Routing of network traffic

• US 4,862,496 A
• Filed: 12/16/1986
• Issued: 08/29/1989
• Est. Priority Date: 12/18/1985
• Status: Expired due to Term

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Whitehead, Martin J., Turton, Paul A., Stacey, Roger R., Key, Peter B., Gibbens, Richard J., Kelly, Francis P.
• Primary Examiner(s): BROWN, THOMAS
• Application Number:
  US06/942,323
• Time in Patent Office: 987 Days
• Field of Search: 379/221, 379/220, 340/827
• US Class Current: 379/221.01
• CPC Class Codes: H04Q 2213/13141 Hunting for free outlet, circuit or channel
• CPC Class Codes: H04Q 2213/13164 Traffic (registration, measurement,...)
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13332 Broadband, CATV, dynamic bandwidth allocation
• CPC Class Codes: H04Q 2213/13344 Overflow
• CPC Class Codes: H04Q 3/66 Traffic distributors

Abstract

A method and apparatus for routing traffic in a circuit switched network. A call between two nodes interconnected by a direct link is first offered to the direct route, and if that is blocked it is offered to a currently nominated two-link alternative route between the two nodes. If that route is busy, the call is lost, and a randomly chosen two-link route is assigned to be the new current nominated alternative route. The strategy is particularly effective because it is simple, available routes are quickly located and once one available route is found, that same route is used for rerouting further calls until it is full. Trunk reservation protection is applied on alternative routes.

Claims

1. A method of routing traffic in a circuit-switched network, said method comprising:

offering calls between an origin node and a destination node to one or more pre-assigned preferred routes, and

if the or each of said one or more preferred routes is not available, offering said calls to at least one alternative route, wherein calls continue to be offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

said current nominated alternative route being an alternative route which the origin node immediately offers to a call blocked on the pre-assigned preferred route.

10. A method as claimed in claim 1, wherein the replacement nomination is made by a stochastic, pseudo-random or cyclic mechanism.

17. A method as claimed in claim 1, wherein the circuit-switched network is a virtual circuit network.

2. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein a call between an origin node and a destination node which is blocked on the said one or more preferred routes is offered to only one current nominated alternative route, and if the said one current nominated alternative route is not available, the call is lost, and the replacement nomination is made.

3. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein calls between an origin node and a destination node which are blocked on the said one or more preferred routes are offered to a first current nominated alternative route, and if the said first current nominated alternative route is not available said replacement nomination is made, and said calls are offered to a second current nominated alternative route.

4. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein successive replacement nominations are made by stepping cyclically through the set of alternative routes.

5. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein a set of current nominated alternative routes is chose, and each successive call which is blocked on said one or more preferred routes is offered to a respective cyclically selected member of the set, and wherein if the respective member to which a call is so offered is not available, that member is replaced in the set of current nominated alternative routes by a said replacement nomination.

6. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein the or each of said one or more preferred routes is a single link route and the alternative routes are two-link routes.

7. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein links between pairs of nodes are assigned respective trunk reservation parameters, and an alternative route is available if, for each link of the route, the sum of current traffic and trunk reservation parameter is less than the capacity of the link.

8. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alternative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein the replacement nomination is made such as to give equal weight to each of the said alternative routes.

9. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one or more preferred routes, and

if the or each of said one or more preferred routes is not available, offering at least one alterative route,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of alternative routes to the destination node,

wherein the replacement nomination is made on the basis as to which route is intrinsically likely to be available.

11. A method of routing traffic in a circuit-switched network, said method comprising:

offering calls between an origin node and a destination node to one of a plurality of routes,

wherein calls are and continue to be offered to one or more current nominated routes until the or one of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of said routes,

a current nominated route being an alternative route which the origin node immediately offers to a call blocked on previously offered routes.

14. A method as claimed in claim 11, wherein if a desired call between an origin node and a destination node is not available on a first current nominated route, the call is offered to a second current nominated route, and if the said second current nominated route is not available, the said call is offered to a third current nominated route.

