Lenovo ThinkSystem NE2552E, Application Manual

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© Copyright Lenovo 2018 Chapter 10: Spanning Tree Protocols
187
Rapid Spanning Tree Protocol
RSTP provides rapid convergence of the Spanning Tree and provides the fast
re ‐ configuration critical for networks carrying delay ‐ sensitive traffic such as voice
and video. RSTP significantly reduces the time to reconfigure the active topology
of the network when changes occur to the physical topology or its configuration
parameters. RSTP reduces the bridged ‐ LAN topology to a single Spanning Tree.
RSTP was originally defined in IEEE 802.1w (2001) and was later incorporated into
IEEE 802.1D (2004), superseding the original STP standard.
RSTP parameters apply only to Spanning Tree Group (STG) 1. The PVRST mode
STGs 2 ‐ 128/256 are not used when the switch is placed in RSTP mode.RSTP is
compatible with devices that run IEEE 802.1D (1998) Spanning Tree Protocol. If the
switch detects IEEE 802.1D (1998) BPDUs, it responds with IEEE 802.1D
(1998) ‐ compatible data units. RSTP is not compatible with Per ‐ VLAN Rapid
Spanning Tree (PVRST) protocol.
Note:
In RSTP mode, Spanning Tree for the management ports is turned off by
default.
Port States
RSTP port state controls are the same as for PVRST:
discarding
,
learning
and
forwarding
.
Due to the sequence involved in these STP states, considerable delays may occur
while paths are being resolved. To mitigate delays, ports defined as edge ports
( “Port Type and Link Type” on page 193 ) may bypass the
discarding
and
learning
states, and enter directly into the
forwarding
state.
RSTP Configuration Guidelines
This section provides important information about configuring RSTP. When RSTP
is turned on, the following occurs:
 STP parameters apply only to STG 1.
 Only STG 1 is available. All other STGs are turned off.
 All VLANs, including management VLANs, are moved to STG 1.