XDSL-based internet access router

Details XDSL-based internet access router XDSL-based internet access router

1998-12-02

2002-12-10

Kizou, Hassan (Department: 2662)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S356000, C370S395100, C370S398000, C370S535000

Reexamination Certificate

active

06493348

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to an Internet protocol (IP) based system, and more particularly, to an IP based system that facilitates communication and quality of service (QoS) between remote user terminals and Web servers across parts of the Internet that are configured by an asynchronous transfer mode (ATM) network or other communication networks.
BACKGROUND OF THE INVENTION
An asynchronous transfer mode network is a network that can transfer information from one or more sources to one or more destinations. The ATM network can be deployed for configuring parts of the Internet, thus comprising a communication network. The communication network itself may be composed of multiple communicating nodes (e.g., terminals, routers, servers, switches, etc.) that are interconnected to each other by physical communication links (wires, cables, optical fibers, RF channels, etc.). An ATM-equipped node transmits a signal containing a bit stream to an adjacent node via the communication link that connects the two adjacent nodes. The transmitted bit stream is organized into fixed sized packet or “cell”slots for carrying, e.g., 53 byte packets called cells. Illustratively, each cell has a 5 byte header for communicating control information, and a 48 byte payload for communicating a message to be conveyed between nodes. A node allocates a “virtual channel” to each communication, which, amongst other things, identifies an adjacent node to which cells of the communication must be transmitted. A sequence of virtual channels of nodes on a path between a source node and a destination node identifies a virtual channel connection.
The source node transmits cells to the destination node via this sequence of virtual channels, i.e., from node to node on the path, in a bucket brigade like fashion. Prior to transmitting the information, the source node segments the information into 48 byte sized messages and appends a 5 byte header to each such message to form a cell. The source node writes a virtual address, such as a virtual channel identifier, which enables each node on the path that receives the cell to determine the outgoing virtual channel on which to transmit the cell. A destination node receiving the cells extracts the messages from the payloads and reassembles the messages (in the appropriate order) into the originally transmitted information.
It is important to note that, when communicating between Local Area Networks (LANs) (such as Ethernets) on the Internet which is configured by various links and networks including the ATM network, the data-link layer communications in LAN networks are different than those in the ATM networks. Thus, bridges are utilized to receive information from one network (e.g., LAN) transmitted according to the respective data-link layer and retransmit the information in the other network (e.g., ATM network) according to its respective data-link layer. In other words, bridges decouple the two incompatible data-link layers from each other, yet enable communication between nodes in each of the two networks.
At the network layer, all of the nodes may communicate using the same protocol, e.g., the Internet protocol (IP). Like the Ethernet protocol, each node that can serve as a source or destination node is assigned an IP identifier, or IP address. Information is transmitted from a source node to a destination node in a bit stream that is organized into packets. As previously stated, each packet has a header and a payload. The IP address of the source node is written in a source field of the packet header, and the IP address of the destination node is written in a destination field of the packet header. The data is then written in the payload. The packet is then transmitted according to the appropriate data-link layer protocol for the network (e.g., formed into Media Access Control (MAC) frames, divided into ATM cells, etc.) and then transmitted to its respective destination node. IP provides a routing function for routing a packet from node to node in a sequence of nodes until the packet arrives at its destinations using routing tables.
Such communications networks are becoming increasingly important vehicles for delivering video, audio and other data to and from remote user terminals. For example, such networks are used to support video-on-demand, near video-on-demand, and pay-per-view applications. However, problems are evident in terms of adequate bandwidth.
Typically, wideband (1-10 Mb/s) access technologies are relatively expensive and specialized (such as T1 lines), such that their use has been primarily by large institutional customers, such as large corporations, universities, and government agencies. However, a number of new network access technologies are now moving from the research labs into general availability. For example, some network providers have started to deploy hybrid fiber coax access lines, as well as cable modems. Further, trials and limited deployments of a variety of Digital Subscriber Line (xDSL) (e.g., Asymmetrical Digital Subscriber Lines—ADSL) technologies are also ongoing. All of this activity is intended to bring broadband networks to the mass market. The ATM network, as previously described, is intended to “bridge the gap” in providing wideband transmission rates to a remote user in an Internet environment.
A conventional IP based system is shown in FIG.
1
. System
10
includes groups
12
a,
12
b
through
12
N of remote user terminals
15
, where each group is part of an Ethernet or other LAN system. Each group
12
a,
12
b
through
12
N is connected to a respective Ethernet bridge, illustratively an Asymmetrical Digital Subscriber Line (ADSL) termination unit—remote side (as opposed to a central office side) ATU-R
18
a,
18
b
through
18
N, respectively, for providing an Ethernet bridge between the LAN system and the respective default IP router. ATU-Rs
18
a,
18
b,
18
c
through
18
N are also connected to respective telephones
16
a,
16
b,
16
c
through
16
N.
System
10
further includes a plurality of ADSL based Digital Subscriber Line Access Multiplexors (DSLAM)
20
a
through
20
N, each of which is connected to a plurality of ATURs. Each DSLAM provides basic transport and multiplexing functions between each respective ATU-R
18
and an ATM switch
22
. ATM switch
22
is further connected to a plurality of Web servers
28
a
through
28
N, IP edge routers
26
a
through
26
N and IP backbone router
24
for connection to the Internet. The function of each will be described below.
First, we describe the ADSL technology. ADSL was motivated by the goal of achieving wideband transmission rates over existing copper loops. The concept has achieved a growing acceptance by the telecommunications industry and resulted in a standardization effort.
The main idea behind ADSL is that overlapping parts of the spectrum should be present only for signals that are propagating in the same direction within a single bundle of copper wire pairs. This approach reduces the effect of near-end and far-end crosstalk, and hence makes wideband transmission rates feasible for reasonably large loop lengths (up to 18,000 ft). Several characteristics of traditional ADSL systems are specifically tailored to their intended application in residential local loops. These include the asymmetry of bandwidth and the support for life-line telephony as an inseparable component. Note that ADSL technology is suitable for Internet access service. For example, a 10 baseT (10 bT) interface is located at the ATU-R for personal computer protocols.
A DSLAM is utilized in the IP based system to support ATM bearer service for IP applications. In an ATM bearer service scenario, the interface on the user side is configured as an ATM user to network interface over an ADSL. On the ATM network (trunk) side, the interface is configured as a network to network interface over a synchronous optical network (SONET) transport. Typically, DSLAMs are located in the central office; however they can also be remote such that they are connected over sign

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