Bandwidth on my 100 user network drops from 5Mbps to 312kbps but only during working hours
Posted on 2007-11-20
My network consists of a LAN with 40 users, 50 VPN connections, 1 DNS/DHCP Server running Server 2003, 1 Exchange Server running Exchange 2003, 1 Microsoft SQL 2000 Server. I have had it all running on a 2X2 connection until my bandwidth dies the other day. I called my ISP and have them kick my downstream speed to 5Mbps. They do this and I still can only pull 386kbps. The odd thing is that the bandwidth drain starts when the workday begins and I regain all speed when it ends. I thought, ok, must be my connection. Nope, if you kill the network and plug directly into the cable modem your speeds are great. So then I went and disconnected each users and server one by one and that did not fix it. If you kill a server you regain some of the bandwidth but it still crawls back down.
Our Sonicwall monitors bandwidth and nothing is out of the ordinary there. We also have software installed on all computers that monitors Bandwidth, and nothing bad is showing there. Did a virus sweep on everything at that point, but the only thing that showed was a vundo virus on one of my workstations. I then changed out all of my switches hoping one of them were bad, nothing there. I then turned my attention the software on the servers. I checked all of the server logs with no luck. I was thinking maybe DNS or Active Directory could be messing up but they look fine and act fine otherwise. I then checked all my queues in Exchange hoping there was something stuck, but they were fine. I rebooted all of the servers for good measure but that didnÃƒÂ¢Ã‚Â€Ã‚Â™t help either. The strange part is that it only does this during working hours and if fine otherwise. I am out of ideas and need something new to try. You would think it was a user or server on the network, but it all checks out ok.