RAM was the place we took the hit (such as it was) when enabling Flows
(which was 2-3 years ago so sadly not on IM) on our network.
Some of Cisco's older edge-class routers (exporters) don't have the
memory to run the correct IOS version.
Similarly, on the server (collector) end - at least on our Windows-
based, non-IM-based system - Flows consumed A LOT of memory. In that
case depending on the strategy for RAM use, there could be a
difference in operation between our old system vs. IM
Flows....probably whether a significant amount of memory is used to
keep the Flow data online for performance reasons vs on just disk.
For what it's worth, we never ran into an issue with bandwidth use (or
CPU use for that matter) - neither on the router/exporter side nor on
the server/collector side.
Good luck!
-Matt
On Sep 12, 2008, at 11:04 AM, Chip Old wrote:
On our remote Cisco 2811 routers I am exporting flows for two
interfaces each, and even at our busiest sites the processor load is
never above 6%. On two 7206VXR / NPE400 routers that handle many
more interfaces and much more traffic, processor usage stays in the
15% - 20% range. We've been using netflow on all of these for about
a year and have never noticed a performance hit. YMMV depending on
the capacity of your equipment. I'd hate to do this with the 25xx
routers we used to have at our remote sites.
--
Chip Old (Francis E. Old) <[EMAIL PROTECTED]>
Administrator, Network Operations
Baltimore County Public Library
320 York Road
Towson, MD 21204-5179 US
410-887-6180 office
410-236-8582 mobile
410-887-2091 fax
________________________________
From: Tim Huffman <[EMAIL PROTECTED]>
Reply-To: InterMapper Discussion <[email protected]>
Date: Fri, 12 Sep 2008 10:46:35 -0400
To: InterMapper Discussion <[email protected]>
Subject: RE: [IM-Talk] New InterMapper Feature - NetFlow Add-on -
Call forTesters
Andrey is right. The bandwidth involved is very low, although a
large number of collectors (or flows!) could eat a VERY large amount
of disk space!
Exporting flows is not bandwidth intensive (it's basically just
text), but it can be processor intensive on the routers (depending
on the router, how many interfaces you are exporting flows on, and
how much traffic/how many flows the router has to keep track of),
which is one of the reasons the CAT3500 series won't do it.
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--
Matt Carroll
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