Nexus 4001i and MST tons of log errors

lyranvolcrane · ‎07-05-2013

Went looking through my Nexus 4001i logs today, and started noticing a bunch of STP role and port change messages:

2013 Jul 5 14:40:31 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/1 instance MST0000 role changed to designated

2013 Jul 5 14:40:31 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port port-channel2 instance MST0000 role changed to alternate

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port port-channel1 instance MST0000 role changed to root

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/14 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/14 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/13 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/13 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/12 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/12 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/11 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/11 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/10 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/10 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/9 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/9 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/8 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/8 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/7 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/7 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/6 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/6 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/5 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/5 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/4 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/4 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/3 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/3 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/2 removed as MST Boundary port

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-PORT_ROLE: Port Ethernet1/2 instance MST0000 role changed to designated

2013 Jul 5 14:40:32 N4k-SLOT7-SW1 %STP-6-MST_PORT_BOUNDARY: Port Ethernet1/1 removed as MST Boundary port

After going through a variety of configuration validations, spanning-tree root and priority validations as well as making sure the instances and revisions between the various MST speaking switches (all of the Nexus gear including Nexus 5596 which are vPC peers, 4001i's which connect via vPC's to the 5596's, and Catalyst 3110X's which also use MST, but only have one uplink at this time to the 5596's not in a vPC setup).

None of the other devices appear to be experiencing this problem.

I am quite confused as to what is going on, and cannot figure out why the 4001i is wigging out like this.

A quick output of MST::

N4k-SLOT7-SW1# show spanning-tree mst

##### MST0 vlans mapped: 801-3109,3111-4094

Bridge address 6073.5c8d.7e82 priority 24576 (24576 sysid 0)

Root address 0023.04ee.be03 priority 16384 (16384 sysid 0)

port Po1 path cost 0

Regional Root address 0023.04ee.be03 priority 16384 (16384 sysid 0)

internal cost 500 rem hops 19

Operational hello time 2 , forward delay 15, max age 20, txholdcount 6

Configured hello time 2 , forward delay 15, max age 20, max hops 20

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Root FWD 500 32.4096 P2p

Po2 Altn BLK 1000 64.4097 P2p

Eth1/1 Desg FWD 2000 128.129 Edge P2p

Eth1/2 Desg FWD 2000 128.130 Edge P2p

Eth1/3 Desg FWD 2000 128.131 Edge P2p

Eth1/4 Desg FWD 2000 128.132 Edge P2p

Eth1/5 Desg FWD 2000 128.133 Edge P2p

Eth1/6 Desg FWD 2000 128.134 Edge P2p

Eth1/7 Desg FWD 2000 128.135 Edge P2p

Eth1/8 Desg FWD 2000 128.136 Edge P2p

Eth1/9 Desg FWD 2000 128.137 Edge P2p

Eth1/10 Desg FWD 2000 128.138 Edge P2p

Eth1/11 Desg FWD 2000 128.139 Edge P2p

Eth1/12 Desg FWD 2000 128.140 Edge P2p

Eth1/13 Desg FWD 2000 128.141 Edge P2p

Eth1/14 Desg FWD 2000 128.142 Edge P2p

##### MST1 vlans mapped: 2-499,600-800,3110

Bridge address 6073.5c8d.7e82 priority 24577 (24576 sysid 1)

Root address 0023.04ee.be03 priority 16385 (16384 sysid 1)

port Po1 cost 500 rem hops 19

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Root FWD 500 128.4096 P2p

Eth1/1 Desg FWD 2000 128.129 Edge P2p

Eth1/2 Desg FWD 2000 128.130 Edge P2p

Eth1/3 Desg FWD 2000 128.131 Edge P2p

Eth1/4 Desg FWD 2000 128.132 Edge P2p

Eth1/5 Desg FWD 2000 128.133 Edge P2p

Eth1/6 Desg FWD 2000 128.134 Edge P2p

Eth1/7 Desg FWD 2000 128.135 Edge P2p

Eth1/8 Desg FWD 2000 128.136 Edge P2p

Eth1/9 Desg FWD 2000 128.137 Edge P2p

Eth1/10 Desg FWD 2000 128.138 Edge P2p

Eth1/11 Desg FWD 2000 128.139 Edge P2p

Eth1/12 Desg FWD 2000 128.140 Edge P2p

Eth1/13 Desg FWD 2000 128.141 Edge P2p

Eth1/14 Desg FWD 2000 128.142 Edge P2p

##### MST2 vlans mapped: 1,500-599

Bridge address 6073.5c8d.7e82 priority 24578 (24576 sysid 2)

Root address 0023.04ee.be03 priority 16386 (16384 sysid 2)

port Po2 cost 1000 rem hops 19

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po2 Root FWD 1000 128.4097 P2p

