Subject: RE: [rohc] draft-saifullah-rohc-tcp-early-comp*-00.txt

From: [email-masked]
Date: Tue, 5 Nov 2002 12:25:35 -0600

Hi Richard,
I see your point regarding the use of profile. If I don't use profile and use any other bits for early compression indication, then that would be addition in the IR packet. With a new profile for early compression enabler, I intended not add any extra bits. Perhaps, I could comment more once I see the format of IR-REPLICATE.

Regards,
Yousuf

-----Original Message-----
From: ext Price, Richard [mailto:[email-masked]]
Sent: 05 November, 2002 11:01 AM
To: Saifullah Yousuf (NRC/Dallas); [email-masked];
[email-masked]
Subject: RE: [rohc] draft-saifullah-rohc-tcp-early-comp*-00.txt

Hi Yousuf,

The precise format of the IR-REPLICATE packet hasn't yet been
defined (we'll do this later once we've decided what TCP/IP
field behaviours need to be supported).

Note however that the purpose of defining a ROHC profile is to
specify how to compress a certain protocol stack in a certain
environment. New profiles may be introduced to compress new
protocol stacks (e.g. TCP/IP) or to boost the performance of
existing profiles in particular environments (e.g. the link-
layer assisted profile for RTP/UDP/IP described in RFC 3242).

Since the mechanisms for allowing context replication are
useful for TCP/IP compression in general, as Lars-Erik has
pointed out the consensus is that we should include these
mechanisms within the basic TCP/IP profile itself in the
form of a new IR-REPLICATE packet type (rather than as a
new ROHC profile).

Your idea to provide a more general mechanism for allowing
certain TCP/IP fields to be signalled outband is an excellent
suggestion and something we should take into account when
designing the packet formats for TCP compression. I'd avoid
creating a new ROHC profile for this task however, because it
would be useful to have this functionality within the basic
TCP/IP profile itself. Instead, my suggestion would be to
include a generalised version of the IR-REPLICATE packet type
(perhaps with a more general name such as IR-OUTBAND?)
supporting both context replication and any other mechanisms
for sending fields outband to the decompressor.

Regards,

Richard

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]
> Sent: Tuesday, November 05, 2002 4:27 PM
> To: [email-masked]; [email-masked]
> Subject: RE: [rohc] draft-saifullah-rohc-tcp-early-comp*-00.txt
> 
> 
> Hi Lars-Erik,
> I have seen different proposals in the ROHC mail list 
> archive, using packet type, using the spare bit in the packet 
> type, etc. I haven't seen any conclusive format for 
> IR-REPLICATE yet. Whatever, it will be it would take some 
> bits for indicating specifically IR-REPLICATE. 
> 
> I would like to clarify that Early Compression is not 
> competing with context replication in a sense that you can 
> have one or the other. Early Compression Enabler can provide 
> context replication plus other mechanisms. The enhancements 
> in ROHC-TCP protocol defined by Early Compression Enabler are 
> accomodating context replication also. 
> 
> 
> Regards,
> Yousuf
> 
> 
> -----Original Message-----
> From: ext Lars-Erik Jonsson (EAB)
> [mailto:[email-masked]]
> Sent: 05 November, 2002 10:01 AM
> To: [email-masked]
> Subject: RE: [rohc] draft-saifullah-rohc-tcp-early-comp*-00.txt
> 
> 
> Yousuf,
> 
> > Early Compression enabler can send the fields like IP version 
> > and IP destination address without defining a new 
> > IR-REPLICATE packet. Existing IR packet can be used for 
> > sending the information, mentioned in your email, by defining 
> > a new profile type.
> 
> We are defining a new profile for ROHC TCP. The IR packet for
> that profile will include replication capabilities, i.e. the
> profile specific part of the IR packet will indicate whether
> it is an ordinary (full) IR or an IR-REPLICATE. Please see
> the ROHC mail list archive.
> 
> I'll come back with comments on your drafts when I have read them.
> 
> Cheers,
> /L-E
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