ATM Telecommunications Systems and Method for Routing Narrow Band Traffic

Abstract

A telecommunications system comprises an asynchronous transfer mode (ATM) network having uncommitted bandwidth, and a plurality of adaptive grooming routers (AGR) coupled to the network. The AGRs comprise a group adapted to function as a virtual transit exchange whose fabric and control are distributed over the group. The visual comprising the AGRs incorporates independent connection control and call routing functions and has means for determining the current system status whereby to set up narrow band connections across the ATM network based on that status determination.

1 . A telecommunications system comprising:—
 a broadband digital communications network;   a call routing server configured to determine, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network; and   a connection controller configured to establish one or more connections in the broadband digital communications network on the basis of a route in the set of candidate routes, the connection being for transmitting traffic in respect of the call.   
   
   
       2 . A telecommunications system according to  claim 1 , wherein the call routing server and connection controller are configured to communicate with each other in order to maintain or remove connections in the network in addition to establishing connections to enable transmission of call traffic over said route. 
   
   
       3 . A telecommunications system according to  claim 1 , wherein the connection controller is distributed across a plurality of nodes of the network. 
   
   
       4 . A telecommunications system according to  claim 1 , wherein the call routing server is distributed across a plurality of nodes of the network. 
   
   
       5 . A telecommunications system according to  claim 1 , wherein the call routing server implements narrowband signaling. 
   
   
       6 . A telecommunications system according to  claim 1 , wherein the call routing server is a proxy call routing server. 
   
   
       7 . A telecommunications system according to  claim 6 , wherein the proxy call routing server uses a proxy signaling protocol to enable said call routing server and connection controller to communicate with each other. 
   
   
       8 . A telecommunications system according to  claim 6 , wherein the proxy call routing server implements a service that goes beyond the routing capabilities of narrowband signaling. 
   
   
       9 . A telecommunications system according to  claim 6 , wherein the proxy call routing server is a multimedia server. 
   
   
       10 . A telecommunications system according to  claim 1 , wherein the route identifies endpoints of the network between which call traffic may be transmitted. 
   
   
       11 . A telecommunications system according to  claim 1 , wherein the call routing server is arranged to prioritize ones of a plurality of potential call routes according to a static priority. 
   
   
       12 . A telecommunications system according to  claim 1 , wherein the call routing server is arranged to prioritize ones of a plurality of potential call routes according to a dynamic priority. 
   
   
       13 . A telecommunications system according to  claim 1 , wherein the call routing server is arranged determine the set of candidate routes based on a digit analysis using one or more digits in an initial address message received by the call routing server. 
   
   
       14 . A telecommunications system according to  claim 1 , wherein the call connection server is configured to receive the set of candidate routes from the call routing server and eliminate one or more routes from the set of candidate routes. 
   
   
       15 . A telecommunications system according to  claim 14 , wherein call connection server is configured to eliminate one or more routes from the set of candidate routes on the basis of the status of one or more of the connections making up the route. 
   
   
       16 . A telecommunications system according to  claim 1 , wherein the call routing server is arranged to determine availability of a call destination point and to reject a call to that destination point in the event that the destination point is unavailable. 
   
   
       17 . A telecommunications system according to  claim 16 , wherein the destination point is unavailable as a result of a resource on at least part of a call route to the destination being congested. 
   
   
       18 . A telecommunications system according to  claim 1 , comprising a local exchange coupled to the network. 
   
   
       19 . A telecommunications system according to  claim 1 , wherein the network is a packet-switched network. 
   
   
       20 . A telecommunications system according to  claim 1 , wherein the network is a connection-oriented network. 
   
   
       21 . A telecommunications system according to  claim 20 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       22 . A telecommunications system according to  claim 1 , wherein the network is a wide area network (WAN). 
   
   
       23 . A telecommunications system according to  claim 1 , wherein the call routing server resolves contention for resources. 
   
   
       24 . A telecommunications system according to  claim 1 , wherein the call routing server responds to changes in state of a call by communicating with the connection controller, thereby to add, modify or remove connections in the network for transmitting call traffic for said call. 
   
   
       25 . A telecommunications system according to  claim 1 , wherein the call routing server responds to changes in state of a call by arranging for an echo canceller to be used in the call. 
   
   
       26 . A telecommunications system according to  claim 1 , wherein the network carries types of traffic other than said call traffic. 
   
   
       27 . A telecommunications system according to  claim 1 , wherein one or more of the connections are unidirectional. 
   
