Internet service via ISDN

Details Internet service via ISDN Internet service via ISDN

1997-09-26

2001-04-24

Kizou, Hassan (Department: 2662)

Multiplex communications

Pathfinding or routing

Combined circuit switching and packet switching

C370S438000, C370S264000, C370S230000, C370S524000

Reexamination Certificate

active

06222837

ABSTRACT:

TECHNICAL FIELD
This invention relates to the providing of Internet protocol (IP) based data service, and more particularly, for providing Internet service using the D-channel of an integrated services digital network (ISDN) line.
BACKGROUND OF THE INVENTION
It is well known in the art that Internet service can be provided over an integrated services digital network (ISDN) line. One such service utilizes multilink point-to-point protocol (MLPPP). MLPPP has been used to bond the two ISDN B-channels to provide Internet service at 128 Kbps. In addition, there is a proposal to allow the D-channel of an ISDN line to be bonded to the two B-channels, thus providing Internet service at approximately 144 Kbps. However, this proposal suffers from several drawbacks.
First, because the Internet protocol (IP) traffic is divided only according to available bandwidth, without regard for the type of application in which the packet is going to be used at its destination, packets for continuous media applications, e.g., audio or video, may wind up being transmitted over the D-channel. As is well known, the D-channel is a packet switched data channel, and so it has unpredictable delays. Consequently, it is unknown when a packet that is sent over the D-channel will arrive at its destination.
When using MLPPP for Internet service, all the packets must be reordered upon receipt at the first IP access server, e.g., a gateway or a router, to the order in which they were transmitted. Since some of packets that require reordering may have been sent over the D-channel, and this may have resulted in a significant delay, the release of packets that were transmitted and received over the B-channel may be correspondingly delayed while awaiting for the arrival of a D-channel packet that precedes them in order. Thus, the delay of the D-channel causes delays in the B-channel. In other words, packets sent over the D-channel may hold packets sent over the B-channel “hostage”.
As a result of such delays, continuous media applications may suffer from poor performance. Also, for continuous media applications, the buffer requirements at the access server is increased because the packets from the B-channel must be stored until any preceding packets from the D-channel arrives.
Second, because packets over the D-channel used with MLPPP are in the well known X.25 format, the information transmitted is preceded by several different protocol layer packet headers. Thus, the use of MLPPP and X.25 introduce unnecessary complexity, while reducing the effective bandwidth available for information transfer.
SUMMARY OF THE INVENTION
We have recognized that enhanced Internet service can be achieved over an ISDN line by eliminating from the D-channel any packets that will introduce unacceptable delay in packets transmitted over the B-channel, which may occur for continuous media applications transmitted as in the prior art described above. The enhancement is achieved by segregating the packets between the B-channels and the D-channel based on the stream to which the packets belong. Furthermore, in accordance with an aspect of the invention, instead of bonding together both B-channels and the D-channel, as in the prior art, only the B-channels may be bonded to each other, while the D-channel is kept independent. To do so, in one embodiment of the invention, instead of using MLPPP over the combination of both B-channels and the D-channel, as in the prior art, MLPPP is used over only both B-channels, while data that is separately directed to the D-channel employs another protocol, e.g., point-to-point protocol (PPP). Advantageously, the number of protocols used to transmit the information over the D-channel may be reduced, resulting in a higher bandwidth for applications.
In an exemplary embodiment of the invention, packets for continuous media applications, such as voice and video, are identified by examining the source, destination, and type information in the packet header. These packets are prevented from being transmitted via the D-channel, and instead are purposely placed only within the B-channel by the endpoint, e.g., via software that is interposed between the TCP/IP protocol stack and the link layer protocol stack. Other packets, which are also identified by examining the source, destination, and type information in the packet header, such as containing information for push-content model applications, active directory, or home appliance related information, are sent over the D-channel.
Packets may also be limited to being sent only over the D-channel.


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patent: 6073176 (2000-06-01), Baindur et al.
patent: 6115460 (2000-09-01), Crowe et al.
European Search Report dated Jun. 17, 1999 for Application No. EP 98 30 7219.

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