show interface trunk and n-isl

[hanwucisco]

Could you tell me that is n-isl under the show command?

this came when two sides are in default setting. once i configured encapsulation to isl, it changed to isl.

What is difference between isl and n-isl?

thanks,

Han

[Jon Marshall]

The n in n-isl means negotiated. So basically the switches at either end negotiated to ISL encapsulation for the trunk link.

Once you hardcoded the encapsulation there was no need to negotiate so then the n disappeared.

Jon

[hanwucisco]

Jon,

I tried on two 3750s. it seems that it is different from what you said. any idea?

thanks,

Han

[Jon Marshall]

What do you mean by "it is different". What behaviour did you see ?

Jon

[paul driver]

Hi, as Jon has stated - the trunk is either

n-isl / n-dot1q = negociated

or

isl / dot1q =full trunk mode

for N-ISL/dot1q to happen you need one of the trunk links to be in a negociated stated - like

switchport trunk encap ISL /dot1q

switchport mode dyanmic desirable/auto

hardcoding the trunk would be

switchport trunk encap ISL /dot1q

switchport mode trunk

res

Paul

[gcmills]

Default negotiation for 3750's is dot1q. That's why you see the difference between your first and second post.

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