ZyXEL Communications PLA-470 V2 - V3.0.5 Installationsanleitung PDF herunterladen (Seite 51)

•

Peer-to-peer mode. May be compared to a peer-to-peer IP network, where all

the PLC devices of the network play the same role and have the same hierar-

chical level. These devices may have interchanges without being monitored by

a master device.

•

Centralized mode. Blending of the two preceding modes, in which a centraliz-

ing device is responsible for managing the network and exchanges between

PLC devices. The other devices may also exchange with one another without

having to go through the centralizer.

The main advantages and disadvantages of these three modes are summarized in

Table 3.1.

Master-Slave Mode

The master-slave mode makes it possible to use the logic of the electrical network

consisting of an electrical meter at the head of the network, which is considered as a

master of the electrical network, its circuit-breakers and bus-bar connections, con-

sidered as slaves of these circuit breakers on which the PLC network is based for its

physical medium and to place the so-called master device on the network head part

and the slave devices on the various network strands.

In the case of PLC networks on public MV or LV electrical networks, the main

functionalities expected from the master are the following:

•

Management of the secured connections of the various slave devices. Each

device belongs to a private logical network thanks to a dedicated connection

channel on the electrical medium used as a shared medium. Therefore, the

PLC frames circulate freely on the various strands of the electrical network.

•

Management of the quality of service (QoS) of the PLC physical links between

the slaves and the master by means of various physical level analysis methods

(signal-to-noise level in each frequency sub-band, calculation of transmittable

32 Functionality

Table 3.1 Advantages and Disadvantages of Master-Slave, Peer-to-Peer, and Centralized Modes

MODE ADVANTAGES DISADVANTAGES

Master-slave

— Centralized administration

— Gateway role for PLC network

— Management of Qos levels (TDMA)

— Management of the roles of each device

— PLC and IP network hierarchy

— Easier network supervision

— Need for redundancy

— Weak points concerning security

— Possible bandwidth congestion

— More complex configuration

Peer-to-Peer

— Bandwidth distribution

— Distribution of PLC routing tables at a

physical level

— Easy to deploy

— No network hierarchy

— Poor PLC gateway definition

Centralized

— Centralized administration

— Only administration traffic passes via the

coordinator

— Weak point on centralizer

— Need for coordinator to manage

TDMA frames

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