Is there a specific time that your network slows down? Do you share your connection with other businesses in the building?
You may also want to check into changing your passwords for wireless access, one of the previous employees here was connecting to our wireless system from his home via a cantanna after he was let go and using the bandwidth here to play WoW -.-
There may be monitoring software already configured in your firewall or router pending on what hardware you are using.
Spiceworks has a free trial that you can run that is supported by their forums.
A few things to consider:
- Malicious software – are machines infected and downloading payloads?
- Application updates being downloaded.
- Mis-matched speed/duplex settings. This might only show up during periods of higher utilization. Check switch ports for error counters incrementing. You do have a switched network architecture, right? If not, remove any hubs and replace them with switches. Again, make sure the links are set to appropriate speed with full duplex.
- Is this a DSL or cable link? If it is, remember that this is a shared bandwidth architecture. The carrier (ISP) may have significantly oversubscribed their network and may not be able to deliver the bandwidth you expect. You should review the SLA with your provider for the language about delivered capacity vs normal usage capacity. If you do enable QOS at your network edge, remember that the provider may not “honor” the tags that the Cisco boxes put on the traffic. It’s just something to be aware of and not of major concern. Maybe your provider can provide usage reports, request them. They are worth getting to show what is being delivered at the price you are paying.
- Perform some network analysis. Place a network tap between the router and the LAN. Get a spare computer and install ntop and attach to the network tap port. It will give you the ability to see what all IP traffic is going across the link. It won’t show other protocols very easily though. You may need to use Wireshark to see other issues on the network.
Here’s a blog entry on Network speed & capacity are NOT the same that may also help with your understanding of the network and potential capacity/speed issues.
See this similar question and answer.
Good luck & let us know how it goes!
In the IT trenches? So am I – read my IT-Trenches blog.