User`s guide

FX-16NW

Ordinary data is finally sent at this stage.

■ Spanning Tree Topology (Structure)

A path cost refers to the relative “distance” between each port on the switch

and the root switch. This section describes the role of a switch and ports in

a spanning tree topology.

● Root Switch: This is the switching hub that has the smallest Switch ID in

a given switch network. There is only one root switch in a switch

network.

● Root Port: Refers to the port that is closest to the root switch. One root

port is assigned on each switch in a network. Only one port can be set to

a root port on each switching hub.

● Designated Switch: Refers to the switch that has the lowest root path cost

(the distance between the root switch and the device) in each segment.

● Designated Port: Refers to a port on each switch that is connected to

● Enables the redundant path(s) whenever the main path fails

< About STP State Transitions >

Just as each switching hub is identified by its switch ID, each port

(interface) of a switching hub is identified by its port ID. The state of STP

changes (shifts) with the actual condition of the port.

Each port can be either enabled or disabled. At any moment, an enabled

port is set to one of the following states:

● Listening: Switches send BPDU messages to each other and construct a

topology (tree structure) on a network to identify the shortest path

(distance) to each segment. At this stage, other data is not sent out.

● Blocking: When a path with a higher priority is detected, the state shifts

from Listening to Blocking. Ordinary (users’) data is not sent yet.

● Learning: When a path with a higher priority is not found during

Listening state, the state shifts to Learning state. Learned entries are

stored in Unicast Destination Forwarding Table. Ordinary data is still not

sent.

● Forwarding: When a certain period of time passes after the state has

shifted to Learning state, it will further shift to Forwarding state. (The

user can specify this duration as “forwarding delay time” in advance.)

Figure C-1