RAD Data comm 100 Spécifications télécharger pdf (Page 53)

Installation and Operation Manual Chapter 1 Introduction

Egate-100 Ver. 4.0 Functional Description 1-21

 Allow on-the-fly addition/deletion of group members.

• Up to 100 ms differential delay.

GFP Technical Overview

TX Traffic Path

In this direction, the ETHERNET packet with the CRC32 is encapsulated into GFP.

The encapsulation can be divided into two main sections: a Core Header and a

Payload Area.

The Core Header contains the packet length and a CRC16 result of the length. It

is used by the frame-delineation procedure (as explained in the RX path

description below) to detect the boundaries of the frame. The Core Header is

scrambled by xoring the 32 bits (length and CRC16) with the 32 bits B6AB31E0.

The scrambling of the GFP Core Header improves the robustness of the frame-

delineation procedure, and provides a sufficient number of 0-1 and 1-0

transitions during idle transmission periods.

Figure

1-14. GFP Encapsulation

The Payload Area is divided into three subsections: the Payload header, the User

data (Ethernet packet), and an optional FCS (CRC 32) that is calculated on all

payload information filed. For encapsulation of Ethernet frames, this CRC appears

to be unnecessary. The PFCS addition is user configurable.

All octets in the GFP Payload Area are scrambled using a 1 + x^43 scrambler; this

scrambler is always activated.

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RAD Data comm 100 Spécifications Page 53