OSI/TS Configuration and Management Manual

Managing a Transport Connection

OSI/TS Configuration and Management Manual—424831-001

6-10

OSI/TS as Connection-Establishment Initiator

The application should try to determine the reason for the failure. You can get error

information either by using a WRITEREAD request with the appropriate MCW or by

using the SPI STATUS SU command.

If the failure is permanent, the application should do the following:

•

Not retry the connection attempt.

•

Report the error to the user or operator via EMS.

If the failure is due to a temporary problem—for example, temporary network

congestion, or a remote application that is still in the startup phase and not yet ready for

the connection request—the application should retry the request after a small delay

(from 30 seconds to a few minutes).

OSI/TS as Connection-Establishment Responder

The application should try to determine the reason for the failure. You can get error

information either by using a WRITEREAD request with the appropriate MCW

(message control word) or by using the SPI STATUS SU command.

Your application should treat any error in the Network Layer as a permanent error; no

retry is necessary. In all other cases, limit the number of retry attempts to a small

number (two or three) and a small delay (one or more seconds).

Data Transfer

After successful connection establishment, the transport peer entities enter the data-

transfer phase. During this phase, peer entities transfer user data between endpoints of

the transport connection.

Since transport entities establish connections with a host-to-host protocol, the Transport

Layer provides special services for verifying the integrity of application data as it is

transferred between OSI end systems. These transport services supplement services

already provided by the communications subnetwork. Subnetwork protocols verify

transfer of data between immediately adjacent nodes transport protocols verify transfer

of data between the end systems in which the applications reside. When a transport

entity receives an acknowledgment that a message has been received, this

acknowledgment comes from the remote end system.