Criteria for Chapter 7 Hands-on Lab

Chapter 7 Hands-On Lab

The hands-on lab in Chapter 7 asks you to complete an STP design for the network shown in Figure 7-32 which shows a three building campus.

Each building contains two MDF switches (A and B) and two IDF switches (C and D). The number of IDF switches in each building is expected to grow dramatically in the near future. The server farm has its own switch that connects to Cat-1A and Cat-1B. The network contains 20 VLANs. Assume that each server can be connected to a single VLAN (for example, the SAP server can be connected to the Finance VLAN). Assume that all links are Fast Ethernet except the ring of links between the MDF switches, which are Gigabit Ethernet.

Be sure to address the following items: STP timers, Root Bridges, Load Balancing, failover performance, and traffic flows. Diagram the primary and backup topologies for your design.

Solution to Chapter 7 Hands-on Lab

The solution that follows is one of many possible solutions to this lab.

The Root Bridges are best located on Cat-1A and Cat-1B at the entrance to the server farm. Cat-1A can be the Root Bridge for the odd-numbered VLANs and Cat-1B can be the Root Bridge for the even-numbered VLANs.

Because of the danger associated with STP timer tuning, this strategy is avoided here. Instead, UplinkFast can be configured on all of the IDF switches to reduce wiring closet failover to 2 3 seconds. BackboneFast can be configured on all of the switches to improve the convergence time after an indirect failure.

Figure A-7 shows the odd-numbered VLANs. Cat-1A is the Root Bridge. Only forwarding links are shown. The port state information is shown for Building 1 (the other building would follow the same pattern).

Figure A-7. Primary Topology for Odd VLANs; Backup Topology for Even VLANs

Figure A-8 shows the same information for the even-numbered VLANs. Cat-1B is the Root Bridge.

Figure A-8. Primary Topology for Even VLANs; Backup Topology for Odd VLANs

Cat-1A is the backup Root Bridge for the even VLANs and Cat-2B is the backup Root Bridge for the odd VLANs. Therefore, the backup topology for the odd VLANs is the same as Figure A-7c, whereas the backup topology for the even VLANs is the same as Figure A-7b.