Multiplex communications – Wide area network – Packet switching
Patent
1995-08-09
1997-11-04
Lee, Thomas C.
Multiplex communications
Wide area network
Packet switching
39520021, 39520017, 370393, H04J 300, H04J 324, H04L 1246
Patent
active
056849540
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention concerns a method and an apparatus for scanning data streams in a communication network and extracting connection information to provide for unique protocol connection identifiers.
BACKGROUND OF THE INVENTION
The technological convergence of computer and communication networks, as well as the fast development in either one of these two areas, has led to such an intimate mixture of information processing and communication that the transmission and exchange of data, voice, images etc. becomes more and more complex. Each transmission or exchange of information--information used as synonym for various kinds of data, services, and communications--has necessarily to be governed by rules of procedure.
When different units, e.g. two remote computer terminals, or two procedures are interacting via an interface, which is not necessarily a hardware interface, respective protocols are employed. Depending on the network, various protocols are hierarchically ordered, resulting in a vertical stack of protocols, each of these protocols interacting with the adjacent ones. Basic transport protocols are known to organize the information exchange and transmission between remote systems, such as host computers. A typical example is the ARPA (Advanced Research Projects Agency) host-to-host protocol. Such a basic protocol enables the higher-level protocols of the vertical protocol stack to base all their operations on the basic protocol mechanisms.
Depending on the network environment, there are several higher-level protocols set up on the basic protocol. A schematic representation of a typical vertical protocol stack, known as OSI (Open Systems Interconnection) reference model for CCITT (Consultative Committee on International Telephone and Telegraph) applications is defined in the CCITT Recommendation X.200, "Reference Model of Open Systems Interconnection for CCITT Applications", Blue Book, Fascicle VIII.4, Geneva, 1989. Said OSI reference model uses seven levels, referred to as layers. Each layer has its own specific function and offers a defined service to the layer above using the services provided by the layer below.
If an application program, for example, which runs on a first system requires the use of data held in a second, remote system, an exchange of information takes place. When said second system receives a request to send a specific data packet, this data packet has to be transmitted from the highest protocol level, e.g. the application layer, down through all lower protocol levels, prior to be sent along the physical link. Each of these protocol layers adds its layer-specific connection information to the data packet received from the higher layer. Therefore, a communication connection between two systems is defined in a packet header, hereinafter referred to as protocol header, by the aggregate of fields carrying connection information of the vertical protocol stack.
When receiving a data stream made up of data packets at a receiver site, prior to routing, multiplexing or compressing it, said protocol header has to be scanned to extract the respective words comprising connection information for further processing
To date, most of the protocol connections are identified by sequentially processing the protocol headers in software. This operation consumes a considerable amount of time in the protocol processing, in particular when dealing with many connections, e.g. in a server, or when processing multimedia data streams.
A microprogrammed controller, used to recognize the protocol type of a protocol header and to extract protocol specific data fields, has been described in "Implementing PE-1000 Based Internetworking Nodes", H. W. Chin et al., Part 3 of 3, Transfer, Vol. 5, No. 3, May/June 1992, pp. 5-8.
The hardware implementation of a routing table for the translation of packet identifiers into an appropriate physical output link is described in "Putting Routing Tables in Silicon", T.-B. Pei and C. Zukowski, IEEE Network Magazine, January 1992, pp. 42-50. This approach i
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Kaiserswerth Matthias
Ruetsche Erich
Dinh D.
International Business Machine Corp.
Lee Thomas C.
Ray-Yarletts Jeanine S.
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