Electrical computers and digital data processing systems: input/ – Input/output data processing – Data transfer specifying
Reexamination Certificate
1997-08-25
2001-01-30
Lee, Thomas C. (Department: 2782)
Electrical computers and digital data processing systems: input/
Input/output data processing
Data transfer specifying
C710S005000, C710S041000, C709S213000, C709S219000, C709S237000, C711S100000, C714S001000, C714S006130
Reexamination Certificate
active
06182166
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a method and apparatus for interfacing two remotely disposed devices over a transmission medium capable of transmitting data over long distances. The invention may be used, for example, to interface a master storage device of a host CPU to a remotely disposed mirroring storage device, particularly where the master storage device communicates with its host CPU using the ESCON protocol.
BACKGROUND OF THE INVENTION
ESCON is a standard computer system interface and protocol developed by International Business Machines (IBM). ESCON is applicable to an environment such as the one shown in
FIG. 1
, in which a central processing unit (CPU)
1
is coupled to a channel
3
having direct access to a main memory (not shown) of the CPU. The channel provides input/output capability to the CPU. More particularly, the channel
3
is coupled, over a link
5
, to one or more control units
7
, which each is in turn coupled to a plurality of I/O peripherals
9
. Control unit
7
controls access to CPU
1
, via channel
3
, for each of the I/O peripherals
9
, allowing each to have direct access to the CPU memory.
ESCON defines the interface and protocol for communicating over link
5
between channel
3
and control unit
7
, and is described in detail, for example, in “ENTERPRISE SYSTEMS ARCHITECTURE/390—ESCON I/O INTERFACE”, Third Edition (1992) published by IBM, which is incorporated herein by reference. Dedicated ESCON links have been provided so that control unit
7
, along with its associated I/O peripherals
9
, can be disposed at a location somewhat remote from CPU
1
and channel
3
. However, these dedicated links have conventionally been limited to relatively short distances. For example, IBM states that its dedicated ESCON links are limited to approximately 60 km. Although this number may be conservative, it is believed that conventional dedicated ESCON links are limited to distances of approximately 80 km, even when appropriate repeaters are used along the line.
Conventional dedicated ESCON links between a channel and control unit suffer from two significant disadvantages. First, the above-described limit on the maximum supported distance may be insufficient for some applications. Second, it is often costly to implement these dedicated links because they are not part of a public communication network, and may not be capable of being implemented over pre-existing communication lines.
It is an object of the present invention to provide an improved interface for enabling communication between two remotely disposed devices, including ESCON compatible devices.
SUMMARY OF THE INVENTION
In one illustrative embodiment of the invention, a method is provided of communicating a plurality of commands from a first device to a second device over a data communication link coupling the first and second devices, the plurality of commands including at least a first command and a second command. The method comprises the step of transmitting the first and second commands over the data communication link from the first device to the second device in a single data transmission such that only a single propagation delay through the data communication link is incurred in transmitting both the first and second commands over the data communication link.
In another illustrative embodiment of the invention, a device is provided for transmitting a plurality of commands to another device over a data communication link, the plurality of commands including at least a first command and a second command. The device comprises transmitting means for transmitting the plurality of commands over the data communication link from the device to the another device, the transmitting means including means for transmitting the first and second commands over the data communication link in a single data transmission such that only a single propagation delay through the data communication link is incurred in transmitting both the first and second commands over the data communication link.
In a further illustrative embodiment of the invention, a communication system is provided comprising a first device, a second device and a data communication link coupling the first device to the second device. The first device includes transmitting means for transmitting a plurality of commands to the second device over the data communication link, the plurality of commands including at least a first command and a second command. The transmitting means includes means for transmitting the first and second commands over the data communication link in a single data transmission such that only a single propagation delay through the data communication link is incurred in transmitting both the first and second commands over the data communication link.
REFERENCES:
patent: 4818984 (1989-04-01), Chang et al.
patent: 5010547 (1991-04-01), Johnson et al.
patent: 5179660 (1993-01-01), Devany et al.
patent: 5412803 (1995-05-01), Bartow et al.
patent: 5446871 (1995-08-01), Shomler
patent: 5504861 (1996-04-01), Crockett et al.
patent: 5526484 (1996-06-01), Casper et al.
patent: 5530948 (1996-06-01), Islam
patent: 5544347 (1996-08-01), Yanai et al.
patent: 5555371 (1996-09-01), Duyanovich et al.
patent: 5638384 (1997-06-01), Hayashi et al.
patent: 5734818 (1998-03-01), Kern et al.
patent: 5901327 (1999-05-01), Ofek
patent: 5915092 (1999-06-01), Morita et al.
patent: 5960216 (1999-09-01), Vishlitzky et al.
Ofek Yuval
Shetty Ramprasad
Shklarsky Gadi
Vishlitzky Natan
EMC Corporation
Lee Thomas C.
Nguyen Tanh Q.
Wolf Greenfield & Sacks P.C.
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