6.1 Introduction to STP/RSTP
This section describes definition and purpose of STP/RSTP.
Definition
Generally, redundant links are used on an Ethernet switching network to provide link backup
and enhance network reliability. The use of redundant links, however, may produce loops,
causing broadcast storms and making the MAC address table unstable. As a result, network
communication may encounter quality deterioration or even be interrupted. The Spanning Tree
Protocol (STP) solves this problem.
STP refers to STP defined in IEEE 802.1D, the Rapid Spanning Tree Protocol (RSTP) defined
in IEEE 802.1W, and the Multiple Spanning Tree Protocol (MSTP) defined in IEEE 802.1S.
MSTP is compatible with RSTP and STP, and RSTP is compatible with STP.
compares the STP, RSTP, and MSTP protocols.
Table 6-1
Comparison of STP, RSTP, and MSTP
Spanning
Tree
Protocol
Characteristics
Usage Scenario
STP
l
A loop-free tree topology is form
in an STP region to prevent
broadcast storms while
implementing link redundancy.
l
Route convergence is slow.
STP or RSTP is used in a scenario
where all VLANs share one spanning
tree. In this situation, users or services
do not need to be differentiated.
RSTP
l
A loop-free tree topology is form
in an STP region to prevent
broadcast storms while
implementing link redundancy.
l
RSTP achieves fast network
convergence.
MSTP
l
A loop-free tree topology is form
in an MSTP region to prevent
broadcast storms while
implementing link redundancy.
l
MSTP achieves fast network
convergence.
l
MSTP implements load balancing
among VLANs. Traffic in
different VLANs is transmitted
along different paths.
MSTP is used in a scenario where
traffic in different VLANs is
forwarded through different spanning
trees for load balancing. The spanning
trees are independent of each other. In
this situation, users or services are
distinguished by VLANs.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
6 STP/RSTP Configuration
Issue 01 (2014-11-30)
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