Eth1/1 Desg FWD 2000 128.129 Edge P2p

Eth1/2 Desg FWD 2000 128.130 Edge P2p

Eth1/3 Desg FWD 2000 128.131 Edge P2p

Eth1/4 Desg FWD 2000 128.132 Edge P2p

Eth1/5 Desg FWD 2000 128.133 Edge P2p

Eth1/6 Desg FWD 2000 128.134 Edge P2p

Eth1/7 Desg FWD 2000 128.135 Edge P2p

Eth1/8 Desg FWD 2000 128.136 Edge P2p

Eth1/9 Desg FWD 2000 128.137 Edge P2p

Eth1/10 Desg FWD 2000 128.138 Edge P2p

Eth1/11 Desg FWD 2000 128.139 Edge P2p

Eth1/12 Desg FWD 2000 128.140 Edge P2p

Eth1/13 Desg FWD 2000 128.141 Edge P2p

Eth1/14 Desg FWD 2000 128.142 Edge P2p

N4k-SLOT7-SW1# show spanning-tree detail | i occur|from|exec

MST0000 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 1 last change occurred 3:48:09 ago

from port-channel1

MST0001 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 1 last change occurred 3:48:07 ago

from port-channel1

MST0002 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 1 last change occurred 3:48:07 ago

from port-channel2

(topology change was due to testing rapid-PVST for this switch, and then putting it back, the previous change occured 555 hours ago).

N4k-SLOT9-SW2# show spanning-tree

MST0000

Spanning tree enabled protocol mstp

Root ID Priority 16384

Address 0023.04ee.be03

Cost 0

Port 4096 (port-channel1)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 24576 (priority 24576 sys-id-ext 0)

Address 2c54.2ded.b704

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Root FWD 500 128.4096 P2p

Po2 Altn BLK 1000 128.4097 P2p

Eth1/1 Desg FWD 2000 128.129 Edge P2p

Eth1/2 Desg FWD 2000 128.130 Edge P2p

Eth1/3 Desg FWD 2000 128.131 Edge P2p

Eth1/4 Desg FWD 2000 128.132 Edge P2p

Eth1/5 Desg FWD 2000 128.133 Edge P2p

Eth1/6 Desg FWD 2000 128.134 Edge P2p

Eth1/7 Desg FWD 2000 128.135 Edge P2p

Eth1/8 Desg FWD 2000 128.136 Edge P2p

Eth1/9 Desg FWD 2000 128.137 Edge P2p

Eth1/10 Desg FWD 2000 128.138 Edge P2p

Eth1/11 Desg FWD 2000 128.139 Edge P2p

Eth1/12 Desg FWD 2000 128.140 Edge P2p

Eth1/13 Desg FWD 2000 128.141 Edge P2p

Eth1/14 Desg FWD 2000 128.142 Edge P2p

MST0001

Spanning tree enabled protocol mstp

Root ID Priority 16385

Address 0023.04ee.be03

Cost 500

Port 4096 (port-channel1)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 24577 (priority 24576 sys-id-ext 1)

Address 2c54.2ded.b704

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Root FWD 500 128.4096 P2p

Eth1/1 Desg FWD 2000 128.129 Edge P2p

Eth1/2 Desg FWD 2000 128.130 Edge P2p

Eth1/3 Desg FWD 2000 128.131 Edge P2p

Eth1/4 Desg FWD 2000 128.132 Edge P2p

Eth1/5 Desg FWD 2000 128.133 Edge P2p

Eth1/6 Desg FWD 2000 128.134 Edge P2p

Eth1/7 Desg FWD 2000 128.135 Edge P2p

Eth1/8 Desg FWD 2000 128.136 Edge P2p

Eth1/9 Desg FWD 2000 128.137 Edge P2p

Eth1/10 Desg FWD 2000 128.138 Edge P2p

Eth1/11 Desg FWD 2000 128.139 Edge P2p

Eth1/12 Desg FWD 2000 128.140 Edge P2p

Eth1/13 Desg FWD 2000 128.141 Edge P2p

Eth1/14 Desg FWD 2000 128.142 Edge P2p

MST0002

Spanning tree enabled protocol mstp

Root ID Priority 16386

Address 0023.04ee.be03

Cost 1000

Port 4097 (port-channel2)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 24578 (priority 24576 sys-id-ext 2)

Address 2c54.2ded.b704

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po2 Root FWD 1000 128.4097 P2p

