Spanning Tree; 3-4.1 Bridge Settings - ZyXEL Communications XGS3600 Series Manual

3-4 Spanning Tree

The Spanning Tree Protocol (STP) can be used to detect and disable network loops, and to
provide backup links between switches, bridges or routers. This allows the switch to interact
with other bridging devices (that is, an STP-compliant switch, bridge or router) in your network
to ensure that only one route exists between any two stations on the network, and provide
backup links which automatically take over when a primary link goes down.
STP - STP uses a distributed algorithm to select a bridging device (STP- compliant switch,
bridge or router) that serves as the root of the spanning tree network. It selects a root port on
each bridging device (except for the root device) which incurs the lowest path cost when
forwarding a packet from that device to the root device. Then it selects a designated bridging
device from each LAN which incurs the lowest path cost when forwarding a packet from that
LAN to the root device. All ports connected to designated bridging devices are assigned as
designated ports. After determining the lowest cost spanning tree, it enables all root ports and
designated ports, and disables all other ports. Network packets are therefore only forwarded
between root ports and designated ports, eliminating any possible network loops.
Once a stable network topology has been established, all bridges listen for Hello BPDUs
(Bridge Protocol Data Units) transmitted from the Root Bridge. If a bridge does not get a Hello
BPDU after a predefined interval (Maximum Age), the bridge assumes that the link to the Root
Bridge is down. This bridge will then initiate negotiations with other bridges to reconfigure the
network to reestablish a valid network topology.

3-4.1 Bridge Settings

The section describes that how to configure the Spanning Tree Bridge and STP System
settings. It allows you to configure STP System settings are used by all STP Bridge instance
in the Switch Stack.
Web Interface
To configure the Spanning Tree Bridge Settings parameters in the web interface:
1. Click Configuration, Spanning Tree, Bridge Settings
2. Scroll to select the parameters and write down available value of
parameters in blank field in Basic Settings
3. Evoke to enable or disable the parameters and write down available
value of parameters in blank field in Advanced settings
4. Click the Apply to save the setting
5. If you want to cancel the setting then you need to click the Reset button.
It will revert to previously saved values
XGS3600 Series User's Guide
79