Configuring Rapid-PVST+
IEEE 802.1w known as Rapid Spanning Tree has several improvements over the legacy spanning tree protocol. This lab will discuss and demonstrate the configuration and verification of RPVST+.
Real World Application & Core Knowledge
In the previous lab (if you read and/or completed it) you learned about Cisco’s proprietary Per VLAN Spanning Tree Protocol which enables a spanning-tree instance for each VLAN that the switch hosts.
This lab will deal with the new 802.1w IEEE Rapid Spanning Tree Protocol standard; that of which Cisco modified to run on a “Per VLAN” basis to suit their needs.
Rapid Spanning Tree (802.1w) provides several benefits over the IEEE 802.1D STP Standard including faster convergence time after a topology change where the STP standard took up to 45 seconds to converge, the RSTP standard can respond to changes after 3 hello’s. (6 Seconds)
Rapid Spanning Tree Protocol (RSTP) can also revert back to 802.1D STP for interoperability with older switches and existing infrastructures.
Several new features were added in the RSTP standard such as Edge Ports (aka; PortFast) which transitions an access port which can never become a layer2 loop in the network automatically to designated (forwarding) and does not have to listen and learn to determine which type of port type to assign to a particular port.
A feature similar to Cisco’s UplinkFast was also added to RSTP standard which automatically places an alternate port into the root port mode shall the predecessor root port fail.
The root bridge is now able to inform all switches in the switching topology that the topology has changed by setting a TC bit in the BPDU’s that it advertises.
The majority of the commands you familiarized yourself with in the previous lab you’ll use again in this lab. shown below however is a new command you’ll familiarize yourself with;
| Command | Description |
|---|---|
| spanning-tree mode rapid-pvst | Is executed in global configuration mode to configure the switch to use the 802.1w compatible Rapid Per VLAN Spanning Tree protocol. |
| spanning-tree vlan # priority # | This command is executed from global configuration mode and manually sets the bridge priority per vlan on a switch. |
| show spanning-tree vlan # | This command can be executed only in privileged mode and displays spanning-tree information relating to a specific VLAN number. |
| show spanning-tree summary | This command can be executed only in privileged mode and displays a summary of all spanning-tree instances and port counts. |
| show spanning-tree detail | This command can be executed only in privileged mode and displays detailed information on a per port basis of each port participating in a spanning-tree process. |
| show spanning-tree bridge | This command can be executed only in privileged mode and displays all spanning-tree processes per VLAN on the switch and other information including the priority per vlan, the sum of the bridge priority (vlan priority + sys-id-ext), Bridge MAC address, timers and effective spanning tree protocol. |
Lab Prerequisites
- If you are using GNS3 than load the Free CCNA Workbook GNS3 topology than start devices; SW1, SW2 and SW3.
- Establish a console session with devices SW1, SW2 and SW3 than configure the devices respected hostname(s).
- Configure interfaces Fa0/10, Fa0/11 and Fa0/12 on both SW1 and SW2 in an EtherChannel and configure the channel to trunk.
- Configure interfaces Fa0/13, Fa0/14 and Fa0/15 on SW1 and interfaces Fa0/10, Fa0/11 and Fa0/12 on SW3 in an EtherChannel and configure the channel to trunk.
- Configure interfaces Fa0/13, Fa0/14 and Fa0/15 on SW2 and interfaces Fa0/13, Fa0/14 and Fa0/15 on SW3 in an EtherChannel and configure the channel to trunk.
- Configure SW1 as a VTP server and SW2 and 3 as VTP clients using the VTP domain name CISCO and VTP Version 2. Create VLAN 10, 20 and 30 on the VTP Server, ensure the VLAN’s have propagated to SW2 and SW3.
Lab Objectives
- Configure SW1, SW2 and SW3 to run Rapid Per-VLAN Spanning Tree Protocol.
- Configure SW1 as the ROOT bridge for VLAN 1 and 10. Verify your configuration on SW2.
- Configure SW2 as the ROOT bridge for VLAN 20. Verify your configuration on SW1.
- Configure SW3 as the ROOT bridge for VLAN 30. Verify your configuration on SW1.
Lab Instruction
Step 1. – Configure SW1, SW2 and SW3 to run Rapid Per-VLAN Spanning Tree Protocol.
