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In this Cisco Packet Tracer Spanning Tree Configuration Example, we will configure STP with STP Mode PVST+ with Packet Tracer. As you know, Per VLAN STP Plus is the STP Mode that uses one STP instances per VLAN.
For this Configuration Example, we will use the below switch topology.
We will do the below configuration steps for our PVST+ Configuration on Cisco Packet Tracer.
We will define VLAN 1,2,3 and for on each switch. VLAN 1 is also defined by default. So, it is not necessary to create it. The below configuration will be done on each switch.
Switch-1# configure terminal Switch-1(config)# vlan 2 Switch-1(config-vlan)# vlan 3 Switch-1(config-vlan)# vlan 4 Switch-1(config-vlan)# exit
We will configure allt he interfaces between the switches as Trunk interfaces and we will set the allowed VLANs on these interfaces. Allowed VLANs are our VLANs that we have created before. We will do the same configuration on each switch.
Switch-1(config)# interface fastethernet 0/1 Switch-1(config-if)# switchport mode trunk Switch-1(config-if)# switchport trunk allowed vlan 1-4 Switch-1(config-if)# exit Switch-1(config)# interface fastethernet 0/2 Switch-1(config-if)# switchport mode trunk Switch-1(config-if)# switchport trunk allowed vlan 1-4
We will set the STP Mode as PVST on each switch.
Switch-1 (config)# spanning-tree mode ? pvst Per-Vlan spanning tree mode rapid-pvst Per-Vlan rapid spanning tree mode Switch-1 (config)# spanning-tree mode pvst
After setting the STP Mode, the VLANs in the Per VLAN STP Domain will be defined on each switch like below.
Switch-1(config)# spanning-tree vlan 1-4 Switch-1(config)# exit
After the configuration, we will save the configuration on each switch.
Switch-1 # copy running-config startup-config
To verify our Per VLAN STP Plus configuration, we will use the below commands. You can find the outpıuts of some of them to learn PVST+ better.
Switch-1 # show spanning-tree summary Switch is in pvst mode Root bridge for: Extended system ID is enabled Portfast Default is disabled PortFast BPDU Guard Default is disabled Portfast BPDU Filter Default is disabled Loopguard Default is disabled EtherChannel misconfig guard is disabled UplinkFast is disabled BackboneFast is disabled Configured Pathcost method used is short Name Blocking Listening Learning Forwarding STP Active ---------------------- -------- --------- -------- ---------- ---------- VLAN0001 0 0 0 2 2 VLAN0002 0 0 0 2 2 VLAN0003 0 0 0 2 2 VLAN0004 0 0 0 2 2 ---------------------- -------- --------- -------- ---------- ---------- 4 vlans 0 0 0 8 8
Switch-1 # show spanning-tree VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 32769 Address 0001.977C.4BD8 Cost 19 Port 1(FastEthernet0/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 000D.BD4B.0AB2 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Root FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p VLAN0002 Spanning tree enabled protocol ieee Root ID Priority 32770 Address 0001.977C.4BD8 Cost 19 Port 1(FastEthernet0/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32770 (priority 32768 sys-id-ext 2) Address 000D.BD4B.0AB2 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Root FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p VLAN0003 Spanning tree enabled protocol ieee Root ID Priority 32771 Address 0001.977C.4BD8 Cost 19 Port 1(FastEthernet0/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32771 (priority 32768 sys-id-ext 3) Address 000D.BD4B.0AB2 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Root FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p VLAN0004 Spanning tree enabled protocol ieee Root ID Priority 32772 Address 0001.977C.4BD8 Cost 19 Port 1(FastEthernet0/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32772 (priority 32768 sys-id-ext 4) Address 000D.BD4B.0AB2 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Root FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p
