User Manual
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34
6
Link Backup
6.1
Rapid Ring
The supported ring network protocols of switch are SW-Ring and RSTP.
SW-Ring
SW-Ring is a self-developed Ethernet ring network algorithm designed for highly
reliable industrial control network application that requires link redundancy
backup. It has Ethernet link redundancy and quick and automatic recovery from
failure The Ring adopts non-master station design. In a multi-ring network of up to
250 switches, the network self-recovery time is less than 20 milliseconds. Each
port in this series of switches can be used as a ring port and connected with other
switches. When an interruption occurs in the network connection,
the SW-Ring
redundant mechanism enables the backup link to quickly recover the network
communication.
RSTP
To address loop problem in switched network, STP (Spanning Tree Protocol) is
put forward. Because of the slow speed of STP topological convergence, IEEE
released 802.1W standard in 2001 which has defined RSTP (Rapid Spanning
Tree Protocol). RSTP has made improvement on the basis of STP, which has
achieved quick topological convergence of network. (The fastest speed could be
in 1 second) The device that runs STP/RSTP protocol finds the loop in the
network by interacting information, and be selective to congest a particular port,
so eventually ring network structure will be pruned to a tree network structure
without loop, thus preventing message from looping in the ring network, and the
device from declining its processing ability caused by receiving the same
message repetitively.
The working process of STP:
