From my existing configuration, I can see that 3 cisco 2900XL switches are trunked to a Cisco 2970 gigabit switch and the command portfast trunk is enabled on each link?........I must add network is working fine with several vlans configured on a router on a stick model.
What are the likely consequences of this command enabled?
the 'portfast trunk' command places that trunk port in the SpanningTree portfast state.
portfast allows the port to go from blocking state to forwarding state without having to go through the delay of the listening and learning states.
this provides for faster port forwarding of packets. the downside is that without the STP listening/learning states, the ability to induce a loop into the network is greatly increased.
your consequences of this is that you'll want to assure you do not make another trunk, that has portfast trunk, between the two devices already trunked with the original trunk that has portfast trunk enabled currently.
(this would have the effect of creating a loop in your topology. ethernet does not like loops and your network will more than likely grind to a halt.)
it's just like a regular portfast port, but works for trunks.
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...