ICND2 - switchport trunk encapsulation {dot1q|isl|negotiate}

Node Man

Hi Everybody,
Is there anything wrong with this command:

switchport trunk encapsulation isl ?

i cant seem to make it work and i read in Odom that 2960's and newer only use dot1q trunking.

Can anyone fill in the blanks for me? Advice?

Thanks so much.

Mrock4

What device are you trying this on?

ajmatson

What model switch are you trying on? ISL has been eliminated on the newest switches and IOS versions. If you try to type the command it will fail. Here is the command on my 2950 running 12.2:

Cisco_2950T(config-if)#switchport trunk ?
allowed Set allowed VLAN characteristics when interface is in trunking mode
native Set trunking native characteristics when interface is in trunking mode
pruning Set pruning VLAN characteristics when interface is in trunking mode

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Per Cisco doccumentaiton:

!-- In case of 2940/2950 series switches, none of the above two commands are used,!-- 2940/2950 series switches only support 802.1q encapsulation which is configured automatically,!-- when trunking is enabled on the interface by using switchport mode trunk command.

Configuring InterVLAN Routing and ISL/802.1Q Trunking on a Catalyst 2900XL/3500XL/2950 Switch Using an External Router - Cisco Systems
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