Chapter 4: Web management
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NS3550-8T-2S Industrial Managed Switch User Manual
The switch with the lowest bridge ID (switch C) was elected the root bridge, and the
ports were selected to give a high port cost between switches B and C. The two
(optional) Gigabit ports (default port cost = 20,000) on switch A are connected to one
(optional) Gigabit port on both switch B and C. The redundant link between switch B
and C is deliberately chosen as a 100 Mbps Fast Ethernet link (default port cost =
200,000). Gigabit ports could be used, but the port cost should be increased from the
default to ensure that the link between switch B and switch C is the blocked link.
STP system configuration
The STP Bridge Configuration page permits configuration of the STP system settings.
The settings are used by all STP bridge instances in the switch. The industrial
managed switch supports the following spanning tree protocols:
•
Compatible
– Spanning Tree Protocol (STP): Provides a single path between end
stations, avoiding and eliminating loops.
•
Normal
– Rapid Spanning Tree Protocol (RSTP) : Detects and uses network
topologies that provide faster spanning tree convergence, without creating
forwarding loops.
•
Extension
– Multiple Spanning Tree Protocol (MSTP) : Defines an extension to
RSTP to further develop the usefulness of virtual LANs (VLANs). This "Per-VLAN"
MSTP configures a separate spanning tree for each VLAN group and blocks all but
one of the possible alternate paths within each spanning tree.