Telephonic communications – With usage measurement – Call charge metering or monitoring
Reexamination Certificate
1998-03-20
2001-06-05
Matar, Ahmad (Department: 2642)
Telephonic communications
With usage measurement
Call charge metering or monitoring
C379S220010
Reexamination Certificate
active
06243449
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method and system for avoiding congestion in a network of switches (nodes) due to a mass calling event (MCE).
A terminating number (TN) is a destination number serviced by a terminating switch (which switch may be inside or outside a given switch network). A focussed MCE occurs where the rate of calls to any given TN (the “congestion TN”) increases dramatically resulting in a large number of incomplete calls directed towards that number. For example, where a TN is a number for a ticket outlet, a focussed MCE may occur as soon as tickets for a popular concert go on sale.
Most circuit switched communications networks allocate a call path in a forward fashion in that they will begin routing of each call until the call is blocked by a network element which is “busy” (i.e., fully occupied). In such a network, a focussed MCE may quickly congest the entire network precluding calls to other TNs from being connected. Even if the focussed MCE does not congest the entire network, it will result in a waste of switching resources (causing unnecessary processing at each switch) and transmission resources (i.e., trunks between switches).
U.S. Pat. No. 5,295,183 issued March 15, 1994 to Langlois describes a system for coping with non-focussed MCEs (i.e., MCEs which are not caused by calls to one or a few specific TNs but result from general network congestion). In Langlois, switch occupancy rates are sent by each switch to a network processor (NP) on a periodic basis. When the occupancy rate of a switch exceeds a threshold, the NP sends back a recommendation to all switches in the network with an identifier of the congested switch and a call gap for calls to the congested switch. Upon receiving the recommendation, the switches begin timing a “call gapping time”. When a switch receives a call that is directed toward the congested switch, if the call gapping time has elapsed, the call is routed as usual and the gapping time is reset. On the other hand, if a switch receives a call directed to the congested switch and the gap time has not elapsed, the call is blocked. When the NP receives new occupancy rates from the switches, it may broadcast a new recommendation. When the occupancy rate for a congested switch falls below a threshold, the NP may broadcast a message such that call gapping of calls directed to the previously congested switch ceases.
This invention seeks to cope with an MCE in a circuit switched communications network which allocates a call path in a forward fashion.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a method for handling a mass calling event (MCE) at a switch of a network, comprising the steps of, repetitively:
(a) logging ineffective attempts (IAs) to terminating numbers (TNs) which are on a monitoring list;
(b) sending a monitoring message to a network processor (NP) with the IA rate for each TN on said monitoring list;
(c) if, based on IAs logged in step (a), an IA rate in respect of a monitored TN is below a release threshold for a pre-determined time, removing said monitored TN from said monitoring list.
In accordance with another aspect of the present invention, there is provided a method for handling a mass calling event (MCE) at a switch of a network, comprising the steps of, repetitively:
(a) logging at least a portion of ineffective attempts (IAs) to at least a portion of terminating numbers (TNs) which are not on a monitoring list;
(b) logging IAs to TNs which are on said monitoring list;
(c) sending a monitoring message with the IA rate for each TN on said monitoring list;
(d) if, based on IAs logged in step (a), an IA rate in respect of a TN exceeds an alert threshold, sending an alert message specifying said TN and storing said TN on said monitoring list; and
(e) if, based on IAs logged in step (b), an IA rate in respect of a monitored TN is below a release threshold for a pre-determined time, removing said monitored TN from said monitoring list.
The alert and monitoring messages are received by a network processor which, in response, broadcasts call gapping messages to each switch of the network in respect of the TN(s) subject of the alert and monitoring messages. Each call gapping message instructs a switch to place a guard time between calls to the TN in the message.
In accordance with a further aspect of the present invention, there is provided a method for handling a mass calling event at a network processor (NP) of a network, comprising the steps of: receiving a monitoring message from at least one switch of said network specifying a controlled terminating number (TN), a number of calls blocked by said at least one switch due to application of a call gapping process and a number of calls passed by said at least one switch due to application of said call gapping process; broadcasting a call gapping message to switches on said network indicating a call gap to be applied to calls to said controlled TN, said call gap differing from switch to switch and, for a given switch, being based on a proportion of a sum of a number of calls to said controlled TN blocked and passed by said given switch to a sum of a number of calls to said controlled TN which are blocked and passed network-wide.
In accordance with yet another aspect of the present invention, there is provided a method for dynamically controlling access to a terminating number (TN) subject of a mass calling event (MCE) at a network processor (NP) of a first network, comprising the steps of: receiving a count of ineffective attempts (IAs) to the MCE TN from a first network detecting switch; determining an adjusted IA count as a sum of:
(i) IAs to said MCE TN resulting from calls arriving at said detecting switch on trunks from other switches in said first network and
(ii) a portion of a sum of:
(A) IAs to said MCE TN resulting from calls arriving at said detecting switch on local lines and
(B) IAs to said MCE TN resulting from calls arriving on trunks from outside of networks to which said detecting switch belongs determined by a ratio of:
(I) IAs to said MCE TN resulting from calls arriving on trunks from other switches in said first network to
(II) a sum comprised of, for each network of which said detecting switch is a part and which dynamically controls access to said MCE TN, IAs to said MCE TN resulting from calls arriving on trunks from other switches in said each network;
determining a call gap to apply to switches in said first network based on said adjusted IA count and; broadcasting a call gap message based on said call gap to switches in said first network.
REFERENCES:
patent: 5295183 (1994-03-01), Langlois et al.
patent: 5450483 (1995-09-01), Williams
patent: 5828729 (1998-10-01), Clermont et al.
patent: 5878224 (1999-03-01), Smith
patent: 5923742 (1999-07-01), Kodialam
patent: 5974126 (1999-10-01), Hollas et al.
Driesse Anton
LeBon Andre A.
Margulis Eugene E.
Wang Weilin W.
Agdeppa Hector
Matar Ahmad
Nortel Networks Limited
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