Switch-1 # show spanning-tree vlan 1 VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 32769 Address 0001.977C.4BD8 Cost 19 Port 1(FastEthernet0/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 000D.BD4B.0AB2 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Root FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p
Switch-1 # show spanning-tree vlan 2 VLAN0002 Spanning tree enabled protocol ieee Root ID Priority 32770 Address 0001.977C.4BD8 Cost 19 Port 1(FastEthernet0/1) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32770 (priority 32768 sys-id-ext 2) Address 000D.BD4B.0AB2 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Root FWD 19 128.1 P2p Fa0/2 Desg FWD 19 128.2 P2p Switch-2 # show spanning-tree vlan 1 VLAN0001 Spanning tree enabled protocol ieee Root ID Priority 32769 Address 0001.977C.4BD8 Cost 38 Port 2(FastEthernet0/2) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 0002.1737.C58D Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Altn BLK 19 128.1 P2p Fa0/2 Root FWD 19 128.2 P2p
Switch-2 # show spanning-tree vlan 2 VLAN0002 Spanning tree enabled protocol ieee Root ID Priority 32770 Address 0001.977C.4BD8 Cost 38 Port 2(FastEthernet0/2) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32770 (priority 32768 sys-id-ext 2) Address 0002.1737.C58D Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Altn BLK 19 128.1 P2p Fa0/2 Root FWD 19 128.2 P2p
Switch-2 # show spanning-tree vlan 3 VLAN0003 Spanning tree enabled protocol ieee Root ID Priority 32771 Address 0001.977C.4BD8 Cost 38 Port 2(FastEthernet0/2) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32771 (priority 32768 sys-id-ext 3) Address 0002.1737.C58D Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Altn BLK 19 128.1 P2p Fa0/2 Root FWD 19 128.2 P2p
Switch-2# show spanning-tree vlan 4 VLAN0004 Spanning tree enabled protocol ieee Root ID Priority 32772 Address 0001.977C.4BD8 Cost 38 Port 2(FastEthernet0/2) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32772 (priority 32768 sys-id-ext 4) Address 0002.1737.C58D Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 20 Interface Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- Fa0/1 Altn BLK 19 128.1 P2p Fa0/2 Root FWD 19 128.2 P2p
Switch-1 # show spanning-tree interface fastEthernet 0/1 Vlan Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- VLAN0001 Root FWD 19 128.1 P2p VLAN0002 Root FWD 19 128.1 P2p VLAN0003 Root FWD 19 128.1 P2p VLAN0004 Root FWD 19 128.1 P2p
Switch-1 # show spanning-tree interface fastEthernet 0/2 Vlan Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- VLAN0001 Desg FWD 19 128.2 P2p VLAN0002 Desg FWD 19 128.2 P2p VLAN0003 Desg FWD 19 128.2 P2p VLAN0004 Desg FWD 19 128.2 P2p
Switch-2 # show spanning-tree interface fastEthernet 0/1 Vlan Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- VLAN0001 Altn BLK 19 128.1 P2p VLAN0002 Altn BLK 19 128.1 P2p VLAN0003 Altn BLK 19 128.1 P2p VLAN0004 Altn BLK 19 128.1 P2p
Switch-2 # show spanning-tree interface fastEthernet 0/2 Vlan Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- VLAN0001 Root FWD 19 128.2 P2p VLAN0002 Root FWD 19 128.2 P2p VLAN0003 Root FWD 19 128.2 P2p VLAN0004 Root FWD 19 128.2 P2p
Switch-4 # show spanning-tree interface fastEthernet 0/1 Vlan Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- VLAN0001 Desg FWD 19 128.1 P2p VLAN0002 Desg FWD 19 128.1 P2p VLAN0003 Desg FWD 19 128.1 P2p VLAN0004 Desg FWD 19 128.1 P2p
Switch-4 # show spanning-tree interface fastEthernet 0/2 Vlan Role Sts Cost Prio.Nbr Type ---------------- ---- --- --------- -------- -------------------------------- VLAN0001 Root FWD 19 128.2 P2p VLAN0002 Root FWD 19 128.2 P2p VLAN0003 Root FWD 19 128.2 P2p VLAN0004 Root FWD 19 128.2 P2p
