Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-06-26
2002-11-12
Vu, Huy D. (Department: 2665)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S255000
Reexamination Certificate
active
06480488
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method and apparatus for sorting and transmitting a data packet, and more particularly, to a method and apparatus for sorting and transmitting a data packet in a local area network.
REFERENCE TO PRIOR APPLICATION
This application has been filed in the R.O.C. (Taiwan) as Patent Application No. 87100995 on 1998.
BACKGROUND OF THE INVENTION
A local area network (LAN) having advantages of source sharing, data sharing and data switching, can be implemented via appropriately connecting the computers and communication equipment in a company, is widely used by many enterprises. A HUB is a frequently used constituent part for constructing a LAN. Referring to
FIG. 1
, it illustrates the functional block of a conventional HUB utilizing Carrier Sense with Multiple Access/Collision Detection (CSMAICD) technology, wherein n terminal equipment such as computers are connected to the same cable via n ports (
11
,
12
. . .
1
n
). CSMA/CD utilizes a “listen before talk” algorithm in which each terminal equipment will detect whether the shared cable is transmitting data before transmitting a frame signal. If there is no transmission on the shared cable, the signal to be transmitted is then transmitted. Two terminal equipment may simultaneously determine that there is no transmission on the shared cable and thus both start to transmit their frames simultaneously. A collision is then occurred once the frame signals are simultaneously transmitted to the shared cable. When a collision is occurred, the transmitted data is deemed as collided data and will be neglected. The terminal equipment wishing to transmit data have to wait for a period of time (3~5 seconds) to transmit the data again. Therefore, the more the terminal equipment, the more the collisions and the worse the network efficiency. To improve such a disadvantage, a switch utilizing switching technology for transmitting data is used to connect a network. The switching technology of the switch provides simultaneous data transmission between/among at least two pairs of ports in the same network, and thus the network efficiency is significantly improved.
Referring to
FIG. 2
, it illustrates the structure of a LAN having a switch fabric, wherein a network is formed by connecting unicast output channels
40
a
,
40
b
,
40
c
and
40
d
and unicast input channels
41
a
,
41
b
,
41
c
and
41
d
of four port controllers
20
,
21
,
22
and
23
to a switch fabric
24
. The port controllers
20
,
21
,
22
and
23
each comprises a plurality of ports (
20
a
,
20
b
, . . .
20
n
,
21
a
,
21
b
, . . .
21
n
,
22
a
,
22
b
, . . .
22
n
, and
23
a
,
23
b
, . . .
23
n
) for connecting a plurality of terminal equipment. Besides, the port controllers
20
,
21
,
22
and
23
are connected to the switch fabric
24
via an intercom channel
25
.
Referring to
FIG. 3
, it illustrates the functional block of the port controller
21
. A terminal equipment is connected to the port controller
21
via port
21
n
, wherein a medium access controller (MAC)
211
receives and decodes the data packet transmitted from the terminal equipment. The data packet format is as follows:
Destination Address
Source Address
Data to be Transmitted
(DA)
(SA)
(Data)
wherein the DA and SA are each the network card identifier, which is embedded in the network card with a length of 48 bits during manufacture, of the destination and source terminal equipment. The data packet is decoded by the MAC
211
, then the DA and SA are transmitted to a router
212
, and the DA, SA and the data to be transmitted (Data) are transmitted to a data queue
213
for storing. The router
212
compares the DA with the addresses stored in the address table
214
. If the corresponding address of the DA of the Data can be located in the address table
214
, a port number corresponded to the address can be got and is used to be the destination port. The router
212
transmits the Data stored in the queue
213
and the corresponding address (MAC address and the port number) from channel
40
b
to the switch fabric
24
. The switch fabric
24
decodes the destination port number to get a destination channel (
41
a
,
41
c
or
41
d
) and then transmits the Data from the destination channel to the specific port of the specific port controller. If the Data is a broadcast frame, the router
212
will broadcast the broadcast frame to every terminal equipment in the LAN via the intercom channel
25
. If the DA to be located can not be located in the address table, the router
212
will deem the Data as a broadcast frame and transmit the Data to every port controller. The comparing and recording operation of the SA relate to a learning process. That is to say, the source is deemed as a new coming source when the corresponding address of the SA can not be located in the address table
214
. The recorded reference list in the address table
214
itself should be refreshed, thereby recording the corresponding port of the source address. Besides, the source address of the address table of the destination port will also be refreshed when the Data is transmitted to the destination port such that the source address and the source port number of every Data can be recorded in the address table of every port controller. Therefore, the source address and source port number of the Data. can be learned only by the port controller that the Data passes. If the Data is transmitted to one of the port controllers in a unicast manner, then the source address and source port number of the Data can be learned only by the port controller that receives the Data. The other port controllers that do not receive the Data can not learn (or record) the source address and source port number of the Data. Therefore, in the prior art, the Data from the source address that can not be located in the address table will be broadcasted by the port controller. However, when a lot of terminal equipment are equipped in the LAN and the broadcast frame is frequently used, the network speed will be significantly reduced. Therefore, it is the main object of the invention to improve the drawbacks of the prior art.
SUMMARY OF THE INVENTION
In view of the disadvantages of the prior art, it is an object of the present invention to provide a method and apparatus for sorting and transmitting a data packet which is applied to a LAN. The LAN is formed by connecting a switch fabric and a plurality of port controllers. Each of the port controllers comprises a plurality of ports for connecting a plurality of terminal equipment. The port controllers are connected to the switch fabric via an intercom channel. Each of the port controllers comprises an address table for storing a reference list consisting of the port numbers of the port controllers connected to the terminal equipment and the network card addresses (identifiers) of the terminal equipment. A data packet to be transmitted from a first terminal equipment to a second terminal equipment comprises a destination address represented the network card identifier of the second terminal equipment, a source address represented the network card identifier of the first terminal equipment and data to be transmitted. The method comprises the steps of: (a) searching and comparing the source address of the data packet with the reference list stored in the address table of the port controller connected to the first terminal equipment; (b) refreshing the content of the reference list by adding. the source address representing the network card identifier of the first terminal equipment and the port number of the port controller connected to the first terminal equipment when the source address of the data packet can not be located in the address table; and (c) transmitting a new address learning frame, formed by assembling the source address representing the network card identifier of the first terminal equipment and the port number of the port controller connected to the first terminal equipment, via an intercom channel to the address tables of other port control
Accton Technology Corporation
Nguyen Steven
Thomas Kayden Horstemeyer & Risley LLP
Vu Huy D.
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