I am encountering a unique network bandwidth issue between two school locations.
Site 1 has an HP Procurve 1800-24G managed gigabit switch, with an HP Singlemode GBIC which connects to an AT&T gigaman 1-gigabit fiber connection to another school location in another town. In that town the fiber terminates as multi-mode connection and connects via a mulitmode GBIC which is installed in a Cisco 7606 core router.
The issue I am having is using iperf, I am only able to push 455 megabit of throughput (TCP) through the gigaman link. AT&T has come out and said the line is clear, shows no errors, and the issue must be either with my HP switch or the Cisco router.
Anyone have any suggestions on why the link only allows approx 450 megabit of throughput across it? Both GBIC's show 1000/Full on their statuses. AT&T says there's no devices between the two schools that would restrict bandwidth. We're really stumped as to what or where to fix. We've even swapped out GBIC's and got no improvement in throughput.