GB2309619A - Protocol coverter card for ATM/Token ring - Google Patents

Protocol coverter card for ATM/Token ring Download PDF

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Publication number
GB2309619A
GB2309619A GB9601346A GB9601346A GB2309619A GB 2309619 A GB2309619 A GB 2309619A GB 9601346 A GB9601346 A GB 9601346A GB 9601346 A GB9601346 A GB 9601346A GB 2309619 A GB2309619 A GB 2309619A
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GB
United Kingdom
Prior art keywords
protocol
data
accordance
communication network
interface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9601346A
Other versions
GB9601346D0 (en
Inventor
Mark Alexander Leith Smallwood
John Bain
Richard William Todd
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Madge Networks Ltd
Original Assignee
Madge Networks Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Madge Networks Ltd filed Critical Madge Networks Ltd
Priority to GB9601346A priority Critical patent/GB2309619A/en
Publication of GB9601346D0 publication Critical patent/GB9601346D0/en
Publication of GB2309619A publication Critical patent/GB2309619A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
    • H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
    • H04Q11/0478—Provisions for broadband connections
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/66—Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/42—Loop networks
    • H04L12/427—Loop networks with decentralised control
    • H04L12/433—Loop networks with decentralised control with asynchronous transmission, e.g. token ring, register insertion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5614—User Network Interface
    • H04L2012/5615—Network termination, e.g. NT1, NT2, PBX
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5614—User Network Interface
    • H04L2012/5616—Terminal equipment, e.g. codecs, synch.
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/54—Store-and-forward switching systems 
    • H04L12/56—Packet switching systems
    • H04L12/5601—Transfer mode dependent, e.g. ATM
    • H04L2012/5629—Admission control
    • H04L2012/563—Signalling, e.g. protocols, reference model
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/08—Protocols for interworking; Protocol conversion

Abstract

A communication network end station comprises a host processor (6) programmed to cooperate with interface electronics suitable for transferring data between the host processor and a communication network (5) operating in accordance with a first protocol. An interface device (7) connects the end station to a communication network on which data is carried in accordance with a second protocol. The interface device includes: a) a first interface (9) which cooperates with the programmed host processor (6) to transfer data to and from the host processor in accordance with the requirements of the first protocol; b) a second interface (13) which transfers data to and from the communication network (5) in accordance with the requirements of the second protocol; and, c) a conversion system (10-12) for transferring data between the first and second interfaces and for suitably converting the format of the data passing therebetween. The protocols can be ATM and token ring.

