U.S. patent application number 12/426092 was filed with the patent office on 2009-10-22 for fault analysis and monitoring applications using out-of-band based modules.
This patent application is currently assigned to FINISAR CORPORATION. Invention is credited to Luke M. Ekkizogloy, Lucy G. Hosking, Cheng Liu, Gayle L. Noble.
Application Number | 20090265142 12/426092 |
Document ID | / |
Family ID | 41201850 |
Filed Date | 2009-10-22 |
United States Patent
Application |
20090265142 |
Kind Code |
A1 |
Liu; Cheng ; et al. |
October 22, 2009 |
FAULT ANALYSIS AND MONITORING APPLICATIONS USING OUT-OF-BAND BASED
MODULES
Abstract
One example embodiment includes a testing device. The testing
device comprises a signal reception element, an out-of-band
detector and testing logic. The signal reception element is
configured to receive a physical layer signal from a communication
module via a physical link and to produce an incoming double
modulated signal, the incoming double modulated signal including a
high-speed data signal and an out-of-band data signal. The
out-of-band data signal comprises diagnostic data of the
communication module. The out-of-band detector is coupled to the
signal reception element and is configured to extract the
out-of-band data signal from the incoming double modulated signal.
The testing logic is coupled to the out-of-band detector and is
configured to extract and analyze the diagnostic data from the
out-of-band data signal.
Inventors: |
Liu; Cheng; (Fremont,
CA) ; Noble; Gayle L.; (Boulder Creek, CA) ;
Hosking; Lucy G.; (Santa Cruz, CA) ; Ekkizogloy; Luke
M.; (San Jose, CA) |
Correspondence
Address: |
Workman Nydegger;1000 Eagle Gate Tower
60 East South Temple
Salt Lake City
UT
84111
US
|
Assignee: |
FINISAR CORPORATION
Sunnyvale
CA
|
Family ID: |
41201850 |
Appl. No.: |
12/426092 |
Filed: |
April 17, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61045954 |
Apr 17, 2008 |
|
|
|
61045950 |
Apr 17, 2008 |
|
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Current U.S.
Class: |
702/190 |
Current CPC
Class: |
H04L 41/00 20130101;
H04L 43/50 20130101 |
Class at
Publication: |
702/190 |
International
Class: |
G06F 15/00 20060101
G06F015/00 |
Claims
1. A testing device, comprising: a signal reception element
configured to receive a physical layer signal from a communication
module via a physical link and to produce an incoming double
modulated signal, the incoming double modulated signal including a
high-speed data signal and an out-of-band data signal, the
out-of-band data signal comprising diagnostic data of the
communication module; an out-of-band detector that is coupled to
the signal reception element and is configured to extract the
out-of-band data signal from the incoming double modulated signal;
and testing logic that is coupled to the out-of-band detector and
is configured to extract and analyze the diagnostic data from the
out-of-band data signal.
2. The testing device of claim 1, wherein the communication module
comprises a first communication module, the testing device further
comprising a second communication module that includes the signal
reception element and the out-of-band detector.
3. The testing device of claim 2, wherein the first and second
communication modules each comprise an optoelectronic transceiver
or an optoelectronic transponder.
4. The testing device of claim 1, wherein the testing device
further comprises a rover.
5. The testing device of claim 1, wherein the testing device
further comprises an analyzer.
6. The testing device of claim 1, wherein the testing device
further comprises a probe.
7. The testing device of claim 1, wherein the signal reception
element comprises an optical detector.
8. The testing device of claim 1, wherein the testing logic is
further configured to identify one or more physical conditions of
the physical link using the diagnostic data.
9. The testing device of claim 1, wherein the diagnostic data
includes one or more of: a temperature of the communication module,
a supply voltage of the communication module, a bias current of an
optical transmitted included in the communication module, a receive
power of an optical detector included in the communication module,
an error indicator for the communication module, or a power on time
for the communication module.
10. The testing device of claim 1, wherein the diagnostic data
comprises first diagnostic data, the out-of-band data signal
further comprising second diagnostic data that includes one or more
of a control signal from a host to which the communication module
is coupled or a firmware update.
11. A system for collecting physical layer data for a physical
link, the system comprising a first communication module configured
to emit a physical layer signal onto a first physical link for
reception by a second communication module, the physical layer
signal comprising a double modulated signal modulated with a
high-speed data signal and an out-of-band data signal, the
out-of-band data signal comprising diagnostic data of the first
communication module; and means for receiving the physical layer
signal, the means for receiving being coupled to the first physical
link; means for extracting the out-of-band data signal from the
physical layer signal, the means for extracting being coupled to
the means for receiving; and means for extracting and analyzing the
diagnostic data from the out-of-band data signal to identify one or
more physical conditions of the first physical link, the means for
extracting and analyzing being coupled to the means for
extracting.
12. The system of claim 11, further comprising a tap coupled
between the first physical link and the means for receiving, the
tap configured to split a percentage of the double modulated
physical layer signal from the first physical link to direct to the
means for receiving.
13. The system of claim 11 wherein the means for receiving
comprises an optical detector.
14. The system of claim 11, wherein the means for extracting
comprises an out-of-band detector.
15. The system of claim 11, wherein the means for extracting and
analyzing comprises one or more of: testing logic, a processor, a
microprocessor, a controller, or a microcontroller.
16. The system of claim 11, wherein the means for receiving, means
for extracting, and means for extracting and analyzing are included
in one or more of: a rover, a probe, an analyzer, or a diagnostic
module.
17. The system of claim 11, further comprising a rover configured
to rove a plurality of physical links including the first physical
link such that the means for receiving receives each of a plurality
of physical layer signals transmitted on the plurality of physical
links, the means for extracting extracts an out-of-band data signal
from each of the physical layer signals, and the means for
extracting and analyzing extracts and analyzes diagnostic data from
each of the out-of-band data signals to identify one or more
physical conditions of each of the plurality of physical links.
18. The system of claim 11, further comprising a probe coupled to
the means for receiving.
19. The system of claim 11, further comprising an analyzer coupled
to the means for extracting and analyzing.
