We have an EBS 2008 network comprising of the usual management server, exchange server and Forefront server (ISA).
The installation and migration was pretty much issue free and went well and has been running for about 4 months now. I would say that on average, internet access is slower than what would be considered normal. But the real problem is that internet access has diminished to a crawl. This started to happen randomly and for different lengths of time. It didnt happen everyday but when it did, it maybe lasted for 40 minutes or 3 - 4 hours. Then it returned to normal with no intervention. Now it is constantly slow. I mean web sites take 30 seconds to load. Download speeds are reduced to 4Kb/s.
I have added a few rules to ISA to allow access to ftp sites but other than that the system is pretty much the same as the default EBS configuration.
During troubleshooting, i have:
- rebooted ISA server and router - result: no change. Problem still exists.
- disconnected the ISA server and replaced it with a single, separate router. Result: internet access was amazingly fast - ie the problem disappeared. Reconnecting the ISA server causes the problem to re-appear.
It looks like the problem is involving the ISA sevrer in some part. I thought it might be a setting in ISA's configuration but since the problem is random it wouldnt make sense.
I have read a few articles on DNS causing problems for ISA but i'm fairly sure that DNS is setup ok. The LAN card DNS points to internal DNS servers. The internal DNS servers have forwarders setup to the ISP's DNS servers. The WAN card has no DNS entries.
I have also applied MS KB839510 with no change. My NICs are binded in the correct order ie LAN first then WAN. There are no teamed network ports or anything else out-of-the-ordinary.
I have very limited knowledge of ISA and would prefer to keep it in the configuration as i know it is a good firewall/proxy solution and is a well repsected product.
Any help much appreciated. My head hurts.
