RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Synchronization Delay and Offset Metrics Reporting
draft-ietf-xrblock-rtcp-xr-synchronization-09

[Ballot discuss]


This should be a quickly resolved discuss.

I don't agree with the security considerations section
here. Has someone checked in any detail to see if these
offsets can assist a potential timing side channel
attack? (I'm guessing not.) This has been a common
question for xrblock documents, so I think there's text
in other recent RFCs, but in this case I think the
potential attack could be more realistic. (That is not
covered in 3611 btw.) For example, if this could be used
to access measurements of fine grained timing of the
timing differences between a succession of failed session
setup attempts that could in principle expose key
material or plaintext.

I think the right wording to add should be easy to arrive
at based on a bit of discussion but will be to the effect
of noting the vulnerability and saying something like "if
there's crypto involved, don't do this thousands of times
in the face of errors without raising an alarm" or some
such.

Or, perhaps you have thought about it, and this doesn't
create a timing side channel vulnerability, in which case
noting that would be a fine resolution of the discuss.

[Ballot comment]
      A multimedia session comprises a set of concurrent RTP sessions
      among a common group of participants, using one RTP session for
      each media type.

Thank you for using "comprises" correctly!  I really appreciate that.

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-xrblock-rtcp-xr-synchronization-07.  Authors should review the comments and/or questions below.  Please report any inaccuracies and respond to any questions as soon as possible.

We received the following comments/questions from the IANA's reviewer:

IANA understands that, upon approval of this document, there are two actions which IANA must complete.

First, in the RTCP XR Block Type subregistry of the RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry located at:

http://www.iana.org/assignments/rtcp-xr-block-types/

two new XR Block Types will be registered as follows:

BT: [ TBD-at-registration ]
Name: RTP Flows Initial Synchronization Delay
Reference: [ RFC-to-be ]

BT: [ TBD-at-registration ]
Name: RTP Flows Synchronization Offset Metrics Block
Reference: [ RFC-to-be ]

Second, in the RTCP XR SDP Parameters registry in the RTP Control Protocol Extended Reports (RTCP XR) Session Description Protocol (SDP) Parameters Registry located at:

http://www.iana.org/assignments/rtcp-xr-sdp-parameters/

two new XR SDP Parameters will be registered as follows:

Parameter: rtp-flow-init-syn-delay
Reference: [ RFC-to-be ]

Parameter: rtp-flow-syn-offset
Reference: [ RFC-to-be ]

IANA understands that these are the only actions required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed
until the document has been approved for publication as an RFC.
This message is only to confirm what actions will be performed.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Synchronization Delay and Offset Metrics Reporting) to Proposed Standard


The IESG has received a request from the Metric Blocks for use with
RTCP's Extended Report Framework WG (xrblock) to consider the following
document:
- 'RTP Control Protocol (RTCP) Extended Report (XR) Blocks for
  Synchronization Delay and Offset Metrics Reporting'
  as Proposed
Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2014-02-04. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the
beginning of the Subject line to allow automated sorting.

Abstract


  This document defines two RTP Control Protocol (RTCP) Extended Report
  (XR) Blocks that allow the reporting of synchronization delay and
  offset metrics for use in a range of RTP applications.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-xrblock-rtcp-xr-synchronization/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-xrblock-rtcp-xr-synchronization/ballot/


No IPR declarations have been submitted directly on this I-D.