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Subject: Re: Packet compression
From: "Allan Latham" <alatham,AT,flexsys-group,DOT,com>
Date: Mon, 28 May 2001 22:53:14 +0200
In-reply-to: <Pine.LNX.4.21.0105271616540.30775-100000@raid.kaico.com>

I does help (on average data) - about 50% can be normal for web pages and
plain text etc.

BUT:

1. It's heavy on kernel memory
2. It's ineffective on much binary data
3. It's something else to go wrong
(4. It uses CPU cycles - not a problem any more!)

I implemented this on a much earlier version of cipe - it's way out of
date - but we have used it for a couple of years trouble free.

Much more interesting is packet compression by removing redundant ip/tcp/udp
header fields (a bit like VJ). This does not increase throughput much but it
has a massive effect on latency and hence responsiveness of interactive
sessions.

Best regards to all

Allan

----- Original Message -----
From: <ewheeler,AT,kaico,DOT,com>
To: "Karl Kleinpaste" <karl,AT,charcoal,DOT,com>
Cc: <cipe-l,AT,inka,DOT,de>
Sent: Monday, May 28, 2001 1:21 AM
Subject: Re: Packet compression

> On 27 May 2001, Karl Kleinpaste wrote:
>
> > ewheeler,AT,kaico,DOT,com writes:
> > > Would there be any appreciable performance increase over low bandwidth
> > > lines if the packets were compressed using zlib before they were
> > > encrypted?
> >
> > It doesn't do that much good.  But it helps a little.
> >
> > As a comparison point, experiment a bit with ssh, using different
> > compression levels in .ssh/config, e.g.
> >
> > Host your.chosen.test.destination.host
> >   Compression yes
> >   CompressionLevel 9
> >
> > Try various digits, and do some large file copying over your slow link
> > with scp.  Time the results.
> >
>
> I know this can help alot w/ ssh on plain text and the like but I was
> wondering specifically about CIPE.  Could this be implemented inthe packet
> encapsulation and would we see a performance increase accross low
> bandwidth lines.    My guess is that it would;  I just took a block of
> text:
>
> [root@dev dev]# dd if=/var/log/messages bs=1400 count=1 | gzip -v9 | wc -c
> 1+0 records in
> 1+0 records out
>  77.7%
>     330
>
> You can see that even for mall 1400 byte packets we can get a 77% size
> cut.  Would it be feasible to implement this into CIPE?
>
> --Eric
>
>
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