Description

COMMUNICATION NETWORK END STATION AND ADAPTOR CARD The invention relates to a communication network end station for use with a communication network and also to an adaptor card for insertion into such a communication network end station.
Data communication networks are provided to enable the transfer of data between end stations such as personal computers, file servers and other communication networks.
Data is transmitted around such networks in accordance with standard protocols such as token ring, ethernet, FDDI or ATM. Conventionally, an end station will interface to the network through a connecting device, typically an adaptor card, installed in the end station. The end station will include a host processor programmed to cooperate with interface electronics on the adaptor card so as to provide data for the network in a format compatible with the network protocol and it will also convert data received from the network into a format compatible with the end station. The connecting device controls the flow of data from the end station onto the network and from the network on to the end station.
A problem arises if the end station is to be connected to another network operating a different protocol. In that situation, not only is it necessary to change the connecting device or adaptor card, but it is also necessary to reprogramme the host processor.
In accordance with one aspect of the present invention, a communication network end station comprises a host processor programmed to cooperate with interface electronics suitable for transferring data between the host processor and a communication network operating in accordance with a first protocol; and an interface device for connecting the end station to a communication network on which data is carried in accordance with a second protocol, the interface device including: a) first interface means which cooperates with the programmed host processor to transfer data to and from the host processor in accordance with the requirements of the first protocol; b) second interface means which transfers data to and from the communication network in accordance with the requirements of the second protocol; and, c) conversion means for transferring data between the first and second interface means and for suitably converting the format of the data passing therebetween.
In accordance with a second aspect of the present invention, an adaptor card for insertion into a communication network end station which includes a host processor programmed to cooperate with interface electronics suitable for transferring data between the host processor and a communication network operating in accordance with a first protocol, the adaptor card comprising an interface device for connecting the end station to a communication network on which data is carried in accordance with a second protocol, the interface device including: a) first interface means which cooperates with the programmed host processor to transfer data to and from the host processor in accordance with the requirements of the first protocol; b) second interface means which transfers data to and from the communication network in accordance with the requirements of the second protocol; and, c) conversion means for transferring data between the first and second interface means and for suitably converting the format of the data passing therebetween.
We have designed a new interface device which avoids the need to reprogramme the host processor even if there is a change in communication network protocol. The interface device simply needs to be replaced which, when it is fabricated as an adaptor card, is a very straightforward operation. The interface device presents to the host processor the appearance of a communication network operating in accordance with the first protocol while it presents to the communication network the appearance of an end station operating in accordance with the second protocol.
It should be understood that although the first and second interface means and conversion means have been specified as identifiable, separate components, in practice they are likely to be intermixed. Typically the interface device includes processing means to provide part or all of one or more of the first interface means, the second interface means, and the conversion means.
The conversion means will be designed to handle a particular protocol conversion, for example token ring/ATM, and will identify the relevant parts of a token ring frame needed to set up an ATM cell and vice versa. The first interface means will provide the necessary acknowledgements expected by the host processor on transmitting data to the interface device while the second interface means will provide the expected acknowledgements to the communication network.
An example of a communication network end station and adaptor card according to the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a communication network; Figure 2 is a block diagram of one of the end stations incorporating an interface device shown in Figure 1; Figure 3 illustrates a typical ATM cell structure; and, Figure 4 illustrates a typical token ring frame structure.
The communication network shown in Figure 1 comprises four end stations 1-4 connected together by a communication medium 5. The end stations 1-4 could include a personal computer, a file server or another communication network.
In this example, data is transmitted between the end stations 1-4 in accordance with an ATM protocol.
Figure 2 illustrates the construction of one of the end stations of Figure 1 in more detail. The end station comprises a host processor 6 to which is connected an adaptor card 7 which interfaces with the communication medium 5. The host processor 6 includes a computer programme 8 suitable for handling data transfer with the adaptor card in accordance with a token ring protocol such as that defined by the international standard IEEE802.5.
The adaptor card includes a set of token ring buffers 9, a processor 10, a set of ATM buffers 11, an ATM protocol handler 12, and an ATM front end circuit 13. The buffers 9,11 could be provided on the same memory chip.
The function of the adaptor card 7 is to present to the host processor 6 the appearance of a token ring interface while presenting to the communication network 5 an ATM interface.
Figure 3 illustrates the format of a typical ATM cell.
The cell is 53 bytes long and contains two main fields: a header field 20 of 5 bytes and an information field or data field 21 of 48 bytes.
The header field 20 includes a flow control field (GFC) 22. Three bytes are provided for the logical identifier VPI,VCI 23,24. Three bits are provided for Payload Type Identification (PTI) 25 and one bit 26 for Cell Loss Priority (CLP). Finally, one Header Error Control byte 27 is provided for detecting errors and for correcting simple errors involving the header.
A typical token ring frame format is shown in Figure 4. The frame commences with a starting delimiter 30, an access control byte 31 and a frame control byte 32. A destination address is stored at 33 and a source address at 34. This is followed by information 35 carried by the frame. The frame terminates with a frame check sequence 36, an ending delimiter 37, and a frame status byte 38.
In use, when the host processor 6 has data to transmit, it constructs a token ring frame in accordance with the programme 8 and this frame is transferred in a conventional manner to the adaptor card 7 and in particular the token ring buffers 9. The processor 10 responds to the arrival of such a frame by transmitting an acknowledgement signal back to the host processor 6 which assumes that the token ring frame has been accepted for transmission.
The processor 10 extracts and reads the data frame header 30-34 from the token ring frame supplied to the buffers 9. The destination address 33 contained in the header is mapped to an associated VPI and VCI and the processor creates an ATM cell structure which contains the VPI and VCI information. Up to 48 bytes of a token ring frame structure, stored in the buffers 9 is placed into the ATM cell structure by the processor 10. The processor 10 also prepends other control data onto the front of the ATM cell to allow the interface device output means to control the flow of the ATM cell structures to the output interface. The ATM cell structure is then stored in the buffers 11. A transmit buffer manager within the protocol handler 12 then extracts the ATM cell structure at the appropriate time and passes the cell structure to the transmit circuitry or front end 13 to be passed onto the network. This process continues until the whole token ring frame supplied from the host processor has been output on to the ATM network.
On receipt of an ATM cell from the communication network 5, the front end 13 informs a receive buffer manager within the protocol handler 12 that an ATM cell has arrived. The processor 10 informs the receive buffer manager of the first free location in the buffers 11. The receive buffer manager then creates ATM structure buffer locations for the received ATM cell. The processor 10 then creates a token ring frame structure in the buffers 9. To do this, the processor extracts the ATM cell data and places the data into the relevant token ring frame. When all the ATM data for a specific token ring frame has been placed in the token ring frame the adaptor device informs the end station that it has data ready to send to it. The host processor 6 responds to the storing of a frame in the buffers 9 as if the frame had arrived on a token ring protocol network.
More details on the manner in which a token ring frame is stored can be found in the IBM standard "Token Ring Network Adapter Interface" Version 1 Release 1.0 Ref: SC303588-00. The process of cell segmentation and reassembly to emulate a token ring network follows the ATM Forum standard "LAN Emulation Over ATM Version 1.0" Ref: af-lane0021.000. The acknowledgements which are provided to the host are also in accordance with the IBM standard "Token Ring Network Adapter Interface".

