Network speed problems
bhaskie99 at yahoo.co.uk
Thu Apr 1 07:26:18 PST 2004
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>>> On Thursday 01 Apr 2004 6:23 pm, JC <Jeroen Coumans> said:
JC> Anybody want to hit me with a cluebat to properly debug network speed
JC> The problem is on a LAN with several 100Mbps Linux boxes, routed by a
JC> Cisco 3600 router running IOS 12.2(6c).
JC> The maximum speed to copy 5Mb of data never gets above 900K/s. That's
JC> approx. 12 times as slow as theoretically (100Mbps / 8= 12 Mb/s)
JC> possible! I've benchmarked from inside and outside the network;
inside I JC> get 1Mb/s max and outside 300kb/s. Tried various protocols,
such as ssh, JC> smb and http, each with similar results.
JC> What can I do to pinpoint the bottleneck?
I suspect you are having the full vs half duplex problem.
"A common source of LAN trouble with 100BT networks is that the host is set to
full duplex, but the Ethernet switch is set to half-duplex, or visa versa.
Most newer hardware will auto-negotiate this, but with some older hardware,
auto-negotiation sometimes fails. result is a working but very slow network
(typically only 1-2 Mbps). Best for both to be in full duplex if possible,
but some older 100BT equipment only supports half-duplex."
ifconfig should give you the information whether autoselect is enabled and if
the network is running at full or half duplex.
Bhaskar Dutta <bhaskie99 at yahoo.co.uk>
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