Spanning tree issue

[lobo66]

I have a Cisco 4948 with two trunk running back to two separate 6513’s. Last week I had a few end users complain they lost their session on their application. When I took a look at the switch the log showed:

%SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 GigabitEthernet1/48 moved to Forwarding (UplinkFast).

%SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN0001 GigabitEthernet1/47 moved to Forwarding (UplinkFast).

So it looks like STP changed from blocking to forwarding on both my trunks.
, I reviewed the logs on my 6513 and it did not show anything. Question here is why would STP act like this when there were no port issues or physical disconnects?

Anyone have any insight? Thanks all…

 

[lerdalt]

Did you have more to your logs just before that? I've had ports "bounce" when making other changes at the 6k. Usually in my cases it has happened because of a change, or something else getting connected causing spanning-tree to converge.

 

[lobo66]

No thats it, no changes.

 

[burtsbees]

Did you look at sh log on both switches, or did you just look at output after the change occurred?

Burt

 

[lobo66]

I looked at both and it only turned up on the 4948.

 

[zinkann]

are you running any other optional STP features?

 

[lobo66]

Here is how the port/trunk is setup:

interface GigabitEthernet1/48
description USCHI00SW01 Gi 9/42
switchport trunk encapsulation dot1q
switchport trunk native vlan 1001
switchport trunk allowed vlan 1,172,224,225,245,1000
switchport mode trunk
switchport nonegotiate
media-type rj45
speed 1000
duplex full
spanning-tree portfast disable
spanning-tree bpdufilter disable
spanning-tree bpduguard disable
spanning-tree link-type point-to-point

 

[brianinms]

I assume you arent using vlan 1001 anywhere.

 

[lerdalt]

I'm not totally thinking spanning-tree right yet, but isn't it kind of odd to not have your native vlan in your allowed statement?

 

[lobo66]

Interesting what else would cause a log message of that nature if it is not a spanning-tree problem? Also should the native VLAN be placed in the allowed list?

THX

 

[brianinms]

I am confused, what is the purpose for the native vlan in your environment. Are you actually using it?

 

[pmoorey]

lobo66 (IS/IT--Management)
Interesting what else would cause a log message of that nature if it is not a spanning-tree problem? Also should the native VLAN be placed in the allowed list?

THX

Yes you do need to include the native VLAN when using 802.1q trunking, if you do not include it in the permited vlans you will recieve an error message!






Peter
CCNA, Cisco Qualified Specialist

 

[burtsbees]

The other thing I am wondering is if (and if not, WHY not) you have redundant trunk links from the 4948's to the 6513's...like two trunk links to each 6513. And what is VLAN 0001??? How is G0/47 set up?

Burt