>>> 
>>>> Cheers,
>>>> Charles
>>>> 
>>>> On 2/25/15, 7:01 AM, "Alissa Cooper" <[email-masked]> wrote:
>>>> 
>>>>> rfc4583 has not had an AD review yet. Richard can hopefully take
>>>>> care of that while I¹m on leave (starting today, actually).
>>>>> 
>>>>> On Feb 25, 2015, at 2:56 AM, Gonzalo Camarillo
>>>>> <[email-masked]> wrote:
>>>>> 
>>>>>> Hi Alissa,
>>>>>> 
>>>>>> I have noted that while rfc4582bis in on the agenda of the March
>>>>>> 5th telechat (thanks for handling that!), rfc4583bis isn't. Tom
>>>>>> revised rfc4583bis on February 20th. Should rfc4583bis be on the
>>>>>> agenda of the telechat as well or there is still something left
>>>>>> for Tom to take care of?
>>>>>> 
>>>>>> Thanks,
>>>>>> 
>>>>>> Gonzalo
>>>>>> 
>>>>>> On 18/02/2015 9:28 PM, Alissa Cooper wrote:
>>>>>>> Pinging on this.
>>>>>>> 
>>>>>>> March 5 will likely be my last telechat before going on leave, so
>>>>>>> it would be great to get this scheduled on that one. To do that,
>>>>>>> the rev needs to be posted today. The updates are pretty minimal
>>>>>>> and are all basically written up in Charles¹ response to my AD
>>>>>>>review.
>>>>>>> 
>>>>>>> Alissa
>>>>>>> 
>>>>>>> On Feb 15, 2015, at 9:13 AM, Gonzalo Camarillo
>>>>>>> <[email-masked]
>>>>>>> <mailto:[email-masked]>>
>>>>>>> wrote:
>>>>>>> 
>>>>>>>> I have talked offline with the other authors and Tom is holding
>>>>>>>> the pen. Tom, do you think you can meet the time frame below?
>>>>>>>> 
>>>>>>>> Cheers,
>>>>>>>> 
>>>>>>>> Gonzalo
>>>>>>>> 
>>>>>>>> Sent from my mobile
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> ---- Alissa Cooper wrote ----
>>>>>>>> 
>>>>>>>> Just wanted to see if this rev might get done in the next couple
>>>>>>>> of days. If so, we could get it on the next telechat agenda
>>>>>>>>(March 5).
>>>>>>>> 
>>>>>>>> Alissa
>>>>>>>> 
>>>>>>>> Begin forwarded message:
>>>>>>>> 
>>>>>>>>> *From: *Alissa Cooper <[email-masked]
>>>>>>>>> <mailto:[email-masked]>>
>>>>>>>>> *Subject: **Re: [bfcpbis] AD evaluation:
>>>>>>>>> draft-ietf-bfcpbis-rfc4582bis-12*
>>>>>>>>> *Date: *February 9, 2015 at 3:58:52 PM PST
>>>>>>>>> *To: *"Charles Eckel (eckelcu)" <[email-masked]
>>>>>>>>> <mailto:[email-masked]>>
>>>>>>>>> *Cc: *"[email-masked] <mailto:[email-masked]>"
>>>>>>>>> <[email-masked]
>>>>>>>>> <mailto:[email-masked]>>
>>>>>>>>> 
>>>>>>>>> Hi Charles,
>>>>>>>>> 
>>>>>>>>> Thanks, some responses inline.
>>>>>>>>> 
>>>>>>>>> On Feb 4, 2015, at 10:40 AM, Charles Eckel (eckelcu)
>>>>>>>>> <[email-masked] <mailto:[email-masked]>> wrote:
>>>>>>>>> 
>>>>>>>>>> HI Alissa,
>>>>>>>>>> 
>>>>>>>>>> Thank you for the review. Please see my thoughts on your
>>>>>>>>>> comments and questions inline.
>>>>>>>>>> 
>>>>>>>>>> From: Alissa Cooper <[email-masked]
>>>>>>>>>> <mailto:[email-masked]>>
>>>>>>>>>> Date: Thursday, January 29, 2015 at 10:19 PM
>>>>>>>>>> To: "[email-masked] <mailto:[email-masked]>"
>>>>>>>>>> <[email-masked] <mailto:[email-masked]>>
>>>>>>>>>> Subject: [bfcpbis] AD evaluation:
>>>>>>>>>> draft-ietf-bfcpbis-rfc4582bis-12
>>>>>>>>>> 
>>>>>>>>>>> I have reviewed this draft in preparation for IETF LC.
>>>>>>>>>>> Overall the document appears in good shape. I have a few
>>>>>>>>>>> questions and comments I¹d like to discuss before issuing the
>>>>>>>>>>> IETF last call. I¹ve also included some editorial nits that
>>>>>>>>>>> should be addressed together with any last call comments.
>>>>>>>>>>> 
>>>>>>>>>>> Comments and questions:
>>>>>>>>>>> 
>>>>>>>>>>> = Section 5.1 =
>>>>>>>>>>> "If an endpoint receives a message with an  unsupported
>>>>>>>>>>> version field value, the receiving server MUST send an  Error
>>>>>>>>>>> message with parameter value 12 (Unsupported Version) to
>>>>>>>>>>> indicate this.²
>>>>>>>>>>> 
>>>>>>>>>>> This seems a little misleading since RFC 4582 didn¹t specify
>>>>>>>>>>> what to do upon receipt of a message with a version other than
>>>>>>>>>>>1.
