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Community Member

2950G-24 No ISL trunking?

I was just setting up a trunk between a 2950G-24 and a 2924XL and noticed that when I typed "switchport mode trunk" on the 2950, it established a dot1q trunk. This is the first 2950G-24 that I've configured, but in the past ISL was the default encapsulation on the 2924XL's. It appears I can't even specify ISL trunking if I wanted to. The IOS version I'm running is 12.1(6)EA2a. Has Cisco stopped supporting ISL trunking? Or do I need a different IOS version?



Cisco Employee

Re: 2950G-24 No ISL trunking?

The Catalyst 2950 switches do not support Inter-Switch Link (ISL) trunking. It's a hardware limitation

Community Member

Re: 2950G-24 No ISL trunking?

2950 is hardware limited to support only dot1q. dot1q should work regardless with other cisco switches or non-cisco switches the same way.

Cisco Employee

Re: 2950G-24 No ISL trunking?

Cisco is still supporting ISL and will for a long time. The issue has to due with the components used to make the 2950. Not supporting ISL on the 2950 makes the product less expensive to the end customer.

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