Recommendation/ Best Practices/Design recommendation.
1. Use Rapid PVST instead PVST on all the switches to make spaning-tree convergence faster.
2. Make Core switch as spaning-tree root bridge by making highest spanning-tree priority on
switch since core switch connects to all distribution.
3. To prevent other switch to become spanning-tree root bridge, always apply spanning-tree
root guard on all downstream links connecting to distribution switch.
4. Enable spanning-tree portfast bpduguard on all the port on access switches.
5. Etherchannel misconfig guard has already been enabled.
6. Root bridge for all VLANS should be in MST region when interacting with PVST+/RPVST+
boundary.
Commands to use while troubleshooting.
Show spanning-tree mst details.
Clear spanning-tree counters
show spanning-tree mst configuration.
Show spanning-tree details | i BPDU|from|exec|ieee|last
Facts :
1) MST runs MST0 (one instance for all VLANS even when there is no VLAN mapped to MST0 instance) for interacting with PVST+/RPVST switches.
2) PVST+/RPVST+ switches always follow the priority of MST0 instance and its properties.
3) MST0 (Commom spanning tree or CIST root bridge) informed other MST 1 or another MST instance about the TCN changes received from PVST+/RPVST+ switches.
4) PVST+/RPVST+ switches sees entire MST region as one PVST /RPSVT switch bridge.
5) If MST instance is not configured correctly , it sees as RSTP boundary ports.
6) During testing, it is found that native vlan not used for MST BPDU- still have doubt on it.
7) In PVST , whenever TCN generates by switch, it informs the neigbor switch towards the ROOT bridge and neigbor switch ackwnowledge the TCN BPDU to switch to make him stop the BPDU. Same process goes up to the root bridge and then root bridge starts sending the TCN BPDU to inform all the switch to reduce the aging timer to forward timer and flush the mac address table.
8) In contrast to PVST, RSTP behaved differently in TCN. Whenever TCN is generated in RPVST, it flush the mac address table and inform other switches at the same.
1. Use Rapid PVST instead PVST on all the switches to make spaning-tree convergence faster.
2. Make Core switch as spaning-tree root bridge by making highest spanning-tree priority on
switch since core switch connects to all distribution.
3. To prevent other switch to become spanning-tree root bridge, always apply spanning-tree
root guard on all downstream links connecting to distribution switch.
4. Enable spanning-tree portfast bpduguard on all the port on access switches.
5. Etherchannel misconfig guard has already been enabled.
6. Root bridge for all VLANS should be in MST region when interacting with PVST+/RPVST+
boundary.
Commands to use while troubleshooting.
Show spanning-tree mst details.
Clear spanning-tree counters
show spanning-tree mst configuration.
Show spanning-tree details | i BPDU|from|exec|ieee|last
Facts :
1) MST runs MST0 (one instance for all VLANS even when there is no VLAN mapped to MST0 instance) for interacting with PVST+/RPVST switches.
2) PVST+/RPVST+ switches always follow the priority of MST0 instance and its properties.
3) MST0 (Commom spanning tree or CIST root bridge) informed other MST 1 or another MST instance about the TCN changes received from PVST+/RPVST+ switches.
4) PVST+/RPVST+ switches sees entire MST region as one PVST /RPSVT switch bridge.
5) If MST instance is not configured correctly , it sees as RSTP boundary ports.
6) During testing, it is found that native vlan not used for MST BPDU- still have doubt on it.
7) In PVST , whenever TCN generates by switch, it informs the neigbor switch towards the ROOT bridge and neigbor switch ackwnowledge the TCN BPDU to switch to make him stop the BPDU. Same process goes up to the root bridge and then root bridge starts sending the TCN BPDU to inform all the switch to reduce the aging timer to forward timer and flush the mac address table.
8) In contrast to PVST, RSTP behaved differently in TCN. Whenever TCN is generated in RPVST, it flush the mac address table and inform other switches at the same.
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