[dccp] What's in the new drafts?

[Eddie Kohler <kohler@icir.org>]

Hi all,

This message is to lay out the changes that made it into the new dccp
drafts released today (spec-05, ccid2-04, ccid3-04).

General
* We addressed pretty much every reviewer comment.
* Added examples and context.

spec-05
* Rearchitected feature negotiation, using the Change L/Change R/Confirm L/
  Confirm R mechanism we sent mail about a few months ago. The new
  mechanism is much simpler than the old; every negotiation takes exactly
  one exchange, for example. It also solves simultaneous negotiation
  problems. Also explicitly allow for streamlined negotiation.
* New sequence number validity/synchronization mechanism, including a new
  packet, DCCP-Sync. The basic sequence number validity rules were nicely
  simplified by this mechanism; also, MD5 hashes are no longer required to
  get back in sync after a burst of loss.
* Mobility: Added a Mobility ID, a nonce chosen by the stationary endpoint,
  to avoid problems with NAT traversal. Remove Old Address and Old
  Port. NB: This might remove the other reason for the MD5 hash mechanism.
* Add Null ID Regime for CCID 3-Thin.
* Extended sequence numbers, as described in the mail sent last week.
* Generic packet header rearrangement to support extended sequence
  numbers. Includes a reduction of # NDP to 3 bits (from 4).
* Allow more information in Ignored (multiple bytes of option data) and
  DCCP-Reset (a textual error message).
* Allow CCID-specific Reset Reasons.
* Add Mandatory option, which lets an endpoint declare that an option MUST
  be processed (or the connection will be reset).
* Other updates, often only explanatory, including to DCCP-Request, Init
  Cookie (specify retransmissions), Elapsed Time, Timestamp, CCID-specific
  options and features, Slow Receiver, Data Dropped, Payload Checksum,
  security considerations, maximum packet size, middlebox considerations,
  RTP considerations, IANA considerations.

ccid2-04:
* Add a better usage scenario.
* Disallow direct tracking of TCP updates.
* Other explanatory updates, particularly to Sending Acknowledgements, and
  Packet Sizes.

ccid3-04:
* Add a better usage scenario.
* Change Loss Intervals option to be wholly delta-encoded, for trivial
  support of extended sequence numbers. Add examples for clarity.
* Disallow direct tracking of TFRC.
* Import more explanatory information about TFRC.
* Receive Rate is measured in bytes/sec, not bits/sec.
* Other updates, mostly explanatory.

NOT CHANGED
* No text figure of the state diagram.
* Some [[XXX]]s in ccid3-04, particularly around support for Data Dropped.

Eddie

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