Solved: Multiple STP Roots for the same VLAN??

mikegrous · ‎01-06-2010

How is this possible? Multiple Switches claiming to be spanning tree root.

The network has 2 cores. Both 6513. 1 is catos 1 is IOS. Spanning tree seems to be messed up with multiple switches claiming to be root for most of the VLANS here. STP is configured only on the cores. Yet the access layer switches seem to claim to be the root? Strange? Is this some bug in CATos?

CORE1:

At the core is an old 6513.
WS-C6513 Software, Version NmpSW: 8.6(4)
System Bootstrap Version: 7.1(1)
System Boot Image File is 'bootflash:cat6000-sup2k8.8-6-4.bin'

Core6513> (enable) show spantree 2
VLAN 4
Spanning tree mode PVST+
Spanning tree type ieee
Spanning tree enabled

Designated Root             00-0b-fc-d3-10-00
Designated Root Priority    4100
Designated Root Cost        0
Designated Root Port        1/0
Root Max Age   20 sec   Hello Time 2 sec   Forward Delay 15 sec

Bridge ID MAC ADDR          00-0b-fc-d3-10-00
Bridge ID Priority          4100 (bridge priority: 4096, sys ID ext: 4)
Bridge Max Age 20 sec   Hello Time 2 sec   Forward Delay 15 sec

Topology change initiator           4/9
Last topology change occured        Tue Jan 5 2010, 18:22:49
Topology change count               409

Port                     Vlan Port-State    Cost      Prio Portfast Channel_id
------------------------ ---- ------------- --------- ---- -------- ----------
3/11                    4    forwarding            4   32 disabled 0
3/15-16                  4    forwarding            3   32 disabled 1737

set spantree priority 4096 1-2,4-20,22-24,26-45,50-53,55,67,80,99-103,105,130,150-154,156,175,222,237,239,265-268,272,290-295,302,310-311,371,666,700,803

Core2:
cisco WS-C6513 (R7000) processor (revision 1.0) with 458720K/65536K bytes of memory.
Cisco Internetwork Operating System Software
IOS (tm) s72033_rp Software (s72033_rp-ENTSERVICESK9_WAN-M), Version 12.2(18)SXF, RELEASE SOFTWARE (fc1)

VLAN0004
Spanning tree enabled protocol ieee
Root ID    Priority    4100
             Address     000b.fcd3.1000
             Cost        3
             Port        1665 (Port-channel159)
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    36868 (priority 36864 sys-id-ext 4)
             Address     0014.1b33.1d40
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

spanning-tree vlan 1-2,4-20,22-24,26-4094 priority 36864

Access Switch #1:

Cisco IOS Software, C3750 Software (C3750-IPBASE-M), Version 12.2(25)SEB2, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Wed 08-Jun-05 01:19 by yenanh

ROM: Bootstrap program is C3750 boot loader
BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(25r)SEA, RELEASE SOFTWARE (fc)

CISCO3750POE-6thFloor uptime is 43 weeks, 4 days, 7 hours, 9 minutes
System returned to ROM by error - Debug Exception (Could be NULL pointer dereference) Exception (0x2000)!, PC 0x757C7C
System restarted at 06:35:30 UTC Sat Mar 7 2009
System image file is "flash:c3750-ipbase-mz.122-25.SEB2/c3750-ipbase-mz.122-25.SEB2.bin"

VLAN0004
Spanning tree enabled protocol ieee
Root ID    Priority    32772
             Address     0015.628a.c000
             This bridge is the root
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32772 (priority 32768 sys-id-ext 4)
             Address     0015.628a.c000
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/1          Desg FWD 4         128.1    P2p
Gi2/0/1          Desg FWD 4         128.53   P2p

Access Switch #1

C3750 Software (C3750-IPBASE-M), Version 12.2(25)SEB2, RELEASE SOFTWARE (fc1)

VLAN0004
Spanning tree enabled protocol ieee
Root ID    Priority    32772
             Address     0015.628a.c000
             This bridge is the root
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32772 (priority 32768 sys-id-ext 4)
             Address     0015.628a.c000
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/1          Desg FWD 4         128.1    P2p
Gi2/0/1          Desg FWD 4         128.53   P2p

Access Switch #2

C2970 Software (C2970-I6L2-M), Version 12.2(20)SE4, RELEASE SOFTWARE (fc1)

VLAN0004
Spanning tree enabled protocol ieee
Root ID    Priority    32772
             Address     0013.1a99.0980
            This bridge is the root
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32772 (priority 32768 sys-id-ext 4)
             Address     0013.1a99.0980
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi0/25           Desg FWD 4         128.25   P2p
Gi0/26           Desg FWD 4         128.26   P2p

RANDOM SW1

VLAN0004
Spanning tree enabled protocol ieee
Root ID    Priority    32772
             Address     0015.628a.c000
             This bridge is the root
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32772 (priority 32768 sys-id-ext 4)
             Address     0015.628a.c000
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/1          Desg FWD 4         128.1    P2p
Gi2/0/1          Desg FWD 4         128.53   P2p

RANDOM SW2

VLAN0004
Spanning tree enabled protocol ieee
Root ID    Priority    32772
             Address     0015.2b5b.6300
             This bridge is the root
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority    32772 (priority 32768 sys-id-ext 4)
             Address     0015.2b5b.6300
             Hello Time   2 sec Max Age 20 sec Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi2/0/1          Desg FWD 4         128.53   P2p
Gi3/0/1          Desg FWD 4         128.105 P2p

Jon Marshall · ‎01-06-2010

Mike

This can happen if your trunks are not correctly configured or are not operating properly. You need to check the status of trunk links between access-layer switches and 6500 switches and also which vlans are pruned/allowed on the links.