20. The system of claim 11, further comprising a repeater that
includes the first communication module, the repeater comprising: a
receiver adapted to receive a data signal; a signal processor
coupled to the receiver, the signal processor being adapted to
perform processing tasks on the data signal; a transmitter coupled
to the signal processor, the transmitter adapted to receive the
data signal from the processor and to transmit the data signal; and
out-of-band logic coupled to the signal processor, the out-of-band
logic configured to: extract out-of-band data from the data signal,
wherein the out-of-band data includes diagnostic data from at least
one remote repeater; concatenate data corresponding to diagnostic
data for the repeater to the out-of-band data such that the
out-of-band data includes the diagnostic data for the repeater and
the at least one remote repeater; and insert the out-of-band data
including the data corresponding to diagnostic data for the
repeater and the at least one remote repeater onto the data signal;
wherein: the means for receiving is further configured to receive
the data signal; the means for extracting is further configured to
extract the out-of-band data from the data signal; and the means
for extracting and analyzing is further configured to extract and
analyze the diagnostic data for the repeater and the at least one
remote repeater from the out-of-band data to identify one or more
physical conditions of a physical link between the repeater and the
at least one repeater.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of and priority
to U.S. Provisional Application Ser. No. 61/045,954, entitled
"FAULT ANALYSIS AND MONITORING APPLICATIONS USING OOB BASED SFPS,"
filed Apr. 17, 2008, and U.S. Provisional Application Ser. No.
61/045,950, entitled "OUT-OF-BAND DATA TRANSFER," filed Apr. 17,
2008. Both of the foregoing applications are fully incorporated
herein by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] Embodiments of the invention relate generally to the field
of data transmission in communication networks. More specifically,
embodiments of the present invention relate to devices and systems
for collecting physical layer data in communication networks.
[0004] 2. The Relevant Technology
[0005] Modern day communication is, in large part, accomplished by
transmitting and receiving large amounts of digital data. Digital
data signals can be used to transmit information such as database
information, financial information, personal and business
information, and the like. In addition, digital data signals can be
used to transmit voice, video, images etc.
[0006] Typically, data transmission in such networks is implemented
by way of a communication module, such as a transceiver or
transponder. A transceiver includes a signal power source including
electronic hardware for transmitting data signals along a physical
link such as a copper wire link or fiber-optic link. The signal
power source may be a laser, electronic amplifier, radio
transmitter or the like. The transceiver may also include a
physical layer signal reception element to receive physical layer
signals. The physical layer reception element may be a photodiode,
an electronic amplifier, a radio receiver, or the like.
[0007] The transceiver may include electronic hardware for decoding
signals that are sent between clients into data signals, such as
binary representations, readable by digital devices or hosts to
which the transceiver is connected. The transceiver may also
include electronic hardware for encoding signals that are sent
between clients from a binary representation to a physical layer
level signal that can be transmitted across a physical link. Thus,
in one example, a binary representation is converted to one of a
modulated electronic signal, a modulated optical signal, a
modulated radio signal or another appropriate signal.
[0008] A transceiver may communicate data for the benefit of the
transceiver to the connected host device. For example, a
transceiver may be configured to generate digital diagnostic
information by monitoring the health of the transceiver. The
transceiver may then communicate information about the health of
the transceiver to its connected host. This communication typically
takes place on an I.sup.2C or MDIO bus for communicating between
integrated circuits. As a transceiver deteriorates due to age,
component failure or other reasons, the host may be aware of the
deterioration using such communications received from the
transceiver.
[0009] Digital diagnostics logic (also referred to herein as
"digital diagnostics") may be used to handle various tasks and to
generate monitoring and operating data. These task and data may
include some of the following: [0010] Setup functions. These
generally relate to the required adjustments made on a part-to-part
basis in the factory to allow for variations in component
characteristics such as laser diode threshold current. [0011]
Identification. This refers to general purpose memory, typically
EEPROM (electrically erasable and programmable read only memory) or
other nonvolatile memory. The memory may be accessible using a
serial communication standard, that is used to store various
information identifying the transceiver type, capability, serial
number, and compatibility with various standards. While not
standard, this memory may also store additional information, such
as sub-component revisions and factory test data. [0012] Eye safety
and general fault detection. These functions are used to identify
abnormal and potentially unsafe operating parameters and to report
these to the host and/or perform laser shutdown, as appropriate.
[0013] Temperature compensation functions. For example,
compensating for known temperature variations in key laser
characteristics such as slope efficiency. [0014] Monitoring
functions. Monitoring various parameters related to the transceiver
operating characteristics and environment. Examples of parameters
that may be monitored include laser bias current, laser output
power, receiver power levels, supply voltage and temperature.
Ideally, these parameters are monitored and reported to, or made
available to, a host device and thus to the user of the
transceiver. [0015] Power on time. The transceiver's control
circuitry may keep track of the total number of hours the
transceiver has been in the power on state, and report or make this
time value available to a host device. [0016] Margining.
"Margining" is a mechanism that allows the end user to test the
transceiver's performance at a known deviation from ideal operating
conditions, generally by scaling the control signals used to drive
the transceiver's active components. [0017] Other digital signals.
A host device may configure the transceiver so as to make it
compatible with various requirements for the polarity and output
types of digital inputs and outputs. For instance, digital inputs
are used for transmitter disable and rate selection functions while
outputs are used to indicate transmitter fault and loss of signal
conditions. The configuration values determine the polarity of one
or more of the binary input and output signals. In some
transceivers, these configuration values can be used to specify the
scale of one or more of the digital input or output values, for
instance by specifying a scaling factor to be used in conjunction
with the digital input or output value.
[0018] The data generated by the digital diagnostics described
above is generally only available to the host on which a
transceiver is installed. Thus, when troubleshooting problems with
individual transceivers, a user must access the host on which the
transceiver is installed to discover any digital diagnostic data
about a transceiver. This may cause various difficulties when the
host and transceiver are located in a remote location such as on
the ocean floor or in remote desert locations. Further, some
applications make use of repeaters, which are transceiver pairs
that simply receive an optical data stream, amplify the optical
data stream, and retransmit the optical data stream. In repeater
applications, the digital diagnostic data is stored on the
repeater. Thus to troubleshoot the repeater, the repeater must be
physically retrieved and queried for any digital diagnostic
data.
[0019] The subject matter claimed herein is not limited to
embodiments that solve any disadvantages or that operate only in
environments such as those described above. Rather, this background
is only provided to illustrate one exemplary technology area where
some embodiments described herein may be practiced.
BRIEF SUMMARY OF THE INVENTION
[0020] Example embodiments of the invention relate to devices and
systems for collecting physical layer data in communication
networks.