Eth1/1 Desg FWD 2000 128.129 Edge P2p

Eth1/2 Desg FWD 2000 128.130 Edge P2p

Eth1/3 Desg FWD 2000 128.131 Edge P2p

Eth1/4 Desg FWD 2000 128.132 Edge P2p

Eth1/5 Desg FWD 2000 128.133 Edge P2p

Eth1/6 Desg FWD 2000 128.134 Edge P2p

Eth1/7 Desg FWD 2000 128.135 Edge P2p

Eth1/8 Desg FWD 2000 128.136 Edge P2p

Eth1/9 Desg FWD 2000 128.137 Edge P2p

Eth1/10 Desg FWD 2000 128.138 Edge P2p

Eth1/11 Desg FWD 2000 128.139 Edge P2p

Eth1/12 Desg FWD 2000 128.140 Edge P2p

Eth1/13 Desg FWD 2000 128.141 Edge P2p

Eth1/14 Desg FWD 2000 128.142 Edge P2p

N4k-SLOT9-SW2# show spanning-tree detail | i occur|from|exec

MST0000 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 18758 last change occurred 4:01:03 ago

from port-channel1

MST0001 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 45742 last change occurred 4:01:02 ago

from port-channel1

MST0002 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 21007 last change occurred 599:47:47 ago

from port-channel2

N4k-SLOT9-SW2#

N5596-DC-SW1# show spanning-tree

MST0000

Spanning tree enabled protocol mstp

Root ID Priority 16384

Address 0023.04ee.be03

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 16384 (priority 16384 sys-id-ext 0)

Address 0023.04ee.be03

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Desg FWD 1000 128.4096 P2p

Po2 Desg FWD 200 128.4097 (vPC) P2p

Po3 Desg FWD 200 128.4098 (vPC) P2p

Po57 Desg FWD 200 128.4152 (vPC) P2p

Po100 Desg FWD 1000 128.4195 (vPC peer-link) Network P2p

Eth1/15 Desg FWD 2000 128.143 Edge P2p

Eth1/16 Desg FWD 2000 128.144 Edge P2p

MST0001

Spanning tree enabled protocol mstp

Root ID Priority 16385

Address 0023.04ee.be03

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 16385 (priority 16384 sys-id-ext 1)

Address 0023.04ee.be03

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po2 Desg FWD 200 128.4097 (vPC) P2p

Po3 Desg FWD 200 128.4098 (vPC) P2p

Po57 Desg FWD 200 128.4152 (vPC) P2p

Po100 Desg FWD 1000 128.4195 (vPC peer-link) Network P2p

MST0002

Spanning tree enabled protocol mstp

Root ID Priority 16386

Address 0023.04ee.be03

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 16386 (priority 16384 sys-id-ext 2)

Address 0023.04ee.be03

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Desg FWD 1000 128.4096 P2p

Eth1/15 Desg FWD 2000 128.143 Edge P2p

Eth1/16 Desg FWD 2000 128.144 Edge P2p

N5596-DC-SW1# show spanning-tree detail | i occur|from|exec

MST0000 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 44578 last change occurred 4:11:57 ago

from port-channel2

MST0001 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 98707 last change occurred 4:11:55 ago

from port-channel2

MST0002 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 4 last change occurred 4:11:55 ago

from port-channel1

N5596-DC-SW2# show spanning-tree

MST0000

Spanning tree enabled protocol mstp

Root ID Priority 16384

Address 0023.04ee.be03

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 16384 (priority 16384 sys-id-ext 0)

Address 0023.04ee.be03

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Desg FWD 1000 128.4096 P2p

Po2 Desg FWD 200 128.4097 (vPC) P2p

Po3 Desg FWD 200 128.4098 (vPC) P2p

Po57 Desg FWD 200 128.4152 (vPC) P2p

Po100 Root FWD 1000 128.4195 (vPC peer-link) Network P2p

Eth1/9 Desg FWD 20000 128.137 P2p

Eth1/15 Desg FWD 2000 128.143 Edge P2p

Eth1/16 Desg FWD 2000 128.144 Edge P2p

MST0001

Spanning tree enabled protocol mstp

Root ID Priority 16385

Address 0023.04ee.be03

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 16385 (priority 16384 sys-id-ext 1)

Address 0023.04ee.be03

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po2 Desg FWD 200 128.4097 (vPC) P2p

Po3 Desg FWD 200 128.4098 (vPC) P2p

Po57 Desg FWD 200 128.4152 (vPC) P2p

Po100 Root FWD 1000 128.4195 (vPC peer-link) Network P2p

Eth1/9 Desg FWD 20000 128.137 P2p

MST0002

Spanning tree enabled protocol mstp

Root ID Priority 16386

Address 0023.04ee.be03

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 16386 (priority 16384 sys-id-ext 2)