Claims (13)

1. A communication network end station comprising a host processor programmed to cooperate with interface electronics suitable for transferring data between the host processor and a communication network operating in accordance with a first protocol; and an interface device for connecting the end station to a communication network on which data is carried in accordance with a second protocol, the interface device including: a) first interface means which cooperates with the programmed host processor to transfer data to and from the host processor in accordance with the requirements of the first protocol; b) second interface means which transfers data to and from the communication network in accordance with the requirements of the second protocol; and, c) conversion means for transferring data between the first and second interface means and for suitably converting the format of the data passing therebetween.
2. An end station according to claim 1, wherein the interface device includes processing means to provide part or all of one or more of the first interface means, the second interface means, and the conversion means.
3. An end station according to claim 1 or claim 2, further comprising a memory into which data can be stored in accordance with the first and second protocols.
4. An end station according to any of the preceding claims, wherein the first protocol comprises a token ring protocol.
5. An end station according to any of the preceding claims, wherein the second protocol comprises an ATM protocol.
6. A communication network end station substantially as hereinbefore described with reference to the accompanying drawings.
7. A communication network which connects together a number of end stations, at least one of the end stations being in accordance with any of claims 1 to 6, the communication network carrying data in accordance with the second protocol.
8. An adaptor card for insertion into a communication network end station which includes a host processor programmed to cooperate with interface electronics suitable for transferring data between the host processor and a communication network operating in accordance with a first protocol, the adaptor card comprising an interface device for connecting the end station to a communication network on which data is carried in accordance with a second protocol, the interface device including: a) first interface means which cooperates with the programmed host processor to transfer data to and from the host processor in accordance with the requirements of the first protocol; b) second interface means which transfers data to and from the communication network in accordance with the requirements of the second protocol; and, c) conversion means for transferring data between the first and second interface means and for suitably converting the format of the data passing therebetween.
9. An adaptor card according to claim 8, wherein the interface device includes processing means to provide part or all of one or more of the first interface means, the second interface means, and the conversion means.
10. An adaptor card according to claim 8 or claim 9, further comprising a memory into which data can be stored in accordance with the first and second protocols.
11. An adaptor card according to any of claims 8 to 10, wherein the first protocol is a token ring protocol.
12. An adaptor card according to any of claims 8 to 11, wherein the second protocol is an ATM protocol.
13. An adaptor card substantially as hereinbefore described with reference to the accompanying drawings.
GB9601346A 1996-01-24 1996-01-24 Protocol coverter card for ATM/Token ring Withdrawn GB2309619A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9601346A GB2309619A (en) 1996-01-24 1996-01-24 Protocol coverter card for ATM/Token ring

