Basic Trunking Question

[mattipler]

Hey guys, 

Default trunk encapsulation is isl upon 2900 switches. My question is this... 

If I have existing active trunk ports that are utilising the default isl encapsulation, but I want to uplink to a new, additional device utilising dot1q and so configure the connecting port to utilise encap dot1q - this is not going to interfere with my existing trunks utilising isl is it?

I guess my question is can I use different encapsulations on different trunk ports upon the same 2960 switch? I just want to be sure that if I set the encapsulation to dot1q on the new uplink ports it's only going to be port specific and not change anything globally and bring down my active isl uplinks. 

Apologies, realise this is a very basic question. 

Cheers. 

[Giuseppe Larosa · Accepted solution]

Hello Mattipler,

>> I guess my question is can I use different encapsulations on different trunk ports upon the same 2960 switch? I just want to be sure that if I set the encapsulation to dot1q on the new uplink ports it's only going to be port specific and not change anything globally and bring down my active isl uplinks. 

Your understanding is correct the command

switchport trunk enc dot1q

is given in interface mode and affects only the configured interface. Other ports keep their current configuration.

Hope to help

Giuseppe

[Georg Pauwen · Accepted solution]

Hello, 

there is no problem whatsoever configuring different trunks with different (ISL or dot1q) encapsulations.

[mattipler]

Thank you gentlemen. I thought as much although I don't have a L2 lab environment within which I could test. 

Thank you again.