Cisco WS-C2980G-A Software Guide - Page 119

Chapter 7 Configuring Spanning Tree Using PVST+ Default PVST+ Configuration Table 7-4 shows the default PVST+ configuration. Table 7-4 PVST+ Default Configuration Feature VLAN 1 Enable state MAC address reduction Bridge priority Bridge ID priority Port priority Port cost Default spantree port cost mode Port VLAN priority Port VLAN cost Maximum aging time Hello time Forward delay time Default Value All ports assigned to VLAN 1 PVST+ enabled for all VLANs Disabled 32,768 32,769 (bridge priority plus system ID extension of VLAN 1) 32 • Gigabit Ethernet: 4 • Fast Ethernet: 10 • FDDI/CDDI: 10 • Ethernet: 100 Short (802.1D) Same as port priority but configurable on a per-VLAN basis in PVST+ Same as port cost but configurable on a per-VLAN basis in PVST+ 20 sec 2 sec 15 sec Setting the PVST+ Bridge ID Priority The bridge ID priority is the priority of a VLAN when the switch is in PVST+ mode. When the switch is in PVST+ mode without MAC address reduction enabled, you can enter a bridge priority value between 0-65,535. The VLAN bridge ID priority becomes that value. When the switch is in PVST+ mode with MAC address reduction enabled, you can enter one of 16 bridge priority values: 0, 4096, 8192, 12,288, 16,384, 20,480, 24,576, 28,672, 32,768, 36,864, 40,960, 45,056, 49,152, 53,248, 57,344, or 61,440. The switch creates the bridge ID priority by combining the VLAN bridge priority with the system ID extension (that is, the ID of the VLAN). To set the spanning tree bridge priority for a VLAN, perform this task in privileged mode: Step 1 Step 2 Task Set the bridge ID priority for a VLAN. Verify the bridge ID priority. Command set spantree priority bridge_ID_priority [vlan] show spantree [vlan] [active] 78-15486-01 Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide-Release 8.1 7-23