The questions do not attempt to cover more breadth or depth than the exam however, they are designed to make sure that you know the answers. The questions and scenarios in this book are more difficult than what you should experience on the actual exam. ■ MST Instances (MSTIs)-Used inside an MST region to maintain loop-free topologies for sets of mapped VLANsģ00 Chapter 12: Advanced Spanning Tree Protocol ■ Internal Spanning Tree (IST)-Used like CST to maintain a single, loop-free topology inside an MST region ■ Common Spanning Tree (CST)-Used to maintain a single loop-free topology for the entire network If you are doing your final preparation before the exam, this information is a convenient way to review the day before the exam. If you just read this chapter, this review should help solidify some key facts. If you are already comfortable with the topics in this chapter, this summary can help you recall a few details. The Foundation Summary is a collection of information that provides a convenient review of many key concepts in this chapter. This is because all instance timers are defined through the IST instance and BPDUs.Ģ98 Chapter 12: Advanced Spanning Tree Protocol Notice that the timer configurations are applied to MST as a whole, and not to a specific MST instance. Table 12-2 summarizes the commands as a quick reference. Rather than tuning STP for a VLAN instance, you use an MST instance. The parameters and timers are identical to those discussed in Chapter 10, “Spanning Tree Configuration.” In fact, the commands are very similar except for the addition of the mst keyword and the instance-id. You can also tune the parameters that MST uses when it interacts with CST or traditional 802.1D. A switch cannot run both MST and PVST+ at the same time. Step 7 Exit the MST configuration mode commit the changes to the active MST region configuration:Īfter MST is enabled and configured, PVST+ operation stops and the switch changes to RSTP operation. Step 6 Show the pending changes you have made: (Remember that by default, all VLANs are mapped to instance 0, the IST.) You can also add a range of VLANs to the list by separating numbers with a hyphen. The list can contain one or more VLANs separated by commas. The instance-id (0 to 15) carries topology information for the VLANs listed in vlan-list. Switch(config-mst)# instance instance-id vlan vlan-list
#Cst to mst update#
Therefore, you also need to update the revision numbers on the other switches to match. Remember that the region configuration (including the revision number) must match on all switches in the region. Each time you make changes to the configuration, you should increase the number by one. The configuration revision number gives you a means to track changes to the MST region configuration. Step 4 Assign a region configuration revision number (0 to 65,535): Step 3 Assign a region configuration name (up to 32 characters): Switch(config)# spanning-tree mst configuration 296 Chapter 12: Advanced Spanning Tree Protocol