Dell S5148F-ON OS10 Enterprise Edition User Guide Release 10.3.2E-R1 - Page 158

Port enabled with loop guard conditions • Loop guard is supported on any STP-enabled port or port-channel interface in RPVST+ mode. • You cannot enable root guard and loop guard at the same time on an STP port - the loop guard configuration overwrites an existing root guard configuration and vice versa. • Enabling 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 you configure both Portfast BPDU guard and loop guard: • If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and no traffic forwards on the port. • If no BPDU is received from a remote device which was sending BPDUs, loop guard places the port in a Loop-Inconsistent Blocking state and no traffic forwards on the port. • When used in a PVST+ network, STP loop guard performs per-port or per port-channel at a VLAN level. If no BPDUs are received on a port-channel interface, the port or port-channel transitions to a Loop-Inconsistent (Blocking) state only for this VLAN. Global parameters All non-root bridges accept the timer values on the root bridge. Forward-time Hello-time Max-age Amount of time required for an interface to transition from the Discarding to the Learning state or from the Learning to the Forwarding state. Time interval within which the bridge sends BPDUs. Length of time the bridge maintains configuration information before it refreshes information by recomputing the RPVST+ topology. • Modify the forward-time (in seconds) in CONFIGURATION mode (4 to 30, default 15). spanning-tree vlan vlan-id forward-time seconds • Modify the hello-time (in seconds) in CONFIGURATION mode (1 to 10, default 2). With large configurations (involving more number of ports), Dell EMC recommends increasing the hello-time. spanning-tree vlan vlan-id hello-time seconds • Modify the max-age (in seconds) in CONFIGURATION mode (6 to 40, default 20). spanning-tree vlan vlan-id max-age seconds View RPVST+ global parameters OS10# show spanning-tree active Spanning tree enabled protocol rapid-pvst with force-version rstp VLAN 1 Executing IEEE compatible Spanning Tree Protocol Root ID Priority 32769, Address 90b1.1cf4.a523 Root Bridge hello time 2, max age 20, forward delay 15 Bridge ID Priority 32769, Address 90b1.1cf4.a523 We are the root of VLAN 1 Configured hello time 2, max age 20, forward delay 15 RPVST+ commands clear spanning-tree counters Clears the counters for STP. Syntax clear spanning-tree counters [interface {ethernet node/slot/port[:subport] | port-channel number}}] 158 Layer 2