Verilink 9000 Series (34-00271) Product Manual Manual de usuario descargar pdf (Pagina 107)

NISYS

OLL

ELECT

Introduction

This chapter provides specific information for the Unisys Poll/Select protocol and

how it operates using the TXPORT MultiPro platforms and NMCS software.

Poll/Select

Basics

The basic concept of poll/select operation is simple. All information is stored at

the central site for all branch sites to use. The centralized mainframe where this

information is stored is commonly referred to as the host. All branch-site locations

extract and send information commonly from terminals, therefore these locations

are referred to as terminals. Two examples of non-terminal devices are ATM

machines and printers. They communicate with the network poll/select protocol

being used. The host site polls all terminal devices at the branch sites, querying

whether there is data to receive from them. Upon being polled, the terminal device

transmits some indication to the host as to whether there is information to be

transmitted or received. The host, having an indication of a terminal device

needing service, selects that terminal device, and the transaction is completed.

Polling then resumes from the host site.

TXPORT MultiPro platforms support the Unisys Poll/Select protocol. This

protocol follows the same concepts as other poll/select-type protocols. If a port is

connected to a host end on the TXPORT device, that port should be configured

using that particular protocol’s host port parameters. If the port selected is

connected to a terminal end on the TXPORT device, that port should be configured

using that particular protocol’s terminal parameters. All host TXPORT device ports

must have a list of which terminal addresses to service. Likewise, each terminal

TXPORT device port must have a unique host name where the terminal data

should be sent.

All host and terminal TXPORT device ports emulate a host or terminal

respectively, thereby only passing non-polling sequences through the transport

(WAN) connection. This protocol emulation is commonly referred to as spoofing.

Spoofing allows more efficient use of the WAN connection, freeing up bandwidth

as well as keeping bandwidth costs down, particularly in the frame relay

environment.

Figure 5-1 on page 86 shows a typical Unisys Poll/Select network using Frame

Relay as the transport medium. This figure shows addressing information as

address table information for Port 4 on unit 002 and unit 003, Port 1 Frame Relay

Endpoint Lists for all units, and the Host name field on unit 001’s Port 4.

1 2 ... 102 103 104 105 106 107 108 109 110 111 112 ... 439 440

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Verilink 9000 Series (34-00271) Product Manual Manual de usuario Pagina 107