Address 0023.04ee.be03

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Desg FWD 1000 128.4096 P2p

Eth1/9 Desg FWD 20000 128.137 P2p

Eth1/15 Desg FWD 2000 128.143 Edge P2p

Eth1/16 Desg FWD 2000 128.144 Edge P2p

N5596-DC-SW2# show spanning-tree | i occur|from|exec

N5596-DC-SW2# show spanning-tree detail | i occur|from|exec

MST0000 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 44234 last change occurred 4:12:45 ago

from port-channel100

MST0001 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 97804 last change occurred 4:12:43 ago

from port-channel100

MST0002 is executing the mstp compatible Spanning Tree protocol

Number of topology changes 49801 last change occurred 599:58:06 ago

from Ethernet1/9

Except from MST configs:

Nexus 4001i switches:

vlan 1,301-499

vlan 500

fip-snooping enable

vlan 600-800

spanning-tree mode mst

spanning-tree pathcost method long

spanning-tree mst 0-2 priority 24576

spanning-tree mst configuration

revision 1

instance 1 vlan 2-499,600-800,3110

instance 2 vlan 1,500-599

Nexus 5596 switches:

N5596-DC-SW1

spanning-tree mode mst

spanning-tree pathcost method long

spanning-tree mst 0-2 priority 16384

spanning-tree pseudo-information

mst 0-2 root priority 16384

mst 0-2 designated priority 16384

spanning-tree mst configuration

revision 1

instance 1 vlan 2-499,600-800,3110

instance 2 vlan 1,500-599

N5596-DC-SW2

spanning-tree mode mst

spanning-tree pathcost method long

spanning-tree mst 0-2 priority 16384

spanning-tree vlan 3110 priority 24576

spanning-tree pseudo-information

mst 0-1 designated priority 20480

mst 2 designated priority 16384

vlan 1-499,501,600-800 designated priority 20480

spanning-tree mst configuration

revision 1

instance 1 vlan 2-499,600-800,3110

instance 2 vlan 1,500-599

5596's vPC configs

N5596-DC-SW1

vpc domain 3

peer-switch

role priority 100

peer-keepalive destination 192.168.92.223 source 192.168.92.222

auto-recovery

N5596-DC-SW2

vpc domain 3

peer-switch

role priority 200

peer-keepalive destination 192.168.92.222 source 192.168.92.223

auto-recovery

Quick rundown of connections between devices:

Nexus 4001's connect to Nexus 5596's for ethernet data via twinax cables in a four port vPC between both Nexus 5596's.

Nexus 4001's connect to one Nexus 5596 a piece for FCoE two port LACP port channel. (hence the two instances, and vlan 1,500-599 in the same instance)

Catalyst 3110X connects via one Fiber-Optic connection to the N5596-DC-SW2, eventually will have two in a port-channel

Also keep in mind I corrected a priority conflict between the 3110X and Nexus 5596's earlier last month, which would explain all of the topology changes.

I can provide any other information if it is useful. I am just confused!

lyranvolcrane · ‎07-05-2013

To add to this, the logs I am seeing are constantly repeating. This isn't just a single instance of the problem, and when running debugs of spanning-tree and bpdu_rx, the only ports on the 4001i's receiving BPDU's are the port-channel uplinks. The ports themselves do not seem to transition out of a designated state, they just keep saying they are being reflagged as designated.

lyranvolcrane · ‎07-24-2013

I identified the problem.

Refer to

http://www.cisco.com/en/US/docs/switches/datacenter/sw/4_2/nx-os/interfaces/configuration/guide/if_vPC.html

for more information.

The problem I encountered was self-inflicted.

Using the spanning-tree pseudo-information command creates a psuedo priority setup that if implemented after the global spanning-tree commands sits alongside the spanning-tree priority and vlan definitions. This is intended to allow for non-vPC VLANs to have their own spanning-tree definitions separate of the spanning-tree environment for the vPC vlans. I am not sure the best way to describe it, but if you are not running a hybrid vPC setup (where you have vPC member VLANs and non-vPC VLANS with a separate link between the 5596's for the non-vPC VLANs) this setup would help you ensure you have a stable spanning-tree and prevent unnecessary blocking.

When I enabled this command, I applied it to the vPC VLAN's as well, and that caused the Nexus 4001i's vPC links to constantly change port role, and update all of the edge ports subsequently. While I didn't see a performance impact to end hosts (not much traffic is on the Nexus DataCenter environment yet), I did get a torrent of logs as shown above.

Once I removed the spanning-tree pseudo-information, the switches quieted down and spanning-tree stabilized on the Nexus 4001i's.

I will revisit the configuration though for trunks not using vPC if it is needed.

Andras Dosztal · ‎07-27-2013

Thank you for sharing the resolution too.

Sent from Cisco Technical Support Android App

lyranvolcrane · ‎07-27-2013

We all get better when we all have the answers. I hope someone learns from my mistakes and does not have to frustrate themselves over the same issues!