Method and system for improving traffic operation in an...

Details Method and system for improving traffic operation in an... Method and system for improving traffic operation in an...

1999-04-29

2003-08-05

Ton, Dang (Department: 2661)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S389000, C370S469000, C709S227000, C709S230000, C709S238000

Reexamination Certificate

active

06603769

ABSTRACT:

FIELD OF INVENTION
A method and system for improving traffic communications operation over a complex interconnected network by speeding up data packet transfers using conventional protocols such as Internet Protocol (IP). More particularly, the invention interconnects Ethernet/IP Hosts over Ethernet switches, Local Area Networks (LAN) and Wide Area Networks (WAN) by virtually enlarging the LAN until it encompasses the WAN so that dynamic self-bridging can communicate anywhere in the network.
BACKGROUND ART
Modern digital networks are made to operate in a multimedia environment and interconnect, upon request, a large number of users and applications through complex digital communication networks.
Accordingly, due to the variety of user's profiles and distributed applications, the corresponding traffic is consuming more and more bandwidth, non-deterministic and requiring more connectivity. This has been causing emergence of fast packet switching techniques in which data from multimedia origin are chopped into fixed length packets (e.g., in Asynchronous Transfer Mode (ATM) type of operation) or into variable length packets (e.g., in so-called Frame Relay (FR) type of operation). These packets are then transferred upon request for communication purposes between data sources and targets via so-called high speed communication networks. One of the key requirements for high speed packet switching networks is to reduce the end to end delays.
Also, due to the increase of traffic, several types of networks have been installed which need to be interconnected together to optimize the possibilities of organizing traffic between any source host and a target host both located anywhere on different LANs. This is made possible by using so-called internetworking. An internet is a collection of heterogeneous networks using a set of networking protocols (i.e., TCP/IP, Transmission Control Protocol/Internet Protocol) developed to allow cooperating computers to share resources across the network. TCP/IP products are made by many vendors and a fairly large number of networks of all kinds use it. Accordingly, IP switching technologies may incorporate new proprietary protocols, which complicates networking operations. TCP/IP is a set of data communication protocols that are referred to as the Internet protocol (IP) suite. Because TCP and IP are the best known of the protocols, it has become common to use the term TCP/IP to refer to the whole family. TCP and IP are two of the protocols in this suite. Other protocols that are part of the Internet suite are User Datagram Protocol (UDP), Internet Control Message Protocol (ICMP), Address Resolution Protocol (ARP), Real Time Protocol (RTP), Reservation Protocol (RSvP) etc.
The Internet is a collection of heterogeneous networks using TCP/IP. The administrative responsibilities for Internet (for example, to assign IP addresses and domain names) can be within a single group or distributed among multiple groups. Networks comprising an internetwork can use either the same or different technologies.
(For more information on TCP/IP one may refer to “Internet Working with TCP/IP” by Douglas Comer).
For example, as represented in
FIG. 1
, an internetwork may include networks A and B with attached stations (S
1
, S
2
, S
3
) using so-called Local Area Network (LAN) technology, such as token-ring, Ethernet, FDDI etc., to communicate. While within a network C, including nodes (N interconnected by links L) communication is made possible through so-called Wide Area Network (WAN) technologies including Frame Relay (FR), X.25, Asynchronous Transfer Mode (ATM) etc.
Host stations such as S
1
, S
2
, S
3
. . . can each send messages from any of them to any other station. Communication within a single network is referred to as intranetworking, and communications between stations that are attached to different networks is called internetworking. Stations within a same network can communicate directly, while internetworking communications have to go across special internetworking devices called gateways and labeled R in
FIG. 1
(sometimes referred to as routers as they route data from one network to another).
As shall be discussed in the following description, the gateways or routers may, in some cases, be replaced by so-called bridges. Both have specific characteristics as they operate at different layers of protocol of the network.
As computer networks have developed, various approaches have been used in the choice of communication characteristics such as communication medium, network topology, message formats, protocols for channel access etc. Some of these approaches have been converted into Standards. A model of these Standards is known as the International Standards Organization (ISO) Open System Interconnection (OSI) model. This model specifies a hierarchy of protocol layers and defines the function of each layer in the considered network. Each layer in one station which might be a host computer or a router/bridge, carries a conversation with the corresponding layer in another station with which communication is taking place, in accordance with the protocol defining the rules of this communication. In fact, information is transferred down from layer to layer in one host or router source then through the channel medium back up the successive layers in the other host or router/bridge.
Three layers (out of seven), which have been defined by the OSI Standards iclude: the physical layer, the data link layer and the network layer. The physical layer is the lowest layer assigned to transmission of data bits over the communication channel. Design of the physical layer involves issues of electrical, mechanical or optical engineering depending on the physical medium used to build the communications channel. (IETF standardizes TCP/IP thru RFCs (Requests for comments).
The main task of the layer next to the physical layer, i.e. the data link layer, is to transform the physical layer interfacing with the channel into a communication link that appears error-free to the next above layer, i.e. the network layer. The data link layer performs such functions as structuring data into packets or frames and attaching control information numbers to the packets or frames to enable checking data validity and reinserting reconstructed packets at the right location into the data flow. There are two point-to-point types: connectionless and connection oriented.
Although the data link layer is primarily independent of the nature of the transmission medium, certain aspects of the data link layer functions are dependent on the transmission medium. This is why, in some network architectures, the data link layer is divided into two sub-layers: a local control sublayer which performs all medium-independent functions of the data link layer, and a Media Access Control (MAC) sub-layer. The MAC sub-layer determines which station should get access to the communications channel, when requests for access are in conflictual situation. The functions of the MAC sub-layer are more likely to be dependent on the transmission medium nature. Bridges may be designated to operate in the MAC sub-layer.
As the internetwork topologies become more and more complex, the number of routers or bridges used to interconnect the network (see
FIG. 1
) become more and more important. Consequently, the choice between router and bridge devices for performing the interconnecting function may seriously impact the whole internetwork performances, e.g., in terms of transmission time delay, as each has its own advantages and disadvantages as known by any person skilled in the art.
To enable fully understanding the concerns, we shall briefly describe some of the respective characteristics of both routers and bridges.
The basic function of a bridge is to make large interconnected networks look like a single flat LAN. Bridges act at MAC layer level and listen to all message traffic on all networks (e.g. LANs) to which it is connected and to forward each message onto the networks other than the one from which the message was heard. Bridg

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