Connecting Catalyst 3548 XL to 2924XL Problems

I am attempting to connect a Catalyst 3548 to a 2924. Using a crossover cable, I connect one of the fast Ethernet ports on one switch to one on the other. After a considerable amount of playing around, I was finally able to get both ports to come up. They appear to be communicating, but a considerable amount of errors appear on the 2924 interface. The interface on the 2924 continuously goes down...then comes up...then goes back down....and so on.

If anyone has any ideas how to rectify this, it would be greatly appreciated.

Thanks in advance.

Adam Block

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Adam Block
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Set the interface configs to 100 full duplex on both ports you're using for the "uplink" and also make sure that "spanning tree portfast" is disabled on those ports too.

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Hello Adam,

make sure the configuration on both sides matches (802.1Q encapsulation for trunks, or make both ports access ports). If the ports are access ports, make sure to configure =B4spaning-tree portfast=B4 on both. Also, make sure the speed and duplex settings on both ports are set to full/100 fixed (no autonegotiation). There also is a possibility that the switches belong to different VTP domains, which could happen when the switches have been previously configured. Do a =B4show vtp status=B4 on both switches and check if the VTP domain name (case-sensitive), as well as the VTP version, match... Have you made that crossover cable yourself ? That could also be the problem...


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We=B4ve got answers !

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If you are not using VLANs, then you do not need trunk-ports. Default the Cisco ports will auto-negotiate trunking, whenever it sees a other cisco switch. This might cause what you see. Simply set the ports to "not trunking" by the cmd "switchport mode access" I wouls start on the 3500xl ...

Also you might want to get the latest IOS into them both.

HTH Martin

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