Switch-1 # show spanning-tree detail VLAN0001 is executing the ieee compatible Spanning Tree Protocol Bridge Identifier has priority of 32768, sysid 1, 000D.BD4B.0AB2 Configured hello time 2, max age 20, forward delay 15 Current root has priority 32769 Root port is 1 (FastEthernet0/1), cost of root path is 19 Topology change flag not set, detected flag not set Number of topology changes 0 last change occurred 00:00:00 ago from FastEthernet0/1 Times: hold 1, topology change 35, notification 2 hello 2, max age 20, forward delay 15 Timers: hello 0, topology change 0, notification 0, aging 300 Port 1 (FastEthernet0/1) of VLAN0001 is root forwarding Port path cost 19, Port priority 128, Port Identifier 128.1 Designated root has priority 32769, address 0001.977C.4BD8 Designated bridge has priority 32769, address 0001.977C.4BD8 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default Port 2 (FastEthernet0/2) of VLAN0001 is designated forwarding Port path cost 19, Port priority 128, Port Identifier 128.2 Designated root has priority 32769, address 0001.977C.4BD8 Designated bridge has priority 32769, address 000D.BD4B.0AB2 Designated port id is 128.2, designated path cost 19 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default VLAN0002 is executing the ieee compatible Spanning Tree Protocol Bridge Identifier has priority of 32768, sysid 2, 000D.BD4B.0AB2 Configured hello time 2, max age 20, forward delay 15 Current root has priority 32770 Root port is 1 (FastEthernet0/1), cost of root path is 19 Topology change flag not set, detected flag not set Number of topology changes 0 last change occurred 00:00:00 ago from FastEthernet0/1 Times: hold 1, topology change 35, notification 2 hello 2, max age 20, forward delay 15 Timers: hello 0, topology change 0, notification 0, aging 300 Port 1 (FastEthernet0/1) of VLAN0002 is root forwarding Port path cost 19, Port priority 128, Port Identifier 128.1 Designated root has priority 32770, address 0001.977C.4BD8 Designated bridge has priority 32770, address 0001.977C.4BD8 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default Port 2 (FastEthernet0/2) of VLAN0002 is designated forwarding Port path cost 19, Port priority 128, Port Identifier 128.2 Designated root has priority 32770, address 0001.977C.4BD8 Designated bridge has priority 32770, address 000D.BD4B.0AB2 Designated port id is 128.2, designated path cost 19 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default VLAN0003 is executing the ieee compatible Spanning Tree Protocol Bridge Identifier has priority of 32768, sysid 3, 000D.BD4B.0AB2 Configured hello time 2, max age 20, forward delay 15 Current root has priority 32771 Root port is 1 (FastEthernet0/1), cost of root path is 19 Topology change flag not set, detected flag not set Number of topology changes 0 last change occurred 00:00:00 ago from FastEthernet0/1 Times: hold 1, topology change 35, notification 2 hello 2, max age 20, forward delay 15 Timers: hello 0, topology change 0, notification 0, aging 300 Port 1 (FastEthernet0/1) of VLAN0003 is root forwarding Port path cost 19, Port priority 128, Port Identifier 128.1 Designated root has priority 32771, address 0001.977C.4BD8 Designated bridge has priority 32771, address 0001.977C.4BD8 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default Port 2 (FastEthernet0/2) of VLAN0003 is designated forwarding Port path cost 19, Port priority 128, Port Identifier 128.2 Designated root has priority 32771, address 0001.977C.4BD8 Designated bridge has priority 32771, address 000D.BD4B.0AB2 Designated port id is 128.2, designated path cost 19 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default VLAN0004 is executing the ieee compatible Spanning Tree Protocol Bridge Identifier has priority of 32768, sysid 4, 000D.BD4B.0AB2 Configured hello time 2, max age 20, forward delay 15 Current root has priority 32772 Root port