Trunk port configuration

In case two trunk port is configured on each switch and inter-connect

Do I need to configure LACP first to group these two ports ?

If you mean 2 interfaces on 1 switch going to 2 interfaces on a 2nd switch, then the answer is yes.

By grouping, I think you meant bundling. You need an ether-channel for both ports to be active. If ether-channel (pagp or lacp) is not configured, spanning tree will block one port to prevent loop.

Hi Arnold,

To clarify my understanding, suppose on switch A , two ports has been configured with trunk port that connecting to the corresponding ports on switch . It would not work, correct as switch will disable one port to prevent looping, correct ?

Tks

To clarify my understanding, suppose on switch A , two ports has been configured with trunk port that connecting to the corresponding ports on switch

I hope you meant corresponding port on another switch B.
Correct, if they are not bundled

<pre>
           /---------trunk port 1 switch A port12 trunk. \
Router                                                                           |
           \--------trunk port 1 switch B port 11 trunk. /
</pre>
Presumably this is what you are considering?
Most likely switch A will lock port 12 while switch B will lock port A.
Should switch A loose feed on port 1 from router, I am not sure what the convergence tine for port12 to be unblocked, the same is true for port 11 on switch B.