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Dell Converged Enhanced Ethernet Administrator’s Guide 57
53-1002116-01
STP, RSTP, and MSTP configuration and management
6
Flushing MAC addresses (RSTP and MSTP)
For RSTP and MSTP, use this command to flush the MAC addresses from the VLAN filtering
database (FDB). The VLAN FDB determines the forwarding of an incoming frame. The VLAN FDB
contains information that helps determine the forwarding of an arriving frame based on MAC
address and VLAN ID data (see “VLAN configuration guidelines and restrictions” on page 33).
There are two ways to flush the MAC addresses:
• Standard method—When one port receives a BPDU frame with a topology change flag, it
flushes the FDB for the other ports in the switch. If a BPDU frame with the topology change flag
is received continuously, the switch continues to flush the FDB. This behavior is the default
behavior.
• Dell method—With this method, the FDB is only flushed for the first and last BPDU with a
topology change flag.
Both methods flush the FDB when the switch receives BPDUs with a topology change flag, but the
Dell method causes less flushing.
To flush the MAC addresses from the VLAN FDB, perform the following steps.
1. Enter the configure terminal command to access global configuration mode.
2. Enter the appropriate form of the spanning-tree command based on how you want to flush the
address:
• To flush the MAC address using the standard method:
switch(config)#spanning-tree tc-flush-standard
• To flush the MAC addresses from the VLAN FDB using the Dell method:
switch(config)#no spanning-tree tc-flush-standard
Clearing spanning tree counters
In Privileged EXEC mode, use this command to clear spanning tree counters on all interfaces or on
the specified interface.
To clear spanning tree counters, perform the following steps from Privileged EXEC mode.
1. Enter the appropriate form of the clear command based on what you want to clear:
• To clear all spanning tree counters on all interfaces:
switch#clear spanning-tree counter
• To clear the spanning tree counters associated with a specific port-channel or CEE port
interface:
switch#clear spanning-tree counter interface intengigabitethernet 0/1
Clearing spanning tree-detected protocols
In Privileged EXEC mode, restart the protocol migration process (force the renegotiation with
neighboring switches) on all interfaces or on the specified interface.