[c-nsp] Centos upload speed slower on 1000m than 100m over WAN links

[Paul]

I'm not even sure this is the right forum but since we use mainly Cisco 
equipment I'll give this a shot. :)
I have tried several centos based servers and compiled various kernels 
and the results have been extremely weird.
90% of the cases the remote hosts can download from a server at 
1-5megabytes per second, and most of these are over
the internet ranging from 30-200ms away.  Local (1ms or less) is super 
fast 100MB/s for example. 
Ok that sounds normal since it's going over the internet, etc.  But 
here's the )(!@*! part..
If I set the port speed to 100 megabits full duplex on the switch and 
server , the clients that get 1-5MB/s now get 11MB/s which is
approximately the limit of the 100mbit port. 
Totally stumped here, tried different nics, servers, even 4 different 
switches.  Is a very interesting problem and I'm probing to see
if anyone else has encountered it. 
So far the only OS i have tried is centos, but different versions and 
kernels and hardware.
All the switches/routers are Cisco based, but I seriously doubt that has 
anything to do with this. :P

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