Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1999-12-27
2003-10-14
Vu, Kim (Department: 2172)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C709S230000, C709S238000, C370S392000, C370S401000, C370S474000
Reexamination Certificate
active
06633866
ABSTRACT:
Japanese Patent Application No. 10-373384 has not been published in English under Article 21(2) of the Patent Cooperation Treaty.
BACKGROUND OF THE INVENTION
This application is based on Japanese Patent Application No. 10-373384, filed Dec. 28, 1998, the contents of which is incorporated herein by reference.
The present invention relates to a data search apparatus and an internetwork relay apparatus which mutually connects a plurality of networks such as LAN (Local Area Network), WAN (Wide Area Network), and the like to one another to perform data exchange and relay in a data link layer and a network layer.
In a communication network system including such a network as LAN, WAN, and the like, an internetwork relaying apparatus which is called a router, a layer
3
switch or the like has been used.
In general, an apparatus of this type determines a transmission destination from a destination address of a received frame to perform relay processing for transmitting the frame to a desired destination, in which the relay processing is performed for each processing of frame receipt, protocol analysis, destination determination and frame destination processings.
FIG. 1
illustrates one example of a configuration of a conventional internetwork relay apparatus which comprises a frame receipt portion
11
, a frame buffer
12
, a protocol analysis portion
13
, a destination determination portion
14
, a forwarding table
15
, a frame transmission portion
16
, and a control portion
17
.
The frame receipt portion
11
receives a frame transmitted from an upstream network (not shown) to store the received frame in the frame buffer
12
. Then, for each completion of reception of the frame, the frame receipt portion
11
notifies the control portion
17
of completion of reception and receives a frame buffer address for storing the next frame from the control portion
17
.
When the protocol analysis portion
13
is notified from the control portion
17
that an unprocessed frame has been stored in the frame buffer
12
, it reads frame data from the frame buffer
12
to perform a determination about a layer
2
frame form and a layer
3
protocol of the frame using a comparator inside the protocol analysis portion
13
. Then, after completion of the determination, the protocol analysis portion
13
stores the determination result in the frame buffer
12
and notifies a completion notification to the control portion
17
. Also, when another unprocessed frame has been stored in the frame buffer
12
, further protocol analysis processing is performed.
When the destination determination portion
14
is notified from the control portion
17
that an unprocessed frame has been stored in the frame buffer
12
, it reads a destination address included in a header of the received frame from the frame buffer
12
to determine a destination of the frame using the forwarding table
15
. Then, after completion of the determination, the destination determination portion
14
stores the destination of the frame in the frame buffer
12
and notifies a completion notification to the control portion
17
. This destination determination processing is performed on each of all the unprocessed frames which have been stored in the frame buffer
12
.
Since processings to be performed and data positions to be processed are different due to difference in layer
2
frame form and layer
3
protocol, the destination determination processing is performed by reading the frame data, after the determination results about the layer
2
frame form and the layer
3
protocol which have been obtained by the protocol analysis portion
13
and which have been stored in the frame buffer
12
is read out.
As soon as the frame transmission portion
16
is notified from the control portion
17
that a frame to be transmitted has been stored in the frame buffer
12
, it reads a destination to be transmitted and a data frame to be transmitted on the basis of the frame buffer address which has been notified from the control portion
17
to transmit the same to a desired destination. Then, when the transmission is completed, a completion notification is notified to the control portion
17
.
The control portion
17
performs control among respective processings and manages a frame buffer address in which an unprocessed frame has been stored for each processing.
The protocol analysis portion
13
is configured in the following manner.
FIG. 2
is a circuit block diagram showing a configuration of the protocol analysis portion
13
. That is, the protocol analysis portion
13
comprises a protocol analysis processing control portion
21
, and a plurality of comparators
221
to
22
n
provided so as to correspond to types of the layer
2
frame form and the layer
3
protocol.
As soon as the protocol analysis processing control portion
21
is notified from the control portion
17
that an unprocessed frame has been stored in the frame buffer
12
, it reads the frame data from the frame buffer
12
on the basis of the frame buffer address which has been notified from the control portion
17
, and notifies the respective comparators
221
to
22
n
of what byte the read data is from a head of the frame.
Data (field data representing a protocol) to be compared with the frame data read from the frame buffer
12
is preliminarily stored in each of the comparators
221
to
22
n
, and the respective comparators
221
to
22
n
determine which of set data the read data coincides with. When the read data coincides with any of the set data, the layer
2
frame form and the layer
3
protocol of the frame are identified. Also, a data position to be compared is preliminarily set with the number of bytes counted from a head of a frame for each of the comparators
221
to
22
n
, and data to be compared is inputted to each of the comparators
221
to
22
n
, taking account of the position information provided from the protocol analysis processing control portion
21
.
For example, in a comparator where a frame format having a DIX (DEC/Intel/Xerox) as the layer
2
frame form and an IPv4 as the layer
3
protocol on Ethernet is identified, the following identification processing is performed. That is, in order to identify the frame format having the DIX and the IPv4, it is required that Type field positioned at the 13th to the 14th bytes is 0x0800. Therefore, in the comparator, data to be compared is set to 0x0800 and the position is set to the 13th to the 14th bytes.
Also, in order to identify a frame format where the layer
2
frame form is LLC (Logical Link Control) header+SNAP (Subnetwork Packet Protocol) on Ethernet and the layer
3
protocol is IPX (Internetwork Packet Exchange), it is required that the 13th to the 14th bytes of a frame are at most 1500 and the 15th to the 22th bytes are 0xAAAA030000008137. For this reason, in the comparator for identifying this frame format, a circuit for determining that the 13th and the 14th bytes are less than or equal to 1500 and information for indicating that the 15th to the 22th bytes is 0xAAAA030000008137 are set.
When the protocol analysis processing control portion
13
is notified of correspondence of data from any one of the comparators, the corresponding layer
2
frame form and the layer
3
protocol are respectively written in the same frame buffer region where the frame data has been stored. Then, after the writing, the control portion
17
is notified of completion of the protocol analysis.
However, there are the following problems to be solved in a conventional apparatus for performing such protocol processings. That is, the reason why the protocol analysis is required is because it is assumed that a plurality of layer
3
protocols which have been received in a plurality of layer
2
frame forms are processed in a relay processing. In a conventional approach, since the comparators
221
to
22
n
for identification are provided for respective layer
2
frame forms and layer
3
protocols, a circuit for the protocol analysis portion
13
is large-scaled when the number of kinds of layer
2
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Pham Hung
Vu Kim
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