I have a 5513 with two sup III's and two ws-u5534-gesx mods installed. Whenever I use the gigabit interfaces my upload speed crawls while my download speed is not much better. I have used all 4 ports and all respond about the same. Knowing that there are 3 buses, I have placed fast Ethernet uplinks on each bus and have had acceptable performance on each. So, I think that's rules out. I have another chassis with the exact same configuration and all works fine. Show test reveals no problems, no errors and I think I have tried everything. Buffers are fine, not discarding packets, cpu is fine and utilization is 0%. there are no spanning tree errors, duplex and speed match on both sides of the link. Tried with and without flow control and udld enabled. Looking for some ideas on this one. Other than declaring it a bad chassis, I'm beyond my knowledgebase on this one.
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