SPANTREE-2-BLOCK_PVID_LOCAL: Blocking FastEthernet0

cyber.noc · ‎10-04-2007

hi, I have 2924 and getting error meesage for a port i.e. SPANTREE-2-BLOCK_PVID_LOCAL: Blocking FastEthernet0/1 on vlan 11.

Inconsistent local vlan. what could be the causes...

Kevin Dorrell · ‎10-04-2007

Could you tell us more about your topology and configuration? With the information you have given, we can only guess.

I would be looking at whether this is a trunk, and the native VLAN is different at each end of the link. Or whether it is receiving BPDUs for a VLAN that is not configured on the switch. (Normally it would drop thise silently.)

Or whether this is a private VLAN that has not been declared on this switch.

Could you give us a bit more detail please?

Kevin Dorrell

Luxembourg

cyber.noc · ‎10-04-2007

Dear kevin,

we have 2924 at one side of the link and its configuration is as follows :

interface FastEthernet0/19

description *** test ***

load-interval 30

switchport access vlan 14

spanning-tree portfast

spanning-tree vlan 1 port-priority 5

no cdp enable

!

and other side of the link we have 2950, config for this as folows:

interface FastEthernet0/17

description *** Testing ***

switchport mode access

spanning-tree portfast

at 2950 port is up and line protocol is also up whereas at 2924 port LED is in stable amber state but it also shows line protocol up. but we cannot ping through the link.

Kevin Dorrell · ‎10-04-2007

There are a couple of points that disturb me here. One is that according to your original posting, the port getting blocked is F0/1, and not F0/19 we have here.

The second is that 2924-F0/19 is an access port on VLAN 14, while 2950-F0/17 is an access port on VLAN 1. If you are using PVST, that seems to a recipe for an inconsistent Spanning-Tree, especially if these switches are joined by some other path as well (perhaps via F0/1 ?). The risk is compounded by the portfast.

Perhaps we could have a glimpse of your overall topology.

Kevin Dorrell

Luxembourg

cyber.noc · ‎10-04-2007

Thanks for your immediate response,

let me clarify more we have wireless link between two switches and getting two ethernets from wireless, at Side A we have 2950, Eth0 of wireless is terminated on fa0/19, Eth1 of wireless is on Fa0/17, fa0/19 is in trunk mode whereas fa0/17 is access on vlan 1 and at Side B we have two switches 2950 and 2924, trunck port(fa0/19) of side A is terminated on 2950 at side B on fa0/21 with mode trunck, and access port (fa0/17) of Side A is terminated on 2924 at side B on fa0/19 with access port on vlan 14. we do not have any connectivity between 2950 and 2924 at side B, which may causes inconsistency..

looking forward for response

thanks

Kevin Dorrell · ‎10-04-2007

What is on F0/1 of the 2924? And what is VLAN 11?

I am tempted to put bpdu-filters in, but that would be a huge risk until we understand full what is going on.

I presume that you have disallowed VLAN 1 on the trunk of Side A F0/19, and VLAN 14 on Side B 2950 F0/21.

I think it would help if your VLAN numbering were consistent between the two sides.

Can you post a show run int and show switchport for all 5 ports involved in this scenario?

Kevin Dorrell

Luxembourg