Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1998-06-05
2001-11-27
Yao, Kwang B. (Department: 2664)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S424000
Reexamination Certificate
active
06324176
ABSTRACT:
TECHNICAL FIELD
This invention relates to the switching of connectionless data traffic through digital switches of the type used for switching voice traffic.
Problem:
In recent years, the volume of Internet traffic has grown tremendously. Much of this traffic originates, is switched through, or terminates in a telephone switching system having a digital time slot interchange switching network. These switches which are now pervasive through the modern public switched telephone network were designed initially to handle voice and circuit switched data traffic. Subsequently, many of these switches were adapted to handle integrated switched digital network (ISDN) traffic which combines switched voice, circuit switched data traffic, and some (D-channel) data switched data traffic. At this point, these switches are being adapted to handle data traffic required for serving Internet customers, traffic which when it enters the Internet backbone network, becomes connectionless.
The arrangements available in the prior art for serving connectionless traffic in telephone type switching systems are not efficient. One such arrangement uses an adjunct processor connected from and to a time slot interchange (TSI) network via trunk circuits of the type used for communicating with distant switching systems. This arrangement is expensive in its use of time slots and requires a large amount of memory in addition to the memory provided within the TSI.
In the prior art, connections through a telephone access switch are made directly to the Internet backbone network; this ties up a trunk to the Internet network for the duration of an Internet call.
Another alternative is to use the type of packet switch unit added to digital switches in order to process the relatively small amount of data switched traffic of ISDN lines. Such units have inadequate capacity, and also require the use of extra time slots and extra memory in addition to the TSI memory. A first problem with the prior art, therefore, is that there is no efficient way of handling the connectionless data traffic of Internet type data traffic.
Solution:
The above problem is solved, and an advance is made over the prior art in accordance with our invention wherein a processor means is directly tied to the memory of a TSI. This processor accumulates and transmits packets in a packet assembler-disassembler, and inserts output packets into an output buffer. In one embodiment of the Applicants' invention, the processor inserts output packets into a loopback buffer (normally used to write diagnostic patterns into the TSI memory); this processor, advantageously can access all time slots of the TSI since this is a fundamental characteristic of the TSI. The processor provides a centralized location for rate adaptation to allow slow rate Internet traffic to be adapted to fast rate transmission. The operations and mainten-ance (OA&M) arrangements for the processor can be readily combined with the OA&M arrangements of the switch. The higher reliability of a telephone switch can be used advantageously to provide similar high reliability for this Internet type traffic. The processor can readily access the subscriber data base, translations, and the subscriber line signaling information received in the switch.
In accordance with one preferred embodiment of the Applicants' invention, a digital signal processor in the TSI is used to modulate/demodulate PCM signals generated using analog lines and modems prior to being accumulated in the packet assembler-disassembler. Advantageously, this eliminates the need for external modems, that require extra time slots, to condition the PCM signals. In accordance with Applicant's preferred embodiment, the routing processor has access to all egress links via the loopback buffer access to all memories of the TSI. Advantageously, the processor may be connected to any idle time slot.
In a second embodiment of the Applicants' invention, the processor may be directly connected to data interfaces such as an ATM data interface that can be readily added to the TSI. In this embodiment, the Internet traffic is transmitted over a data network as a plurality of ATM cells.
In accordance with a third embodiment of the Applicants' invention, the processor may be directly connected to an LAN Interface such as Ethernet that could be readily added to the TSI. In this embodiment, the Internet traffic is transmitted directly to resident server advantageously providing Intranet capabilities for subscribers.
REFERENCES:
patent: 6101187 (2000-08-01), Cukier et al.
patent: 0836353A2 (1997-08-01), None
Bodnar Bohdan Lew
Dunn James Patrick
Herse Conrad Martin
Tammaru Enn
Lucent Technologies - Inc.
Ulrich Werner
Yao Kwang B.
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