[0021] One example embodiment includes a testing device. The
testing device comprises a signal reception element, an out-of-band
detector and testing logic. The signal reception element is
configured to receive a physical layer signal from a communication
module via a physical link and to produce an incoming double
modulated signal, the incoming double modulated signal including a
high-speed data signal and an out-of-band data signal. The
out-of-band data signal comprises diagnostic data of the
communication module. The out-of-band detector is coupled to the
signal reception element and is configured to extract the
out-of-band data signal from the incoming double modulated signal.
The testing logic is coupled to the out-of-band detector and is
configured to extract and analyze the diagnostic data from the
out-of-band data signal.
[0022] Another example embodiment includes a system for collecting
physical layer data for a physical link. The system comprises a
first communication module configured to emit a physical layer
signal onto a first physical link for reception by a second
communication module. The physical layer signal comprises a double
modulated signal modulated with a high-speed data signal and an
out-of-band data signal. The out-of-band data signal comprises
diagnostic data of the first communication module. The system also
comprises means for receiving the physical layer signal, the means
for receiving being coupled to the first physical link. The system
also comprises means for extracting the out-of-band data signal
from the physical layer signal, the means for extracting being
coupled to the means for receiving. The system further comprises
means for extracting and analyzing the diagnostic data from the
out-of-band data signal to identify one or more physical conditions
of the first physical link, the means for extracting and analyzing
being coupled to the means for extracting.
[0023] Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
obvious from the description, or may be learned by the practice of
the invention. The features and advantages of the invention may be
realized and obtained by means of the instruments and combinations
particularly pointed out in the appended claims. These and other
features of the present invention will become more fully apparent
from the following description and appended claims, or may be
learned by the practice of the invention as set forth
hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] To further clarify the above and other advantages and
features of the present invention, a more particular description of
the invention will be rendered by reference to specific embodiments
thereof which are illustrated in the appended drawings. It is
appreciated that these drawings depict only typical embodiments of
the invention and are therefore not to be considered limiting of
its scope. The invention will be described and explained with
additional specificity and detail through the use of the
accompanying drawings in which:
[0025] FIG. 1 illustrates an example communication network in which
embodiments of the invention can be implemented;
[0026] FIG. 2 illustrates one example of a testing device that can
be employed in the communication network of FIG. 1;
[0027] FIG. 3A illustrates another communication network in which
embodiments of the invention can be implemented;
[0028] FIG. 3B illustrates yet another communication network in
which embodiments of the invention can be implemented;
[0029] FIG. 4 illustrates an example method that can be implemented
in the communication network of FIG. 3A; and
[0030] FIG. 5 illustrates yet another communication network in
which embodiments of the invention can be implemented.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] Embodiments of the invention include devices, systems, and
methods for collecting and analyzing out-of-band diagnostic data
transmitted on a physical link between components in a network of
connected hosts. This allows for monitoring and identifying
physical conditions of the physical link. In some embodiments, the
out-of-band diagnostic data is included in a double modulated
signal that additionally includes high-speed data. As such,
high-speed data that is ordinarily transmitted on the physical link
can be transmitted with out-of-band data on the same physical
link.
[0032] The term "high-speed data," as used herein, does not refer
to any particular defined bandwidth or frequency of data. Rather,
high-speed data refers to data typically transmitted on a network
such as the data typically transmitted for the benefit of the
various hosts on a network. High-speed data may also be referred to
herein as in-band data which is a reference to the communication
band typically used by host systems to communicate data. High-speed
and in-band data are distinguished from out-of-band data which is
typically used to transmit data from communication module to
communication module. While a host may subsequently receive the
out-of-band data, the host usually receives the out-of-band data
from a communication module through a low speed bus such as an
I.sup.2C or MDIO bus. This is contrasted to high-speed data which
is typically received by a host from a communication module through
some type of high-speed data interface. Notably, a host may also
produce the out-of-band data and transmit the out-of-band data to a
communication module on a low speed bus.
[0033] The term "diagnostic data" includes environmental and/or
operational parameters measured by the communication modules at
each end of a physical link. For instance, the parameters can
include temperature, supply voltage, bias current, transmit power,
receive power, error indicators such as Hi and Lo threshold alarms
and warnings, power on time, and/or other parameters. Hi and Lo
threshold alarms can be generated by a communication module when a
particular parameter exceeds a given threshold. For instance, Hi
and/or Lo threshold alarms can be generated when supply voltage
exceeds a particular voltage range or when transmit power exceeds a
particular power range, or the like.
[0034] Diagnostic data alternately or additionally includes data
beyond environmental and/or operational parameters measured by the
communication modules. For instance, diagnostic data can include
control signals and/or firmware updates from a host to one or more
communication modules. Alternately or additionally, diagnostic data
can include identification/authentication data stored in memory of
a communication module and provided to a host or other
communication module for identification/authentication
purposes.
[0035] Each physical link generally includes the hardware that
interconnects two nodes in the network and can include, for
example, the communication module at each node, a transmission
medium, such as fiber optic cable or electrical cable, that
interconnects the communication modules, connectors, and the like
or any combination thereof The parameters, either individually or
in combination, are generally indicative of the physical condition
of a physical link. Accordingly, by collecting and analyzing
digital diagnostic data exchanged between the communication modules
at each end of a physical link, the physical condition of the
physical link can be determined, and if necessary, appropriate
corrective action can be taken.
I. EXAMPLE COMMUNICATION NETWORK
[0036] Referring now to FIG. 1, one example communication network
100 is disclosed in which embodiments of the invention can be
practiced. The communication network 100 includes a first host
device 102, a second host device 104, one or more physical links
106A, 106B, 108A, 108B and a system comprising components 110A-110C
(referred to herein as "system 110") for collecting physical layer
data, including diagnostic data. More particularly, the system 110
includes at least a first communication module 110A, a testing
device 110B, and optionally a second communication module 110C.
[0037] The communication network 100 accomplishes digital
communication using any one of a number of different models,
including the Open Systems Interconnection ("OSI") model, although
other models can alternately or additionally be employed. The OSI
model defines a framework for accomplishing digital communications
with seven layers on clients (e.g., hosts 102, 104) communicating
in a network. These seven layers are understood by those of skill
in the art, and include from the highest level to the lowest level:
the application layer, the presentation layer, the session layer,
the transport layer, the network layer, the data link layer, and
the physical layer. At the application layer, data is used in end
user processes. Data is packaged by each of the other layers of the
OSI model prior to being sent using the physical layer. The
physical layer defines how the data is actually sent on the
network, such as by electrical signals, light carried on optical
fibers, radio signals etc. Thus, at the physical layer, actual
voltages, light levels and radio amplitudes or frequencies are
defined as having certain logical values.
