Nova Patents
EP0595751B1

Method of routing electronic messages

Abstract

This record has no abstract on file.

EP0595751B1, drawing sheet 1
Sheet 1 of 17

Term

Term ended

Expired 21 September 2013, 13 years ago.

  1. Priority
  2. Filed
  3. Granted
  4. Expired
  5. Today

16 claims: 13 independent, 3 dependent

  1. 1
    A method of sending an electronic message from a source station through a network of a plurality of switches and links to a destination station, said method comprising:generating a series of one or more route signals, each route signal identifying an output port of a switch in the network of switches;generating an electronic message comprising the series of route signals;and sequentially sending the message to each of a series of one or more switches, each switch reading a route signal in the message and sending the message to a switch or a station having an input port connected to an output port identified by the route signal;characterized in that the step of generating the series of route signals comprises the steps of: (a) storing a weight w m o for each switch link connecting an output port o m of a switch m to an input port of another switch;(b) identifying one or more candidate paths through the switch network starting at the source station and ending at initial candidate destinations, each initial candidate destination comprising a switch or a station having an input port directly connected to an output port of a switch having an input port directly connected to the source station;(c) if one or more candidate destinations are the destination station, selecting a candidate path ending at the destination station, and generating a series of route signals corresponding to the selected candidate path;otherwise (d) if no candidate destination is the destination station, identifying one or more extended candidate paths through the switch network starting at the source station and ending at next candidate destinations, each next candidate destination comprising a switch or a station having an input port directly connected to an output port of a prior candidate destination, each extended candidate path having a path weight comprising the weights of switch links along the candidate path;and then (e) if one or more candidate destinations are the destination station, selecting a candidate path ending at the destination station and having a path weight which is better than or equal to the path weight of each other candidate path ending at the destination station, and generating a series of route signals corresponding to the selected candidate path;otherwise (f) return to step (d).
  2. 2
    A method as claimed in Claim 1, characterized in that each candidate path comprises:a series of one or more switches starting with the switch having an input port directly connected to the source station and ending with a switch having an output port directly connected to the candidate destination of the candidate path;a station link connecting the source station to an input port of the starting switch;and a station link connecting the output port of the ending switch to the destination station.
  3. 3
    A method as claimed in Claim 2, characterized in that each extended candidate path further comprises one or more switch links connecting an output port of a switch in the path with an input port of another switch in the path.
  4. 4
    A method as claimed in any one of the previous claims, characterized in that each pair of extended candidate paths contain a common root path extending from the source station to a common branch switch from which the paths diverge;the path weight of a first candidate path is better than the path weight of a second candidate path if the weight of the switch link of the first candidate path connected to an output of the common branch switch for the first and second candidate paths is better than the weight of the switch link of the second candidate path connected to an output of the common branch switch for the first and second candidate paths.
  5. 5
    A method as claimed in any one of the previous claims, characterized in that the step of generating a series of route signals corresponding to the secandidate path comprises generating a series of route signals identifying switch output ports connected to the links forming the selected candidate path.
  6. 6
    A method as claimed in any one of the previous claims, characterized in that the step of storing weights for the switch links comprises storing an initial value K for the weight w m o for each switch link connected to an output port 0 m of a switch m, where K is a selected constant.
  7. 7
    A method as claimed in any one of the previous claims, characterized in that the step of selecting a candidate path ending at the destination station further comprises changing the weight w m o of each switch link forming the selected candidate path.
  8. 8
    A method as claimed in any one of the previous claims, characterized in that the step of changing the weights of switch links forming the selected candidate path comprises increasing the weight of each switch link forming the selected candidate path by a constant K'.
  9. 9
    A method as claimed in any one of the previous claims, characterized in that K=0 and K'=+1.
  10. 10
    A method as claimed in Claim 9, characterized in that the path weight of a first candidate path is better than the path weight of a second candidate path if the weight of the switch link of the first candidate path connected to an output of the common branch switch for the first and second candidate paths is less than the weight of the switch link of the second candidate path connected to an output of the common branch switch for the first and second candidate paths.
  11. 11
    A method as claimed in any one of the previous claims, further comprising the steps of:storing the series of route signals in a route table;and generating the message by reading the series of route signals from the route table.
  12. 12
    A method as claimed in any one of the previous claims, characterized in that:the destination station has an input port;and the last route signal in the series of route signals in the message identifies a switch output port directly connected to the input port of the destination station.
  13. 13
    A method as claimed in any one of the previous claims, characterized in that the step of sequentially sending the message comprises the steps of:(1) sending the message to a first switch having an input port directly connected to the source station, said first switch having at least two output ports;(2) reading a route signal in the message, said route signal identifying an output port of the first switch;and (3) sending the message to a second switch having an input port directly connected to the output port of the first switch identified by the read route signal.
  14. 14
    A method as claimed in any one of the previous claims, further comprising the step of disabling the route signal in the message after reading the route signal.
  15. 15
    A method as claimed in any one of the previous claims, characterized in that each extended candidate path has a path weight comprising the sum of the weights of switch links along the candidate path.
  16. 16
    The method of any one of the previous claims characterized in that it is used for assigning a communication route from a source station through a network of a plurality of switches and links to a destination station.
Independent claims16