Ethereal-users: Re: [Ethereal-users] Specs for monitoring full 100 Mb line

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From: "Ronnie Sahlberg" <ronnie_sahlberg@xxxxxxxxxxxxxx>
Date: Wed, 5 Mar 2003 07:35:10 +1100
No need for highend/expensive stuff:
Try a single CPU linux box.
100Mbit/s full duplex is ~24MB/s in theoretical max throughput.

24MB/s => 2TB/day
Well it is not realistic to put 2TB disk in a sniffer, but the link is
probably not 100% saturated
in both directions all the time either.
Maybe something like 500GB of storage is enough?


So get a single CPU cheap linux box. (no need to waste money on high end cpu
for such low speeds line
100baseT.)   with 2 100baseT cards.
Get 2  250GB IDE disks and stripe them together.
Tweak the disks until you get maximum throughput when doing sequential
writes.
One modern IDE disk today can do 25MB/s easily. Two shoudl be able to do
40-45MB/s,
that puts us on the safe side if there are long bursts where the link is
saturated.


Hook up both 100BaseT interfaces so one captures the traffic in one
direction and the other in the other direction.
Run Linux and capture from the ANY interface.

That should do it.





----- Original Message -----
From: "Robert Casto"
Sent: Wednesday, March 05, 2003 3:26 AM
Subject: [Ethereal-users] Specs for monitoring full 100 Mb line


I am trying to get specs together for a machine that will be able to
capture all the packets going over a 100 Mb Ethernet line. I will be
logging all the data to drives and then nightly when the line is slow,
take the captures and run Ethereal on them.

How much machine will I need to keep up with a busy 100 Mb line? Single
processor at 3.06 GHz, dual CPU? 15k RPM SCSI drives? Is there anywhere
I can go to help me figure out how fast the machine has to be?

Robert Casto
Tel (513) 755-2221
Cell (513) 349-5282
robert@xxxxxxxxxxxxx
http://www.cincijava.com

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