RE: IPCOMP and IPSEC

[Stephen Waters <[e-mail]>]

Saroop,

Well IPSEC does change the whole picture for compression.  With
encryption being performed at the IP layer, compression needs to happen
there too (not at the datalink).  The IP-layer compression (IPPCP) calls
for zero-history compression - for which the performance can be bad.
When we did LZS zero-history support for X.25 links, we used a minimum
packet size of 500bytes, i.e. we would not even try to compress the
packet if it was smaller than that. 

On my office link (ISDN/PPP/LZS with history),  I average 2:1
compression.   I suspect this would reduce noticeably for zero-history.


Steve.



-----Original Message-----
From:	Saroop Mathur [SMTP:[e-mail]]
Sent:	Friday, May 29, 1998 1:02 AM
To:	Eric Dean; Daniel Harkins
Cc:	Stephen Waters; [e-mail]; [e-mail]
Subject:	Re: IPCOMP and IPSEC 

Eric,

The compression ration depends a lot on the type of data and the packet
size. Using IPSEC will not change the compression ratio since
compression
is done before IPSEC.

- Saroop

----------
> From: Eric Dean <[e-mail]>
> To: Daniel Harkins <[e-mail]>
> Cc: Stephen Waters <[e-mail]>;
[e-mail]; [e-mail]
> Subject: Re: IPCOMP and IPSEC 
> Date: Thursday, May 28, 1998 3:39 PM
> 
> > Anybody out there want to test IPSec and IPCOMP together? Send me an
> > email.
> > 
> 
> Sure, we tried IPCOMP without IPSec and got about 1.05:1 compression
ratio
> though.  I can't wait for after IPSec.
>  
> _______________________________________________________________
> Eric Casey Dean    
> Supervisor: IP Product Engineering
> Tel#: [phone]  Fax#: [phone]  Mobile#: [phone]
>