Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-09-24
2004-08-17
Hsu, Alpus H. (Department: 2665)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S447000
Reexamination Certificate
active
06778545
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of computer networks and in particular, to transferring of voice information over frame relay in packet switching network environments.
2. Description of the Prior Art
In a networking environment where information, such as data, voice, video, audio and like information, is destined to travel from one remotely situated device to another device, two types of such networking environments may be employed: circuit switching network and packet switching network.
FIG. 1
shows conceptual views of both of these types of networking environments. A circuit switching network
10
is shown to include a first telecommunication device
12
, which may be a telephone, coupled through a path
14
to a second telecommunication device
16
, which may also be a telephone. The coupling between the two devices
12
and
16
, through the path
14
, includes various equipment,
18
and
20
, which effect transfer of the information being communicated through the path
14
. The circuit switching network
10
is shown in
FIG. 1
to demonstrate that when information is being transferred from a given source to a particular destination, such as from device
12
to device
16
, the information will always take the same path, i.e. through the equipment
18
and
20
.
In contrast thereto, a packet switching network
22
is shown in
FIG. 1
to demonstrate that the information being transferred does not necessarily take the same path when it is transferred from one device to another. In
FIG. 1
, the packet switching network
22
is shown to include a first telecommunication device
24
, coupled through a packet switching network structure
26
, to a second telecommunication device
28
.
The packet switching network structure
26
includes a plurality of network equipment, such as routers
30
,
32
and
34
. Information that is being, for example, transferred from the first device
24
to the second device
28
, does not necessarily take the same path every time. At one time, such an information may take a path
36
, which goes through the equipment
30
and
32
and when sent again another time, the same information may go through a different path
38
, which includes the equipment
34
. In fact, in packet switching networks, there is much equipment through which information may travel to get from one device to another. The path that information takes is in part a function of the intensity of traffic through the network. For example, if the devices
24
and
28
were telephone devices and there were calls being made during a time when many callers were initiating phone calls, the path that the voice information would take is likely to be entirely different than when the devices
24
and
28
transfer voice information during a time when there are not many callers accessing the system. An example of what the packet switching network structure
26
may be is the Internet, in which case, voice may travel therethrough to get from the device
24
. In this case, examples of what the devices
24
and
28
may be are personal computers (PCs).
Thus, in circuit switching networks, the same path is used to transfer information and that path is apriori known, whereas, in the case of packet switching networks, the path that information takes is firstly based upon the availability of the equipment and circuits and secondly not a dedicated path or apriori known. Accordingly, transfer of voice information through the Internet is less costly than the transfer of the same kind of information through a circuit switching network. That is, in a circuit switching network, such as used by traditional telephone companies, each user is assigned a dedicated path whereas in an Internet environment, multiple users share the same path.
In a packet switching environment such as the Internet, since different paths may be taken for transfer of information, different amounts of time delay are associated with the transfer of data. For example, in
FIG. 1
, in the packet switching network
22
, if the information being transferred between devices
24
and
28
takes the path
36
, this may result in less delay than if the same information transfer were to take the path
38
since the latter is going through an additional router. As the path that information will take in a packet switching network environment is unknown, so is the delay associated with that path. Accordingly, information being transferred is first buffered (or temporarily stored) to account for the delay associated with the transfer of information.
When information is sent through a packet switching network environment, it is broken up into various packets and each packet is sent in a frame over the network. When all of the packets of the same information arrive at their destination, they are placed back together for use by the user. Data being sent in this respect is not much affected by the delay that each packet may experience because even if this delay accumulates to minutes, a user is not particularly disturbed to wait that long before receiving data. However, when this information is in the form of voice, i.e. voice sent over the Internet, the accumulative amount of delay experienced by the separate packets that are sent through the Internet is often times annoying to the users. For example, if one were to speak through a telephone that was coupled to transfer information through the network and would have to wait 10 seconds to receive a voice back from another user at the destination site, there would be much disturbance to the listener.
To account for this delay, prior art methods and apparatus have employed buffering techniques to store the information that is to be transferred in a temporary location while previous information is being sent through the network. On the receiving side, the information that is received is buffered while the user is listening to the information previously received. However, due to the buffer size differences between the sending side and the receiving side of the network, there, nevertheless, remains a significant problem with the delay associated with transferring voice information through a packet switching networking environment, such as the Internet, that has proven to be disturbing to users of this type of system.
There is therefore a need to maximize the performance of a system for transfer of voice information from one device to another through a packet switching network such as to avoid unnecessary delay experienced by users of the system.
SUMMARY OF THE INVENTION
Briefly, a packet switching network system for use in transferring information that is in the form of packets includes an originating device and a destination device for communicating therebetween through a packet switching network. The originating device includes a sending device having a first buffer with a predetermined first buffer size, the first buffer being used to store information that is to be sent to the destination unit. The sending device sends a request packet including the first buffer size, through the packet switching network, to the destination device, the latter including a receiving device having a second buffer with a predetermined second buffer size, the second buffer being used for storing information that is received from the originating device. The receiving device receives a request packet including the first buffer size from the originating device, determines whether or not the received first buffer size is supported by the destination device, and accordingly sends back a response, through the packet switching network, to the originating device, wherein the originating device and the destination device enter into negotiations as to a mutually-acceptable buffer size that is to be used for information transfer by the packet switching network system.
The foregoing and other features of the invention will no doubt become apparent after reading the following detailed description of the preferred embodiments, which is illustrated in the sever
Cisco Technology Inc.
Hsu Alpus H.
Law Offices of Imam
Nguyen Toan D.
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