>>>>>>>>>>> Implementations that do not get upgraded to be compliant with
>>>>>>>>>>> 4582bis (which could certainly account for some of those that
>>>>>>>>>>> will not support version 2) will therefore never send the
>>>>>>>>>>> error specified here. This seems like it should at least be
>>>>>>>>>>> noted given the MUST-level requirement. The same applies in
>>>>>>>>>>> Section 13.7.
>>>>>>>>>> 
>>>>>>>>>> Good point. I believe we made this a MUST because we were
>>>>>>>>>> thinking in terms of implementations compliant with this bis
>>>>>>>>>>version.
>>>>>>>>>> Adding
>>>>>>>>>> your suggested note about rfc 4582 implementations here and in
>>>>>>>>>> section 13.7 seems useful to me.
>>>>>>>>> 
>>>>>>>>> Ok
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> = Section 7 =
>>>>>>>>>>> "BFCP entities MUST support, at a minimum, the
>>>>>>>>>>> TLS_RSA_WITH_AES_128_CBC_SHA ciphersuite [6].²
>>>>>>>>>>> 
>>>>>>>>>>> I realize this requirement comes from RFC 4582, but I¹d like
>>>>>>>>>>> to understand why it has not been updated to be consistent
>>>>>>>>>>> with more current guidance on cipher suite selection (e.g.,
>>>>>>>>>>> 
>>>>>>>>>>>https://tools.ietf.org/html/draft-ietf-uta-tls-bcp-08#section-4)
>>>>>>>>>>>.
>>>>>>>>>> 
>>>>>>>>>> How about we keep this minimum requirement, and add a
>>>>>>>>>> reference to draft-ietf-uta-tls-bcp along with a
>>>>>>>>>> recommendation to adhere to the best practices it outlines in
>>>>>>>>>>section 4?
>>>>>>>>> 
>>>>>>>>> I think MUST support TLS_RSA_WITH_AES_128_CBC_SHA for backwards
>>>>>>>>> compatibility and SHOULD support the ones listed in the UTA
>>>>>>>>> drafts would be ok.
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> = Sections 8, 8.1, 8.2 =
>>>>>>>>>>> It seems like the transaction ID requirements regarding
>>>>>>>>>>> non-reuse/monotonically increasing IDs are re-stated multiple
>>>>>>>>>>> times across these three sections, in slightly different
>>>>>>>>>>> ways, to the point where it¹s not clear exactly what they
>>>>>>>>>>> are. It seems like they are:
>>>>>>>>>>> 
>>>>>>>>>>> (1) Reliable transport, server-initiated transaction: ID is 0
>>>>>>>>>>> (2) Unreliable transport, server-initiated transaction: ID
>>>>>>>>>>> MUST be monotonically increasing (except for wrap-around)
>>>>>>>>>>> (3) Reliable transport, client-initiated transaction: ID MUST
>>>>>>>>>>> NOT be 0 and MUST NOT be reused in another message from the
>>>>>>>>>>> client until a response from the server is received for the
>>>>>>>>>>> transaction, but need not be monotonically increasing (e.g.,
>>>>>>>>>>> a lower, recently used ID could be re-used once a response is
>>>>>>>>>>> received)
>>>>>>>>>>> (4) Unreliable transport, client-initiated transaction: ID
>>>>>>>>>>> MUST be monotonically increasing (except for wrap-around)
>>>>>>>>>>> 
>>>>>>>>>>> Is (3) the correct interpretation of the text in 8.1? If so,
>>>>>>>>>>> why not just require IDs in all client-initiated transactions
>>>>>>>>>>> to be monotonically increasing?
>>>>>>>>>> 
>>>>>>>>>> Agree we can and should simplify this. Sections 8.1 and 8.2
>>>>>>>>>> cover the client behavior and server behavior in detail. As
>>>>>>>>>> such, the transaction ID related information at the start of
>>>>>>>>>> Section 8 is superfluous. I recommend reducing the text in
>>>>>>>>>> Section 8 to the
>>>>>>>>>> follow:
>>>>>>>>>> 
>>>>>>>>>> 8. Protocol Transactions
>>>>>>>>>> 
>>>>>>>>>> In BFCP, there are two types of transactions: client-initiated
>>>>>>>>>> transactions and server-initiated transactions.
>>>>>>>>>> 
>>>>>>>>>> Client-initiated transactions consist of a request from a
>>>>>>>>>> client to a floor control server and a response from the floor
>>>>>>>>>> control server to the client.
>>>>>>>>>> 
>>>>>>>>>> Server-initiated transactions have different behavior
>>>>>>>>>> depending on underlying transport:
>>>>>>>>>> 
>>>>>>>>>>    When using a reliable transport, server-initiated
