Browse Prior Art Database

Differentiated Service for Telnet 3270 Services

IP.com Disclosure Number: IPCOM000123885D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 2 page(s) / 107K

Publishing Venue

IBM

Related People

Giroir, D: AUTHOR [+2]

Abstract

When a Telnet 3270 (TN3270) Client exchanges files with an SNA Host across a Telnet 3270 Server, the packets of information related to the file being exchanged are sent between the Client and its Server using the same sessions (TCP and SNA sessions) than those used for screen related interactions such as a screen refresh. This means that across the IP network, data packets related to the transfer of files are using the same priority than the priority used for the interactive traffic due to screen related interactions. In a sense, this mode of operation violates SNA fundamental rules associated with SNA Class Of Service (COS) and Transmission Priority (TP) within SNA networks.

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Differentiated Service for Telnet 3270 Services

   When a Telnet 3270 (TN3270) Client exchanges files
with an SNA Host across a Telnet 3270 Server, the packets of
information related to the file being exchanged are sent between the
Client and its Server using the same sessions (TCP and SNA sessions)
than those used for screen related interactions such as a screen
refresh.  This means that across the IP network, data packets related
to the transfer of files are using the same priority than the
priority used for the interactive traffic due to screen related
interactions.  In a sense, this mode of operation violates SNA
fundamental rules associated with SNA Class Of Service (COS) and
Transmission Priority (TP) within SNA networks.  These rules assume
that interactive traffic (such as screen related interactions) gets a
better treatment within the network than lower priority traffic such
as batch traffic (file transfer  related traffic).

   Transfer of large files between Clients and their Servers
generate a huge amount of data packets that should not flow on the
same priority as the interactive, screen related traffic.  As a
differentiation is not made, overall response time is severely
impacted as now, the true interactive traffic but also the non-SNA
data traffic will be penalized by a flooding of data packets related
to the exchange of files across the network.  Exchanging files
consumes bandwidth and processing resources within the network.  In
fact, from an SNA standpoint, the packets related to the exchange of
files between a Client and its Server should have a lower priority
than the real interactive traffic allowing the higher priority
traffic to get a better  service than any other low priority traffic.

   Patent FR999-9021, "Method and System for improving overall
network response time during the exchange of files between Telnet
3270 Servers and Telnet 3270 Clients", by Didier Giroir and Jean
Lorrain describes a set of mechanisms allowing TN3270 Clients and
TN3270 Servers to dynamically specify a lower IP priority for the
traffic relat ed to the exchange of files, than the priority
associated to the traffic related with screen interactive traffic.

   The Client and the associated Server specify an IP
transport priority (Precedence / Type Of Service) for the data
packets exchanged over TN3270 TCP sessions.  The Client, when
performing the transfer of a file to or from the SNA Host over the
Telnet session dynamically changes (i.e downgrade) the IP priority
associated to the interactive screen traffic for all data packets
flowing to the Telnet 3270 Server during the whole duration of the...