Chapter 22 Wireless LAN Commands

 

Table 69 General Wireless Commands (continued)

 

COMMAND

DESCRIPTION

 

wlan qos setwmmac <0:AP1:STA>

Sets the ZyXEL Device’s current WMM settings for

 

<0:VO1:VI2:BE3:BK> <aifs>

the specified access category, as follows.

 

<cwmin> <cwmax> <txop-g><txop-b>

VO: Voice

 

<ack-policy>

VI: Video

 

 

BE: Best effort

 

 

BK: Background

 

 

aifs is the arbitration inter-frame space number

 

 

(1~1023). This controls the additional waiting period

 

 

prior to sending a packet of the previously-specified

 

 

type.

 

 

The waiting period itself is known as the arbitration

 

 

inter-frame space or AIFS (as distinct from the

 

 

arbitration inter-frame space number aifs). In this

 

 

command, the aifs parameter allows you to

 

 

specify the AIFS as follows:

 

 

AIFS = aifs * slot-time.

 

 

Standard slot times are as follows:

 

 

IEEE 802.11a: 9 µs

 

 

IEEE 802.11b: 20 µs

 

 

IEEE 802.11g: 9 µs

 

 

IEEE 802.11b/g: 20 µs

 

 

so an aifs of 100 in an IEEE802.11g network

 

 

results in an AIFS of 900µs.

 

 

When the AIFS time has elapsed, the ZyXEL Device

 

 

waits for a further time period, known as the

 

 

contention window (CW), for collision avoidance

 

 

purposes.

 

 

cwmin is the minimum contention window value,

 

 

and cwmax is the maximum contention window

 

 

value. The cwmin and cwmax values are 2n-1 in the

 

 

range 1~1024, so allowed values are 1, 3, 7, 15, 31,

 

 

63, 511 and 1023.

 

 

The cwmin value must be smaller than or equal to

 

 

the cwmax value. The cwmin and cwmax values are

 

 

multiples of the slot time, so a cwmin value of 15 in

 

 

an IEEE 802.11g network would result in a minimum

 

 

contention window of 135µs.

 

 

The CW length is defined by a random number

 

 

between the cwmin and cwmax values. The CW

 

 

length increases with every retry, until it reaches

 

 

cwmax.

 

 

txop-gis the transmission opportunity limit for

 

 

packets sent over an IEEE802.11g network, and

 

 

txop-bis the transmission opportunity limit for

 

 

packets sent over an IEEE802.11b network. The

 

 

transmission opportunity limit is the largest

 

 

permitted single wireless transmission; when data is

 

 

too big, it is split up into separate wireless

 

 

transmissions.

 

 

Use ack-policyto set whether received

 

 

transmissions are acknowledged. Enter 0 to send

 

 

acknowledgements, or enter 1 to send no

 

 

acknowledgements. Acknowledgements increase

 

 

reliability, but also increase the quantity of traffic.

 

 

 

 

wlan qos showwmmac

Displays the ZyXEL Device’s current WMM access

 

 

category settings.

 

183

DSL & IAD CLI Reference Guide