Dell MX9116n EMC SmartFabric OS10 User Guide - Page 422

RPVST allows (VLAN, port) based flush until the number of calls sent is equal to the MAC flush threshold value that is configured. When the number of calls sent exceeds the configured threshold, RPVST ignores further (VLAN, port) based flush and starts the MAC flush timer. When the timer starts, the system blocks further flush. When the timer expires for that specific instance, the system triggers VLAN-based flushing. By default, the MAC flush threshold value is set to 5. However, Dell EMC recommends that you configure this value based on the number of ports that participate in the STP topology. Debug configurations Use the debug spanning-tree bpdu command to monitor and verify that the MST configuration is communicating as configured. To ensure all necessary parameters match - region name, region version, and VLAN to instance mapping, examine your individual devices. Use the show spanning-tree mst command to view the MST configuration, or use the show runningconfiguration command to view the overall MST configuration. MST flags for communication received from the same region MST region name and revision MST instances The MST routers are located in the same region. If the debug logs indicate that packets are coming from a Different Region, one of the key parameters does not match. The configured name and revisions must be identical among all devices. If the region name is blank, a name was configured on one device and was not configured or was configured differently on another - spelling and capitalization count. Verify the VLAN-to-MST instance mapping using the show commands. If you see extra MST instances in the Sending or Received logs, an additional MST instance was configured on one router but not the others. • View BPDUs in EXEC mode. debug spanning-tree bpdu • View MST-triggered topology change messages in EXEC mode. debug spanning-tree events View MST configuration OS10# show spanning-tree mst configuration Region Name: force10 Revision: 100 MSTI VID 0 1,31-4093 1 2-10 2 11-20 3 21-30 Setting spanning-tree link type for rapid state transitions As specified in IEEE 802.1w, OS10 assumes a port that runs in full-duplex mode is a point-to-point link. A point-to-point link transitions to forwarding state faster. By default, OS10 derives the link type of a port from the duplex mode. You can override the duplex mode using the spanning-tree link-type command. OS10 assumes a port that runs in half-duplex mode is a shared link, to which the fast transition feature is not applicable. Also, If you explicitly designate a port as a shared link, you cannot use the fast transition feature, regardless of the duplex setting. To hasten the spanning-tree state transitions, you can set the link type to point-to-point. To set the link type to point-to-point: • Use the following command in INTERFACE mode. spanning-tree link-type point-to-point 422 Layer 2