Avaya Configuring XNS Services Manuel d'utilisateur télécharger pdf (Page 23)

XNS Overview

303548-A Rev 00

1-7

Echo Protocol

The Echo Protocol is a Level 2 protocol. It provides a relatively simple means to

verify the existence and correct operation of a host’s IDP implementation and a

path to a host.

The Echo Protocol packet contains an Operation field, which indicates whether

the packet is a request (1) or a response (2). The Bay Networks router running

XNS software generates responses only to echo requests it receives on the

well-known error socket, Socket 2. It does not generate echo request packets.

When the destination host receives an echo request packet, it generates a response

packet and copies the data from the Data field of the request packet to the Data

field of the response packet. The destination host then forwards the response

packet to the source socket of the host that sent the echo request. This lets the

requesting host verify the data.

Table 1-1. XNS Error Protocol Numbers

Error Number

(Octal) Description of Error

0 An unspecified error is detected at the destination.

1 A serious inconsistency, such as an incorrect checksum, is detected

at the destination.

2 The destination socket specified in the incorrect packet does not

exist in the destination host.

3 The destination dropped the packet because of resource limitations.

1000 An unspecified error occurred before reaching the destination.

1001 A serious inconsistency, such as an incorrect checksum, occurred

before reaching the destination.

1002 The destination host cannot be reached from here.

1003 The packet’s hop count reached its upperbound threshold without

reaching its destination.

1004 The packet is too large for an intermediate network. The Error

Parameter field of the Error Protocol packet contains the maximum

packet length allowed.

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 71 72

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Avaya Configuring XNS Services Manuel d'utilisateur Page 23