   
       28 . A telecommunications system according to  claim 1 , wherein one or more of the connections are bi-directional. 
   
   
       29 . A telecommunications system according to  claim 1 , wherein the connections are each established across one or more virtual trunks interconnecting nodes of the network. 
   
   
       30 . A telecommunications system according to  claim 1 , wherein virtual trunks are arranged to provide physically diverse paths through the network for resiliency. 
   
   
       31 . A node for use in a telecommunications system comprising a broadband digital communications network, the node comprising:—
 a call routing server configured to determine, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network; and   a connection controller configured to establish one or more connections in the broadband digital communications network on the basis of a route in the set of candidate routes, the connection being for transmitting traffic in respect of the call.   
   
   
       32 . A node according to  claim 31 , wherein the call routing server and connection controller are configured to communicate with each other in order to maintain or remove connections in the network in addition to establishing connections to enable transmission of call traffic over said route. 
   
   
       33 . A node according to  claim 31 , wherein at least one of the call routing server and the connection controller is distributed across a plurality of nodes of the network. 
   
   
       34 . A node according to  claim 31 , wherein the call routing server responds to changes in state of a call by communicating with the connection controller, thereby to add, modify or remove connections in the network for transmitting call traffic for said call. 
   
   
       35 . A call routing server for use in a telecommunications system comprising a broadband digital communications network, the call routing server comprising:—
 a call routing information determiner configured to determine, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network.   
   
   
       36 . A call routing server according to  claim 35 , wherein the call routing server is configured to communicate with a connection controller in the network in order to maintain or remove connections in the network in addition to establishing connections to enable transmission of call traffic over a route determined by the call routing server. 
   
   
       37 . A call routing server according to  claim 35 , wherein the connection controller is distributed across a plurality of nodes of the network. 
   
   
       38 . A call routing server according to  claim 35 , wherein the call routing server implements narrowband signaling. 
   
   
       39 . A call routing server according to  claim 35 , wherein the call routing server is a proxy call routing server. 
   
   
       40 . A call routing server according to  claim 39 , wherein the proxy call routing server uses a proxy signaling protocol to perform said communicating. 
   
   
       41 . A call routing server according to  claim 39 , wherein the proxy call routing server implements a service that goes beyond the routing capabilities of narrowband signaling. 
   
   
       42 . A call routing server according to  claim 39 , wherein the proxy call routing server is a multimedia server. 
   
   
       43 . A call routing server according to  claim 35 , wherein the route identifies endpoints of the network between which call traffic may be transmitted. 
   
   
       44 . A call routing server according to  claim 35 , wherein the call routing server is arranged to prioritize ones of a plurality of potential call routes according to a static priority. 
   
   
       45 . A call routing server according to  claim 35 , wherein the call routing server is arranged to prioritize ones of a plurality of potential call routes according to a dynamic priority. 
   
   
       46 . A call routing server according to  claim 35 , wherein the call routing server is arranged to determine availability of a call destination point and to reject a call to that destination point in the event that the destination point is unavailable. 
   
   
       47 . A call routing server according to  claim 46 , wherein the destination point is unavailable as a result of a resource on at least part of a call route to the destination being congested. 
   
   
       48 . A call routing server according to  claim 35 , wherein the network is a packet-switched network. 
   
   
       49 . A call routing server according to  claim 35 , wherein the network is a connection-oriented network. 
   
   
       50 . A call routing server according to  claim 49 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       51 . A call routing server according to  claim 35 , wherein the network is a wide area network (WAN). 
   
   
       52 . A call routing server according to  claim 35 , wherein the network carries types of traffic other than said call traffic. 
   
   
       53 . A call routing server according to  claim 35 , wherein the call routing server responds to changes in state of a call by communicating with the connection controller, thereby to add, modify or remove network for transmitting call traffic for said call. 
   
   
       54 . A call routing server according to  claim 35 , wherein the call routing server responds to changes in state of a call by arranging for an echo canceller to be used in the call. 
   
   
       55 . A connection controller for use in a telecommunications system comprising a broadband digital communications network and a call routing server, the connection controller comprising:—
 a connection establisher configured to establish one or more connections in the broadband digital communications network on the basis of a route in a set of candidate routes determined by the call routing server, the connection being for transmitting traffic in respect of the call.   
   
   
       56 . A connection controller according to  claim 55 , wherein the connection controller is configured to communicate with a call routing server in the network in order to maintain or remove connections in the network in addition to establishing connections to enable transmission of call traffic over a route determined by the call routing server. 
   
