Nortel 120 Using Manual page 61

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Spanning Tree Protocol—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.
After 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 then initiates negotiations with other bridges to reconfigure the
network to reestablish a valid network topology.
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Copyright © 2006, Nortel Networks
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— Bridge: Operates as a bridge to other access points. The Parent link
to the root bridge must be configured. Up to five other Child links are
available to other bridges.
— Repeater: Operates as a wireless repeater, extending the range for
remote wireless clients and connecting them to the root bridge. The
Parent link to the root bridge must be configured. In this mode, traffic
is not forwarded to the Ethernet port from the radio interface.
— Root Bridge: Operates as the root bridge in the wireless bridge
network. Up to six Child links are available to other bridges in the
network.
Bridge Parent—The physical layer address of the root bridge unit or
the bridge unit connected to the root bridge. (12 hexadecimal digits in
the form xx-xx-xx-xx-xx-xx)
Bridge Child—The physical layer address of other bridge units for which
this unit serves as the bridge parent or the root bridge. Note that the first
entry under the list of child nodes is reserved for the root bridge, and
can only be configured if the role is set to Root Bridge. (12 hexadecimal
digits in the form xx-xx-xx-xx-xx-xx)
Bridge—Enables/disables STP on the wireless bridge or repeater.
(Default: Disabled)
Bridge Priority—Used in selecting the root device, root port, and
designated port. The device with the highest priority becomes the STP
root device. However, if all devices have the same priority, the device
Using the Nortel Business Access Point 120
NN47921-301 01.01 Standard
1.0 August 2006
BAP120
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