16. A method as claimed in claim 11, wherein a set of current nominated routes is chosen, and each successive call is offered to a respective selected member cyclically of the set, and wherein if the respective member to which a call is so offered is not available, that member is replaced in the set of current nominated routes by a said replacement nomination.

18. A method as claimed in claim 11, wherein the circuit-switched network is a virtual circuit network.

12. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one of a plurality of routes,

wherein calls are offered to one or more current nominated routes until the or one of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of said routes,

wherein if a call between an origin node and a destination node is blocked on the or a first of said one or more current nominated routes, the call is lost, and said replacement is made.

13. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one of a plurality of routes,

wherein calls are offered to one or more current nominated routes until the or one of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of said route,

wherein if a desired call between an origin node and a destination node is not available on a first current nominated route, the call is offered to only one other current nominated route, and if the said other current nominated route is not available, the call is lost

15. A method of routing traffic in a circuit-switched network, comprising:

offering calls between an origin node and a destination node to one of a plurality of routes,

wherein calls are offered to one or more current nominated routes until the or one of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of said routes,

wherein successive replacement nominations are made by stepping cyclically through the set of alternative routes.

19. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more pre-assigned preferred routes and, if the one or each of said one or more preferred routes is not available, offering alternative routes,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made form a set of said alternative routes to the destination node,

said current nominated alternative route being an alternative route which the origin node immediately offers to a call blocked on the pre-assigned preferred route.

20. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more preferred routes and if the one or each of said one or more preferred routes is not available, offering alternative routes,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of said alternative routes to the destination node,

wherein each processor is adapted to offer a call which is blocked on the said preferred routes to only one current nominated route, and if the said current nominated route is not available, the call is lost, and said replacement nomination is made.

21. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processor at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more preferred routes and if the one or each of said one or more preferred routes is not available, offering alternative routes,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of said alternative routes to the destination node,

wherein the or each of said one or more preferred routes in a single link route and the alternative routes are two-link routes.

22. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to continue to offer calls between their respective node and a destination node to one or more current nominated routes until the one or more of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of routes to the destination node,

a current nominated route being an alternative route which the origin node immediately offers to a call blocked on previously offered routes.

23. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more current nominated routes until the one or more of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of routes to the destination node,

wherein each processor is adapted to offer a call which is blocked on the or a first of said one or more current nominated routes to only one other current nominated route, and if the said other current nominated route is not available, the call is lost, and said replacement nomination is made.

24. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more preferred routes and if the one or each of said one or more preferred routes is not available, offering alternative routes,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of said alternative routes to the destination node,

wherein successive replacement nominations are made by stepping cyclically through the set of alternative routes.

25. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more current nominated routes until the one or more of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of routes to the destination node,

wherein successive replacement nominations are made by stepping cyclically through the set of alternative routes.

26. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more preferred routes and if the one or each of said one or more preferred routes is not available, offering alternative routes,

wherein calls are offered to one or more current nominated alternative routes until the or one of said current nominated alternative routes is not available, at which point a replacement nomination for the unavailable current nominated alternative route is made from a set of said alternative routes to the destination node

wherein the said processors are adapted to nominate a set of current nominated alternative routes, to successive calls which are blocked on said one or more preferred routes to respective cyclically selected members of the set, and , if a respective member to which a call is offered is not available, to replace said respective member in the set by a said replacement nomination.

27. Apparatus for routing traffic through a circuit-switched network comprising:

a plurality of processors at respective nodes,

the said processors being adapted to offer calls between their respective node and a destination node to one or more current nominated routes until the one or more of said current nominated routes is not available, at which point a replacement nomination for the unavailable current nominated route is made from a set of routes to the destination node,

wherein the said processors are adapted to nominate a set of current nominated routes, to offer each successive call to a respective cyclically selected member of the set, and, if a respective member to which a call is offered is not available, to replace said respective member in the set by a said replacement nomination.