Net Flow over a WAN link

pguenther

We have just purchased the Netflow module. I am going to install in this week but have some concerns on bandwidth. We have a particular problem site that I really would like to see Netflow data on. However the site is located in the Manila, PH. I am in Columbus, OH where the Orion install and DB is as well. I know syslog and SNMP over a tunnel doesn't take up a lot of bandwidth but what about netflow? I should mention that the site in question has approx 400 users. I would start with a single 3750 as the Netflow device. This is their current core switch where all user stacks terminate before heading out the VPN or Internet. Can Netflow traffic overwhelm their internet pipe (10 Mb)?

mcbridea

Hi pguenther,

This is a very good question - shows some good thought and planning. I don't think Netflow will overwhelm your 10Mb link alone, but it will have to share bandwidth (b/w)  with user traffic. I would first look at your peak and average b/w is now and historically and determine how close to full the link is. If you are not running topped out then you will probably be OK. I suggest adding Netflow to only one IF first (sounds like you may not need more than 1 IF) on off peak hours start collecting and monitor the b/w. One strange feature of Netflow, as a technology, is that it does not collect Netflow as a traffic type, so you can't use netflow to measure netflow. 

Andy