[0038] At the physical layer, one method of communicating digital
data involves the use of communication modules, including
transceiver modules or transponder modules. Communication modules
can have a variety of different form factors, including SFF, SFP,
SFP+, XFP, CFP, XPAK, XENPAK, without restriction. A communication
module includes a signal power source including electronic hardware
for transmitting data signals along a physical link such as a
copper wire link or fiber-optic link. The signal power source may
be a laser, electronic amplifier, radio transmitter or the like.
The communication module may also include a physical layer signal
reception element to receive physical layer signals. The physical
layer reception element may be a photodiode, an electronic
amplifier, a radio receiver, or the like.
[0039] The communication module may further include electronic
hardware for decoding signals that are sent between clients into
data signals, such as binary representations, readable by digital
devices or hosts to which the communication module is connected.
The communication module may also include electronic hardware for
encoding signals that are sent between clients from a binary
representation to a physical layer level signal that can be
transmitted across a physical link. Thus, in one example, a binary
representation is converted to one of a modulated electronic
signal, a modulated optical signal, a modulated radio signal or
another appropriate signal.
[0040] With continuing reference to FIG. 1, each of the first and
second host devices 102, 104 comprises, for example, a media access
controller ("MAC") card, a SONET framer, an FEC processor, or the
like. Further, the first and second host devices 102, 104 are
configured to communicate with each other via physical links 106A,
106B, 108A, 108B.
[0041] Physical links 106A, 106B (collectively "physical link 106")
can include, for instance, at least a portion (such as a TOSA) of
the first communication module 110A, one or more transmission media
and/or connectors, and at least a portion (such as a ROSA) of the
second communication module 110C. Similarly, physical links 108A,
108B (collectively "physical link 108") can include, for example,
at least a portion (such as a TOSA) of the second communication
module 110C, one or more transmission media and/or connectors, and
at least a portion (such as a ROSA) of the first communication
module 110A.
A. Communication Modules 110A, 110C
[0042] The first communication module 110A is configured to produce
physical layer signals that include high-speed data received from
the first host 102 and out-of-band data comprising diagnostic data
generated by the first communication module 110A and/or received by
the first communication module 110 from the first host 102. The
first communication module 110A emits such physical layer signals
onto physical link 106A for transmission to second communication
module 110C. The second communication module 110C can be similarly
configured to produce and emit physical layer signals onto physical
link 108A using high-speed data received from the second host 104
and out-of-band data comprising diagnostic data generated by the
second communication module 110C and/or received by the second
communication module 110C from the second host 104.
[0043] The first communication module 110A is alternately or
additionally configured to receive physical layer signals from
physical link 108B, to extract high-speed data and out-of-band data
from such physical layer signals, and to provide the extracted
high-speed data and optionally the out-of-band data to the first
host 102. Similarly, the second communication module 110C can
alternately or additionally be configured to receive physical layer
signals from physical link 106B, to extract high-speed data and
out-of-band data from such physical layer signals, and to provide
the extracted high-speed data and optionally the out-of-band data
to the second host 104.
[0044] In more detail, the first communication module 110A includes
a transmitter optical subassembly ("TOSA") 112 for transmitting
physical layer signals across physical link 106A. The first
communication module 110A also includes a receiver optical
subassembly ("ROSA") 114 for receiving physical layer signals
across physical link 108B. The TOSA 112 is connected to a
high-speed data control 116, which may include a high-speed
modulator that modulates the power output of a signal power source
such as a laser in the TOSA 112 such that the high-speed data is
converted to a form that can be transmitted across the physical
link 106A. As shown in FIG. 1, the high-speed data control 116
modulates the TOSA 112 to produce a high-speed data signal 118.
Also connected to the TOSA 112 is an out-of-band data control 120
or out-of-band logic, which may include an out-of-band modulator.
The out-of-band data control 120 further modulates the laser in the
TOSA 112 using the out-of-band data modulator such that an
out-of-band data stream 122 is modulated onto the high-speed data
signal 118 to produce an outgoing double modulated signal 123 that
includes high-speed data and out-of-band data.
[0045] In the example shown, the modulations of the out-of-band
data appear as a change in peak power 124 of the outgoing double
modulated signal 123. Thus the outgoing double modulated signal 123
includes both high-speed data and out-of-band data. The out-of-band
data may be modulated using a number of different modulation
techniques including but not limited to phase shift keying, binary
phase shift keying, quadrature phase shift keying, and Manchester
encoding. The out-of-band data may actually have a frequency range
that is orders of magnitude less than the in-band data. However, to
illustrate the principle of double modulation in a simple graphical
form, the frequency of the out-of-band data stream 122 is
illustrated in FIG. 1 as having only a slightly lower frequency
than the high-speed data signal 118. Regardless, the principles of
the present invention are not limited to the relative frequency
between the out-of-band data stream 122 and the high-speed data
signal 118.
[0046] To perform receiving functions, the ROSA 114 includes a
signal reception element such as an optical detector, including a
photodiode, that receives an incoming double modulated signal. The
ROSA 114 sends all or portions of the incoming double modulated
signal to the out-of-band data control 120 and the high-speed data
control 116. The out-of-band data control 120 may include an
out-of-band demodulator that extracts the out-of-band data from the
incoming double modulated signal. The high-speed data control 116
may include a high-speed data demodulator that extracts high-speed
data from the incoming double modulated signal.
[0047] The out-of-band data stream 122 may be modulated onto the
high-speed data stream 118 using any one or more of a number of
techniques, including varying the average power, peak power, or
extinction ratio of the outgoing physical layer signal. Similarly,
an out-of-band data stream may be demodulated from an incoming
physical layer signal using any one or more of a number of
techniques, including measuring average power, peak power, or
extinction ratio of the incoming physical layer signal. Additional
details regarding techniques for modulating and/or demodulating
out-of-band data are disclosed in U.S. patent application Ser. No.
10/824,258, entitled "OUT-OF-BAND COMMUNICATION BETWEEN NETWORK
TRANSCEIVERS," filed Apr. 14, 2004, which application is fully
incorporated herein by reference in its entirety.
[0048] The second communication module 110C can include one or more
of the same components as the first communication module 110A,
including a ROSA, TOSA, high-speed data control, and/or out-of-band
data control. As such, the second communication module 110C may be
similar in configuration and operation to the first communication
module 110A, and need not be explained in detail herein.
