ormation regarding the root bridge for every VLAN: Cat-3550#sho spanning-tree root Hello Max Fwd Root ID Age Dly Root Port VLAN0001 24577 0009.43b5.0f80 Fao/20 VLAN0002 32770 000f.8f5c.5a00 Chapter 8: Spanning Tree VLAN0003 32771 000d.edc2.0000 Fao/13 VLAN0004 32772 000d.edc2.0000 Fao/13 VLAN0010 32778 000d.edc2.0000 Fao/13 VLAN0100 32868 000d.edc2.0000 Fao/13 VLAN0200 32968 000f.8f5c.5a00 And the same command from a Nexus 7000: NX-7K-1-Cozy# sho spanning-tree root Hello Max Fwd Root ID Age Dly Root Port VLAN0001 32769 0026.9807.95c2 This bridge is root VLAN0010 32778 0026.9807.95c2 This bridge is root There is no equivalent command in CatOS. Additional Spanning Tree Features Spanning tree was originally designed for bridges with few ports. With the advent of Ethernet switches, some enhancements were made to spanning tree. These commonly seen enhancements helped make spanning tree more palatable by decreasing the time a host needs to wait for a port, and decreasing the convergence time in a Layer-2 network. PortFast PortFast is a feature on Cisco switches that allows a port to bypass all of the other spanning tree states (see Figure 8-5, shown earlier) and proceed directly to the for- warding state. PortFast should be enabled only on ports that will not have switches connected. Spanning tree takes about 30 seconds to put a normal port into the for- warding state, which can cause systems using DHCP to time out and not get an IP address (on a Windows machine, a default IP address may be used). Enabling the Port- Fast feature on a port alleviates this problem, but you should be very careful when using this feature. If a switch were to be connected to a port configured with PortFast active, a loop could occur that would not be detected. To enable PortFast on an IOS switch, use the spanning-tree portfast interface com- mand. The switch will deliver a nice warning about the dangers of PortFast when you enable the feature: Cat-3550(config-if)#spanning-tree portfast %Warning: portfast should only be enabled on ports conn