VLAN Pruning - Misconfiguration

[nap.deguzman]

Hi Everyone!

I've got this quick question that I suspect is causing unnecessary traffic in my network. I've got this in one of my trunk interfaces. What is the impact of this configuration given that one end of the trunk has pruning enabled while the other end has none?

Core-SW01#sh run int g1/0/11
interface GigabitEthernet1/0/11
 description To-Server-SW01-Gig1/1/1
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 1-23,25-4094
 switchport mode trunk
 logging event trunk-status

Server-SW01#sh run int g1/1/1
interface GigabitEthernet1/1/1
 description To-Core-SW01-Int-Gig1/0/11
 switchport trunk encapsulation dot1q
 switchport mode trunk
 logging event trunk-status

[Jon Marshall]

Very little impact in terms of unnecessary traffic unless vlan 24 is sending most of it.

Your allowed list is for all vlans 1 - 4094 except the above vlan whereas your other end allows all so it is just that single vlan.

In terms of operation the core switch would not send any or receive and forward any traffic on the trunk for that vlan.

The other switch may send traffic for that vlan though.

But then if that vlan is on the server switch I would have thought you would want it on the trunk.

Can you elaborate as to why you think it is might be an issue in terms of traffic ?

You should make them match though..

Jon

[nap.deguzman]

Thanks Jon. The reason why I ask if it can cause unnecessary traffic is because on that same Core SW and interface, I can see a lot of broadcast traffic which makes the Core SW CPU utilization hit 90%.