Jon

View solution in original post

Jon Marshall · ‎01-06-2010

Mike

This can happen if your trunks are not correctly configured or are not operating properly. You need to check the status of trunk links between access-layer switches and 6500 switches and also which vlans are pruned/allowed on the links.

Jon

mikegrous · ‎01-06-2010

Makes sence

CORE

clear trunk 3/9 2,4-6,8-20,22,24-1000,1006-1023
set trunk 3/9 on dot1q 1,3,7,21,23,1001-1005,1024-4094

set spantree priority 4096 1-2,4-20,22-24,26-45,50-53,55,67,80,99-103,105,130,150-154,156,175,222,237,239,265-268,272,290-295,302,310-311,371,666,700,803
set spantree priority 8192 3,21,25

3/9 is an uplink to a swithc claiming to be root.

And this matches up the the swithc on the other side of the 3/9 link. Thanks Jon. Now if i config the link on the access switch to:

interface GigabitEthernet3/0/1
switchport trunk encapsulation dot1q
sw trunk allowed vlan 1,3,7,21,23,1001-1005,1024-4094 (adding this config line)

switchport mode trunk
end

This should take core of it? Testing i go.

CISCO3750POE-3rdFloor#show spann | i VLAN|This

VLAN0001
VLAN0002
             This bridge is the root
VLAN0003
VLAN0004
             This bridge is the root
VLAN0005
             This bridge is the root
VLAN0006
             This bridge is the root
VLAN0007
VLAN0008
             This bridge is the root
VLAN0009
             This bridge is the root
VLAN0010
             This bridge is the root
VLAN0011
             This bridge is the root
VLAN0012
             This bridge is the root
VLAN0013
             This bridge is the root
VLAN0014
             This bridge is the root
VLAN0015
             This bridge is the root
VLAN0016
             This bridge is the root
VLAN0017
             This bridge is the root
VLAN0018
             This bridge is the root
VLAN0019
             This bridge is the root
VLAN0020
             This bridge is the root
VLAN0021
VLAN0022
             This bridge is the root
VLAN0023
VLAN0024
             This bridge is the root
VLAN0025
             This bridge is the root
VLAN0026
             This bridge is the root
VLAN0027
             This bridge is the root
VLAN0028
             This bridge is the root
VLAN0030
             This bridge is the root
VLAN0031
             This bridge is the root
VLAN0032
             This bridge is the root
VLAN0033
             This bridge is the root
VLAN0034
             This bridge is the root
VLAN0035
             This bridge is the root
VLAN0036
             This bridge is the root
VLAN0037
             This bridge is the root
VLAN0038
             This bridge is the root
VLAN0039
             This bridge is the root
VLAN0040
             This bridge is the root
VLAN0041
             This bridge is the root
VLAN0042
             This bridge is the root
VLAN0043
             This bridge is the root
VLAN0044
             This bridge is the root
VLAN0045
             This bridge is the root
VLAN0050
             This bridge is the root
VLAN0051
             This bridge is the root
VLAN0052
             This bridge is the root
VLAN0053
             This bridge is the root
VLAN0055
             This bridge is the root
VLAN0067
             This bridge is the root
VLAN0080
             This bridge is the root
VLAN0099
             This bridge is the root
VLAN0100
             This bridge is the root
VLAN0101
             This bridge is the root
VLAN0102
             This bridge is the root
VLAN0103
             This bridge is the root
VLAN0105
             This bridge is the root
VLAN0130
             This bridge is the root
VLAN0150
             This bridge is the root
VLAN0151
             This bridge is the root
VLAN0152
             This bridge is the root
VLAN0153
             This bridge is the root
VLAN0154
             This bridge is the root
VLAN0156
             This bridge is the root
VLAN0222
             This bridge is the root
VLAN0237
             This bridge is the root
VLAN0239
             This bridge is the root
VLAN0265
             This bridge is the root
VLAN0266
             This bridge is the root
VLAN0267
             This bridge is the root
VLAN0268
             This bridge is the root
VLAN0272
             This bridge is the root
VLAN0290
             This bridge is the root
VLAN0291
             This bridge is the root
VLAN0292
             This bridge is the root
VLAN0293
             This bridge is the root
VLAN0294
             This bridge is the root
VLAN0295
             This bridge is the root
VLAN0302
             This bridge is the root
VLAN0310
             This bridge is the root
VLAN0311
             This bridge is the root
VLAN0371
             This bridge is the root
VLAN0666
             This bridge is the root
VLAN0700
             This bridge is the root
VLAN0803
             This bridge is the root