   
       57 . A connection controller according to  claim 55 , wherein the route identifies endpoints of the network between which call traffic may be transmitted. 
   
   
       58 . A connection controller according to  claim 55 , wherein the network is a packet-switched network. 
   
   
       59 . A connection controller according to  claim 55 , wherein the network is a connection-oriented network. 
   
   
       60 . A connection controller according to  claim 55 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       61 . A connection controller according to  claim 55 , wherein the network is a wide area network (WAN). 
   
   
       62 . A connection controller according to  claim 55 , wherein the network carries types of traffic other than said call traffic. 
   
   
       63 . A connection controller according to  claim 55 , wherein one or more of the connections are unidirectional. 
   
   
       64 . A connection controller according to  claim 55 , wherein one or more of the connections are bi-directional. 
   
   
       65 . A telecommunications system comprising:—
 a broadband digital communications network;   means for determining, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network; and   means for establishing one or more connections in the broadband digital communications network on the basis of a route in the set of candidate routes, the connection being for transmitting traffic in respect of the call.   
   
   
       66 . A node for use in a telecommunications system comprising a broadband digital communications network, the node comprising:—
 means for determining, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network; and   means for establishing one or more connections in the broadband digital communications network on the basis of a route in the set of candidate routes, the connection being for transmitting traffic in respect of the call.   
   
   
       67 . A call routing server for use in a telecommunications system comprising a broadband digital communications network, the call routing server comprising:—
 means for determining, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network.   
   
   
       68 . A connection controller for use in a telecommunications system comprising a broadband digital communications network, the connection controller comprising:—
 means for establishing one or more connections in the broadband digital communications network on the basis of a route in a set of candidate routes determined by the call routing server, the connection being for transmitting traffic in respect of the call.   
   
   
       69 . A method of establishing a call in a telecommunications system comprising a broadband digital communications network; the method comprising:
 determining, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network; and   means for establishing one or more connections in the broadband digital communications network on the basis of a route in the set of candidate routes, the connection being for transmitting traffic in respect of the call.   
   
   
       70 . A method of determining call routing information for use in a telecommunications system comprising a broadband digital communications network, the method comprising the steps of:—
 determining, for a call, a set of candidate routes, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network.   
   
   
       71 . A method according to  claim 70 , wherein the route identifies endpoints of the network between which call traffic may be transmitted. 
   
   
       72 . A method according to  claim 70 , wherein the call routing information is determined by a call routing server and the call routing server prioritizes ones of a plurality of potential call routes according to a static priority. 
   
   
       73 . A method according to  claim 70 , wherein the call routing information is determined by a call routing server and the call routing server prioritizes ones of a plurality of potential call routes according to a dynamic priority. 
   
   
       74 . A method according to  claim 70 , wherein the call routing information is determined by a call routing server and the call routing server selects between a plurality of potential call routes according to an assessment of congestion on the plurality of potential call routes, thereby to balance load across the network. 
   
   
       75 . A method according to  claim 74 , wherein the assessment of congestion is based on advertisements of congestion status received by one or more local nodes from one or more remote nodes of the network. 
   
   
       76 . A method according to  claim 70 , wherein the call routing information is determined by a call routing server and the call routing server determines availability of a call destination point and rejects a call to that destination point in the event that the destination point is unavailable. 
   
   
       77 . A method according to  claim 76 , wherein the destination point is unavailable as a result of a resource on at least part of a call route to the destination being congested. 
   
   
       78 . A method according to  claim 70 , wherein a connection controller selects one of a plurality of potential call routes for transmitting call traffic on the basis of an assessment of congestion in the network, thereby to balance load across the network. 
   
   
       79 . A method according to  claim 78 , wherein the assessment of congestion is based on advertisements of congestion status received by one or more local nodes from one or more remote nodes of the network. 
   
   
       80 . A method according to  claim 70 , wherein a connection controller rejects a call to be routed through a specified endpoint of the network if said endpoint is unreachable as a result of an assessment of congestion in the network. 
   
   
       81 . A method according to  claim 80 , wherein the assessment of congestion is based on advertisements of congestion status received by one or more local nodes from one or more remote nodes of the network. 
   
   
       82 . A method according to  claim 70 , wherein a local exchange is multi homed to the network at a plurality of network ingress points and wherein one of said ingress points through which to route call traffic from said local exchange into the network is selected in dependence on an assessment of congestion in the network thereby to balance load across the network. 
   
