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Catalyst C2950-24

can anybody help with a clue, when i am connecting Catalyst C2950-24 on to the network the network goes down that is casscading with Nortel/3com switch. Where as if i connect directl to a Catalyst 3550 it works

3 REPLIES
VIP Purple

Re: Catalyst C2950-24

Hello,

how are the switches connected ? Is there a trunk between the Cisco and the other switches ? Which Nortel/3Com switch are you using ?

Regards,

GP

Re: Catalyst C2950-24

there is no trunk between those switch just a cross cable between them i m not sure about the nortel/3com switch is it. By the way thanks for the response GP

Community Member

Re: Catalyst C2950-24

By default, those 2950 interfaces are set to dynamic desirable. So once there is link-up, it will send out DTP (aka D-ISL) frame to negotiate ISL trunk. The Nortel will not understand and flood out the entire vlan. If there are other Cisco switches connected to the Nortel, the trunk may bounce. It works ok with 3550 since the 3550 interfaces behave the same way. I suggest to configure switchport mode access under the interface and connect it to Nortel again. Hope this helps.

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