>>>>>>>>>>transactions
>>>>>>>>>>    consist of a single message from a floor control server to a
>>>>>>>>>>    client (notifications).  They do not trigger any response.
>>>>>>>>>> 
>>>>>>>>>>    When using an unreliable transport, server-initiated
>>>>>>>>>> transactions
>>>>>>>>>>    consist of a request from a floor control server to a
>>>>>>>>>> client and a
>>>>>>>>>>    response from the client to the floor control server.
>>>>>>>>>> 
>>>>>>>>>> When using BFCP over an unreliable transport, retransmission
>>>>>>>>>> timer T1 (see Section 8.3) MUST be used for all requests until
>>>>>>>>>> the transaction is completed.
>>>>>>>>>> 
>>>>>>>>>> Then in section 8.1, we add the important details removed from
>>>>>>>>>> section 8.
>>>>>>>>>> 
>>>>>>>>>> 8.1.1 Client Behavior
>>>>>>>>>> 
>>>>>>>>>> A client starting a client-initiated transaction MUST set the
>>>>>>>>>> Conference ID in the common header of the message to the
>>>>>>>>>> Conference ID for the conference that the client obtained
>>>>>>>>>> previously.
>>>>>>>>>> 
>>>>>>>>>> The client MUST set the Transaction ID value in the common
>>>>>>>>>> header to a number that is different from 0 and that MUST NOT
>>>>>>>>>> be reused in another message from the client until a response
>>>>>>>>>> from the server is received for the transaction.  The client
>>>>>>>>>> uses the Transaction ID value to match this message with the
>>>>>>>>>> response from the floor control server. When using BFCP over
>>>>>>>>>> an unreliable transport, it is important to choose a
>>>>>>>>>> Transaction ID value that lets the receiver distinguish the
>>>>>>>>>> reception of the next message in a sequence of BFCP messages
>>>>>>>>>> from a retransmission of a previous message.  Therefore, BFCP
>>>>>>>>>> entities using an unreliable transport MUST use monotonically
>>>>>>>>>> increasing Transaction ID values (except for wrap-around).
>>>>>>>>>> 
>>>>>>>>>> A client receiving a server-initiated transaction over an
>>>>>>>>>> unreliable transport MUST copy the Transaction ID from the
>>>>>>>>>> request received from the server into the response.
>>>>>>>>>> [Question: is there a need to copy the Conference ID and User
>>>>>>>>>> ID, if present?]
>>>>>>>>>> 
>>>>>>>>>> 8.2. Server Behavior
>>>>>>>>>> 
>>>>>>>>>> A floor control server sending a response within a
>>>>>>>>>> client-initiated transaction MUST copy the Conference ID, the
>>>>>>>>>> Transaction ID, and the User ID from the request received from
>>>>>>>>>> the client into the response.
>>>>>>>>>> 
>>>>>>>>>> Server-initiated transactions MUST contain a Transaction ID
>>>>>>>>>> equal to
>>>>>>>>>> 0 when BFCP is used over a reliable transport.  Over an
>>>>>>>>>> unreliable transport, the Transaction ID shall have the same
>>>>>>>>>> properties as for client-initiated transactions. The server
>>>>>>>>>> uses the Transaction ID value to match this message with the
>>>>>>>>>> response from the floor participant or floor chair.
>>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> Thanks, this is better.
>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> = Section 9 (impacts Section 14 as well) = "BFCP clients
>>>>>>>>>>> SHOULD authenticate the floor control server before sending
>>>>>>>>>>> any BFCP message to it or accepting any BFCP message from it.
>>>>>>>>>>> Similarly, floor control servers SHOULD authenticate a client
>>>>>>>>>>> before accepting any BFCP message from it or sending any BFCP
>>>>>>>>>>> message to it.
>>>>>>>>>>> 
>>>>>>>>>>> BFCP supports TLS/DTLS mutual authentication between clients
>>>>>>>>>>> and floor control servers, as specified in Section 9.1.  This
>>>>>>>>>>> is the RECOMMENDED authentication mechanism in BFCP.²
>>>>>>>>>>> 
>>>>>>>>>>> What are the cases where clients and servers do not need to
>>>>>>>>>>> be authenticating each other? I know this requirement and the
>>>>>>>>>>> other SHOULD-level requirements around use of TLS/DTLS are
