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

[Gert Doering]

Hi,

On Sun, Jun 27, 2010 at 02:03:41AM -0400, Paul wrote:
> All the switches/routers are Cisco based, but I seriously doubt that has 
> anything to do with this. :P

Oh, if it's 2960 or 3750 switches, you could run into the "these switches
have too tiny buffers to be useful" problem.

Your server sends out a burst of packets to the client, with the full
interface speed it can handle.  Now if the link switch->internet router
is slower (100m only) or has "other server" traffic on it, the switch
needs to buffer these micro-bursts for a few ms - and that needs some
amount of RAM, which the 2960/3750 just don't have... -> packet loss, 
bad throughput.

(Unfortunately, design goals for the 2960S/3750X were different than "get
this fixed", so the buffer size is the same)

gert
-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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