AMX Modero ViewPoint MVP-5100, Руководство по эксплуатации/справочник

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Appendix B: Wireless Technology
165 MVP-5100/5150 5.2" Modero Viewpoint Touch Panels
Appendix B: Wireless Technology
Overview of Wireless Technology

802.11b/2.4 GHz and 802.11a/5 GHz are the two major WLAN standards and both operate using
radio frequency (RF) technology. Together the two standards are together called Wi-Fi and operate
in frequency bands of 2.4 GHz and 5 GHz respectively.
The
802.11b specification was the first to be finalized and reach the marketplace. The actual
throughput obtained from an 802.11b network will typically be between 4 and 5 Mbps.
Because of the higher frequency (and thus shorter wavelength) that they use,
802.11a signals have a
much tougher time penetrating solid objects like walls, floors, and ceilings. As a result, the price for
802.11a's higher speed is not only a shorter range but also a weaker and less consistent signal.
802.11g provides increased bandwidth at 54 Mbps. As part of the IEEE 802.11g specification,
when throughput cannot be maintained, this card will automatically switch algorithms in order to
maintain the highest spread possible at a given distance. In addition, 802.11g can also step down to
utilize 802.11b algorithms and also maintain a connection at longer distances.

IP Routing is a behavior of the wireless routing is largely dependent on the wired network
interface. Although the panel can be connected to two networks simultaneously, it may only have
one gateway. If the wired network was successfully set up and a gateway was obtained; then the
default route for all network traffic will be via the wired network. In the event that the wired
network was not configured, then the default route for all network traffic will be via the wireless
network. The wired network connection always takes priority.
Example : Imagine a panel connected to the two networks A & B. A is the wired network and B is
the wireless network. If the Master controller is on either of these networks, then it will be reached.
However if the Master controller is on a different network, C, then the gateway determines which
network interface (wired or wireless) will be used.

Access Points (APs) are the cornerstone of any wireless network. An AP acts as a bridge between
a wired and wireless network. It aggregates the traffic from all wireless clients and forwards it
down the network to the switch or router. One AP may be all that is necessary for a standard
installation. However, more APs may be needed, depending on the size of the installation, its
layout, and its construction.

Wireless Equivalent Privacy ( WEP ) Security is a method by which WLANs protect wireless data
streams. A data stream encrypted with WEP can still be intercepted or eavesdropped upon, but the
encryption makes the data unintelligible to the interloper. The strength of WEP is measured by the
length of the key used to encrypt the data. The longer the key, the harder it is to crack.
802.11b implementations provided 64-bit and 128-bit WEP keys. This is known respectively as 64-
bit and 128-bit WEP encryption. 64-bit is generally not regarded as adequate security protection.
Both key lengths are supported by the Modero product line.
Whichever level of WEP used,
using identical settings is crucial (CASE SENSITIVE) --the key
length, and the key itself-- on all devices. Only devices with common WEP settings will be able to
communicate. Similarly, if one device has WEP enabled and another does not, they will not be able
to talk to each other.
Although the calculations required to encrypt data with WEP can impact the performance of your
wireless network, this impact is generally only seen when running benchmarks, and is not large
enough to be noticeable in the course of normal network usage.