B. Testing Device 110B
[0049] The testing device 110B is configured to extract an
out-of-band data stream from at least one of the physical layer
signals transmitted on physical links 106, 108, the out-of-band
data stream comprising diagnostic data, and to analyze the
diagnostic data so as to determine one or more physical conditions
of the physical links 106, 108. FIG. 2 discloses one example
embodiment of the testing device 110B.
[0050] In the example of FIG. 2, the testing device 110B comprises
at least a signal reception element 202, an out-of-band detector
204, and testing logic 206. The signal reception element 202 in the
present example comprises a ROSA and can be similar in
configuration and operation to the ROSA 114 of FIG. 1. Alternately
or additionally, the signal reception element 202 comprises an
optical detector. The signal reception element 202 is configured to
receive a physical layer signal from a communication module, such
as the first communication module 110A of FIG. 1, via physical link
106A, and to produce an incoming double modulated signal that
includes a high-speed data signal and an out-of-band data signal
comprising diagnostic data. Accordingly, the signal reception
element 202 serves as one example of a means for receiving a double
modulated physical layer signal.
[0051] The out-of-band detector 204 can be similar in configuration
and operation to the out-of-band detector 120 of FIG. 1 and can
comprise an out-of-band demodulator. The out-of-band detector 204
is coupled to signal reception element 202 and is configured to
extract the out-of-band data signal from the incoming double
modulated signal. Accordingly, out-of-band detector 204 serves as
one example of a means for extracting an out-of-band data signal
from an incoming double modulated physical layer signal.
[0052] The testing logic 206 is coupled to the out-of-band detector
204 and can comprise a processor, microprocessor, controller,
microcontroller, or other logic. The testing logic 206 is
configured to extract and analyze the diagnostic data from the
out-of-band data signal. Alternately or additionally, the testing
logic 206 identifies or determines one or more physical conditions
of the physical link 106 using the diagnostic data. Accordingly,
the testing logic 206 serves as one example of a means for
extracting and analyzing diagnostic data from an out-of-band data
signal to identify one or more physical conditions of a physical
link.
[0053] With combined reference to FIGS. 1 and 2, in some
embodiments, the testing device 110B is coupled to the physical
link 106A at, e.g., a connector disposed somewhere between the
first communication module 110A and second communication module
110C. As such, the testing device 110B can receive a physical layer
signal, produce a double modulated signal using signal reception
element 202, extract an out-of-band data signal from the double
modulated signal using out-of-band control 204, and extract and
analyze diagnostic data from the out-of-band data signal using
testing logic 206 to identify or determine one or more physical
conditions of the physical link 106.
[0054] Conventional testing devices used for high-speed networks
require relatively expensive circuitry for processing high-speed
data included in the physical layer signals. However, embodiments
of the invention enable the use of relatively inexpensive testing
devices for identifying or determining the physical condition of a
physical link 106. More particularly, embodiments of the invention
include testing devices 110B comprising signal reception element
202, out-of-band data control 204, and testing logic 206. According
to some examples, the testing device 110B doesn't require any
circuitry for processing high-speed data, only for processing
out-of-band data. Further, as mentioned before, in many
communication networks the frequency of the out-of-band data signal
is orders of magnitude lower than the frequency of the high-speed
data signal and can be processed by out-of-band data control 204 or
other circuitry that is much less expensive than the circuitry
required to process the high-speed data signal.
[0055] Optionally, however, the testing device 110B can further
include high-speed data processing circuitry. For instance, in some
embodiments, the signal reception element 202 and out-of-band
detector 204 are included in a third communication module 208 that
additionally includes a TOSA 210 and high-speed data control 212.
Optionally, the testing device 110B further comprises a fourth
communication module 214 comprising a high-speed data control 216,
TOSA 218, out-of-band data control 220 and a ROSA 222.
[0056] Accordingly, in some embodiments, the testing device 110B is
coupled to both of physical links 106 and 108 such that the testing
device 110B allows high-speed data to reach the first and second
communication modules 110A, 110C while still being able to extract
diagnostic data to identify or determine physical conditions of the
physical links 106, 108. In more detail, the signal reception
element 202 receives a physical layer signal from first
communication module 110A via physical link 106 and produces an
incoming double modulated signal. The high-speed data control 212
extracts a high-speed data signal from the incoming double
modulated signal and provides the high-speed data signal to
high-speed data control 216, whereupon high-speed data control 216
modulates the high-speed data signal onto a physical layer signal
produced by TOSA 218 for transmission to second communication
module 110C via physical link 106B. At the same time, the
out-of-band control 204 extracts the out-of-band data signal from
the incoming double modulated signal such that testing logic 206
can extract diagnostic data from the out-of-band data signal.
Optionally, the out-of-band data control 204 can also provide the
out-of-band data signal to the out-of-band data control 220 for
modulation onto the physical layer signal produced by TOSA 218.
[0057] In a similar manner, the testing device 110B can receive a
physical layer signal from the second communication module 110C via
physical link 108A at ROSA 222, extract diagnostic data therefrom,
and produce another physical layer signal including a high-speed
data signal and optionally an out-of-band data signal for
transmission to the first communication device 110A via physical
link 108B.
[0058] Although not shown, the testing device 110B can alternately
or additionally include a user interface or can be communicatively
couple to a user interface, such as a display, to communicate the
physical condition of the physical links 106, 108 to a technician,
system administrator, or other user.
II. SECOND EXAMPLE COMMUNICATION NETWORK
[0059] Referring now to FIG. 3A, a second example communication
network 300 is disclosed in which embodiments of the invention can
be practiced. The communication network 300 includes a first host
device 302, a second host device 304, one or more physical links
306, 308 and a system comprising components 310A-310G (referred to
herein as "system 310") for collecting physical layer data,
including diagnostic data. More particularly, the system 310
includes at least a first communication module 310A and a testing
device 310B. Optionally, the system 310 further includes one or
more of a second communication module 310C, a tap 310D, an analyzer
310E, a probe 310F, or diagnostic module 310G.
[0060] The communication network 300 is similar in some respects to
the communication network 100. For instance, communication network
300 can accomplish digital communication using the OSI model,
although other models can alternately or additionally be employed.
Additionally, first and second communication modules 310A, 310C are
configured to send and receive physical layer signals via physical
links 306, 308. Further, the physical layer signals are double
modulated and include high-speed data signals and out-of-band data
signals. The out-of-band data signals comprise diagnostic data
generated by the first and second communications modules 310A, 310C
and/or received by first and second communication modules 310A,
310C from first or second hosts 302, 304.
