User Manual Managed Switches
61
Chain Ports
Setting
Description
Factory Default
1st Chain Port
Select any port of the Switch to be one of the ports of the
daisy Chain.
Port 01
2nd Chain Port
Select any port of the Switch to be one of the ports of the
daisy Chain.
Port 02
Status
Description
Factory Default
Link down
No connection in this port.
LinkDown
Forwarding
Normal transmission in this port.
Discarding
The port is connected to a backup path and the path is
blocked.
Edge Port
Setting
Description
Factory Default
Check
Configure a port of the daisy Chain as edge port.
Not checked
Uncheck
Does not configure a port of the daisy Chain as edge
port.
3.6.4 STP / RSTP / MSTP
3.6.4.1 The STP / RSTP Concept
Spanning Tree Protocol (STP) was designed to help reduce link failures on a network, and provide
an automatic means of avoiding loops. This is particularly important for networks that have a
complicated architecture, since unintended loops in the network can cause broadcast storms.
Weidmüller switches
’ STP feature is disabled by default. To be completely effective, you must enable
RSTP/STP on every Weidmüller switch connected to your network.
Rapid Spanning Tree Protocol (RSTP) implements the Spanning Tree Algorithm and Protocol
defined by IEEE 802.1D-2004. RSTP provides the following benefits:
•
The topology of a bridged network will be determined much more quickly compared to STP.
•
RSTP is backward compatible with STP, making it relatively easy to deploy.
For example:
•
Defaults to sending 802.1D style BPDUs if packets with this format are received.
•
STP (802.1D) and RSTP (802.1w) can operate on different ports of the same switch, which is
particularly helpful when switch ports connect to older equipment such as legacy switches.
You get essentially the same functionality with RSTP and STP. To see how the two systems differ,
see
section ‘
Differences between STP and RSTP
’ later in this chapter.
NOTE:
The STP protocol is part of the IEEE Std 802.1D, 2004 Edition bridge specification. The
following explanation uses “bridge” instead of “switch.”
STP (802.1D) is a bridge-based system that is used to implement parallel paths for network traffic.
STP uses a loop-detection process to:
•
Locate and then disable less efficient paths (i.e., paths that have a lower bandwidth).
•
Enable one of the less efficient paths if a more efficient path fails.