>>>>>>>>>>> carried over from RFC 4582, but I¹m concerned that they
>>>>>>>>>>> aren¹t as strong as they should be. For a conference where
>>>>>>>>>>> the signaling traffic is authenticated and confidentiality
>>>>>>>>>>> and integrity protected, why is it ok for the floor control
>>>>>>>>>>> traffic not to be? Could these requirements be adjusted to
>>>>>>>>>>> require use of TLS/DTLS at least in cases where the signaling
>>>>>>>>>>> is also protected?
>>>>>>>>>> 
>>>>>>>>>> Yes, but again, this would be at the expense of adding a non
>>>>>>>>>> backward compatible change from rfc 4582. How about saying
>>>>>>>>>> TLS/DTLS MUST be used for BFCP in such cases, while pointing
>>>>>>>>>> out the rfc
>>>>>>>>>> 4582
>>>>>>>>>> based implementations may not comply (similar to what we did
>>>>>>>>>> with the version field).
>>>>>>>>> 
>>>>>>>>> Works for me.
>>>>>>>>> 
>>>>>>>>> Feel free to make all of these changes and submit a rev and
>>>>>>>>> I¹ll issue the IETF LC.
>>>>>>>>> 
>>>>>>>>> Thanks,
>>>>>>>>> Alissa
>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> = Section 14 =
>>>>>>>>>>> See the point above about ciphersuites. ³Non-null encryption²
>>>>>>>>>>> is not a sufficient minimum baseline, and if the requirements
>>>>>>>>>>> change in Section 7 they should be reflected here as well.
>>>>>>>>>> 
>>>>>>>>>> Yep.
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> Editorial nits to be resolved with LC comments:
>>>>>>>>>>> 
>>>>>>>>>>> = Section 5.1 =
>>>>>>>>>>> ³The version field MUST be set to 1 when using BFCP over a
>>>>>>>>>>> reliable transport, i.e. as in [2].²
>>>>>>>>>>> 
>>>>>>>>>>> I find it a little odd to reference the spec you¹re
>>>>>>>>>>> obsoleting in this sentence, especially since BFCP over a
>>>>>>>>>>> reliable transport is completely specified in this bis
>>>>>>>>>>> document. I would suggest dropping the i.e. clause.
>>>>>>>>>> 
>>>>>>>>>> Good catch. This is a carry over from before this draft was
>>>>>>>>>> adopted as a bis version of rfc4582.
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> "The version field MUST be set to 2 when using BFCP over an
>>>>>>>>>>> unreliable transport with the extensions specified in this
>>>>>>>>>>> document.²
>>>>>>>>>>> 
>>>>>>>>>>> The bit about ³with the extensions specified in this
>>>>>>>>>>> document² is extraneous and should be removed.
>>>>>>>>>>> 
>>>>>>>>>>> "If an endpoint receives a message with an unsupported
>>>>>>>>>>> version field value, the receiving server MUST send an Error
>>>>>>>>>>> message with parameter value 12 (Unsupported Version) to
>>>>>>>>>>> indicate this.²
>>>>>>>>>>> 
>>>>>>>>>>> Use of the word ³server² here makes it sound as if only
>>>>>>>>>>> servers could receive headers with unsupported versions.
>>>>>>>>>>> Should this be ³the receiving endpoint²?
>>>>>>>>>>> 
>>>>>>>>>>> = Section 6.2.4 =
>>>>>>>>>>> "[23], Section 6.7 provides useful recommendations Š²
>>>>>>>>>>> 
>>>>>>>>>>> The links in the references are not quite right.
>>>>>>>>>>> 
>>>>>>>>>>> = Section 8.3.2 =
>>>>>>>>>>> s/when fires/when fired/
>>>>>>>>>>> 
>>>>>>>>>>> = Section 14 =
>>>>>>>>>>> s/high-jack/hijack/
>>>>>>>>>>> 
>>>>>>>>>>> = Section B.1 =
>>>>>>>>>>> "situation where multiple different and non-interoperable
>>>>>>>>>>> would
>>>>>>>>>>> co-
>>>>>>>>>>> exist in the market.²
>>>>>>>>>>> 
>>>>>>>>>>> There is a word missing after ³non-interoperable."
>>>>>>>>>> 
>>>>>>>>>> This should read ³non-interoperable implementations². Earlier
>>>>>>>>>> in that same sentence, ³BFCP over UDP were already used²
>>>>>>>>>> should read ³BFCP over UDP is already being used².
>>>>>>>>>> 
>>>>>>>>>> Cheers,
>>>>>>>>>> Charles
>>>>>>>>> 
>>>>>>>>> _______________________________________________
>>>>>>>>> bfcpbis mailing list
>>>>>>>>> [email-masked] <mailto:[email-masked]>
>>>>>>>>> https://www.ietf.org/mailman/listinfo/bfcpbis
>>>>>>>> 
>>>>>>> 
>>>>>> 
>>>>> 
>>>> 
>>> 
>> 
>

---

From: Christer Holmberg <[email-masked]>
Date: Sat, 18 Apr 2015 21:01:36 +0000

Hi Charles,

> [adding bfcppbis list]
>
> Hi Christer,
>
> Thanks for your review and comments. In the BFCP usage, the DTLS connection is dedicated to the BFCP
> stream it contains. As I understand it, the complications around DTLS re-establishement discussed in MMUSIC 
> result from use of a single DTLS connection for multiple RTP and/or SCTP streams. Those complications do 
> not exist with the BFCP usage, so I think it is sufficient to continue to reference RFC 5763 and not use the 
> SDP connection attribute.

The complications do not result from use of a single DTLS connection for multiple streams - it mainly results from the usage of ICE. And, as far as I know, ICE can be used also for BFCP.

And, even without ICE we intend to add text saying that a DTLS connection is only re-established if the underlying transport changes.

Regards,

Christer

>The discussion is still ongoing, but the outcome will most likely NOT 
>be aligned with the text above.
>
>all ICE candidates associated with an m- line. So, even if a candidate 
>changes (read: transport parameter changes), it would not automatically 
>trigger a new DTLS connection.
>
>
>> Christer (cc’d) and I discussed some of the changes offlist in 
>> Dallas, and he is to come back to the list with comments after Dallas 
>> - which is now :)
>> 
>> Cheers,
>> Charles
>> 
>>> Checking in on this — has Christer been prompted to review the 
>>> latest rev of draft-ietf-bfcpbis-rfc4583bis?
>>> 
>>> Thanks,
>>> Alissa
>>> 
>>>> Most of the changes I this recent update to rfc4583bis were 
>>>> inspired by comments and suggested text provided by Christer. He is 
>>>> in the process of reviewing. If all goes well with that, we are 
>>>> ready to proceed with proto writeup (Mary) and AD review.
>>>> 
>>>> Cheers,
>>>> Charles
>>>> 
>>>>>>> March 5 will likely be my last telechat before going on leave, 
>>>>>>>so  it would be great to get this scheduled on that one. To do 
>>>>>>>that,  the rev needs to be posted today. The updates are pretty 
>>>>>>>minimal  and are all basically written up in Charles¹ response to 
>>>>>>>my AD review.
>>>>>>> 
>>>>>>> Alissa
>>>>>>> 
>>>>>>>> Just wanted to see if this rev might get done in the next 
>>>>>>>>couple  of days. If so, we could get it on the next telechat 
>>>>>>>>agenda (March 5).
>>>>>>>> 
>>>>>>>> Alissa
>>>>>>>> 
>>>>>>>> Begin forwarded message:
>>>>>>>> 
>>>>>>>>>>> questions and comments I¹d like to discuss before issuing 
>>>>>>>>>>> the IETF last call. I¹ve also included some editorial nits 
>>>>>>>>>>> that should be addressed together with any last call comments.
>>>>>>>>>>> 
>>>>>>>>>>> Comments and questions:
>>>>>>>>>>> 
>>>>>>>>>>> = Section 5.1 =
>>>>>>>>>>> version field value, the receiving server MUST send an  
>>>>>>>>>>> Error message with parameter value 12 (Unsupported Version) 
>>>>>>>>>>> to indicate this.²
>>>>>>>>>>> 
>>>>>>>>>>>what to do upon receipt of a message with a version other 
>>>>>>>>>>>than 1.
>>>>>>>>>>> Implementations that do not get upgraded to be compliant 
>>>>>>>>>>>with  4582bis (which could certainly account for some of 
