Global Stp Control; Pvrst Mode - Lenovo RackSwitch G8264 Application Manual

Global STP Control

PVRST Mode

© Copyright Lenovo 2016
By default, the Spanning Tree feature is globally enabled on the switch, and is set
for PVRST mode. Spanning Tree (and thus any currently configured STP mode)
can be globally disabled using the following command:
RS G8264(config)# spanning­tree mode disable
Spanning Tree can be re‐enabled by specifying the STP mode:
RS G8264(config)# spanning­tree mode {pvrst|rstp|mst}
where the command options represent the following modes:
rstp:
 RSTP mode
pvrst: PVRST mode

mst:
 MSTP mode
Note: Per‐VLAN Rapid Spanning Tree (PVRST) is enabled by default on the
G8264.
Using STP, network devices detect and eliminate logical loops in a bridged or
switched network. When multiple paths exist, Spanning Tree configures the
network so that a switch uses only the most efficient path. If that path fails,
Spanning Tree automatically sets up another active path on the network to sustain
network operations.
ENOS PVRST mode is based on IEEE 802.1w RSTP. Like RSTP, PVRST mode
provides rapid Spanning Tree convergence. However, PVRST mode is enhanced
for multiple instances of Spanning Tree. In PVRST mode, each VLAN may be
automatically or manually assigned to one of 255 available STGs. Each STG acts as
an independent, simultaneous instance of STP. PVRST uses IEEE 802.1Q tagging to
differentiate STP BPDUs and is compatible with Cisco R‐PVST/R‐PVST+ modes.
The relationship between ports, LAGs, VLANs, and Spanning Trees is shown in
Table 17.
Table 17.
Ports, LAGs, and VLANs
Switch Element
Port
LAG
VLAN (non‐default)
Belongs To
LAG or one or more VLANs
One or more VLANs
 PVRST: One VLAN per STG
 RSTP: All VLANs are in STG 1
 MSTP: Multiple VLANs per STG
Chapter 11: Spanning Tree Protocols
189