Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
2000-01-14
2003-09-02
Olms, Douglas (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S352000, C370S401000, C370S395300, C709S241000, C709S241000
Reexamination Certificate
active
06614803
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to digital communication systems, and is particularly directed to a communication control mechanism, which is installable in the communications controller of a terminal adapter, such as that employed for integrated services digital network (ISDN) communications, and which is operative to enable in-band communications to be conducted between the terminal adapter and a digital terminal device coupled thereto, during an internet communication session between the digital terminal device and a network interface of an internet service provider.
BACKGROUND OF THE INVENTION
As diagrammatically illustrated in the reduced complexity network communication diagram of
FIG. 1
, terminal adapters, such as that shown at
11
, enable digital communication signals, such as ISDN signals, to be interfaced between a customer's digital terminal equipment (DTE)
13
and a network access server
15
for a communication network
17
, by adapting the network's serial line rate and coding into those of the connected digital communication port of the DTE. In addition to serving as a conduit for digital data communications, which are typically encapsulated by means of point-to-point protocol (PPP) between the DTE
13
and the network server
15
, the terminal adapter
11
typically includes additional ports, such as may be employed for analog (POTS) and digital voice (B
1
/B
2
) voice channel communications with telephone devices
14
.
Although a conventional terminal adapter is typically controllably configurable by the user (either directly through panel switches, or from the DTE), modifying its parameters via the DTE requires that the terminal adapter be off-line. Moreover, where the additional ports of the terminal adapter are being used for other calls during an internet session, the user of the DTE may wish to be provided with information relating to their use (for example by way of a pop-up window)—something that is not currently available in a conventional terminal adapter.
SUMMARY OF THE INVENTION
In accordance with the present invention, this conventional inability to conduct on-line communications between the terminal adapter and the user's DTE is successfully obviated by means of a digital message monitoring mechanism, that is installable in the terminal adapter's communications control processor. Pursuant to the invention, this digital message monitoring mechanism is operative to identify the internet protocol addresses for each of the DTE (personal computer) and the internet service provider's digital communication network interface, as these addresses are negotiated during a data link establishment communication exchange between the digital communication network interface and the DTE.
As noted above, the encapsulation and transportation of higher layer packet protocols, such as internet protocol (IP), over a digital communication link, such as a wide area network link, often employs point-to-point protocol (PPP) between peers. One of these peers is the digital terminal equipment (e.g., personal computer (PC)); the other is the network access server. In the course of establishing a communication (internet) session, PPP options are negotiated as a mechanism for relaying information. The link control protocol (LCP) is negotiated first. For IP packet transfer, IP control protocol (IPCP) must be negotiated after the LCP has reached the open state, and after any authentication has been completed. One of the IPCP options involves assigning or announcing the IP address of each peer.
During IPCP negotiation, the network access server will customarily assign the user's personal computer with an IP address for its TCP/IP stack. Also, the network access server can inform the DTE of its (the server's ) IP address. Once a connection or data link has been established between the DTE's terminal adapter and the remote network access server, it is necessary to provide a (logical) port additional to the data port to the DTE for control and status signaling.
In accordance with the invention, the terminal adapter's communication controller monitors the IPCP packets by way of a packet decoder installed in the respective serial transmission paths from the PC to the network access server, and from the network access server to the PC. In the DTE-to-network interface direction, packets are clocked through a serial queue to the PPP packet decoder, the output of which is controllably gated by the communication controller. When a packet is destined for the terminal adapter rather than the network access server, the gate is disabled to prevent the packet from being forwarded to the network access server. In the network interface-to-DTE direction, packets are coupled to the terminal adapter by way of a network interface and clocked through a serial queue to the PPP decoder.
During the IP address negotiation portion of the internet session, the PPP packet decoder examines the contents of the IPCP packets for peer IP address information, that will allow the terminal adapter to communicate in-band with the DTE using user datagram protocol (UDP) -based messages injected into the serial data path to the DTE. In a complementary fashion, the DTE may send UDP-based messages to the terminal adapter. Information in the UDP packets will prompt the communication controller to prevent the packets from being forwarded to the network access server.
The UDP destination (logical) port number may be any random port number, that is predetermined in accordance with the listener task software being run by the DTE. In addition, an IP header created by the terminal adapter contains a source IP address and a destination IP address. The source IP address is the IP address of the network access server and the destination IP address is the IP address of the DTE that were negotiated and stored by the terminal adapter during data link establishment. The listener task routine captures all UDP packets directed to the predetermined port number. The DTE's TCP/IP stack passes status information conveyed in the captured packets to the program for display on a graphic user interface.
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Chang Lin Yow-Chern
Farnsworth Kyle A.
Goodwin C. Brian
Adtran Inc.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Nguyen Van Kim T.
Olms Douglas
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