CCNA LAB 68: Configuring Spanning Tree Protocol Root Bridges Using the IOS Macro

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The objective of this lab exercise is to use the macro in Cisco IOS to configure a switch to automatically adjust its Spanning Tree priority for a particular VLAN, or group of VLANs, ensuring that it is the most likely elected root bridge.


Lab Purpose:
VLAN root bridge configuration is a fundamental skill. It is always recommended that the root bridge be manually configured to ensure that the Layer 2 network is deterministic. However, the macro available in Cisco IOS can also be used. As a Cisco engineer, as well as in the Cisco CCNA exam, you will be expected to know how to configure a switch as a root bridge using the macro available in Cisco IOS.

Certification Level:
This lab is suitable for ICND2 and CCNA certification exam preparation.

Lab Difficulty:
This lab has a difficulty rating of 6/10.

Readiness Assessment:
When you are ready for your certification exam, you should complete this lab in no more than 15 minutes.




Lab Topology:
Please use the following topology to complete this lab exercise:



Task 1:
In preparation for VLAN configuration, configure a hostname on Sw1 and Sw2 and configure the VLANs depicted in the topology above.

Task 2:
Configure the switches to support the VLANs listed in the topology. Configure the VLANs and check that they are visible on both switches. Configure FastEthernet0/1 on both switches as a trunk.

Task 3:
Configure Sw1 as the root bridge for VLANs 2010 and 2030.  Configure Sw2 as the root bridge for VLANS 2020 and 2040. Configure the switches to automatically update their priorities as follows:

a.  Sw1 will always be the root bridge for VLANs 2010 and 2030 and Sw2 will always be the backup root bridge for those VLANs.
b.  Sw2 will always be the root bridge for VLANs 2020 and 2040 and Sw1 will always be the backup root bridge for those VLANs.



Task 4:
Verify your configurations with the appropriate commands.




Configuration and Verification
Task 1:
For reference information on configuring hostnames, please refer to earlier labs.



Task 2:
NOTE: By default, Cisco switches are VTP servers. However, to configure the extended range of VLANs (i.e., VLANs 1006 and above), you need to configure the switch as a VTP Transparent switch.

For reference information on Transparent mode, trunks, and extended VLANs, please refer to earlier labs.

Task 3:
NOTE: The spanning-tree vlan <number> root primary command is a macro that allows Catalyst Switches to automatically configure a Spanning Tree priority value that ensures that the switch this command is issued on will most likely be elected as root bridge. The spanning-tree vlan <number> root secondary is a macro that allows Catalyst Switches to automatically configure a Spanning Tree priority value that ensures that the switch this command is issued on will most likely be elected as backup root bridge.





Task 4:
NOTE: Verify the same for VLAN 2030 on Sw1, as well as for VLANs 2020 and 2040 on Sw2. In addition, you can also issue the show spanning-tree root command to view the Spanning Tree root bridge for all VLANs in the domain. This is illustrated below:








来源: CCNA LAB 59: Configuring IOS Device Logging to a SYSLOG Server
来源: CCNA LAB 60: Performing an IOS Upgrade
来源: CCNA LAB  61: Performing an IOS Upgrade Using FTP
来源: CCNA LAB 62: Performing Password Recovery
来源: CCNA LAB 63: Configuring Extended VLANs on Cisco Catalyst Switches
来源: CCNA LAB 64: Changing the Native VLAN and Shutting Down Unused Ports
来源: CCNA LAB 65: Restricting Extended VLANs on Trunks and Changing the VTP Version
来源: CCNA LAB 66: Verifying Spanning Tree Port States on Catalyst Switches
来源: CCNA LAB 67: Configuring Spanning Tree Protocol Root Bridges Manually

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