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New Member

%CDP-4-DUPLEX_MISMATCH: duplex mismatch between 6506 & WS-CBS3110G-S-I which is a Cisco switch for IBM blade H

cat6500 side is fastethernet and set to speed 100 and duplex full

ibm side is gig is set to auto/ auto

Things working fine with the error above

But when i set the ibm side to speed 100 and duplex full or half ports will show down/down

i have total of 4 ports on each side forming etherchannel using desirable mode non-silent on the 6500 and same mode on ibm side but without the non-silent command

Any help greatly appreciated.


Hall of Fame Super Silver

Re: %CDP-4-DUPLEX_MISMATCH: duplex mismatch between 6506 & WS-CB

Hello Mohammed,

you should use autonegotiation on both sides and all member links have to be configured on the same way both sides.

Hope to help


New Member

Re: %CDP-4-DUPLEX_MISMATCH: duplex mismatch between 6506 & WS-CB

thanks Giuseppe

i was just trying to avoid the auto


Re: %CDP-4-DUPLEX_MISMATCH: duplex mismatch between 6506 & WS-CB

   My guess is you have the wrong cable between them and auto mdix is correcting the pins.  Auto mdix only works when set to auto/auto, when you try to hardcode the ports to a speed it will bring the link down .