Hi,

k.adath2015 · ‎05-28-2016

Hi,

I have attached a topology diagram , Stp shows little different for a vlan ( vlan 15 , root shows Another switch ) .

Could someone help to understand why is that ?

All three interface vlan are sonfigured (hsrp with high priority on aggregator -1 )

Aggregator -1
-----------------------------------
sh spanning-tree vlan 9

VLAN0009
Spanning tree enabled protocol rstp
Root ID Priority 8201
Address 0032.04ee.de01
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 8201 (priority 8192 sys-id-ext 9)
Address 0032.04ee.de01
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po102 Desg FWD 1 128.4316 (vPC) Network P2p
Po103 Desg FWD 1 128.4317 (vPC) Network P2p
Po104 Desg FWD 1 128.4318 (vPC) Network P2p
Po101 Desg FWD 1 128.4350 (vPC peer-link) Network P2p
Eth1/16 Desg FWD 2 128.271 P2p

sh spanning-tree vlan 10

VLAN00010
Spanning tree enabled protocol rstp
Root ID Priority 8201
Address 0032.04ee.de01
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 8201 (priority 8192 sys-id-ext 9)
Address 0032.04ee.de01
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po102 Desg FWD 1 128.4316 (vPC) Network P2p
Po103 Desg FWD 1 128.4317 (vPC) Network P2p
Po104 Desg FWD 1 128.4318 (vPC) Network P2p
Po101 Desg FWD 1 128.4350 (vPC peer-link) Network P2p
Eth1/16 Desg FWD 2 128.271 P2p

sh spanning-tree vlan 15

VLAN0013
Spanning tree enabled protocol rstp
Root ID Priority 1
Address E33e.0608.8491
Cost 2868
Port 4350 (port-channel101)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 8205 (priority 8192 sys-id-ext 13)
Address 0032.04ee.de01
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po102 Desg FWD 1 128.4316 (vPC) Network P2p
Po103 Desg FWD 1 128.4317 (vPC) Network P2p
Po104 Desg FWD 1 128.4318 (vPC) Network P2p
Po101 Desg FWD 1 128.4350 (vPC peer-link) Network P2p
Eth1/16 Desg FWD 2 128.271 P2p

Output from second aggregator
-------------------------------------

sh spanning-tree vlan 10

VLAN00010
Spanning tree enabled protocol rstp
Root ID Priority 8201
Address 0032.04ee.de01
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 8201 (priority 8192 sys-id-ext 9)
Address 0032.04ee.de01
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po102 Desg FWD 1 128.4316 (vPC) Network P2p
Po103 Desg FWD 1 128.4317 (vPC) Network P2p
Po104 Desg FWD 1 128.4318 (vPC) Network P2p
Po101 Root FWD 1 128.4350 (vPC peer-link) Network P2p
Eth1/16 Desg FWD 2 128.271 P2p

VLAN0015
Spanning tree enabled protocol rstp
Root ID Priority 1
Address E33e.0608.8491
Cost 2867
Port 257 (Ethernet1/10)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 8205 (priority 8192 sys-id-ext 13)
Address 0032.04ee.de01
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po102 Desg FWD 1 128.4316 (vPC) Network P2p
Po103 Desg FWD 1 128.4317 (vPC) Network P2p
Po104 Desg FWD 1 128.4318 (vPC) Network P2p
Po101 Desg FWD 1 128.4350 (vPC peer-link) Network P2p
Eth1/10 Root FWD 4 128.257 P2p

Thanks

Reza Sharifi · ‎05-28-2016

Hi,

Can you post "sh run int vlan 10" and "sh run int vlan 15" from both switches?

Or just post "sh run" from both switches.

HTH

k.adath2015 · ‎05-28-2016

Hi,

agg-1

interface Vlan10
no ip redirects
ip address 192.168.9.2/24
ip directed-broadcast 100
no ipv6 redirects
hsrp 10
preempt
priority 200
ip 192.168.9.1
no shutdown

agg-2

interface Vlan10
no shutdown
no ip redirects
ip address 192.168.9.2/24
ip directed-broadcast 100
no ipv6 redirects
hsrp 10
preempt delay minimum 3
priority 50
ip 192.168.9.1

agg-1

interface Vlan15
no ip redirects
ip address 192.168.12.2/24
no ipv6 redirects
hsrp 15
preempt
priority 200
ip 192.168.12.1
no shutdown

agg-2

interface Vlan15
no shutdown
no ip redirects
ip address 192.168.12.3/24
no ipv6 redirects
hsrp 15
preempt
priority 50
ip 192.168.12.1

Please see the below conf for vlan 15 on both switches . Seems some misconfiguration ?

agg1- spanning-tree vlan 1-3967 priority 8192

agg2-
spanning-tree vlan 1-14,16-3967 priority 28672
spanning-tree vlan 15 priority 8192

Thanks

Reza Sharifi · ‎05-28-2016

Hi,

Yes, to make vlan 15 the same as all the other vlan remove this command

spanning-tree vlan 15 priority 8192

no spanning-tree vlan 15 priority 8192

and than include vlan 15 in the list (see below)

spanning-tree vlan 1-3967 priority 28672

HTH

k.adath2015 · ‎05-28-2016

Hi,

How can i figure out why the root changed for vlan 15

Thanks

Reza Sharifi · ‎05-29-2016

Hi,

In your configuration below, why do both switches have the same physical IP (ip address 192.168.9.2/24)?

terface Vlan10
no ip redirects
ip address 192.168.9.2/24
ip directed-broadcast 100
no ipv6 redirects
hsrp 10
preempt
priority 200
ip 192.168.9.1
no shutdown

agg-2

interface Vlan10
no shutdown
no ip redirects
ip address 192.168.9.2/24
ip directed-broadcast 100
no ipv6 redirects
hsrp 10
preempt delay minimum 3
priority 50
ip 192.168.9.1

k.adath2015 · ‎01-28-2017

Hi,

This is by mistake actually 9.3

agg-2

interface Vlan10
no shutdown
no ip redirects
ip address 192.168.9.3/24
ip directed-broadcast 100
no ipv6 redirects
hsrp 10
preempt delay minimum 3
priority 50
ip 192.168.9.1

Thanks

vpc and stp