To configure switches to run the rapid spanning-tree protocol by executing the spanning-tree mode rapid-pvst in global configuration mode as shown below;
SW1 con0 is now available Press RETURN to get started. SW1>enable SW1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW1(config)#spanning-tree mode rapid-pvst SW1(config)#end %SYS-5-CONFIG_I: Configured from console by console SW1#show spanning-tree bridge Hello Max Fwd Vlan Bridge ID Time Age Dly Protocol ---------------- --------------------------------- ----- --- --- -------- VLAN0001 32769 (32768, 1) 0014.f2d2.4180 2 20 15 rstp VLAN0010 32778 (32768, 10) 0014.f2d2.4180 2 20 15 rstp VLAN0020 32788 (32768, 20) 0014.f2d2.4180 2 20 15 rstp VLAN0030 32798 (32768, 30) 0014.f2d2.4180 2 20 15 rstp SW1#
SW2 con0 is now available Press RETURN to get started. SW2>enable SW2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW2(config)#spanning-tree mode rapid-pvst SW2(config)#end %SYS-5-CONFIG_I: Configured from console by console SW2#show spanning-tree bridge Hello Max Fwd Vlan Bridge ID Time Age Dly Protocol ---------------- --------------------------------- ----- --- --- -------- VLAN0001 32769 (32768, 1) 001c.57d8.9000 2 20 15 rstp VLAN0010 32778 (32768, 10) 001c.57d8.9000 2 20 15 rstp VLAN0020 32788 (32768, 20) 001c.57d8.9000 2 20 15 rstp VLAN0030 32798 (32768, 30) 001c.57d8.9000 2 20 15 rstp SW2#
SW3 con0 is now available Press RETURN to get started. SW3>enable SW3#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW3(config)#spanning-tree mode rapid-pvst SW3(config)#end %SYS-5-CONFIG_I: Configured from console by console SW3#show spanning-tree bridge Hello Max Fwd Vlan Bridge ID Time Age Dly Protocol ---------------- --------------------------------- ----- --- --- -------- VLAN0001 32769 (32768, 1) 0014.a964.2e00 2 20 15 rstp VLAN0010 32778 (32768, 10) 0014.a964.2e00 2 20 15 rstp VLAN0020 32788 (32768, 20) 0014.a964.2e00 2 20 15 rstp VLAN0030 32798 (32768, 30) 0014.a964.2e00 2 20 15 rstp SW3#
Step 2. – Configure SW1 as the ROOT bridge for VLAN 1 and 10. Verify your configuration on SW2.
SW1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW1(config)#spanning-tree vlan 1 root primary SW1(config)#spanning-tree vlan 10 root primary SW1(config)#end %SYS-5-CONFIG_I: Configured from console by console SW1#
SW2#show spanning-tree vlan 1 VLAN0001 Spanning tree enabled protocol rstp Root ID Priority 24577 Address 0014.f2d2.4180 Cost 9 Port 216 (Port-channel21) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 001c.57d8.9000 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 sec Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- --------------------------- Po21 Root FWD 9 128.216 P2p Po23 Altn BLK 9 128.232 P2p SW2#show spanning-tree vlan 10 VLAN0010 Spanning tree enabled protocol rstp Root ID Priority 24586 Address 0014.f2d2.4180 Cost 9 Port 216 (Port-channel21) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32778 (priority 32768 sys-id-ext 10) Address 001c.57d8.9000 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 sec Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- --------------------------- Po21 Root FWD 9 128.216 P2p Po23 Altn BLK 9 128.232 P2p SW2#
Step 3. – Configure SW2 as the ROOT bridge for VLAN 20. Verify your configuration on SW1.
SW2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW2(config)#spanning-tree vlan 20 root primary SW2(config)#end %SYS-5-CONFIG_I: Configured from console by console SW2#
SW1#show spanning-tree vlan 20
VLAN0020
Spanning tree enabled protocol rstp
Root ID Priority 24596
Address 001c.57d8.9000
Cost 9
Port 144 (Port-channel12)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32788 (priority 32768 sys-id-ext 20)
Address 0014.f2d2.4180
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- ---------------------------
Po12 Root FWD 9 128.144 P2p
Po13 Altn BLK 9 128.152 P2p
SW1#
Step 4. – Configure SW3 as the ROOT bridge for VLAN 30. Verify your configuration on SW1.
SW3#configure terminal Enter configuration commands, one per line. End with CNTL/Z. SW3(config)#spanning-tree vlan 30 root primary SW3(config)#end %SYS-5-CONFIG_I: Configured from console by console SW3#
SW1#show spanning-tree vlan 30
VLAN0030
Spanning tree enabled protocol rstp
Root ID Priority 24606
Address 0014.a964.2e00
Cost 9
Port 152 (Port-channel13)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32798 (priority 32768 sys-id-ext 30)
Address 0014.f2d2.4180
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- ---------------------------
Po12 Desg FWD 9 128.144 P2p
Po13 Root FWD 9 128.152 P2p
SW1#
