Configuring Layer 2 Features > Configuring Rapid Spanning Tree Protocol (RSTP)
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Configuring Rapid Spanning Tree Protocol (RSTP)
Rapid Spanning Tree Protocol (RSTP), a standard inter-switch protocol, ensures an ad hoc network topology loop-free at Layer 2, on a per-VLAN basis. If your network connections form loops and you disable STP, packets re-circulate between the switches, causing a degradation of network performance. STP does not allow for Layer 2 multipathing and can result in sub-optimal utilization of available network links. Therefore, a fabric of switches does not run RSTP within the boundaries of the fabric. Pluribus Networks recommends the use of RSTP for ad hoc networks that interoperate in a heterogeneous, multi-vendor switch environment.
To build a loop-free topology, switches (“bridges”) determine the root bridge and compute the port roles, root, designated, or blocked. To do this, the bridges use special data frames called Bridge Protocol Data Units (BPDUs) to exchange information about bridge IDs and root path costs. BPDUs exchange regularly, typically at two second intervals, and enable switches to keep track of network topology changes and to start and stop forwarding on ports as required. Hosts should not send BPDUs to the switch ports and to avoid malfunctioning or malicious hosts from doing so, the switch can filter or block BPDUs. If you enable BPDU filtering on a port, BPDUs received on that port drop but other network traffic forwards as usual. If you enable BPDU blocking on a port, BPDUs received on that port drop and the port shuts down.
Rapid Spanning Tree Protocol supports modifying an RSTP port and configuring the port as an edge port.
 
 
Informational Note: RSTP is enabled on the switch by default.
Before you begin, view the status of STP on the switch by using the following command:
CLI network-admin@Leaf1 > stp-show
switch: tac-1
enable: yes
stp-mode: rstp
bpdus-bridge-ports: yes
bridge-id: 3a:7f:b1:43:8a:0f
bridge-priority: 32768
hello-time: 2
forwarding-delay: 15
max-age: 20
cluster-mode: master
 
 
1. To disable STP, use the following command:
CLI network-admin@Leaf1 > stp-modify disable
2. To display the STP state, use the following command:
CLI network-admin@Leaf1 > stp-state-show
switch: Leaf01
vlan: 1
ports: none
instance-id: 1
name: stg-default
bridge-id: 66:0e:94:65:e1:ef
bridge-priority: 8193
root-id: 64:0e:94:c0:06:4b
root-priority: 4097
root-port: 128
hello-time: 2
forwarding-delay: 15
max-age: 20
disabled: none
learning: none
forwarding: 25-28,128-129
discarding: none
edge: 25-28
designated: 25-28,129
alternate: none
backup: none
 
 
To display information about STP on ports, use the stp-port-show command:
CLI network-admin@Leaf1 > stp-port-show
switch port block filter edge bpdu-guard root-guard priority cost
-------- ---- ----- ------ ---- ---------- ---------- -------- ----
draco01 1 off off no no no 128 500
draco01 2 off off no no no 128 2000
draco01 3 off off no no no 128 2000
draco01 4 off off no no no 128 2000
draco01 5 off off no no no 128 500
draco01 6 off off no no no 128 500
draco01 7 off off no no no 128 2000
draco01 8 off off no no no 128 2000
draco01 9 off off no no no 128 2000
draco01 10 off off no no no 128 500
 
3. To filter BPDUs on port 17, use the following command:
CLI network-admin@Leaf1 > stp-port-modify port 17 filter
4. To block BPDUs on port 17 and shut down the port if BPDUs are received on the port, use the following command:
CLI network-admin@Leaf1 > stp-port-modify port 17 block
5. To stop blocking BPDUs on port 17, use the following command:
CLI network-admin@Leaf1 > stp-port-modify port 17 no-block
6. Disable STP on a port or a group of ports. If the host devices connect to the switch ports and not downstream switches, then disable STP and the enabled port becomes much faster when the switch restarts.
7. To enable RSTP on port 35, use the following command:
CLI network-admin@Leaf1 > stp-port-modify port 35 edge
8. To enable STP, use the following command:
CLI network-admin@Leaf1 > stp-modify enable
Managing STP BPDU After Disabling LLDP
Netvisor ONE optimizes STP BPDUs by not sending BPDUs on any ports except on switch ports. Netvisor ONE uses this as the default setting for the parameter, bpdus-bridge-port. By not configuring LLDP, Netvisor One does not detect host ports and does not send BPDU packets. As a result, both ports remain in a Forwarding state.
When you add the parameter, bpdus-all-ports, to allow sending BPDUs on ports even if Netvisor ONE does not detect ports, unless you configure the port as an edge port. On a switch with a port connected to itself with this configuration one of the ports goes into a Discarding state.