A few days ago we stared having 25-50% packet loss on our network. I narrowed it down to the exchange server "2003 R2" and figured it to be a bad NIC. I switched over to the other NIC and within 30min we were having the same issue again. Next I thought it may be a bad switch port, changed ports and it lasted 5 hours and started again. My next course of action was to stop various services. I narrowed it down to one service, the MS exchange information store. I am not sure this means that it is an issue with the store, I am guessing when the store is running the traffic on the NIC is heavier, maybe both NIC's are band? Has anyone seen this before? My client is without email, and I can't start the store without the entire network going down. Thank you!

Store is the database. So all traffic goes to the store service. Therefore it doesn't mean a problem with the database, it could be one of the clients. Could be a loop, something downloading something. You will have to start the service and then see whether a client is using significant resources using exmon. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Spot on Sembee. Though I figured it out prior to reading your post it was just that. There was a remote user, the clients daughter, that was tasked to send out e-mailers for lack of a better term. She was trying to send 2000 1.5 Mb emails. So it was a cat and mouse game, every time I change something it seemed to fix it because she stopped sending due to it failing on her end, then she decided to try to send 200 at a time and the game began again. I had it pegged, but no one locally said they had been doing anything around those times. The queue by chance happened to be empty when I looked at is a couple times. I put wireshark on the exchange server and captured what was happening. Eventually we caught some of the emails in the queue and put two and two together. The sad part about it is we told them several months before that they should look at options like constant contact when they were talking about doing this. It's no doubt that the bill for my time will convince them to use that service. Thank you for your response! Scott

Exchange is a very poor bulk email tool. It isn't designed to do it. It will use all of the bandwidth available and provides no means to deal with bounces, rejects unsubuscribes and throttling. With bulk emailing services so common now it doesn't make sense to do it in-house, or at least though Exchange. The fact that it was a 1.5mb email as well, which isn't the most efficient way of doing things only compounded the problem. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.