best way to monitor traffic on routers

[preston]

I did some basic snmp monitoring to see what my utilization is on some routers. I would like to be able to break that down by the type of traffic, in high utilization spots. (just the wan links)

If I do a

#ip flow-cache timeout active 1

#ip cef

#ip flow-export version 5

Will that interfear with my routing or connections, I can't afford to take a router down. Is there anything to watch out for?

Is useing netflow the easiest way to put together a quick snapshot, any good tools to use for this?

Thanks in advance

[peter.nowack]

Hello,

after enabling ip route-cache flow on interface and ip flow-export you will receive netflow exports. In the netflow you can see all flows that are received on the interface where you set ip route-cache flow... We used CESNET NetFlow Monitor it is free, but it has many disadvantages. We bought Caligare Flow Inspector software (http://www.caligare.com) this year and we are very happy with it. Last week we were under attack, and we easy found our infected workstatation ;o)

Have a nice day,

Peter

[preston]

Does enabling ip route-cache flow, have any effect on the routing or current connections when I turn it on.

Basically is it safe to turn on without worry, like snmp?

[peter.nowack]

I think, that is it safe. We turn on without any power loss.

Peter

[andrew.burns]

Hi,

It's certainly a valid concern - and to satisfy customers Cisco produced the following Netflow Performance Analysis white paper:

http://www.cisco.com/en/US/tech/tk812/technologies_white_paper0900aecd802a0eb9.shtml

If you have enough flows for it to be a concern then there is always sampled-netflow.

HTH

Andrew.

[preston]

IP CEF kills the connection!

Just a heads up if someone reads this post, luckily I tested it, when you turn on IP cef it killed my pings.

Is there anyway to turn on Netflow monitoring without bringing anything down?