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New Member

Catalyst 2950s and isl trunking support

why does the ios release with cat 2950 series switches not support isl trunking? I have checked the documentation and not see any reference to isl only dot1q trunking. In my environment we have multiple 2900,3500 and cat5k switches connected via isl trunks. Does anyone know why Cisco has left this out and is using dot1q as the only option?

7 REPLIES
New Member

Re: Catalyst 2950s and isl trunking support

Like the cat 4000, they are moving away from the proprietary to the standard.

New Member

Re: Catalyst 2950s and isl trunking support

ok so they are standardizing. Thought so. So I am stuck with dot1q.

Isn't isl more efficient than dot1q?

Re: Catalyst 2950s and isl trunking support

I don't think isl is more efficient. Just compare the header size.

New Member

Re: Catalyst 2950s and isl trunking support

I don't know specifically about the 2950's, but I know that the cat4000's only support 802.1Q as well. We have been forced to use ISL and 802.1Q in our Enterprise as well. Don't know if that is a "bad" thing, it just makes management a little tougher sometimes.

New Member

Re: Catalyst 2950s and isl trunking support

You should upgrade your cat2900/3500 to IOS Enterpise Edition, This version can support ISL and dot1q trunk.

Re: Catalyst 2950s and isl trunking support

There is no Standard/Enterprise edition for Cat2950. The only IOS downloadable from CCO is "Enterprise" (see show version CLI command output).

New Member

Re: Catalyst 2950s and isl trunking support

What can I do about my 100+ 1924's that I need to connect to my new 2950's? The 1924's only support ISL even with the latest firmware (9.00.04). This is the first I have heard of ISL support being dropped.

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