Concurrent switching of synchronous and asynchronous traffic

Details Concurrent switching of synchronous and asynchronous traffic Concurrent switching of synchronous and asynchronous traffic

2001-06-04

2004-09-28

Vu, Huy D. (Department: 2665)

Multiplex communications

Channel assignment techniques

Details of circuit or interface for connecting user to the...

C370S458000, C370S354000

Reexamination Certificate

active

06798784

ABSTRACT:

CROSS REFERENCE TO ATTACHMENTS A-I
The following attachments which describe an illustrative embodiment of the present invention are a part of the present disclosure and are incorporated by reference herein in their entirety.
Attachment A entitled “Hardware Architectural Specification;”
Attachment B entitled “GRX ASIC Functional Specification;”
Attachment C entitled “GRX ASIC Packet Crosspoint Module Specification;”
Attachment D entitled “GRX ASIC Synchronous Crosspoint Module Specification;”
Attachment E entitled “GigaPoint Media Access Controller (GP MAC) Module Specification;”
Attachment F entitled “GigaPoint Bus Hardware Architectural Specification;”
Attachment G entitled “GigaPoint Access Processor (GAP) ASIC Functional Specification;”
Attachment H entitled “GAP ASIC GigaPoint Adaptation (GA) Module Specification;”
Attachment I entitled “GAP Virtual Output Queue Controller (VOQC)ASIC Module SpecificationGAP ASIC GigaPoint Adaptation (GA) Module Specification.”
Attachments A-I contain detailed specifications for various portions of the network element.
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appear in the U.S. Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND
Traditionally, central office switches that process telephone calls between subscribers typically use switches called Class 5 switches, such as the 5ESS available from Lucent. A telephone instrument may be directly connected to such a Class 5 switch as illustrated in
FIG. 1
if the telephone instrument is located within 18 kilofoot radius. Beyond the 18 kilofoot radius, support for such telephone instruments that use a copper twisted pair may be provided through a digital loop carrier (DLC) which has two portions; a central office terminal and a remote terminal. The central office terminal is normally located within the central office and communicates with the remote terminal using a digital signal over metallic (such as copper) or optical link (also called “digital line”). The central office terminal of the digital loop carrier is coupled to the Class 5 switch in the central office and the coupling may conform to an aggregation interface, sicj as GR303 (a standard defined by Telcordia). The remote terminal in turn is connected to a number of telephone instruments. Depending on the hardware installed within the remote terminal, such a remote terminal may also provide a high-speed trunk, such as T1 that may be needed by a business and/or be coupled via modems to personal computers to support data traffic.
The DLC remote terminal may be implemented by a digital multiplexer that combines a number of subscriber channels into a single high speed digital signal, and the DLC central office terminal implemented by a de-multiplexer. Because a digital line cannot carry signals as far as a corresponding analog line, the digital line often requires a number of digital repeaters to boost signal level. A typical digital line of a DLC carries from 24 to 3000 POTS circuits. Note that a DLC central office terminal may be eliminated, e.g. as in case of an Integrated Digital Loop Carrier System, wherein the digital line is directly connected to the Class 5 switch.
All of the above-described equipment up to the Class 5 switch in the central office is traditionally referred to as forming the “access” portion of a public switched telephone network (PSTN). The Class 5 switch may be associated with a portion of a telephone number, e.g. the portion
252
in a telephone number 408-252-1735. All telephones that are serviced by a single Class 5 switch are normally assigned a telephone number that includes a preset prefix, e.g.
252
. The Class 5 switch typically forms connections between telephones within its own service area, each of which starts with the preset prefix, e.g.
252
. When a telephone instrument within its service area places a call to a number different from the numbers starting with the preset prefix, the Class 5 switch connects the telephone instrument to another switch which may be of a different class, such as a Class IV switch, commonly referred to as a hub switch.
The hub switch is typically coupled to a number of Class 5 switches through a ring of add/drop multiplexer (ADMs). For example, each central office may have a Class 5 switch co-located with and coupled to an add/drop multiplexer, and in addition the hub switch is also co-located with and coupled to an add/drop multiplexer. All of the add/drop multiplexers are connected to one another in a ring topology. Such a ring topology typically contains two optical fiber connections between each pair of add/drop multiplexers, wherein one of the connections is redundant, and used primarily in case of failure. The just-described ring of add/drop multiplexers that connects a number of central office switches to a hub switch is typically referred to as forming the “interoffice” or “transport” portion of the public telephone network. The hub switch is typically connected to a number of other hub switches by another portion of the network commonly referred to as “core”.
To support data traffic, for example, to provide Internet access to a business, central offices typically contain additional equipment called a DSLAM which provides a digital subscriber line (DSL) connection to the business. The DSLAM may only service businesses that are within 18 kilofeet, e.g. because of the limitations of a copper twisted pair connection. Such DSLAMs are typically connected inside the central office to an add/drop multiplexer so that data traffic can be routed to an Internet Service Provider (ISP). For businesses located outside of 18 kilofeet radius of a central office, a remote terminal of a digital loop carrier can be used to provide an IDSL service, which is based on the use of a ISDN link to the central office, via the central office terminal of the DLC.
The development of DSLAM, IDC and IDSL applications was the result of the need for access to the Class 5 switch by remote businesses and subscribers, particularly due to development remote from the Class 5 switches. Recently, larger businesses have bypassed this copper remote access to the transport layer of networks using larger fiber optic trunks with large bandwidth capabilities. This new access has been called Metro Access. Smaller businesses would also benefit from this access, but so far most applications are too expensive to provide this direct access to small enterprise and subscribers. Thus, it would be highly desirable for a network access solution that provides the bandwidth of fiber access in the place of the typical copper remote access functions, especially that is cost-competitive with the legacy technology. It would also be highly desirable if that some solution could be used to perform cost-effectively at the remote access level, but through simple substitution of line card units to accommodate different types of traffic, could be deployed to interface with the core itself.
SUMMARY
In accordance with the invention, a network element can be configured for connection to any portion of a communication network: access, transport and core. Moreover, a single network element can be configured to couple subscriber equipment directly to the core portion of the network, thereby to bypass the transport portion of the network. Specifically, such a network element can be configured to include a line unit that supports subscriber equipment (also called “subscriber line unit”), and also to include a line unit to support a link to core of the communication network (also called “core line unit”). The subscriber line unit and core line unit is both installed in a single chassis, and each unit can be installed in any of a number of slots of the chassis. Moreover, when configured with appropriate line units, such a network element may support traditional circuit-switched te

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