Subject: Status of <draft-swallow-mpls-simple-hdr-compress-00.txt>

From: "Goran Janevski" <[email-masked]>
Date: Sun, 12 Nov 2000 13:47:03 -0500

I have been trying to get a definitive answer on this, without any success.
I got a couple of conflicting answers from a couple of sources ("it's been
accepted", "the WG hasn 't gotten around to looking at it"), plus I found
the blurb below in the 47th IETF MPLS minutes.  Subsequently to that, there
are some emails discussing the IP/MPLS Header compression drafts in the July
mailing list archive, with passing references to -simple, but again, no
indication what the status of it is.

Meanwhile, the draft seems to have expired;  too bad, I thought it was a
pretty elegant/simple idea, it was end-to-end, and did not have to be on top
of PPP.

Could anyone _please_ shed some light on this?

Thanks,
Goran

From 47th IETF MPLS WG minutes:
==========================
'Simple Header Compression',
<draft-swallow-mpls-simple-hdr-compress-00.txt>, George Swallow 

George Swallow enumerated the motivating factors that lead to this work.
Namely, that in VoIP, headers account for a significant portion of the
packet. And, for networks in which voice traffic dominates, significant
bandwidth savings can be achieved by compressing headers. He then remarked
that a trade-off between less bandwidth efficiency for better processing
efficiency exists.  He went on to say that this could be done from access
point to access point, where allowing compression on access links without
requiring edge routers to perform header compression.  He also stated that
the same techniques are being employed in PacketCable. 

Further, he described the actual compression technique, mentioning that the
technique operates without the need for re-synchronization, that the MPLS
label serves as the Context ID, and so forth.  

George then proceeded to list some draft refinements.  Namely, he noted that
3 flags were used for MPLS TTL, inferring length from received MTU, and for
re-computing checksum.  And, he also mentioned that the SCID (Sub-context
ID) had two purposes: 1) to allow multiplexing across an LSP, and 2) to
handle simple format variations in a packet stream.

During the Q/A period, Shahram Davari asked how does this technique handles
label merging? George's response was that the setup was accomplished via
RSVP signaling, thus, merging is not permitted. 

George Swallow then posed a question to Rob Coltun, who is the Area Director
of the Routing Area. He asked what should be done with the draft he
presented as well as Lou Berger's draft on the same subject. Rob's initial
response was to defer that decision until VoMPLS BOF.  Lou Berger then
mentioned that the generic header compression schemes are not MPLS specific,
thus, he had a 'strong opinion' that this work should reside in the IETF
Generic WG.  Rob then inquired about the operational demand for this work.
Finally, it was decided that this work will be done in the MPLS WG and that
it will be described in the MPLS WG charter. 

Goran Janevski                                        email:
[email-masked]
Wireless Access IP Technology                       phone: 613 765-3544 (ESN
39)
Wireless Technology Labs                            fax:   613 763-2686