Re: [rohc] TCP/IP EPIC profile

["West, Mark (ITN)" <[e-mail]>]

While I don't pretend that it contains all the answers, you could have a 
look at 
http://search.ietf.org/internet-drafts/draft-west-tcpip-field-behavior-01.txt

Certainly where there are correlations that I've missed, it would be 
good if folks could point these out...

Having said that, I don't know of any studies of the strength of 
correlation or its effect on compression.  I suppose that's what we're 
in the process of doing at the moment?

Cheers,

Mark.


Per Synnergren (EPL) wrote:

> Hi all,
> 
>  
> 
> A question "out of the blue"...
> 
>  
> 
> Hongbin Liao wrote:
> 
>     1. whether can TCP/IP EPIC profile correctly describe the behavior
>     of TCP? Or, whether EPIC is powerful enough to describe the
>     complicated behavior of TCP/IP?
> 
>         In EPIC, fields are assumed to be independent from each other.
>     Once each field's behaviors are described well, the whole protocol's
>     behaviors are also well-studied. However, in practice, fields in a
>     protocol may not behave independently completely from each other.
>     There may be some connections (or causality) among several fields.
>     For example, most TCP traffics only contain one-way traffic (WWW
>     browsing, FTP downloading, etc.), i.e., only SEQ changes on the
>     forward path (from server to client) and only ACK changes on the
>     backward path (from client to server). The ACK on the forward path
>     and SEQ on the backward path remain constant. However, in TCP/IP
>     EPIC profile, the probabilities for SEQ and ACK are specified
>     seperately:
> 
>     It is obvious that knowledge about "TCP inter-field correlation"
>     could be useful in order to increase the performance of the header
>     compression. Has anyone heard of/or performed thorough studies of
>     the cross-correlation between TCP-fields? 
> 
>      
> 


-- 
Mark A. West, Consultant Engineer
Roke Manor Research Ltd., Romsey, Hants.  SO51 0ZN
Phone [phone]   Fax  [phone]

(Yes, I do know that my disclaimer is in an attachment.  And, no, I 
didn't ask for it to be that way)