[c-nsp] autonegotiation fail

John Neiberger John.Neiberger at efirstbank.com
Thu Sep 22 11:44:28 EDT 2005


>We observed that in some cases the autonegotiation between Cisco
Catalyst
>switches failed. For example: 
>
>We did the measures with iperf (dast.nlanr.net/Projects/Iperf/).
>The results: 
>	individual test: ~85 Mbit/s up, ~85 Mbit/s down
>	bidirectional test: ~80 Mbit/s up, ~7 Mbit/s down(!)

Did you have both sides set to AUTO?

Be *very* careful when manually setting your speed and duplex settings
on the newer switches, like the 2950. Manually setting these parameters
can cause you more problems that it's worth. You should always use
autonegotiation unless you have a specific situation that requires
manual settings. In my experience over the past three years, this is
extremely rare. Again, I'm referring to newer switches. The XL switches
behave a little differently than later switches like the 2950, 3550, and
6000/6500.

Regards,
John
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