>>>>>>>>>>>those that  will not support version 2) will therefore never 
>>>>>>>>>>>send the  error specified here. This seems like it should at 
>>>>>>>>>>>least be  noted given the MUST-level requirement. The same 
>>>>>>>>>>>applies in  Section 13.7.
>>>>>>>>>> 
>>>>>>>>>> your suggested note about rfc 4582 implementations here and 
>>>>>>>>>>in  section 13.7 seems useful to me.
>>>>>>>>> 
>>>>>>>>> Ok
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> = Section 7 =
>>>>>>>>> I think MUST support TLS_RSA_WITH_AES_128_CBC_SHA for 
>>>>>>>>> backwards compatibility and SHOULD support the ones listed in 
>>>>>>>>> the UTA drafts would be ok.
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> = Sections 8, 8.1, 8.2 =
>>>>>>>>>>> non-reuse/monotonically increasing IDs are re-stated 
>>>>>>>>>>> multiple times across these three sections, in slightly 
>>>>>>>>>>> different ways, to the point where it¹s not clear exactly 
>>>>>>>>>>> what they are. It seems like they are:
>>>>>>>>>>> 
>>>>>>>>>>> (3) Reliable transport, client-initiated transaction: ID 
>>>>>>>>>>> MUST NOT be 0 and MUST NOT be reused in another message from 
>>>>>>>>>>> the client until a response from the server is received for 
>>>>>>>>>>> the transaction, but need not be monotonically increasing 
>>>>>>>>>>> (e.g., a lower, recently used ID could be re-used once a 
>>>>>>>>>>> response is
>>>>>>>>>>> received)
>>>>>>>>>>> why not just require IDs in all client-initiated 
>>>>>>>>>>> transactions to be monotonically increasing?
>>>>>>>>>> 
>>>>>>>>>> In BFCP, there are two types of transactions: 
>>>>>>>>>> client-initiated transactions and server-initiated transactions.
>>>>>>>>>> 
>>>>>>>>>> client to a floor control server and a response from the 
>>>>>>>>>> floor control server to the client.
>>>>>>>>>> 
>>>>>>>>>> timer T1 (see Section 8.3) MUST be used for all requests 
>>>>>>>>>> until the transaction is completed.
>>>>>>>>>> 
>>>>>>>>>> Then in section 8.1, we add the important details removed 
>>>>>>>>>> from section 8.
>>>>>>>>>> 
>>>>>>>>>> 8.1.1 Client Behavior
>>>>>>>>>> 
>>>>>>>>>> Transaction ID, and the User ID from the request received 
>>>>>>>>>> from the client into the response.
>>>>>>>>>> 
>>>>>>>>>>> Similarly, floor control servers SHOULD authenticate a 
>>>>>>>>>>> client before accepting any BFCP message from it or sending 
>>>>>>>>>>> any BFCP message to it.
>>>>>>>>>>> 
>>>>>>>>>>> and floor control servers, as specified in Section 9.1.  
>>>>>>>>>>> This is the RECOMMENDED authentication mechanism in BFCP.²
>>>>>>>>>>> 
>>>>>>>>>>> be authenticating each other? I know this requirement and 
>>>>>>>>>>> the other SHOULD-level requirements around use of TLS/DTLS 
>>>>>>>>>>> are carried over from RFC 4582, but I¹m concerned that they 
>>>>>>>>>>> require use of TLS/DTLS at least in cases where the 
>>>>>>>>>>> signaling is also protected?
>>>>>>>>>> 
>>>>>>>>>>> See the point above about ciphersuites. ³Non-null 
>>>>>>>>>>> encryption² is not a sufficient minimum baseline, and if the 
>>>>>>>>>>> requirements change in Section 7 they should be reflected here as well.
>>>>>>>>>> 
>>>>>>>>>> Yep.
>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>>

