Control and management of ATM networks from server computers

Details Control and management of ATM networks from server computers Control and management of ATM networks from server computers

1998-04-16

2001-10-09

Kizou, Hassan (Department: 2738)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

C370S410000

Reexamination Certificate

active

06301252

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to ATM (Asynchronous Transfer Mode) communication networks, and more specifically, to control and management of such networks.
BACKGROUND ART
ATM (Asynchronous Transfer Mode) high-speed packet switched networks have been proposed as a technology capable of integrating present digital services with new multimedia services, e.g., video on demand, live television from many sources, CD-quality music, LAN interconnection, and high-speed data transport for science and industry. To implement these different services, ATM networks are designed to handle a variety of traffic characteristics, e.g., constant rate, variable rate, and bursty, required for various real time, such as video conferencing, and non-real time, such as E-mail and web browsing, applications. The basic principles of ATM packet-switched networks are well known to those skilled in the art and are discussed in numerous published references (see, for example, Andrew S. Tanenbaum, Computer Networks, Prentice Hall, 1996, 3rd ed.).
FIG. 1
illustrates an ATM network
6
with a simple topology shown herein for purposes of explanation of the operations of an ATM network relevant to the present invention. Users, typically running applications on host computers, are connected to the network, in this figure two users are labeled as A and B. The host computers generally execute applications for the users whereas the ATM switches
1
-
5
of the ATM network
6
are solely concerned with the communication of data among the hosts along paths in the network. A network manager
22
may monitor network status and perform other network tasks.
By way of example, in
FIG. 1
, one possible path of data flow would be from User A across the UNI (user-to-network interface) to switch
1
, and from switch
1
to switch
2
to switch
4
across the NNI (network-to-network interface) interfaces and from switch
4
to User B across the UNI interface. In this example, User A is assumed to be sending data to User B. Hence, User A is considered the source and User B the destination. The roles would reverse in the case where User B sends data to User A. Thus, User A is sending data which flows through the network and reaches User B. A path between User A and User B in the network is referred to herein alternately as a connection, circuit, or virtual path.
In an ATM network, data is transmitted between the switches of the network in small, fixed size 53 byte long ATM cells having 5 bytes for a header and 48 bytes for the data payload. The header of each cell contains a virtual address used for routing the cells over the network. Each ATM cell contains a two-part address in the cell header: a Virtual Path Identifier (VPI) and a Virtual Circuit Identifier (VCI). This two-part address uniquely identifies an ATM virtual connection on a physical interface (a bundle of circuits being contained within a path).
Once a connection is established, data can be exchanged between User A and User B. Typically, the flow of data proceeds as follows. User A opens an application on the computer of User A which sends data to User B. Network software at User A's side will receive the data from the application of user A, and arrange the data into packets. Each packet is arranged as one or more 53 byte ATM cells carrying the data payload preceded by a packet header cell containing information related to the application. The packets are sent over the ATM network cell by cell from User A to User B. The cells are then reassembled into packets by software at User B's end and presented to User B as an application packet.
In an ATM network, before data is exchanged between users, a connection must be established. That is, a call is required by user A to user B, similar to a telephone call, to set up a connection between the two users. Once the connection path is established, all data cells are transferred over the same connection path. This guarantees that cells will be delivered in order. Although ATM establishes a circuit between hosts, it establishes this circuit internally using packet switching technology. When a virtual circuit is established between hosts, what really happens is that table entries storing routing information are made in each switch along the path between the hosts.
Referring to
FIG. 1
, the following is an example of what happens when a user A connects to user B. First, user A sends a call request to user B. The call request arrives at switch
1
. Call processing software located at switch
1
uses signaling procedures combined with routing services to locate user B and establish a virtual connection over which user A and user B exchange data. During the call setup process, messages are being exchanged between the switches of the network and control functions run on the switches until a connection is established allowing transfer of data between user A and user B.
Establishing a connection is a control function of the network. The functions of the control plane of the network are typically concerned with the actual task of creating and maintaining the network path topology. This includes functions for establishing, rerouting, and terminating connections. The functions of the management plane administrates network resources. Examples of management plane function include the collection of traffic statistics, monitoring, and detecting switch failures. The management plane and control plane are distinct from the data plane, which is concerned solely with the routing and switching of data cells within the network.
In conventional network systems, many of the control and management tasks are commonly performed on the switches themselves.
FIG. 2
illustrates one possible configuration of a conventional switch
1
-
5
. The switching fabric
38
accepts ATM cells with data arriving at input lines
33
from the network and puts the cells onto the appropriate output lines
35
to the network. As is well-known to one of ordinary skill in the art, a switching control unit
34
of an ATM switch will route a cell on an incoming line to an outgoing line based on the line number and an address header appearing in the incoming cell. The switching control unit
34
will then replace the header of the cell with a new header stored in the same index location before sending the cell to another switch. Thus, the main function of the switching components
34
and
38
which constitute the switching unit
14
is to carry out the data plane function of mapping ATM cells from input lines to output lines. The CPU
30
communicates instructions to the switching unit
34
on path
12
a
. The switching unit
34
may communicate state information to the CPU
30
on data path
12
b.
As shown in
FIG. 2
, switch
1
-
5
includes a CPU
30
and memory
32
containing control and management software which implements the functionality of the management and control plane, including network routing, network signaling, for example to establish a connection, connection admission control, for example to determine whether to accept a call at the requested quality of service, and other procedures and programs for control and management of the switch. A network manager
22
may be able to transmit information
13
a
and receive information
13
b
from switch
1
-
5
to handle various management functions, such as monitoring. An example of an important control function, would be signaling, i.e. the establishment of a connection between two host machines. In the signaling process, a switch
1
-
5
would receive a request to establish a connection with network
6
. The request may have been generated from a user or another switch. To process this request, CPU
30
will run the signaling routines stored in memory
32
. If a connection is established, the CPU
30
will provide instructions
12
a
to the switching control unit
34
to establish the connection in switching fabric
38
. Since each of the switches may be from different vendors, instructions
12
a
may be different from vendor to vendor. This requires a switch have a CPU and

Affiliated with

Also associated with

Rating

Control and management of ATM networks from server computers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Control and management of ATM networks from server computers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control and management of ATM networks from server computers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2564705