Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1999-03-30
2002-12-10
Patel, Ajit (Department: 2664)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S524000, C709S228000
Reexamination Certificate
active
06493336
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to an Always on Dynamic Integrated Services Digital Network (AO/DI) service and, more particularly, for automatically changing the Always-On-Dynamic Integrated Services Digital Network's (AO/DI's) thresholds that increase or decrease in bandwidth for effecting a corresponding change in the rate of data transfer capacity for an AO/DI subscriber.
2. Description of the Problem Solved
With the increased use of the Internet, World Wide Web, and other networks, the need for increasing access bandwidth to these networks has grown. The Integrated Services Digital Network (ISDN) protocol architecture using a Basic Rate Interface (BRI) user interface is widely used for network access and is relatively high speed. BRI consists of one D-channel and two B-channels. The D-channel has a bandwidth of 16 kilo-bytes-per-second (kbps). The D-channel transfers data through a packet switched network to the Internet (or other Networks). The D-channel is always active and, therefore, is primarily used for transfer of data that does not require high bandwidth and to exchange control information between the user and the network for call establishment and termination. The two B-channels are bearer communication channels. Each B-channel can carry voice, video or packet data at a bandwidth rate of 64 kbps. To transfer data at a rate faster than 64 kbps through a network from one end-point to another destination, the two B-channels in a BRI can be aggregated to provide a total bit rate of 128 kbps. The technique of aggregating two B-channels is called an aggregation of multiple links, and is known as inverse multiplexing. Inverse multiplexing is more thoroughly described in the article entitled “The PPP Multilink Protocol,” RFC 2125, March 1997, and which is incorporated herein by reference. The B-channels are carried through a circuit switched network and are not always on, but are seized and released depending on the need for access capacity. The D-channel is used to carry the requests for seizing and releasing B-channels.
For example, the D-channel can be used to transmit messages that setup a telephone call (a request for a B-channel) through a network from a calling party to a called party. The D-channel can also transmit packet data through the network to notify a calling party that the called party's telephone is ringing and whether the called party has answered the telephone call.
Although data can be transferred faster through a network by aggregating two B-channels of a BRI to serve one end user, it is recognized that it does have a cost. For example, aggregating two B-channels requires the use of two Digital Signal Level
0
(DS
0
) circuits in the circuit switched network, instead of one DS
0
. This results in higher end user, Local Exchange Carrier (LEC) and Internet Service Provider (ISP) cost. Furthermore, it is recognized that end users do not always need the B-channels, when they are reading an e-mail message or have walked away from the computer.
To control these end user, LEC and ISP high costs and still provide two channel bandwidth when needed, the present invention employs AO/DI networking services for fast transfer of data through a network without these higher costs. AO/DI networking services provide an always available connection via the D-channel of BRI to packet-based networks through the Wide Area Network (WAN). AO/DI networking services reduce the costs for the end user by using the D-channel to make low-speed data transfers. For ISPs, AO/DI networking removes a significant amount of holding time from the circuit switched connections (B-channels). Since the D-channel is always available, the customer premises equipment (CPE) can use the D-channel to pass Multilink Point-to-Point and TCP/IP protocols encapsulated in X.25 protocols.
Optionally, when D-channel bandwidth exceeds a defined threshold, the end user computer places one or more ISDN B-channel calls to increase bandwidth. When bandwidth requirements fall below a defined threshold, the B-channel or B-channels are released. AO/DI networking services use the D-channel of BRI to maintain a constant virtual connection to a central office switch in the circuit switched network. In this mode, the 16 kbps D-channel is capable of receiving and transmitting data, in addition to control signals, at 9.6 kbps. This bandwidth is quite suitable for transforming e-mail, stock quotes or news updates. When higher speed data transfers are required, such as downloading Web pages, one or both of the B-channels in the BRI can be activated automatically to transfer the data at bandwidths of 64 kbps or 128 kbps, respectively.
The AO/DI networking configuration uses a Bandwidth Allocation Protocol (BAP) and its associated control protocol, the Bandwidth Allocation Control Protocol (BACP), to transfer data and commands via the network between an end user and the end user's serving ISP. BAP provides a means (via datagrams) to implement dynamically adding and/or removing individual links (B-channels) from a multilink bundle, such as BRI.
BAP and BACP provide a flexible yet robust way of managing bandwidth between two end users. BAP does this by defining Call-Control packets and a protocol that allows end users to coordinate the actual bandwidth allocation and de-allocation. BAP can be used to manage the number of links in a multilink bundle. BAP and BACP are well known in the art. More information about BAP and BACP may be found in the publication entitled “The PPP Multilink 10 Protocol,” RFC 2125, March 1997, and which has been incorporated herein above by reference.
In operation, an end user implementing AO/DI networking services will generally need an AO/DI card. This AO/DI card is integrated with the end′ user's computer and serves as the computer's interface to an ISP via a circuit switched network and a packet switched network. The AO/DI card and ISP communicates with each other using BAPIBACP. The AO/DI card has default threshold parameters set to trigger a message to the ISP, asking for agreement from the ISP to request the circuit switched network to establish certain B-channel connections from the end user's computer to the ISP. Likewise, the ISP has threshold parameters set to trigger a message to the end user, instructing the end user to request the circuit switched network to establish certain B-channel connections between the end user's computer and the ISP. These messages are sent via an already established D-channel connection between the end user's computer and the ISP. For example, if the end user is transmitting information to the ISP, based on default threshold parameters of the AO/DI card, the end user may make a request—via the D-channel—to add a B-channel. The end user makes this request to the ISP via the D-channel connection using BAP/BACP to ask if the ISP is willing to add or remove B-channels from the end user to ISP. If the ISP agrees, the end user will initiate a call (acquisition of a B-channel) or release. The AO/DI card has a threshold table that is comprised of a set of threshold parameters that are used to trigger, when a message is to be sent from the end user's computer to an ISP. This message requests agreement with the ISP for request to the LEC to add or remove B-channels from the end user to the ISP via the circuit switched network. The threshold parameters of the AO/DI card are generally set to certain default parameters before the card is integrated with a computer. These threshold parameters cannot be readily changed. For example, an AO/DI card might be set to trigger sending a message to add one B-channel of a BRI if the end user is sending data at a bandwidth of greater than 7.5 kbps through a network and to remove the B-channel when the bandwidth decreases to less than 5.0 kbps; thereby, reverting back to sending data via the D-channel. The AO/DI card might be set to trigger sending a message to add both B-channels if the end user is sending data through the network
Dagert Patrick J.
Perry Mark J.
Nortel Networks
Nortel Networks Limited
Patel Ajit
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