   
       83 . A method according to  claim 82 , wherein the assessment of congestion is based on advertisements of congestion status received by one or more local nodes from one or more remote nodes of the network. 
   
   
       84 . A method according to  claim 70 , wherein a local exchange is multi homed to the network at a plurality of network ingress points and wherein one of said ingress points through which to route call traffic from said local exchange into the network is selected in dependence on an assessment of congestion in the telecommunications system thereby to balance load on routes homing to the network. 
   
   
       85 . A method according to  claim 70 , wherein the network is a packet-switched network. 
   
   
       86 . A method according to  claim 70 , wherein the network is a connection-oriented network. 
   
   
       87 . A method according to  claim 86 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       88 . A method according to  claim 70 , wherein the network is a wide area network (WAN). 
   
   
       89 . A method according to  claim 70 , wherein the network carries types of traffic other than said call traffic. 
   
   
       90 . A method according to  claim 70 , wherein one or more of the connections are unidirectional. 
   
   
       91 . A method according to  claim 70 , wherein one or more of the connections are bi-directional. 
   
   
       92 . A method in a telecommunications system comprising a broadband digital communications network, the method comprising:—
 establishing one or more connections in the broadband digital communications network on the basis of a route in a set of candidate routes determined by the call routing server, the set of candidate routes including one or more routes through the broadband digital communications network, the routes in the set of candidate routes comprising one or more alternative connections in the broadband digital communications network, and being determined independently of any connections established in the broadband digital communications network   
   
   
       93 . A telecommunications system comprising:—
 a broadband digital communications network;   a call routing server configured to make at least an initial call routing decision in respect of a call independently of any connections established in the network specifically for transmitting call traffic in the network; and   a connection controller configured to establish one or more connections in the network for transmitting traffic in respect of the call thereby to give effect to the at least initial call routing decision, the connection being for transmitting traffic in respect of the call.   
   
   
       94 . A node for use in a telecommunications system comprising a broadband digital communications network, the node comprising:—
 a call routing server configured to make at least an initial call routing decision in respect of a call independently of any connections established in the network specifically for transmitting traffic in respect of the call; and   a connection controller configured to establish one or more connections in the network for transmitting traffic in respect of the call thereby to give effect to the at least initial call routing decision, the connection being for transmitting traffic in respect of the call.   
   
   
       95 . A call routing server for use in a telecommunications system comprising a broadband digital communications network, the call routing server comprising:—
 an initial call routing decision maker configured to make at least an initial call routing decision independently of any connections established in the network specifically for transmitting traffic in respect of the call.   
   
   
       96 . A connection controller use in a telecommunications system comprising a broadband digital communications network, the connection controller comprising:
 a receiver configured to receive an at least initial call routing decision made by a call routing server independently of any connections being established in the network specifically for transmitting traffic in respect of the call, and   a connection establisher configured to establish one or more connections in the network for transmitting traffic in respect of the call thereby to give effect to the at least initial call routing decision.   
   
   
       97 . A method of routing calls in a telecommunications system comprising a broadband digital communications network, the method comprising the following steps:
 making at least initial call routing decisions in respect of a call independently of any connections being established in the network specifically for transmitting traffic in respect of the call.   
   
   
       98 . A telecommunications system comprising:—
 a broadband digital communications network, and   a connection controller for establishing, maintaining, and removing connections in the network, the connections being for transmitting call traffic,   wherein the connection controller is arranged to determine at source a route across the network for a connection and to establish the connection by forwarding a message through the network, the message indicating the route.   
   
   
       99 . A telecommunications system according to  claim 98 , wherein the message indicates the route by indicating one or more virtual trunks interconnecting nodes of the network. 
   
   
       100 . A telecommunications system according to  claim 98 , wherein the selection of nodes is on the basis of logical placement with respect to a local node. 
   
   
       101 . A telecommunications system according to  claim 98 , wherein the network is a packet-switched network. 
   
   
       102 . A telecommunications system according to  claim 98 , wherein the network is a connection-oriented network. 
   
   
       103 . A telecommunications system according to  claim 102 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       104 . A telecommunications system according to  claim 98 , wherein the network is a wide area network (WAN). 
   
   
       105 . A telecommunications system according to  claim 98 , wherein the network carries types of traffic other than said call traffic. 
   
   
       106 . A telecommunications system according to  claim 98 , wherein one or more of the connections are unidirectional. 
   
