ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación Pagina 271

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Integration of advanced network functions (NAT router, DHCP server,
firewall, switch, Wi-Fi, and so forth).
As far as the PLC devices are concerned (filters, coupling systems, PLC signal
injectors, and so forth), it is recommended to use professional products and to install
them with the help of accredited electricians in order to ensure compliance with the
security standards and to obtain a perennial installation.
Service Quality
The integration of the quality of service (QoS) into the various PLC technologies is
required by the development of real-time applications, such as video on demand,
broadcasting of HDTV video streams, IP telephony, computer-supported coopera-
tive work, videoconferencing, and so forth.
The network constraints for such applications can be difficult to reconcile with
the fact that the PLC technologies use as the communication medium the electrical
network that is subjected to interference from the other devices connected to the net-
work.
Table 11.2 summarizes the functionalities implemented in the various PLC tech-
nologies in order to satisfy these constraints.
Among these technologies, HomePlug 1.0 and Turbo are perhaps those offering
the least QoS guarantees, whereas HomePlug AV offers optimal QoS guarantees,
insofar as the PLC signal is based on the 110 to 220V/50 to 60 Hz signal conveyed
over the electrical wirings to synchronize the various PLC network devices.
QoS in HomePlug AV
The HomePlug AV specification benefits from many developments and added
functionalities in comparison with HomePlug 1.0 and Turbo. Among them, the QoS has
been implemented by means of traffic classes with guaranteed performance. The AV name
itself corresponds to audio and video, two application types in which the QoS constraints
252 PLC for Businesses
Table 11.2 QoS Functionalities of the PLC Technologies
PLC TECHNOLOGY QoS FUNCTIONALITY
HomePlug
1.0, Turbo
CA priorities (PRS intervals in the frames) corresponding to the VLAN
labels of the IEEE 802.1Q standard
AV
User priority classes (0 to 7) corresponding to the traffic classes of the
IEEE 802.1D standard, Synchro AC, TDMA, QMP propagation, use of
the VLAN labels of the IEEE 802.1Q standard
AsokaUSA
PLC priorities (VLAN, fixed, fairness), priority levels (0 to 5), limitation
by source (IP or MAC), by destination (IP or MAC) (uplink and
downlink throughput)
DS2 AV200
Default priority, Criterion parameters, use of Offset, Pattern, Bitmask,
use of the VLAN labels of the IEEE 802.1Q standard
Spidcom
Use of the IEEE 802.1Q (VLAN labels) and IEEE 802.1P standards for
the QoS of time critical applications
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