ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación descargar pdf (Pagina 53)

Peer-to-Peer Mode

The telecommunication network theory has been much based on the network device

hierarchy principle. This principle was put into question with the emergence of ad

hoc type architectures, either in wireless local area networks or networks for file

exchange over the Internet, called peer-to-peer networks. The decentralized net-

works offer many advantages in comparison with hierarchical networks or net-

works in the master-slave mode.

In the PLC architecture in the peer-to-peer mode illustrated in Figure 3.1, all the

PLC devices play the same role and permanently exchange a number of parameters

in order to keep the network consistent. In the case of HomePlug 1.0, the devices

exchange and update information locally.

The main parameters that the PLC devices require are the following:

•

Quality of the PLC link between a device and all the other devices. This qual-

ity is assessed on a physical level in the same manner as radio devices assess the

quality of the radio links to evaluate the available services in the upper OSI

layers by means of a permanently updated table known as a tone map table.

•

EKS (encryption key select) encryption keys used to connect to a PLC network

and for exchanges with other devices. There are two EKS in HomePlug 1.0:

DEK (default encryption key) and NEK (network encryption key). We’ll cover

their characteristics again in Chapter 4, which covers security and their config-

uration is covered in Chapter 9. These keys are used to create, over the same

electrical network, several PLC networks in the peer-to-peer mode without

communicating internetwork data. Since these networks use the same electri-

cal network, the data communication throughput may be reduced as the PLC

technology uses all of the 2 to 30 MHz frequency band.

34 Functionality

Figure 3.1 Architecture of a PLC network in the peer-to-peer mode

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ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación Pagina 53