Subject: [AVT] cRTP questions

From: Moter Du <[email-masked]>
Date: Wed, 30 Jan 2002 16:11:46 +0800

Hi,

Is the idea to compress IP/UDP/RTP strictly limited to low-speed serial
line?

The question comes from CSMA/CD, efficiency analysis in theory shows the
larger the frame is, the better the efficiency it achieves.  That means,
CSMA/CD link efficiency (e.g., fast-ethernet) wouldn't gain from header
compression, because the phsical frame is reduced while the headers are
reduced.  But meanwhile, I heard many companies claim their ethernet-based
VoIP gateways outperform due to cRTP.

Thanks.

Moter

---

From: Moter Du <[email-masked]>
Date: Thu, 31 Jan 2002 19:26:59 +0800

Totally agree your words, but they're not what I was pointing.

Given a number of transmitting stations, transmission rate, media type,
etc., mostly the average efficiency (utilization, throughput, whatever) can
be figured out.  No more and less in average.  That case compression
technologies are normally developped under certain consumptions.

My questions came from some commercial announcements which almost misled me
(can't deny, I'm rather new in this area).  And surely now I understand many
rely on underlying multiplexing/segmentation/others capabilities to optimize
the efficiency.  Thanks for your advice.

Moter

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]
Sent: Thursday, January 31, 2002 6:48 PM
To: [email-masked]'
Subject: Re: [AVT] cRTP questions

Efficiency can be misleading.  If you measure efficiency as the total number
of bytes sent in a given period, then having extra bytes increases your
efficiency (even if these bytes are just padding).  But if you measure
efficiency as the number of useful bytes sent in a given period, extra bytes
decrease your efficiency. 

Michael. 

Moter Du <[email-masked]> 
Sent by: [email-masked] 
30/01/02 09:11 
        
        To:        "[email-masked]'" <[email-masked]> 
        cc:         
        Subject:        [AVT] cRTP questions

Hi,