Netflow Performance on Cisco 1841

[johnlloyd_13]

hi all,

we have a 1841 router and would like to enable netflow. please advise if this will degrade the router's CPU and memory performance.

1841>sh ver
Cisco IOS Software, 1841 Software (C1841-IPBASE-M), Version 12.4(1c), RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Tue 25-Oct-05 17:10 by evmiller

ROM: System Bootstrap, Version 12.4(13r)T, RELEASE SOFTWARE (fc1)

1841 uptime is 1 day, 4 hours, 47 minutes
System returned to ROM by power-on
System restarted at 11:04:25 MYT Mon Jan 10 2011
System image file is "flash:c1841-ipbase-mz.124-1c.bin"

Cisco 1841 (revision 7.0) with 114688K/16384K bytes of memory.
Processor board ID FCZ113311Y6
2 FastEthernet interfaces
DRAM configuration is 64 bits wide with parity disabled.
191K bytes of NVRAM.
31360K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0x2102

[spremkumar]

Hi John

I would suggest to check the utilization on your router first also the pattern in which the utilization has been, hope you know the command to verify the same. Once you have the current utilization and the prev utilization pattern you can think off enabling the same on your router.

Also do make sure that you are on the console while enabling it and you are doing during off peak hours to start with.

regds

[johnlloyd_13]

hi,

i'm monitoring the router's performance via MRTG. so far its bandwidth, CPU and memory haven't peaked. my only concern is on it's performance in the long run having this feature enabled.

[sean_evershed · Accepted solution]

Hi,

Please refer to this reference. I've worked with netflow for several years and have found it to have minimal impact on router performance.

You will find that test results are reported for the 1841.

The tradeoff in increased visibility of what is happening in your network is certainly worth it.

http://www.cisco.com/en/US/technologies/tk543/tk812/technologies_white_paper0900aecd802a0eb9_ps6601_Products_White_Paper.html

Please remember to rate all posts that are helpful.

[johnlloyd_13]

hi sean,

thanks for your insight and very helpful link!

[spremkumar]

Hi John

Though your utilizations hasnt peaked up there are good chances of them spiking out once you enable netflow esp when you have suspicious malware or virus sneaks in.Once you have configured netflow in place you need to have proper notification in place to alert any changes within the utilization so that you can act upon it.

regds