On my company's LAN, we are experiencing low upload bandwidth. Download bandwidth is fine. We have a 10 Mbps up and down through our ISP, but the upload has been around 1 Mbps (download around 9.7). This is consistent throughout the entire day. I noticed this trend about a week ago. The only service we use that would affect this would be carbonite backups, but we only use carbonite for a hand full of files, and we've used it for years with no issues.
For a quick and dirty description, we have Netscreen firewall, with a web server, database server, and isa firewall client server behind it. Behind ISA, we have our domain controllers, staff computers, etc. We also have a SAN environment with a dedicated vLAN I installed a few month ago.
- I ruled out ISA as the problem by bypassing it to test bandwidth.
- I checked bandwidth usage on all devices, and I do not see any issues.
- I disconnected everything behind ISA, and nothing changed.
The ISP says we are only using about 30% of our upload bandwidth, with spikes near 100% for a brief period during the morning hours.
Could this be a physical layer problem? What are some avenues I should inspect next? I'm wondering if it's possible to have a bad router.