Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data transfer regulating
Reexamination Certificate
1998-04-08
2001-02-06
Harrell, Robert B. (Department: 2758)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data transfer regulating
Reexamination Certificate
active
06185622
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an electronic apparatus which is connected to and used together with, for example, an IEEE 1,394 serial bus (hereinafter referred to simply as 1,394 serial bus) and also to a communication speed information collection method, a communication method between electronic apparatus of the type mentioned, and a recording medium.
A communication system has been proposed wherein electronic apparatus such as a personal computer, a hard disk apparatus, a digital video tape recorder and a digital television receiver are connected to each other by a 1,394 serial bus so that packets of a digital video signal, a digital audio signal and a control signal are communicated between the electronic apparatus.
An example of such a communication system as described above is shown in FIG.
8
. Referring to
FIG. 8
, electronic apparatus A to E may be a personal computer, a digital video tape recorder and so forth mentioned above. Ports P of the electronic apparatus A and B, B and C, C and D, and D and E are connected to each other by cables
11
,
12
,
13
and
14
of a 1,394 serial bus, respectively. In the following description, each of such electronic apparatus may be referred to as node.
As seen from
FIG. 8
, each of the nodes other than the node C includes, as basic components for communicating with the 1,394 serial bus, a physical layer controller (PHY)
15
, a link layer controller (LINK)
16
, and a CPU (central processing unit)
17
. The node C is only provided with a physical layer controller
15
. The physical layer controller
15
has functions of initialization of the bus, encoding/decoding of data, arbitration, outputting/detection of a bias voltage and so forth. The link layer controller
16
has link layer controlling functions such as production/detection of an error correction code, production/detection of a packet and so forth. The CPU
17
has functions of an application layer.
In a communication system which employs a 1,394 serial bus, each node sends out, upon initialization of the bus, a packet called self ID (Self ID) packet to the bus. In a predetermined field of the self ID packet, communication speed information which is available with the physical layer controller
15
of the node itself is inserted.
FIG. 9
illustrates an example of a construction of a self ID packet. Referring to
FIG. 9
, the self ID packet shown has a length of 4 bytes×2 (in the following description, 4 bytes are referred to as 1 quadlet), and a speed code (sp) is inserted in the 17th and 18th bits of the first quadlet. The two bits of the speed code signify S
100
(98.304 Mbps) with “00”, S
100
and S
200
(196.608 Mbps) with “01”, S
100
, S
200
and S
400
(393.216 Mbps) with “10”, and “reserved” with “11”.
A bus manager in the communication system receives self ID packets of the nodes and produces, using the self ID packets, a speed map indicative of maximum communication speeds between the nodes.
FIG. 10
shows an example of a construction of a speed map. Referring to
FIG. 10
, the speed map shown indicates maximum transfer speeds each between two arbitrary nodes. After completion of initialization of the bus, all nodes can refer to the speed map. When each node tries to communicate with another node, it refers to the speed map to determine a communication speed.
Generally in a communication system, the maximum transfer speed in communication between certain two nodes is limited, where there is a repeating node in the communication route, to a speed which is available with the repeating node.
For example, in a communication system which employs a 1,394 serial bus, repeating is performed by a physical layer controller. The physical layer controller transmits and receives a packet on the 1,394 serial bus. In this instance, also a packet which is not destined for the pertaining node is propagated to an adjacent node, that is, repeated. While the communication speed of each node depends upon the capacity of its link layer controller, when the node repeats a packet, the communication speed does not rely upon the capacity of the link layer controller.
When communication is performed between two nodes, there is no problem if the maximum communication speed of the link layer controller of each of the nodes is equal to or higher than the maximum communication speed of the link layer controller. However, if the maximum communication speed of the link layer controller is lower than the maximum communication speed of the physical layer controller, then a packet received by the node is lost on the level of the link layer.
In asynchronous communication on a 1,394 serial bus, a node on the transmission side of a packet can discriminate an error when a node of the reception side of the packet does not send back ACK (acknowledge). However, in isochronous communication, since communication of the broadcasting type in which ACK is not returned is performed, an error can be discriminated neither by the transmission side nor by the reception side.
Such an error as mentioned above can be eliminated if a maximum communication speed for the physical layer controller is determined based on performances of the link layer controllers of all nodes. However, this gives rise to necessity to lower the communication speed relying upon a repeating node even if two nodes which originally communicate with each other have higher performances.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electronic apparatus, a communication speed information collection method, a communication method between communication method between electronic apparatus and a recording medium which can minimize the possibility of drop of a communication speed by a performance of a repeating node.
It is another object of the present invention to provide an electronic apparatus, a communication speed information collection method, a communication method between electronic apparatus and a recording medium by which communication speed information having a high degree of reliability can be obtained.
In order to attain the objects described above, according to the present invention, communication speeds available with individual nodes or electronic apparatus are indicated separately for a plurality of nodes. More particularly, according to an aspect of the present invention, there is provided a communication speed information collection method applied when communication is performed between a plurality of apparatus, comprising the steps of collecting communicable speed information between physical layers of the apparatus to produce a first speed information table, collecting information processable speed information of layers higher than the physical layers of the apparatus, and modifying the first speed information table with the information processable speed information of the higher layers.
According to another aspect of the present invention, there is provided a communication method applied when communication is performed between a plurality of apparatus, comprising a communication speed information collection step including the steps of collecting communicable speed information between physical layers of the apparatus to produce a first speed information table, collecting information processable speed information of layers higher than the physical layers of the apparatus, and modifying the first speed information table with the information processable speed information of the higher layers, and a communication step of performing communication between the apparatus based on the speed information obtained by the first-mentioned step.
According to a further aspect of the present invention, there is provided an electronic apparatus for communicating with another apparatus, comprising first means for performing processing of a physical layer for communicating with another apparatus, second means for performing processing of a layer higher than the physical layer, and third means for storing information of a relationship in magnitude between a communication speed by the f
Frommer William S.
Frommer Lawrence & Haug LLP.
Harrell Robert B.
Sony Corporation
LandOfFree
Electronic apparatus, communication speed information... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electronic apparatus, communication speed information..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic apparatus, communication speed information... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2602890