---

From: "Charles Eckel (eckelcu)" <[email-masked]>
Date: Mon, 20 Apr 2015 17:39:54 +0000

Hi Christer,

I reread the current draft and went through the following MMUSIC thread on
this subject:
http://www.ietf.org/mail-archive/web/mmusic/current/msg14631.html

As a result, I better understand the issue you are addressing. I suggest
the following changes to be consistent with what is being proposed in
MMUSIC:

------------
Section 9:

OLD: 
Endpoints that use the offer/answer model to establish a DTLS
   association MUST support the 'setup' attribute, as defined in [7].
When DTLS is used with UDP, the 'setup' attribute indicates which of
the endpoints (client or floor control server) initiates the DTLS
association setup. The requirements for the offer/answer exchange
specified in [13], Section 5 of [13] MUST be followed when using DTLS.
Offer/answer considerations are described in Section 10.5.

NEW: 
When DTLS is used with UDP, the requirements specified in Section 5
of [13] MUST be followed.

Section 10.5

OLD
   If the transport parameters or the key fingerprints change, the
   endpoints MUST establish a new DTLS connection.  In such case the
   'active/passive' status of the endpoints will again be determined
   following the procedures in [7], and the new status will be used to
   determine the TLS roles associated with the new DTLS connection.

      Informational note: The procedure above is identical to the one
      defined for DTLS-SRTP in [13].

      Note: A new DTLS connection needs to be established if the
      transport parameters or the key fingerprints change.

NEW: 
The conditions under which endpoints MUST establish a new DTLS
connection are as the same defined for DTLS-SRTP in [13].
————————

This way we avoid any potential conflicts with the intent of RFC 5763, and
when clarifications to RFC 5763 are made, they will be picked up by the
BFCP spec.

Cheers,
Charles

On 4/18/15, 2:01 PM, "Christer Holmberg" <[email-masked]>
wrote:

>>connection is dedicated to the BFCP
>The complications do not result from use of a single DTLS connection for
>multiple streams - it mainly results from the usage of ICE. And, as far
>as I know, ICE can be used also for BFCP.
>
>And, even without ICE we intend to add text saying that a DTLS connection
>is only re-established if the underlying transport changes.
>
>Regards,
>
>Christer
>
>
>
>>Hi,
>>