G-3000H User’s Guide

Table 11 ToS and IEEE 802.1d to WMM QoS Priority Level Mapping

DSCP VALUE

WMM QOS PRIORITY LEVEL

 

 

 

96,

0 a

besteffort

64,

32

background

 

 

 

a.The ZyAIR also uses best effort for any DSCP value for which another WMM QoS priority is not specified (255, 158 or 37 for example).

5.4Spanning Tree Protocol (STP)

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.

5.4.1 Rapid STP

The ZyAIR 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.

5.4.2 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.

Table 12 STP Path Costs

 

LINK SPEED

RECOMMENDED

RECOMMENDED

ALLOWED

 

VALUE

RANGE

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

 

 

 

 

 

62

Chapter 5 Wireless Configuration