[0061] In contrast to the system 110 of FIG. 1, the testing device
310B of system 310 is not disposed directly between the ends of
physical links 306, 308. Instead, the system 310 includes a tap
310D. The tap 310D is coupled between the physical links 306, 308
and the testing device 310B. Further, the tap 310D is configured to
split a percentage of the physical layer signal transmitted on
physical link 306, 308 to direct to the testing device 310B. This
allows the testing device 310B to receive a percentage of the
physical layer signals without significantly interfering with their
transmission along physical links 306, 308. As such, the testing
device 310B can receive physical layer signals and extract
diagnostic data therefrom without retransmitting the physical layer
signals. Although the tap 310D is disclosed as being coupled to two
physical links 306, 308, the tap 310 can alternately or
additionally be coupled to a single physical link or to three or
more physical links.
[0062] In the example of FIG. 3A, the testing device 310B includes
a plurality of signal reception elements 312, 314 configured to
receive physical layer signals transmitted on physical links 306,
308 via the tap 310D. The signal reception elements 312, 314 can be
similar in configuration and operation to signal reception element
202 of FIG. 2 and need not be explained in detail herein. The
testing device 310B further includes an out-of-band data control
316 and testing logic 318A that can be similar in configuration and
operation to out-of-band data control 204 and testing logic 206 of
FIG. 2, and need not be explained in detail herein. Although not
shown in FIG. 3A, in some embodiments each of signal reception
elements 312, 314 is included in a corresponding communication
module inserted into testing device 310B.
[0063] According to the present example, the testing device 310B
comprises a roving device. For instance, the testing device 310B
may comprise the Rover2G181 marketed by the Finisar Corporation or
other type of roving device, such as any one of a variety of
Finisar certified Physical layer switches ("PLS"). Generally, a
roving device is configured to switch between or "rove" across a
plurality of physical links to separately receive physical layer
signals therefrom. The roving behavior of a roving device can be
based on user-defined and/or default policies which determine the
number of physical links in a roving group and/or a length of time
to receive physical layer signals from each physical link before
moving on to the next physical link. Accordingly, in addition to
being configured to receive physical layer signals and extract
diagnostic data therefrom, the testing device 310B can be further
configured to rove across a plurality of physical links to identify
or determine the physical condition of each of the physical
links.
[0064] Although the components of the testing device 310B,
including the signal reception elements 312, 314, out-of-band data
control 316, and testing logic 318A have been described as being
included in a roving device, the components of the testing device
can alternately or additionally be included in other devices,
including one or more of an analyzer 310, probe 310F, or diagnostic
module 310G. As such, testing devices according to embodiments of
the invention can comprise roving devices, analyzers, probes,
diagnostic modules, or virtually any other device that includes a
signal reception element, out-of-band data control, and testing
logic and that can be coupled to a physical link to extract
diagnostic data from physical layer signals transmitted on the
physical link. Alternately or additionally, one or more of
components 312, 314, 316, 318A can be included in one of devices
310B-310G, while the remaining components are included in one or
more different devices 310B-310G. For instance, as shown in FIG.
3A, the diagnostic module 310G can include testing logic 318B,
while signal reception elements 312, 314 and out-of-band data
control 316 are provided on the testing device 310B.
[0065] In the present example, the analyzer 310E is coupled to the
testing device 310B. One example of an analyzer 310E that can be
employed according to some embodiments of the invention is marketed
by the Finisar Corporation as the Xgig Analyzer. Generally, the
analyzer 310E is configured to capture high-speed data at the input
and/or output of certain points in the communication network 300
and to provide the high-speed data to the diagnostic module 310G.
The captured high-speed data can be used by the diagnostic module
310G to, among other things, diagnose problems with traffic in the
communication network 300. The analyzer 310E can be triggered by
the diagnostic module 310G and/or by the testing device 310B upon
the occurrence of one or more events. The triggers/events can be
user-defined and/or default triggers or events.
[0066] The probe 310F is also coupled to the testing device 310B.
One example of a probe 310F that can be employed according to some
embodiments of the invention is marketed by the Finisar Corporation
as the ProbeFCX probe. Generally, the probe 310F is configured to
collect certain metrics from the physical layer signals transmitted
in the communication network 300. For instance, in some
embodiments, the probe 310F collects header data from the
high-speed data signal by stripping out payload data from the
high-speed data signal. Alternately or additionally, the probe 310
can provide the header data or other collected data to the
diagnostic module 310G.
[0067] The diagnostic module 310G can be coupled to one or more of
the testing device 310B, analyzer 310E, or probe 310F. One example
of a diagnostic module 310G that can be employed according to some
embodiments of the invention is marketed by Virtual Instruments
Corporation as the NetWisdom SAN I/O Intelligence product.
Generally, the diagnostic module 310G supports monitoring,
analysis, and diagnosis of the communication network 300. For
instance, the diagnostic module 310G can be configured to identify
traffic trends in communication network 300 based on data collected
by and received from analyzer 310E and/or probe 310F. When actual
traffic on a given physical link 306, 308 deviates from a trend
identified for that physical link 306, 308, the diagnostic module
310G can generate one or more alarms and/or trigger one or more of
the testing device 310B, analyzer 310E or probe 310F to collect
additional data. Further, although FIG. 3A discloses testing logic
318A, 318B provided on the testing device 310B and diagnostic
module 310G, respectively, in some embodiments, the testing logic
318A or 318B is only provided on one of the testing device 310B or
diagnostic module 310G.
III. THIRD EXAMPLE COMMUNICATION NETWORK
[0068] Referring now to FIG. 3B, a third example communication
network 350 is disclosed in which embodiments of the invention can
be practiced. The communication network 300 includes a first host
device 352, a second host device 354, one or more physical links
356, 358 and a system comprising components 360A-360D (referred to
herein as "system 360") for collecting physical layer data,
including diagnostic data. More particularly, the system 360
includes at least a first communication module 360A and a testing
device 360B. Optionally, the system 360 further includes one or
more of a second communication module 360C and a tap 360D.