is 1 (FastEthernet0/1), cost of root path is 19 Topology change flag not set, detected flag not set Number of topology changes 0 last change occurred 00:00:00 ago from FastEthernet0/1 Times: hold 1, topology change 35, notification 2 hello 2, max age 20, forward delay 15 Timers: hello 0, topology change 0, notification 0, aging 300 Port 1 (FastEthernet0/1) of VLAN0004 is root forwarding Port path cost 19, Port priority 128, Port Identifier 128.1 Designated root has priority 32772, address 0001.977C.4BD8 Designated bridge has priority 32772, address 0001.977C.4BD8 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default Port 2 (FastEthernet0/2) of VLAN0004 is designated forwarding Port path cost 19, Port priority 128, Port Identifier 128.2 Designated root has priority 32772, address 0001.977C.4BD8 Designated bridge has priority 32772, address 000D.BD4B.0AB2 Designated port id is 128.2, designated path cost 19 Timers: message age 16, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default
After our PVST+ configuration on Packet Tracer, I will show you some manuplation commands on Cisco switches. Some of the important of these commands are explained one by one below:
The default Bridge Priotiy value is 32768. The priority value can be anything between 0 and 61440 but must be multiples of 4096. (0, 4096, 8192, 12288 etc.)
Switch-1(config)# spanning-tree vlan 1 priority 4096 Switch-2 (config)# spanning-tree vlan 1 priority 8192 Switch-3(config)# spanning-tree vlan 1 priority 8192 Switch-4 (config)# spanning-tree vlan 1 priority 12288
According to above configuration, Switch 1 will be elected as Root Bridge for VLAN 1.
Or for the below configuration, Switch 2 will be elected as Root Bridge for VLAN 4.
Switch-1(config)# spanning-tree vlan 4 priority 12288 Switch-2 (config)# spanning-tree vlan 4 priority 8192 Switch-3(config)# spanning-tree vlan 4 priority 16384 Switch-4 (config)# spanning-tree vlan 4 priority 12288
This priority is configured for each VLAN on each switch. according to these values, the switch with the lowest Bridge ID will be elected as Root Bridge. So, the lowest Priority will effect this election. (Bridge ID = Bridge Priority + MAC)
This Root Bridge election can be done also via “root primary” keyword for each VLAN on each switch. For example, with the below configuration, switch 1 will be the Root Pridge for VLAN 1, Swith 2 will be Root Bridge for VLAN 3 and so on.
Switch-1(config)# spanning-tree vlan 1 root primary Switch-2(config)# spanning-tree vlan 3 root primary Switch-3(config)# spanning-tree vlan 4 root primary Switch-4(config)# spanning-tree vlan 2 root primary
Beside, port priorities can be set like normal STP. But here, for each VLAN, a specific port priority can be given.
witch-1(config)# spanning-tree port-priority 150
Spanning Tree timers are the other configuration parameters for PVST+. We can set the some of the timers as below:
Switch-1(config)# spanning-tree vlan 3 hello-time 5
Switch-1(config)# spanning-tree vlan 2 forward-time 13
Switch-1(config)# spanning-tree vlan 4 max-age 24
To restart PVST+, we will use “clear spanning-tree detected protocol” command. We can also use this protocol for specific interfaces.
Switch-1(config)# clear spanning-tree detected-protocol [interface interface]
After PVST+ configuration, we can verify our configuration with “show spanning-tree” command.
Switch-1 # show spanning-tree
To configure Rapid PVST+ on Cisco switches we should follow the similar steps like PVST+ Configuration. But here, the STP Mode selection is different as you know.
We will configure the below mode change on each switch in the STP Domain.
Switch-1(config)# spanning-tree mode ? pvst Per-Vlan spanning tree mode rapid-pvst Per-Vlan rapid spanning tree mode Switch-1(config)# spanning-tree mode rapid-pvst
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