SPANTREE-5-ROOTCHANGE

[David Kondicz]

Hi all,

i have found some problems in my networks. There cas around 1-2 min outages on bacbone and i have found this messages in my switch.

Can this case that interface 1/0/20 change state to listen and from this reason i have outages or based on this message it cant case int outage.

If i check int 1/0/20 via SNMP the interface uptime is 70 days. Or stale listen didnt change int uptime value?

My next question is what can this case!?

We are using Catalyst 2960S switches lan Base

Please ignore time and date!  I have no ntp server cofigured in switch.

145215: *Dec 15 10:53:59.684: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 8cb6.4f3e.dc80
145216: *Dec 15 10:54:00.685: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 30e4.db38.5500
145217: *Dec 15 10:54:01.687: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 000c.42cd.c9e7
145218: *Dec 15 10:54:16.209: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 000c.423d.afc0
145219: *Dec 15 10:54:52.815: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 8cb6.4f3e.dc80
145220: *Dec 15 10:54:54.818: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 000c.42cd.c9e7
145221: *Dec 15 10:56:17.315: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 999: New Root Port is GigabitEthernet1/0/20. New Root Mac Address is 000c.423d.afc0

Thank you

BR

Dave

[acampbell]

Hi Dave,

I think you need to investigate the issue outside of
this switch.

The switch is reporting that it is re learning the route bridge
for vlan 999 over interface g1/0/20.

What does interface g1/0/20 connect to?

Why is the root bridge changing ?

Look and find where the reporting MAC addresses reside

Have you looked at youe topogy and selected the best
location to configure a root and secondary root for the vlan.

Probably best in the centre of the layer 2 network not on the
periphary.

Regards
Alex