pilc minutes (corrected)

[Aaron Falk <[e-mail]>]

All-

Please substitute the following modified version of the wg minutes.  I have
corrected name spelling for Khafizov.

--aaron

======================================================
Performance Implications of Link Characteristics WG (pilc)

The PILC working group meeting was held on Tuesday, December 11 at
1300-1400.  The meeting was chaired by Aaron Falk and the following
agenda was followed completely.

AGENDA:
Agenda Bashing                          chairs          2min
Working Group Status                    chairs          3min
CDMA2000 issues                         F. Khafizov    10min
  draft-khafizov-pilc-cdma2000-00.txt
  Q: integrate into 2.5g3g or new doc?
2.5g/3g Update                          H. Inamura      10min
  draft-ietf-pilc-2.5g3g-05.txt
  Q: ready for wg last call?
LINK last call comments                 P. Karn         10min
  draft-ietf-pilc-link-design-08.txt    M. Allman
PILC-related issues in ROHC             C. Borman       10min
IP-DVB announcement                     G. Fairhurst    2min
Adjourn

The meeting started promptly at 13:00 and Blue Sheets were circulated.

Aaron Falk went over the Working Group Status ARQ is in IESG
review. ASYM is going to IESG any day.  LINK design is in last call.
Mark Allman will be taking over editing for Phil Karn's 2.5/3G document
is near last call but needs to incorporate CDMA2000 information.


=========================

CDMA2000

F. Khafizov presented slides on TCP performance over CDMA 2000
networks.  Issues to be addressed include bandwidth oscillation, high
BER, and bandwidth asymmetry.  Bandwidth oscillation degrades
throughput through spurious timeouts.  True of any system with widely
varying bandwidth. 

* Bandwidth Oscillations (BO)
  -	Significant throughput degradation
  -	Not cdma2000 specific
  -	Related to resource contention
  -	Fixes include 1) fix TCP, 2) Fix network or 3) leave as is.
  -	Possible fixes
   o	 Adjust RTO value
   o	 enable Time Stamp option
   o	 increase window size
   o	 minimize ACK delay
  -	Other recommendations
   o	 Aggressive link level error recovery
   o	 disable VJ header compression
   o	 use SACK
  -	Options
   o	 Incorporate  BO in 2.5g/3g and/or LINK ID
   o	 make a separate ID for BO
   o	 have a section in 2.5G/#g ID addressing specifics of CMDA2000

Suggestions from chair and floor moved toward including in existing
documents rather than stand-alone document.

F. Khafizov   volunteer to generate text for the documents.


============

Hiroshi Inamura      presented slides on  2.5G/3G
* Reviewed open issues
  -	header compressions
  -	active queue mgt.
  -	Others
* RTO typically 2s is to small?
  -	Yes
* New Sections
  -	 VJ header compression not recommended

Comments from the floor:

ECN section needs expansion as ECN may be quite beneficial.  Question
as to whether or not the effects of cell changes being incorporated
into draft.

=============

Phil Karn commented that the LINK document appears to be very near
completion.  Bandwidth on Demand and bandwidth oscillations may need
some additional attention.

Floor Comments:
Asymmetry may need a bit of revision as it was written early on.

============

Carsten Bormann presented slides on issues in Robust Header
Compression related to PILC

The following is a summary of Carsten's slides:

Robust Header Compression (ROHC)
  -	Header Compression  is prerequisite for all IP wireless
  -	Wireless = lossy, long latency

Work items

Robust Header Compression  of IP/UDP/RTP
  -	need for e2e VoIP/video
  -	RFC3095 july 2001 used by 3GPP and 3GPP2
  -	ROHC over PPP; 0-byte LLA submitted to IESG

ROHC for TCP  is starting to gel

New: signaling compression (reduce latency)
  -	universal decompressor

ROHC is working on MIBs
     Next work will probably be related to  SCTP

RFC 2507 is not good enough as it does not handle options like SACK,
timestamps
  -	need to compress ECN bits well
  -	cope with TCP's extensibility
  -	(state of the ar ha advanced)

Requirements drafts presented:  2 drafts
  -	please read and comment on 01/03 versions once available!

Solutions :  two drafts in the process of merging 
	     Need wider input wrt next generation TCP

ROHC TCP Requirements
  -	Links with few residual erros but may have packet loss
  -	Robustness
   o	 Should not disable TCOP mechanisms
   o	 Must NOT generate damaged headers
   o	 Must deal with current and future TCPs
   o	 TCP sequence numbers and IP ID less predictable

TCP Sample Issues
  -	TCP checksum and.or additional CRC for checking
  -	Unidirectional vs bi-directional compression
  -	Can ROHC ignore IP options?
  -	Compress in tunnel encapsulations, too?
   o	 Reordering (prohibited, detected, allowed)?
  -	Integrate with ASYM mechanisms
  -	What are the assumptions about ECN behavior?
  -	What loss amplifications behaviours are actually acceptable?
  -	IPR

Comments from floor

  - even if residual error is low, what is error distribution (burst
    errors vs uniform distribution errors).  However, residual bit
    errors as defined by ROHC are packet with errors passed from layer
    2 too layer 3.

===================


IP-DVB announcement                     G. Fairhurst    2min

G. Fairhurst extended an invitation to an informal meeting on 12/12 at
15:30 - 17:30.  The meeting will be on IP over DVB.  It is not an BoF,
but a maillist will be created for those interested in this subject.
More information can be found at
http://www.erg.abdn.ac.uk/users/gorry/ip-dvb/.