Dell C1048P Port Extender Networking Command-Line Reference Guide for the C900 - Page 1747

Command History This guide is platform-specific. For command information about other platforms, refer to the relevant Dell Networking OS Command Line Reference Guide. The following is a list of the Dell Networking OS version history for this command. Version 9.9(0.0) 9.2(1.0) 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 C9010. Introduced on the Z9500. Introduced on the S4820T. Introduced on the Z9000. Added support for the optional guard keyword on the CSeries, S-Series, and E-Series TeraScale. Introduced on the S4810. Introduced the hardware shutdown-on-violation options. Introduced on the S-Series. Introduced on the C-Series. Added the optional bridge port data unit (BPDU) guard. Introduced on the E-Series. 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 an 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 an RSTP switch, immediately transitions to the Forwarding state. Only configure ports connected to endhosts as edge ports. Consider an edge port similar to a port with a spanningtree portfast enabled. If you do not enable shutdown-on-violation, BPDUs are still sent to the RPM CPU. You cannot enable STP 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 displays: % Error: RootGuard is configured. Cannot configure LoopGuard. 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. Rapid Spanning Tree Protocol (RSTP) 1747