Network troubleshooting methods?

[nzwasp]

What methods do you guys use to monitor/prevent network problems at work?

i.e

A large amount of users (400 or so) connecting on a 20MB CIR(burstable to 50MB) circuit (private ip) to a datacentre that houses all their data needs etc. This is a thin client(citrix) network and when a user decided to copy something large from a network drive they cause major problems until there file copying is complete or the transfer is stopped.

To try and help my situation i've enabled a port mirror on one of the switches to monitor traffic traversing the link, however i'm a bit concerned if this will help when using a sniffer at the time of the problem, as i imagine there would be alot of information.

There is currently no QoS on the network link.
I am using Cisco 3750 L3 Switches to connect both sides of the link. No VOIP traffic traverses the link.

This is in New Zealand by the way.

Any ideas?

 

[KiscoKid]

MRTG is good (and free) for looking at network utilisation over time. I think any network should have something that can do this so you can spot bottlenecks well before they become a real problem.

Also, and you mentioned this, you should probably consider deploying QoS on that link to prevent users from killing it with non-essential application traffic such as file transfers.

Cisco allow you to broadly classify any traffic as priority/expedited, best effort, less than best effort etc


In the past, I've worked on contracts that had similar issues as you've outlined. We ended up deploying QoS and classifying all file transfer protocols as less than best effort and assigning this kind of traffic only avery small % of the available WAN bandwidth - worked a treat.