[0069] Accordingly, embodiments of the invention include various
testing device configurations. For instance, FIG. 1 discloses a
configuration in which the testing device 110B is directly coupled
to one or more physical links 106, 108. FIG. 3B discloses a
configuration in which the testing device 360B is coupled to one or
more physical links 356, 358 via a tap 360D. FIG. 3A discloses
another configuration in which the testing device 310B (or
diagnostic module 310G comprising testing logic 318B) is coupled to
one or more physical links 306, 308 via a tap 310D, the
configuration of FIG. 3A further including one or more of a roving
device, analyzer, probe or diagnostic module coupled to the testing
device 310B. Other testing device configurations can alternately or
additionally be implemented according to embodiments of the
invention.
IV. FAULT ANALYSIS
[0070] As already explained above, embodiments of the invention
allow a testing device, such as testing devices 110B, 310B, 360B of
FIGS. 1-3B, to extract diagnostic data from a physical layer signal
to identify or determine one or more physical conditions of a
physical link. Such physical conditions can be representative of
one or more faults in a physical link and can be used for fault
analysis and/or diagnosing problems in a communication network.
After a physical condition/fault has been identified or determined
using the testing device 110B, 310B or 360B, a technician, system
administrator, or other user can take appropriate corrective
action.
[0071] For instance, the following Table 1 discloses a few examples
of diagnostic data that can be extracted by the testing device 310B
of FIG. 3A from physical layer signals transmitted via physical
links 306, 308 in the left-hand column, and potential physical
conditions or faults in the right-hand column corresponding to the
diagnostic data in the left-hand column. The examples given in
Table 1 are not intended to be exhaustive or limiting of the
invention in any way and are provided solely by way of example.
Indeed, depending on the configuration of a communication network,
the correspondence between diagnostic data and physical conditions
of a physical link may be the same or different from the
correspondences disclosed in Table 1.
TABLE-US-00001 TABLE 1 Diagnostic Data Potential Physical Condition
of Physical Link 1. Transmit power normal and receive power Cable
included in physical link 306 or 308 is low at first or second
communication module bent, or first or second communication module
310A, 310B 310A, 310C is approaching end of life expectancy 2.
Transmit power normal at first Cable included in physical link 306
is cut communication module 310A and no receive between the first
communication module 310A power at second communication module 310C
and the tap 310D or at signal reception element 312 3. Transmit
power normal at first Cable included in physical link 306 is cut
communication module 310A, no receive power between the tap 310D
and the second at second communication module 310C, receive
communication module 310C power normal at signal reception element
312 4. Transmit power normal at second Cable included in physical
link 308 is cut communication module 310C, no receive power between
the second communication module at signal reception element 314 or
at first 310C and the tap 310D communication module 310A 5.
Transmit power normal at second Cable included in physical link 308
is cut communication module 310C, no receive power between the tap
310D and the first at first communication module 310A, receive
communication module 310A. power normal at signal reception element
314 8. Transmit power low at the first Problem with first
communication module communication module 310A and receive 310A
power low at second communication module 310C and at signal
reception element 312 9. Transmit power low at second Problem with
second communication module communication module 310C and receive
310C power low at first communication module 310A and at signal
reception element 314 10. Lo or Hi voltage out of range alarm or
Problem with power supply at first or second warning message from
first or second communication module 310A, 310C communication
module 310A, 310C 11. Lo or Hi alarm or warning message on Problem
with first or second communication transmission power of first or
second module 310A, 310C communication module 310A, 310C 12. Laser
bias current for first or second First or second communication
module 310A, communication module 310A, 310B is trending 310B is
approaching end of life expectancy higher
[0072] FIG. 4 discloses an example method 400 that can be
implemented in the communication network 300 of FIG. 3A when
collecting diagnostic data and performing fault analysis. In the
example of FIG. 4, the testing logic 318B is implemented in
diagnostic module 310G, rather than implementing testing logic 318A
in testing device 310B.
[0073] The method 400 begins at 402 when the diagnostic module 310G
instructs the testing device 310B, comprising a roving device, to
connect the probe 310F and/or analyzer 310E to signal reception
elements 312, 314 that are coupled to physical links 306, 308 via
tap 310D. In some embodiments, the testing device 310B comprising a
roving device includes a plurality of signal reception elements,
each signal reception element being connected to a different
physical link via tap 310D. Accordingly, step 402 allows the
diagnostic module 310G to collect diagnostic data generated by
particular communication modules, as well as data collected by the
probe 310F and/or analyzer 310E, from particular physical links.
Step 402 can further include the testing device 310B connecting the
probe 310F and/or analyzer 310E to signal reception elements 312,
314.
[0074] At step 404, the first communication module 310A sends
diagnostic data to the second communication module 310C. At step
406, the signal reception element 312 receives, via tap 310D, the
diagnostic data sent by the first communication module 310A to the
second communication module 310C. At step 408, the second
communication module 310C sends diagnostic data to the first
communication module 310A. At step 410, the signal reception
element 314 receives, via tap 310D, the diagnostic data sent by the
second communication module 310C to the first communication module
310A.
[0075] At step 412, testing logic 318B reads diagnostic data from
signal reception elements 312, 314 and/or from the out-of-band data
control 316. At step 414, testing logic 318B performs fault
analysis on the physical links 306, 308, using the diagnostic data
to determine or identify the physical condition of physical links
306, 308. Identifying or determining the physical condition of
physical links 306, 308 can include looking up a particular
combination of diagnostic data in a table accessible to the testing
logic 318B to identify a probable or potential physical condition
or fault of the physical link that is associated with the
particular combination of diagnostic data.
[0076] The method 400 disclosed in FIG. 4 is only one example of a
method that can be implemented in communication networks 100 and
300 according to embodiments of the invention. Embodiments within
the scope of the invention include methods that rearrange the order
of steps 402, 404, 406, 408, 410, 412, 414, that omit one or more
of steps 402, 404, 406, 408, 410, 412, 414 and/or that further
include one or more additional steps.
V. FOURTH EXAMPLE COMMUNICATION NETWORK
[0077] In the communication networks 100, 300, 350 of FIGS. 1-3B,
testing devices 110B, 310B, 360B are coupled between two nodes of
the communication networks 100, 300, 350 to extract diagnostic data
for the physical links 106, 108, 306, 308, 356, 358 between the two
nodes of the communication networks 100, 300, 350. However,
embodiments of the invention are not limited to communication
networks with testing devices that extract diagnostic data for a
given physical link between two nodes by being coupled directly
between the two nodes.
