On the older ios of the 3550's I used the cmd switchport priority extend cos 0 for interfaces connected to ip phones and pc's. I now am configuring a 3550 with newer IOS and this cmd does seem to be there. when i do a show interface switchport fa0/1 the cos is not set. My question is do I need to use this cmd because this is set by default?
No, you do not need to use this command if that is the default for each switch port interface under the newer IOS.
It doesn't hurt, though, especially if you have switches still running older IOS code, or if you have played around with changing that priority from zero to something else.
The switch won't show you the priority command line unless you change it from the default.
To test this, do the following. On one interface set it to the next-lowest priority, 1, then exit config mode and look at the running configuration for that interface. You should see the priority command line. Next, go back into config mode, set priority back to 0, exit and look at the interface's running config again. Priority command line should be gone.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...