Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-10-17
2004-11-16
Olms, Douglas (Department: 2661)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S401000
Reexamination Certificate
active
06819673
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to Wide Area Networks (WANs) and more particularly to a system and method for establishing Systems Network Architecture (SNA) sessions between SNA nodes through a packet/cell switching network using Telnet 3270 access services.
2. Description of the Related Art
SNA and IP Environment
Companies are increasingly interested in consolidating the multiple specialized networks that they operate or lease from service providers onto a single protocol network. These multiple specialized networks operate on diverse networking technologies such as SNA, Internet Protocol (IP) or Internetwork Packet Exchange (IPX). In making consolidation one of their top priorities, companies are almost exclusively selecting IP as their protocol of choice. For the overwhelming majority of these companies that are using SNA protocols and applications, however, there remains the need to maintain the ability to access the enormous quantity of existing corporate data that resides in traditional mainframes and only accessible through SNA applications.
Telnet 3270
In an IP environment, telnet technologies TN3270 and TN3270 Extended are widely utilized to transport SNA information across an IP network. This technique for SNA “green screen” workstation users employs a client/server approach. IBM's “Host On Demand” or “WebClient” by CISCO are examples of client software implementations. Network Utility from IBM or CISCO router's offerings are typical server implementations (hardware and software). The “TN3270 client” component usually runs within the customer's workstation while the “TN3270 server” component is usually placed in front of the customer's Data Center mainframes (or sometimes directly within the mainframe itself) or within the customer's branch offices. As illustrated in
FIG. 1
, IP protocols (
102
) are used between a server (
100
) and clients (
101
), while traditional SNA protocols (
103
) are used between server (
100
) and target SNA applications (
104
) located within a mainframe.
More detailed explanations of telnet, TN3270, and Network Utility, can be found in the following publications incorporated herewith by reference: “TCP/IP Tutorial and Technical Overview” by Martin W. Murhammer, Orcun Atakan, Stefan Bretz, Larry R. Pugh, Kazunari Suzuki, David H. Wood, International Technical Support Organization, October 1998, GG24-3376-05; “Internet in a nutshell” by Valerie Quercia, published by O'Reilly, October 1997; “IBM 2216/Network Utility Host Channel Connection”, Erol Lengerli, Jacinta Carbonell, Thomas Grueter; IBM International Technical Support Organization, January 1999, SG24-5303-00; “IBM Network Utility Description and Configuration Scenarios”, Tim Kearby, Peter Gayek, Gallus Schlegel, Imre Szabo, Zhi-Yong Zhang; IBM International Technical Support Organization, January 1999, SG24-5289-
00; “Internetworking with TCP/IP—Volume I—Principles, Protocols, and Architecture” Douglas E.Comer, Second Edition, Prentice Hall 1991; Request For Comments (RFCs) from the Internet Engineering Task Force (IETF): RFC
1576: TN3270 Current Practices, RFC 1646: TN3270 Extensions for LU name and Printer Selection, RFC 1647: TN3270 Enhancements, and RFC 2355: TN3270 Enhancements.
High Speed Packet Switching Networks
Data transmission is evolving to focus on applications and to integrate a fundamental shift in the customer traffic profile. Driven by the growth of the number of intelligent (programmable) workstations, the pervasive use of local area network interconnections, the distributed processing capabilities between workstations and super computers, the new applications and the integration of various and often conflicting structures—hierarchical versus peer to peer, wide versus local area networks, voice versus data—the data traffic profile has become more bandwidth consuming, bursty, non-deterministic, and requires greater connectivity.
Based on the above observations, there is a growing need for supporting distributed computing applications across high speed wide area networks that can carry local area network communications, voice, video and data traffic among channel attached hosts, business or engineering workstations, terminals, and small to large file server systems. This vision of a high speed multi-protocol network has precipitated the emergence of fast packet switching network architectures such as the IBM's Networking BroadBand Services (NBBS) architecture in which data, voice, and video information is digitally encoded, divided into small packets (of fixed or variable length), and transmitted through a common set of nodes and links. In this continuously evolving environment there remains the need for transporting “legacy” data traffic, such as SNA traffic across wide area networks.
To efficiently transport mixed traffic streams on very high speed lines requires a set of strict requirements in terms of performance and resource consumption that can be summarized as follows: a very high throughput and a very short packet processing time; an efficient set of flow and congestion control mechanisms; and a very large flexibility to support a wide range of connectivity options.
Throughput and Processing Time
One of the key requirements of high speed packet switching networks is to reduce the end-to-end delays in order to satisfy real time delivery constraints and to achieve the necessary high nodal throughput for the transport of voice and video. Increases in link speeds have not been matched by proportional increases in the processing speeds of communication nodes. The fundamental challenge for high speed networks such as those based on NBBS technologies is thus to minimize the packet processing time and to take full advantage of the high speed/low error rate technologies.
Most of the transport and control functions provided by the new high bandwidth network architectures are performed on an end-to-end basis. The flow control and particularly the path selection and bandwidth management processes are managed by the access points of the network (where the NBBS access services reside), which reduces both the required awareness and functionality of the intermediate nodes.
Congestion and Flow Control
Communication networks have at their disposal limited resources to ensure efficient packet transmissions. An efficient bandwidth management strategy is essential to take full advantage of a high speed network. While transmission costs per byte continue to drop year after year, these costs are likely to continue to represent the major expense of operating future telecommunication networks as the demand for bandwidth increases. Thus, considerable efforts have is been spent on designing flow and congestion control processes, bandwidth reservation mechanisms, routing algorithms to economically manage the network bandwidth.
An ideal network should be able to transmit an amount of traffic that is directly proportional to the traffic offered to the network to the maximum transmission capacity. Beyond this limit, the network should operate at its maximum capacity regardless of demand.
Connectivity
In high speed networks, the nodes must provide total connectivity. This includes attachment of end user devices, regardless of vendors or protocols. The network nodes must also be able to allow an end user device to communicate with any other device or group of devices, when justified or required. The network must support any type of traffic such as data (including “legacy” data), voice, video, fax, graphic or image related traffic. Nodes must be able to take advantage of all common carrier facilities and be adaptable to a plurality of protocols. All required conversions must be automatic and transparent to the end user.
High Speed Networks Services
The architectures of most high speed packet switching networks specify a set of generic services that offer end-to-end high bandwidth transport capabilities.
The present invention relates to transmissions in wide-area networks (WANs) based on the IBM's NBBS arc
Giroir Didier
Hericourt Olivier
Dillon & Yudell LLP
International Business Machines - Corporation
McConnell Daniel E.
Olms Douglas
Pivnichny John R.
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