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9601346A GB2309619A (en) 1996-01-24 1996-01-24 Protocol coverter card for ATM/Token ring

Publications (2)

Publication Number Publication Date
GB9601346D0 GB9601346D0 (en) 1996-03-27
GB2309619A true GB2309619A (en) 1997-07-30

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999041936A1 (en) * 1998-02-13 1999-08-19 British Telecommunications Public Limited Company Method and system for requesting a virtual circuit through a packet switched network
GB2336276A (en) * 1998-01-30 1999-10-13 Sgs Thomson Microelectronics Protocol conversion
WO2000038383A2 (en) * 1998-12-18 2000-06-29 Telefonaktiebolaget Lm Ericsson (Publ) Internet protocol handler for telecommunications platform with processor cluster
GB2347829A (en) * 1998-12-30 2000-09-13 Gen American Royalty Inc Communication protocol translator for consumer electronic networks
US6912590B1 (en) 1998-12-18 2005-06-28 Telefonaktiebolaget Lm Ericsson (Publ) Single IP-addressing for a telecommunications platform with a multi-processor cluster using a distributed socket based internet protocol (IP) handler

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06303250A (en) * 1993-01-14 1994-10-28 Roke Manor Res Ltd Atm switch system
EP0648034A1 (en) * 1993-09-08 1995-04-12 ALCATEL BELL Naamloze Vennootschap Communication network and computer network server and interface modules used therein
WO1996035988A1 (en) * 1995-05-10 1996-11-14 3Com Corporation Bridge router for high performance scalable networking

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06303250A (en) * 1993-01-14 1994-10-28 Roke Manor Res Ltd Atm switch system
EP0648034A1 (en) * 1993-09-08 1995-04-12 ALCATEL BELL Naamloze Vennootschap Communication network and computer network server and interface modules used therein
WO1996035988A1 (en) * 1995-05-10 1996-11-14 3Com Corporation Bridge router for high performance scalable networking

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ATM networks,R.Handel,M.N.Huber and S.Schroder pp49-53 2 Ed Pub. 1994 Addison-Wesley *
Data Communications,Computer networks and Open Systems by F.Halsall. pp432-433.Pub 1992 Add.Wesley *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2336276A (en) * 1998-01-30 1999-10-13 Sgs Thomson Microelectronics Protocol conversion
GB2336276B (en) * 1998-01-30 2003-04-30 * Sgs-Thomson Microelectronics Limited Device and method for protocol conversion
WO1999041936A1 (en) * 1998-02-13 1999-08-19 British Telecommunications Public Limited Company Method and system for requesting a virtual circuit through a packet switched network
WO2000038383A2 (en) * 1998-12-18 2000-06-29 Telefonaktiebolaget Lm Ericsson (Publ) Internet protocol handler for telecommunications platform with processor cluster
WO2000038383A3 (en) * 1998-12-18 2000-09-14 Ericsson Telefon Ab L M Internet protocol handler for telecommunications platform with processor cluster
US6912590B1 (en) 1998-12-18 2005-06-28 Telefonaktiebolaget Lm Ericsson (Publ) Single IP-addressing for a telecommunications platform with a multi-processor cluster using a distributed socket based internet protocol (IP) handler
GB2347829A (en) * 1998-12-30 2000-09-13 Gen American Royalty Inc Communication protocol translator for consumer electronic networks

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Publication number Publication date
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