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Normal speed download but slow upload

Occasional Visitor

Normal speed download but slow upload

We have three 2848's and a two 2626's. They are all linked to a new 5412zl-96G via fibre.
An apple xserve is linked to a 2848. That 2848 is dynamically lACP'd to the 5412.
Whenever a user attached to the 5412 tries to download a large file (a few hundred MB+) it downloads at normal speed. However when writing to the xserve it is about 400percent slower.
I have also tried connecting the xserve to different 2848's and a 2626 gig port but have exactly the same issue.
However if a user is attached to the same 2848 as the xserve they can upload at normal speed.
The apple macs in question are all gigabit.
So it's not the xserve, nor the 2848 or 2626 but something else , (the interconnects?). I had this problem before we linked via fibre when linking via copper also.
Someone else who has spare 2848's has been able to replicate this problem but I still have no answer as to how to fix it. Any help appreciated.
Matt Hobbs
Honored Contributor

Re: Normal speed download but slow upload

If the there is a mix of 100Mbit and Gigabit machines (is the x-serve 100Mbit or gig?), then most likely this can be solved by enabling the 'qos passthrough mode' feature on the 2800's. Definitely try enabling this.