ZyXEL NWA-3160 User Manual download pdf (Page 144)

Chapter 8 Wireless Screen

NWA-3160 Series User’s Guide

144

8.3.1 Spanning Tree Protocol (STP)

Spanning Tree Protocol (STP) detects and breaks network loops and provides

backup links between switches, bridges or routers. It allows a bridge to interact

with other STP-compliant bridges in your network to ensure that only one route

exists between any two stations on the network.

8.3.1.1 Rapid STP

The NWA uses IEEE 802.1w RSTP (Rapid Spanning Tree Protocol) that allow faster

convergence of the spanning tree (while also being backwards compatible with

STP-only aware bridges). Using RSTP topology change information does not have

to propagate to the root bridge and unwanted learned addresses are flushed from

the filtering database. In RSTP, the port states are Discarding, Learning, and

Forwarding.

8.3.1.2 STP Terminology

The root bridge is the base of the spanning tree; it is the bridge with the lowest

identifier value (MAC address).

Path cost is the cost of transmitting a frame onto a LAN through that port. It is

assigned according to the speed of the link to which a port is attached. The slower

the media, the higher the cost - see the following table.

On each bridge, the root port is the port through which this bridge communicates

with the root. It is the port on this switch with the lowest path cost to the root (the

root path cost). If there is no root port, then this bridge has been accepted as the

root bridge of the spanning tree network.

For each LAN segment, a designated bridge is selected. This bridge has the lowest

cost to the root among the bridges connected to the LAN.

Table 27 STP Path Costs

LINK SPEED

RECOMMENDE

D VALUE

RECOMMENDE

D RANGE

ALLOWED

RANGE

Path Cost 4Mbps 250 100 to 1000 1 to 65535

Path Cost 10Mbps 100 50 to 600 1 to 65535

Path Cost 16Mbps 62 40 to 400 1 to 65535

Path Cost 100Mbps 19 10 to 60 1 to 65535

Path Cost 1Gbps 4 3 to 10 1 to 65535

Path Cost 10Gbps 2 1 to 5 1 to 65535

1 2 ... 139 140 141 142 143 144 145 146 147 148 149 ... 371 372

No comments

ZyXEL NWA-3160 User Manual Page 144