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cisco moving away from ISL encapsulation?

In reading over some docs for the 2950 series of switches at the urls listed below, there is a strange lack of mention for ISL encapsulation, only .1q

and taken from the config section at

!-- In case of 2950 switches, none of the above two commands are used,

!-- 2950 switches only support 802.1q encapsulation which is configured automatically,

!-- when trunking is enabled on the interface by using switchport mode trunk command.

So is cisco dropping ISL or at least moving away from it??


Re: cisco moving away from ISL encapsulation?

Yes, they are. The reason for this is that ISL was a proprietary solution. Now that .1q has become the standard, all new products will operate according to the standard. So you should indeed be careful in selecting & implementing new equipment in an ISL-based environment.

Cisco Employee

Re: cisco moving away from ISL encapsulation?

We will continue supporting ISL. .1q is an industry standard and hence is more preferred by our customers. Also due to hardware limitation, few hardware boxes do not support ISL

Re: cisco moving away from ISL encapsulation?

When it is Cisco's intention to keep supporting ISL I cannot understand why it is not supported on the 2950. This is the recommended replacement for the 3500 series but it lacks this vital feature. You guys at Cisco must have caused headaches for quite some folks who forgot to check all related docs.

The mentioned "hardware limitations" will have been enforced by your marketing deparment I suppose?

In my opinion ISL was the better solution. At least, it is easier to understand how it operates and you do not need to worry about native vlans.

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