Interface between communication channel segments

• US 4,284,976 A
• Filed: 06/07/1979
• Issued: 08/18/1981
• Est. Priority Date: 06/07/1979
• Status: Expired due to Term

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Gable, Melvin G., Sherman, Richard H.
• Primary Examiner(s): YUSKO, DONALD
• Application Number:
  US06/046,576
• Time in Patent Office: 803 Days
• Field of Search: 340/147 R, 340/147 T, 178/3
• US Class Current: 370/355
• CPC Class Codes: H04L 12/4604 LAN interconnection over a backbone network, e.g. Internet, Frame Relay

Abstract

A plurality of transceivers frequently share a common communication medium or radio frequency channel. A broadcast channel can support only a limited number of transceivers. At some point, the shared channel will become so busy that additional transceivers will divide up more of an already inadequate bandwidth. To reduce the traffic, a broadcast channel is split into separate segments. A segment interface apparatus is used to couple two broadcast segments together. A hierarchical address is employed in the header of each packet transmitted on the medium. The segment interface apparatus compares fields in the header with that of internal registers to determine if the packet should be repeated on the other broadcast segment. An access level within the packet is decremented by the segment interface to control the number of times a packet is repeated.

Claims

1. A communication system having a broadcast medium shared by a plurality of transceivers which are transmitting and receiving communication packets, said broadcast medium including a first communication channel segment and a second communication channel segment, the communication system having an interface means for passing communication packets having a hierarchical address in a packet header, which hierarchical address has at least two levels and includes identification of the final destination of the communication packet, from said first communication channel segment to said second communication channel segment of said broadcast medium, each of the first and second communication channel segments having at least two transceivers, said interface means including:

a first address register means for storing a first register field for comparison with a first packet field in the hierarchical address of the communication packet header and for transmitting the communication packet to the second communication channel segment if said first register and packet field do not match.

2. An interface means as recited in claim 1 further comprising:

a second address register means for storing a second register field for providing information to append to the hierarchical address so that a source field portion of the packet header designating the source of the communication packet, is altered by the addition of said second register field.

3. An interface means as recited in claim 1 further comprising a decrementing means for decrementing a portion of the packet header including an access level for determining the number of retransmissions of the communication packet so as to control the number of times a packet is repeated and the packet either reaches its destination or ceases to be repeated.

4. An interface means as recited in claim 3 further comprising a zero detector means coupled to said decrementing means for detecting a zero in the access level and inhibiting transmission in response to a detected zero.

5. An interface means as recited in claim 1 further comprising:

a buffer means for storing a packet transmission so that said interface means can defer transmission to said second communication channel segment until access can be gained to said second communication channel segment.

6. A communication system having a broadcast medium shared by a plurality of transceivers which are transmitting and receiving communication packets, said broadcast medium including a first communication channel segment and a second communication channel segment, the communication system having an interface means for passing communication packets having a hierarchical address in a packet header, which hierarchical address has at least two levels and can contain a route address having intermediate segment interface addresses and identification of the final destination of the communication packet, from a first communication channel segment of a broadcast medium shared by a plurality of transceivers which are transmitting and receiving the communication packets, to a second communication channel segment of said broadcast medium, each of the first and second communication channel segments having at least two transceivers, said interface means including:

a first address register means for storing a first register field for comparison with a first packet field in the hierarchical address of the communication packet header and for transmitting the communication packet to the second communication channel segmet if said first register and packet fields do not match,

a route detector means for testing the hierarchical address to determine the presence of a route address;

a first address register means for storing a first register field for comparison with a first packet field in the hierarchical address of the communication packet header;

a comparison means for comparing said first register field with said first packet field in the hierarchical address if the route detector means indicates the presence of a route address in the hierarchical address; and

a retransmission means for transmitting the communication packet on the second communication channel segment if said first register field and first packet field are identical.

7. An interface means as recited in claim 6 further comprising:

a removal means for removing said first packet field from the hierarchical address if the packet is to be retransmitted.

8. An interface means as recited in claim 6 wherein said first address register includes means for providing information to append to the hierarchical address so that a source field portion of the hierarchical address, designating the source of the communication packet, is altered by the addition of said first register field.

9. An interface means as recited in claim 6 further comprising:

a buffer means for storing a packet transmission so that said interface means can defer transmission to said second communication channel segment until access can be gained to said second communication channel segment.

10. An interface means as recited in claim 6 further comprising:

a second address register field for storing a second register field for comparison, when said route detector does not indicate the presence of a route address, with a second packet field in the hierarchical address of the communication packet header and for transmitting the communication packet to the second communication channel segment if said second register and said second packet fields do not match.

11. An interface means as recited in claim 10 wherein said first address register includes means for providing information to append to the hierarchical address so that a source field portion of the hierarchical address, designating the source of the communication packet, is altered by the addition of said first register field.

12. An interface means as recited in claim 10 further comprising:

a buffer means for storing a packet transmission so that said interface means can defer transmission to said second communication channel segment until access can be gained to said second communication channel segment.

13. An interface means as recited in claim 10 further comprising a decrementing means for decrementing a portion of the packet header including an access level for determining the number of retransmissions of the communication packet so as to control the number of times a packet is repeated and the packet either reaches its destination or ceases to be repeated.

14. An interface means as recited in claim 13 further comprising a zero detector means coupled to said decrementing means for detecting a zero in the access level and inhibiting transmission in response to a detected zero.

15. An interface means for passing communication packets having a hierarchical address in a packet header from a first communication channel segment, of a broadcast medium shared by a plurality of transceivers which are transmitting and receiving the communication packets, to a second communication channel segment of said broadcast medium, a receiver being coupled between said interface means and said first communication channel segment, a transmitter being coupled between said interface means and said second communication channel segment, said interface means including:

a buffer register means coupled to said receiver for storing packet data;

a first control register means coupled to said buffer register means for storing control information;

a first source address register means coupled to said first control register means for storing a hierarchical source address;

a first destination address register means coupled to said first source address register means for storing a hierarchical destination address;

a level counter means coupled to said first control register means for determining and decrementing an access level characterized by the packet and therefore the retransmission of the communication packet;

a zero detector means coupled to said first control register means for detecting zero in the retransmission access level of the communication packet and generating an inhibit output for preventing retransmission;

a first and a second storage register means for storing information characteristics of the interface means;

a first comparator means coupled to said first storage register means and said first destination address register means for comparing a first and a second portion of the register information and generating a first output when said first portion and said second portion of register information is identical;

a second comparator means coupled to said second storage register means, said second storage register means and said first destination address register means for comparing a third and a fourth portion of the register information and generating a second output when said third and said fourth portion of register information is not identical;

a route detector means coupled to said first destination address register means for determining if the hierarchical address stored in said destination address register means is a route address and generating an output when a route address is detected;

a transmitter control means coupled to said zero detector means for receiving said inhibit output, coupled to said route detector means; and

coupled to said first and second comparator means for selecting the output of either said first or second comparator means in response to information from said route detector means;

a second control register means coupled to said first control register means and said level counter means for storing a portion of said first control register means and for storing the output of said level counter means;

a second source address register means coupled to said first source address register and said first storage register means for storing the contents of the two coupled registers;

a second destination register coupled to said first destination address register means for receiving either a portion of the hierarchical address or the total contents of the hierarchical address as described by said transmitter control means; and

said transmitter control means being adapted to control transmission of the contents of said buffer register means, said second control register, said second source address register and said second destination address register, thereby enabling the transmitter.