Dell Force10 S55T S55 Configuration Guide FTOS 8.3.5.3 - Page 713

STP Root Selection The Spanning Tree Protocol determines the root bridge, but you can assign one bridge a lower priority to increase the likelihood that it will be selected as the root bridge. You can also specify that a bridge is the root or the secondary root. To change the bridge priority or specify that a bridge is the root or secondary root: Task Command Syntax Assign a number as the bridge priority or designate it as the root or secondary root. priority-value range: 0 to 65535. The lower the number assigned, the more likely this bridge will become the root bridge. The default is 32768. • The primary option specifies a bridge priority of 8192. • The secondary option specifies a bridge priority of 16384. bridge-priority {priority-value | primary | secondary} Command Mode PROTOCOL SPANNING TREE View only the root information using the show spanning-tree root command (see Figure 39-9) from EXEC privilege mode. Figure 39-9. show spanning-tree root Command Example Force10#show spanning-tree 0 root Root ID Priority 32768, Address 0001.e80d.2462 We are the root of the spanning tree Root Bridge hello time 2, max age 20, forward delay 15 Force10# SNMP Traps for Root Elections and Topology Changes • Enable SNMP traps for Spanning Tree state changes using the command snmp-server enable traps stp. • Enable SNMP traps for RSTP, MSTP, and PVST+ collectively using the command snmp-server enable traps xstp. Configuring Spanning Trees as Hitless c e Configuring Spanning Trees as Hitless is supported only on platforms: You can configure Spanning Tree (STP), Rapid Spanning Tree (RSTP), Multiple Spanning Tree (MSTP), and Per-Vlan Spanning Tree (PVST+) to be hitless (all or none must be configured as hitless). When configured as hitless, critical protocol state information is synchronized between RPMs so that RPM failover is seamless, and no topology change is triggered. Configure all Spanning Tree types to be hitless using the command redundancy protocol xstp from CONFIGURATION mode, as shown in Figure 39-10. Spanning Tree Protocol | 713