GB2280574A

GB2280574A - User interface for local area networks

Info

Publication number: GB2280574A
Application number: GB9315913A
Authority: GB
Inventors: Francis Yun-Tai Hung; Andrew Paul Lefevre
Original assignee: Northern Telecom Ltd
Current assignee: Nortel Networks Ltd
Priority date: 1993-07-31
Filing date: 1993-07-31
Publication date: 1995-02-01
Anticipated expiration: 2013-07-31
Also published as: GB2280574B; GB9315913D0

Abstract

A multi-user interface for a group of local area networks includes monitoring circuitry for each user to prevent unauthorised use of services. Each user port incorporates a data rate detector circuit which counts data pulses for each service in use during a preset clock period. If this count exceeds a predetermined value, the user is disconnected from that particular service. <IMAGE>

Description

USER INTERFACE FOR LOCAL AREA NETWORKS This invention relates to local area networks (LAN's), and in particular to a bandwidth or data rate detector circuit for use with such networks.

The invention also relates to a user/network interface.

A recent development in local area network (LAN) technology is the introduction of systems in which a user port is provided with access to a number of different local area network ortoken ring services of low and high data rate. Each user is billed for the use of the particular network service or services used, the higher data rate services being in general more expensive than the lower data rate services. Since the user port assignment allows different services to be passed, it is possible for example for a user to continue to use a service for which the subscription has expired. In more extreme cases a low data rate system may be reconfigured by a fraudulent customer e.g. in order to pass high data rate services with a resultant loss of revenue to the system provider.

The object of the invention is to minimise or to overcome this disadvantage.

According to the invention there is provided a circuit for determining the data rate of signals carried on a plurality of data ports accessing a corresponding plurality of data networks, the circuit including means for selectively scanning each said port, means for counting data pulses transmitted via that port in a predetermined time period, and means responsive to the counting means for disabling the data port when the count exceeds a preset value.

According to the invention there is further provided a circuit for determining the data rate of signals carried on a plurality of data ports providing access between a user and a corresponding plurality of data networks, the circuit including means for selectively accessing each said port, a counter for accumulating data bits from a said accessed port, clock means for resetting the counter after a predetermined period, an overflow register for accumulating overflow or carry bits from the counter during each said predetermined period, and control means for comparing the contents of the overflow register with preset values corresponding to each accessed data port whereby to disable a said port when the contents of the overflow register exceeds the preset value for that port.

According to another aspect of the invention there is provided an interface arrangement for providing a coupling between a first plurality of user terminals and a second plurality if data networks, the arrangement including user access ports one for each said user terminal and each incorporating data ports whereby, in use, the user may access one or more of said networks, supervisory means for selectively accessing each said data port and for counting data pulses transmitted via that port during a predetermined time period, and means for disabling the data port when the count exceeds a predetermined value indicative of an unauthorised data rate, An embodiment of the invention will now be described with reference to the accompanying drawings in which:: Fig. 1 is a schematic diagram of an installation providing a number of local area network services to a plurality of users; Fig. 2 shows a user access port incorporating a bandwidth control circuit for use in the installation of Fig. 1.

Referring to Fig. 1, this shows typical multi-network installation providing a number of network services e.g. to an office building. Each network L1 to Ln is coupled to the user terminals U1 to Um via a wiring closet 11 and user links 12. It will be appreciated that each user terminal may have access to more than one network, the networks available to a user being determined by arrangements made between that user and the respective network providers. Typically the networks and the user terminals are interconnected via a cross-point circuit 13 incorporated in the wiring closet 11.Associated with each user terminal is a respective access port B1 to Bm incorporating a bandwidth control circuit whereby the data rates of the services provided to that user terminal are monitored or supervised by a local control unit 14 via a serial data bus 15 so as to ensure that each user accesses only those network services to which that user is entitled.

The construction of a user port is shown in Fig. 2. The user port circuit incorporates data inputs Dli to Dln and corresponding data output DO1 to DOn one for each network. The user terminal should be coupled only to those inputs for corresponding to services that have been authorised for that terminal. However, it is possible that a particular user has accessed a particular service to which that user is not entitled. The path between each data input and data output may incorporate a corresponding amplifier Al to An to provide an appropriate level of gain.

The data rate of each data path is monitored via a counter 21, e.g. a 10-bit counter, which accesses the data paths selectively via switches S1 to Sn. This data rate corresponds to the particular service which the user associated with the bandwidth control circuit has accessed An amplifier 22 may be provided at the input to the counter 21.

Periodic resetting of the counter 21 is effected via a slow clock signal, e.g. of 100 kHz coupled to the reset input of the counter. Overflow or 'carry' bits from the counter are accumulated in an overflow register 23.

In use of the circuit, the switches S1 to Sm are selectively enabled in sequence whereby to monitor each corresponding data port. When a particular port is accessed via the corresponding switch, the counter 21 counts the number of data pulses transmitted through that port in one half of a clock period. If the number of data pulses is sufficiently high that the counter 21 overflows, then a bit is set in the overflow register 23 in an address corresponding to the particular data port being accessed. This provides a measure of the data rate on that port.

When all the data ports have been accessed1 i.e. at the end of a scanning cycle, the contents of the overflow register are transferred to the controller 14 via the serial data bus 15 and the overflow register is reset. The controller is programmed e.g. by the network provider, with user data corresponding to each system user, this data including the list of services to which that user is entitled. This user data is compared with the data received from the overflow register to determine whether a data rate on a particular port accessed by that user exceeds a predetermined rate indicative of misuse of that port.

Where a data rate exceeds a predetermined rate allocated to a particular user, the corresponding data port may be disabled and/or an alerting signal may be relayed to the system provider.

To detect different LAN standards where power spectra overlap, the controller 14 may sample the overflow register over a period of time to obtain sufficient data for statistical analysis to determine the particular LAN standard being used.

Claims

CLAIMS:

1. A circuit for determining the data rate of signals carried on a plurality of data ports accessing a corresponding plurality of data networks, the circuit including means for selectively accessing each said port, means for counting data pulses transmitted via that port in a predetermined time period, and means responsive to the counting means for disabling the data port when the count exceeds a preset value

2.A circuit for determining the data rate of signals carried on a plurality of data ports providing access between a user and a corresponding plurality of data networks, the circuit including means for selectively accessing each said port, a counter for accumulating data bits from a said accessed port, clock means for resetting the counter after a predetermined period, an overflow register for accumulating overflow or carry bits from the counter during each said predetermined period, and control means for comparing the contents of the overflow register with preset values corresponding to each accessed data port whereby to disable a said port when the contents of the overflow register exceeds the preset value for that port.

3. A circuit as claimed in claim 2, wherein the data ports are accessed each by a respective switch, there being means for selectively enabling the switches in sequence.

4. A circuit as claimed in claim 2 or 3, wherein said predetermined period comprises one half period of said clock.

5. A circuit as claimed in claim 2, 3 or 4, wherein said control means is adapted to determine the contents of the overflow register for a number of said predetermined periods whereby to obtain a statistical analysis of the data on said data ports.

6. A circuit for determining signal data rates substantially as described herein with reference to and as shown in the accompanying drawings.

7. An interface arrangement for providing a coupling between a first plurality of user terminals and a second plurality of data networks, the arrangement including user access ports one for each said user terminal and each incorporating data ports whereby, in use, the user may access one or more of said networks, supervisory means for selectively accessing each said data port and for counting data pulses transmitted via that port during a predetermined time period, and means for disabling the data port when the count exceeds a predetermined value indicative of an unauthorised data rate.

8. An interface arrangement substantially as described herein with reference to and as shown in the accompanying drawings.