Dell C1048P Port Extender Networking Command-Line Reference Guide for the C900 - Page 1376

Version 8.3.19.0 8.3.11.1 8.4.2.1 8.3.7.0 8.2.1.0 7.6.1.0 7.5.1.0 7.4.1.0 6.2.1.1 Description Introduced on the S4820T. Introduced on the Z9000. Introduced the loopguard and rootguard options on the E-Series TeraScale, CSeries, and S-Series. Introduced on the S4810. Introduced the hardware shutdown-on-violation option. Introduced on the S-Series. Introduced on the C-Series. Added the optional Bridge Port Data Unit (BPDU) guard. Introduced. Usage Information The BPDU guard option prevents the port from participating in an active STP topology in case a BPDU appears on a port unintentionally, or is misconfigured, or is subject to a DOS attack. This option places the port into the Error Disable state if a BPDU appears, and a message is logged so that the administrator can take corrective action. NOTE: A port configured as an edge port, on a PVST switch, immediately transitions to the forwarding state. Only ports connected to end-hosts should be configured as an edge port. Consider an edge port similar to a port with a spanning-tree portfast enabled. If you do not enable shutdown-on-violation, BPDUs are still sent to the route process module (RPM) CPU. You cannot enable root guard and loop guard at the same time on a port. For example, if you configure loop guard on a port on which root guard is already configured, the following error message is displayed: % Error: RootGuard is configured. Cannot configure LoopGuard. When used in a PVST+ network, loop guard is performed per-port or per-port channel at a VLAN level. If no BPDUs are received on a VLAN interface, the port or port-channel transitions to a Loop-Inconsistent (blocking) state only for this VLAN. Enabling Portfast BPDU guard and loop guard at the same time on a port results in a port that remains in a Blocking state and prevents traffic from flowing through it. For example, when Portfast BPDU guard and loop guard are both configured: • If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and no traffic is forwarded on the port. • If no BPDU is received from a remote device, loop guard places the port in a Loop-Inconsistent Blocking state and no traffic is forwarded on the port. On PE ports and on VP-LAGs (LAGs formed with PE ports) • Spanning-tree with bpdu guard shutdown-on-violation is enabled by default • No spanning tree command is valid. This command is not visible and issuing this command on VP- LAG ports results in a failure. - Example Dell(conf-if-te-1/1)#spanning-tree pvst vlan 3 cost 18000 Dell(conf-if-te-1/1)#end Dell(conf-if-te-1/1)#show config ! interface TenGigabitEthernet 1/1 Per-VLAN Spanning Tree Plus (PVST+) 1376