07-10-2018 06:26 AM - edited 03-08-2019 03:37 PM
Here is an interesting one. Looking for ideas. We have a 6807 running VSS. On port Te2/1/32 we have several vlans on a trunk port connected to a 3750X switch port Gi1/1/1. For vlan 701 and several others the 6807 is root. Vlan 701 appears only on this port. There is an SVI for vlan 701 on the 6807. We notice in the log that int vlan 701 has been going down and then up 15 times in since the 6807 was installed. It replaced a 6509 a little over 1 week ago. So first thought is that int Te2/1/32 is having issues. Checking the port we have logging link-status and there have been no interface flaps for this port. No errors recorded on either end of the link. Yet we have this.
Port 4128 (TenGigabitEthernet2/1/32) of VLAN0701 is designated forwarding
Port path cost 4, Port priority 128, Port Identifier 128.4128.
Designated root has priority 8893, address 0200.0003.3333
Designated bridge has priority 8893, address 0200.0003.3333
Designated port id is 128.4128, designated path cost 0
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 15
Link type is point-to-point by default
BPDU: sent 371903, received 62
Port 49 (GigabitEthernet1/1/1) of VLAN0701 is root forwarding
Port path cost 3004, Port priority 128, Port Identifier 128.49.
Designated root has priority 8893, address 0200.0003.3333
Designated bridge has priority 8893, address 0200.0003.3333
Designated port id is 144.32, designated path cost 0
Timers: message age 16, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 65, received 369628
The real interesting point is that none of the other vlans have the same statistics. All have transitioned to forwarding only once.
Regards.
07-10-2018 06:45 AM
Hi!
Can you post "show spanning-tree interface Te2/1/32"?
Are you running now 6509 connected to 3750X?
/Mohammed
07-10-2018 07:59 AM
You sure that is all you want. Not much to see. I attached detail in a file.
It is the 6807. The 6509 has been replaced.
6807#show spanning-tree int te2/1/32
Vlan Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0006 Desg FWD 4 128.4128 P2p
VLAN0118 Desg FWD 4 128.4128 P2p
VLAN0397 Desg FWD 4 128.4128 P2p
VLAN0398 Desg FWD 4 128.4128 P2p
VLAN0701 Desg FWD 4 128.4128 P2p
VLAN0702 Desg FWD 4 128.4128 P2p
VLAN0739 Desg FWD 4 128.4128 P2p
VLAN0970 Desg FWD 4 128.4128 P2p
07-10-2018 08:25 AM
I also see the below line in your output, which means the vlan is going to blocking and then forwarding state and so this is causing the root switch to receive BPDUs. Can you check the 3750 site and make sure everything is configured correcty for vlan 701? Also, are both switches running the STP for all vlans?
HTH
BPDU: sent 413843, received 74
07-17-2018 08:51 AM
Reza to answer your questions.
Yes both switches are running rapid-pvst. And is enabled on all vlans.
Configuration on the 3750 is pretty much defaults.
spanning-tree mode rapid-pvst
spanning-tree portfast default
no spanning-tree optimize bpdu transmission
spanning-tree extend system-id
I enabled debug spanning tree events on the 6807. This is what happens.
001893: Jul 17 07:49:31.921 EDT: SW1: RSTP(701): Te2/1/32 Dispute!
001894: Jul 17 07:49:31.957 EDT: SW1: RSTP(701): transmitting a proposal on Te2/1/32
001895: Jul 17 07:49:31.961 EDT: SW1: RSTP[701]: Te2/1/32 state change completed. New state is [blocking]
001896: Jul 17 07:49:31.969 EDT: %LINK-SW1-3-UPDOWN: Interface Vlan701, changed state to down
001897: Jul 17 07:49:32.033 EDT: SW1: RSTP(701): received an agreement on Te2/1/32
001898: Jul 17 07:49:32.033 EDT: SW1: RSTP[701]: Te2/1/32 dispute resolved
001899: Jul 17 07:49:32.033 EDT: SW1: RSTP(701): starting topology change timer for 35 seconds
001900: Jul 17 07:49:32.037 EDT: SW1: RSTP[701]: Te2/1/32 state change completed. New state is [forwarding]
001901: Jul 17 07:49:32.049 EDT: %LINK-SW1-3-UPDOWN: Interface Vlan701, changed state to up
001902: Jul 17 07:50:07.035 EDT: SW1: RSTP(701): stopping topology change timer
As you said something triggers the 3750 to send a bpdu on vlan 701 only.
Just noted that the cpu on the 3750 is spiking to 100%. But the spike does not coincide with the BPDU.
I have enabled debug spann events on the 3750 as well.
07-18-2018 12:20 AM
Hi!
Have you any mls rate-limit command on the 3750? Can you post "show mls rate-limit" from 3750?
/Mohammed
07-18-2018 10:59 AM
Sorry that command is not valid.
qos is disabled globally.
Here are the debugs on the 3750 side.
Jul 18 04:53:04 EDT: RSTP(701): Gi1/1/1 rcvd info expired
Jul 18 04:53:04 EDT: RSTP(701): updt roles, information on root port Gi1/1/1 expired
Jul 18 04:53:04 EDT: RSTP(701): we become the root bridge
Jul 18 04:53:04 EDT: RSTP(701): Gi1/1/1 is now designated
Jul 18 04:53:04 EDT: RSTP(701): Gi1/0/1 not in sync
Jul 18 04:53:04 EDT: RSTP(701): updt roles, received superior bpdu on Gi1/1/1
Jul 18 04:53:04 EDT: RSTP(701): Gi1/1/1 is now root port
Jul 18 04:53:04 EDT: RSTP(701): synced Gi1/1/1
Jul 18 04:53:04 EDT: STP[701]: Generating TC trap for port GigabitEthernet1/1/1
Jul 18 04:53:05 EDT: RSTP(701): transmitting an agreement on Gi1/1/1 as a response to a proposal
So it would appear that for vlan 701 only the 3750x have not seen 3 bpdu in a row when the event occurs.
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