   
       107 . A telecommunications system according to  claim 98 , wherein one or more of the connections are bi-directional. 
   
   
       108 . A telecommunications system according to  claim 98 , wherein the connection is established across one or more virtual trunks interconnecting nodes of the network. 
   
   
       109 . A telecommunications system according to  claim 108 , wherein the virtual trunks are arranged to provide physically diverse paths through the network for resiliency. 
   
   
       110 . A connection controller for use in a telecommunications system comprising a broadband digital communications network, the connection controller being for establishing a connection in the network for transmitting call traffic, the connection controller comprising:—
 a source route determiner configured to determine, at source, a route across the network for the connection, and   a connection establisher configured to establish the connection by forwarding a message through the network, the message indicating the route.   
   
   
       111 . A connection controller according to  claim 110 , wherein the message indicates the route by indicating one or more virtual trunks interconnecting nodes of the network. 
   
   
       112 . A connection controller according to  claim 110 , wherein the route is determined in accordance with an assessment of congestion in the network. 
   
   
       113 . A connection controller according to  claim 110 , wherein the network is a packet-switched network. 
   
   
       114 . A connection controller according to  claim 110 , wherein the network is a connection-oriented network. 
   
   
       115 . A connection controller according to  claim 110 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       116 . A connection controller according to  claim 110 , wherein the network is a wide area network (WAN). 
   
   
       117 . A connection controller according to  claim 110 , wherein the network carries types of traffic other than said call traffic. 
   
   
       118 . A connection controller according to  claim 110 , wherein one or more of the connections are unidirectional. 
   
   
       119 . A connection controller according to  claim 110 , wherein one or more of the connections are bi-directional. 
   
   
       120 . A connection controller according to  claim 110 , wherein the connection is established across one or more virtual trunks interconnecting nodes of the network. 
   
   
       121 . A telecommunications system comprising:—
 a broadband digital communications network, and   means for establishing, maintaining, and removing connections in the network, the connections being for transmitting call traffic,   wherein the means for establishing, maintaining, and removing connections is arranged to determine at source a route across the network for a connection and to establish the connection by forwarding a message through the network, the message indicating the route.   
   
   
       122 . A connection controller for use in a telecommunications system comprising a broadband digital communications network, the connection controller being for establishing a connection in the network for transmitting call traffic, the connection controller comprising:—
 means for determining at source a route across the network for the connection, and   means for establishing the connection by forwarding a message through the network, the message indicating the route.   
   
   
       123 . A method of establishing a connection in a broadband digital communications network of a telecommunications system, the connection being for transmitting call traffic, the method comprising:—
 determining at source a route across the network for the connection, and   establishing the connection by forwarding a message through the network, the message indicating the route.   
   
   
       124 . A method according to  claim 123 , wherein the message indicates the route by indicating one or more virtual trunks interconnecting nodes of the network. 
   
   
       125 . A method according to  claim 123 , wherein the network is a packet-switched network. 
   
   
       126 . A method according to  claim 123 , wherein the network is a connection-oriented network. 
   
   
       127 . A method according to  claim 126 , wherein the network is an asynchronous transfer mode (ATM) network. 
   
   
       128 . A method according to  claim 123 , wherein the network is a wide area network (WAN). 
   
   
       129 . A method according to  claim 123 , wherein the network carries types of traffic other than said call traffic. 
   
   
       130 . A method according to  claim 123 , wherein one or more of the connections are unidirectional. 
   
   
       131 . A method according to  claim 123 , wherein one or more of the connections are bi-directional. 
   
   
       132 . A method according to  claim 123 , wherein the connection is established across one or more virtual trunks interconnecting nodes of the network. 
   
   
       133 . A telecommunications system comprising:—
 a broadband digital communications network, and   means for determining a route through the network for a connection, the connection being for transmitting call traffic;   means for establishing a message specifying nodes in the network comprising the route of the connection through the network; and   means for forwarding said message to each of the nodes in the route in a forward direction of said connection and passing said or another message back through the route by way of acknowledging establishment of said connection.   
   
   
       134 . A method of establishing a connection in a broadband digital communications network of a telecommunications system, the connection being for transmitting call traffic, the method comprising:—
 determining a route through the network for the connection;   establishing a message specifying nodes in the network comprising the route of the connection through the network;   forwarding said message to each of the nodes in the route in a forward direction of said connection and passing said or another message back through the route by way of acknowledging establishment of said connection.