ZyXEL Communications B-2000 User Manual
ZyAIR B-2000 Wireless LAN Gateway with 4-Port Switch
3-14
Internet Access
ESS ID
Extended Service Set (ESS) is defined as one or more access points (APs) acting as a bridge between a
wired LAN and the associated wireless clients. The ESS ID is a unique ID given to the APs and the wireless
clients that participate in the same wireless network. You can think the EES ID as being similar to a
workgroup name in a Microsoft network.
wired LAN and the associated wireless clients. The ESS ID is a unique ID given to the APs and the wireless
clients that participate in the same wireless network. You can think the EES ID as being similar to a
workgroup name in a Microsoft network.
Wireless LANs can be as simple as two computers with wireless network interface cards (NICs)
communicating in a peer-to-peer network or as complex as a number of computers with wireless NICs
communicating through access points which bridge network traffic to the wired LAN.
communicating in a peer-to-peer network or as complex as a number of computers with wireless NICs
communicating through access points which bridge network traffic to the wired LAN.
The ESS ID provides minimum security for your network, see section on Wireless Security Setup for more
information.
information.
RTS Threshold
The RTS (Request To Send) Threshold prevents the hidden node problem. Hidden node problem occurs
when two stations are within the range of the same access point, but are not within the range of each other.
The following figure illustrates the hidden node problem. Both stations (STA) are within the range of the
AP, however, they cannot hear each other. Therefore, they are considered as hidden nodes from each other.
When a station starts data transmission with the access point, it might not know that the other station is
already using the wireless medium. When these two stations send data at the same time, they might collide
when arriving simultaneously at the AP. The collision will most certainly result in a loss of messages for
both stations.
when two stations are within the range of the same access point, but are not within the range of each other.
The following figure illustrates the hidden node problem. Both stations (STA) are within the range of the
AP, however, they cannot hear each other. Therefore, they are considered as hidden nodes from each other.
When a station starts data transmission with the access point, it might not know that the other station is
already using the wireless medium. When these two stations send data at the same time, they might collide
when arriving simultaneously at the AP. The collision will most certainly result in a loss of messages for
both stations.
Figure 3-8 RTS Threshold
Thus, RTS Threshold mechanism provides a solution to prevent data collisions. When you enable RTS
Threshold on a possible hidden station, this station and its AP will use a Request to Send/Clear to Send
protocol (RTS/CTS). The station will send an RTS message to the AP, informing that it is going to transmit
the data. Upon receipt, the Access Point will respond with a CTS message to all stations within its range to
Threshold on a possible hidden station, this station and its AP will use a Request to Send/Clear to Send
protocol (RTS/CTS). The station will send an RTS message to the AP, informing that it is going to transmit
the data. Upon receipt, the Access Point will respond with a CTS message to all stations within its range to