[0078] For instance, referring now to FIG. 5, a third example
communication network 500 is disclosed that allows a testing device
to extract diagnostic data for a given physical link between two
nodes without being coupled between the two nodes. In more detail,
the communication network 500 includes a plurality of repeaters
502, 504, 506. Some long-haul data transmission applications and/or
other applications require that intermediary repeaters be used to
ensure that data of suitable quality can be transmitted across the
long haul data link. For example, transmission along a fiber-optic
cable from one end of the United States to the other end of the
United States may require intermediary repeaters to accomplish the
transmission with suitable signal quality.
[0079] FIG. 5 shows a first repeater 502 that includes a ROSA 508
and a TOSA 510. Notably, each of the ROSA 58 and/or TOSA 510 can be
included in one or more communication modules as part of the
repeater 502. The repeater 502 receives a signal at the ROSA 508.
The signal is passed to a signal processor 512 that may perform
various digital signal processing tasks, such as removing noise,
boosting signal power or other tasks to improve the quality of the
signal. The processed signal is then passed to the TOSA 510 for
transmission to repeater 504, where it may be further processed and
retransmitted by repeaters 504 and 506. Repeater 502 also includes
out-of-band logic such as a microprocessor 514 or other out-of-band
data control that, among other things, may be used to extract and
insert out-of-band data onto the signal sent and received by the
repeater 502.
[0080] At any point in the communication network 500, a tap 516 can
be deployed to split a percentage of a physical layer signal to
direct to testing device 518. The tap 516 and testing device 518
can be similar in configuration and operation to the tap 310D and
testing device 310B of FIG. 3A and need not be explained in detail
herein.
[0081] In one example, digital diagnostic data for the repeater 502
is sent as out-of-band data through the communication network 500
of repeaters. The out-of-band data may be concatenated by each of
the repeaters 502, 504, 506 in the chain to include digital
diagnostic data for each of the repeaters 502, 504, 506. Thus, the
health of repeaters in the communication network can be monitored
by the testing device 518 that is remote from at least some of the
repeaters 502, 504, 506. One example of where this is useful is a
network in which a repeater 502 or 504 is located in a remote
location, such as a rural area, an uninhabited region, or on the
ocean floor. When troubleshooting network problems, it may be
prohibitively expensive to physically retrieve and test repeaters.
However, where diagnostic information for each of the repeaters is
included in out-of-band communications, the health and status of
the repeater may be monitored remotely such that it is unnecessary
to physically retrieve and test the repeater. More particularly,
where the out-of-band data is concatenated by each of the repeaters
502, 504, 506, the testing device 518 can extract all of the
concatenated out-of-band data and then extract corresponding
diagnostic data to identify or determine the physical condition of
the repeaters 502, 504, 506 or the physical condition of the
physical links interconnecting the repeaters 502, 504, 506.
[0082] In some embodiments of the invention, the out-of-band data
that includes digital diagnostic data from each of the repeaters
502, 504, 506 may also be used to monitor the health of fiber optic
links between the repeaters 502, 504, 506. For example, when the
digital diagnostic data includes the power of a transmitted signal
and the power of a received signal, calculations can be done by
subtracting the power received by a receiving repeater from the
power sent by a sending repeater to the receiving repeater.
Significant power loss may indicate the need to repair or replace a
link between repeaters.
[0083] Alternately or additionally, configuration information,
firmware updates, control signals, or the like, may be sent as
out-of-band data to a remote host, repeater or other device. This
helps to avoid the expensive prospect of physically retrieving or
being physically in the presence of the device to configure the
device, update the device's firmware, and/or control the device.
Configuration information may include, for example, instructions
for the device to shut off, information designating a communication
rate, information indicating that laser power should be reduced or
suspended, etc.
[0084] Alternately or additionally, diagnostic data may be
requested or automatically sent by a device. In one embodiment, a
device can check to insure compatibility with other devices on a
network by requesting information such as identification
information. In some embodiments, the identification information
includes information about the manufacturer of a particular device
such that a device requesting diagnostic information may be able to
determine that the particular device has been qualified for use
with the device requesting diagnostic information.
[0085] Alternately or additionally, diagnostic data, such as signal
loss across a physical link, can be determined. For example, a
device may indicate the power at which a signal is transmitted. A
device that receives a signal may indicate in out-of-band data the
amount of power received. Thus by comparing the power of the signal
sent with the power of the signal received, the loss caused by the
physical link between the two devices can be determined.
[0086] In yet other embodiments of the invention, security can be
maintained between devices in a network by sending identification
and authentication information using the out-of-band data. Hardware
or software encoded encryption keys exist on devices within the
network which can be used to generate identification information or
encrypted tokens for presenting to other devices in a network. Thus
a secure connection can be implemented between devices where those
devices are appropriately matched to one another using hardware
embedded encryption keys and the out-of-band data to communicate
authentication and identification information.
[0087] The embodiments described herein may include the use of a
special purpose or general-purpose computer including various
computer hardware or software modules, as discussed in greater
detail below.
[0088] Embodiments within the scope of the present invention also
include computer-readable media for carrying or having
computer-executable instructions or data structures stored thereon.
Such computer-readable media can be any available media that can be
accessed by a general purpose or special purpose computer. By way
of example, and not limitation, such computer-readable media can
comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium which can be used to carry or store desired program
code means in the form of computer-executable instructions or data
structures and which can be accessed by a general purpose or
special purpose computer. When information is transferred or
provided over a network or another communications connection
(either hardwired, wireless, or a combination of hardwired or
wireless) to a computer, the computer properly views the connection
as a computer-readable medium. Thus, any such connection is
properly termed a computer-readable medium. Combinations of the
above should also be included within the scope of computer-readable
media.
[0089] Computer-executable instructions comprise, for example,
instructions and data which cause a general purpose computer,
special purpose computer, or special purpose processing device to
perform a certain function or group of functions. Although the
subject matter has been described in language specific to
structural features and/or methodological acts, it is to be
understood that the subject matter defined in the appended claims
is not necessarily limited to the specific features or acts
described above. Rather, the specific features and acts described
above are disclosed as example forms of implementing the
claims.
[0090] As used herein, the term "module" or "component" can refer
to software objects or routines that execute on the computing
system. The different components, modules, engines, and services
described herein may be implemented as objects or processes that
execute on the computing system (e.g., as separate threads). While
the system and methods described herein are preferably implemented
in software, implementations in hardware or a combination of
software and hardware are also possible and contemplated. In this
description, a "computing entity" may be any computing system as
previously defined herein, or any module or combination of
modulates running on a computing system.
[0091] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *