U.S. patent application number 12/852270 was filed with the patent office on 2010-11-25 for enabling/disabling power-over-ethernet software subsystem in response to power supply status.
This patent application is currently assigned to Foundry Networks, Inc.. Invention is credited to Rakesh Hansalia.
Application Number | 20100299544 12/852270 |
Document ID | / |
Family ID | 38749432 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100299544 |
Kind Code |
A1 |
Hansalia; Rakesh |
November 25, 2010 |
Enabling/Disabling Power-Over-Ethernet Software Subsystem In
Response To Power Supply Status
Abstract
An Ethernet switch includes 12-Volt and 48-Volt power sourcing
modules, system software, Ethernet interface modules and optional
power over Ethernet (PoE) modules. The Ethernet interface modules
are motherboards that include the circuitry required to implement a
non-PoE system. The PoE modules are daughter boards that include
the circuitry required to supply powered devices in a PoE
subsystem. A PoE module may be connected to a corresponding
Ethernet interface module. During start up, all of the Ethernet
interface modules are first powered up in response to the 12-Volt
power sourcing module. If the system software subsequently
determines that the 48-Volt power sourcing module is operational,
then (and only then) the system software attempts to detect the
presence of any PoE modules. Upon detecting one or more PoE
modules, the PoE modules are initialized and configured, thereby
enabling PoE operation.
Inventors: |
Hansalia; Rakesh; (Milpitas,
CA) |
Correspondence
Address: |
Brocade Communications;c/o Bever, Hoffman & Harms, LLP
1730 Holmes Street, Building B
Livermore
CA
94550
US
|
Assignee: |
Foundry Networks, Inc.
San Jose
CA
|
Family ID: |
38749432 |
Appl. No.: |
12/852270 |
Filed: |
August 6, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11420458 |
May 25, 2006 |
7774628 |
|
|
12852270 |
|
|
|
|
Current U.S.
Class: |
713/320 ;
713/300 |
Current CPC
Class: |
H04L 12/66 20130101 |
Class at
Publication: |
713/320 ;
713/300 |
International
Class: |
G06F 1/32 20060101
G06F001/32; G06F 1/26 20060101 G06F001/26 |
Claims
1. An interface module for an Ethernet switch comprising: a printed
circuit board having a first connector element for receiving a
first supply voltage and a second supply voltage, and a second
connector element for receiving a daughterboard; a digital system
on the printed circuit board, wherein the digital system is powered
by the first supply voltage; a power over internet (PoE) module
located on a daughterboard inserted into the second connector
element of the printed circuit board, wherein the PoE module is
powered by the second supply voltage; and one or more Ethernet
ports, each coupled to the digital system and the PoE module by the
printed circuit board.
2. The interface module of claim 1, wherein the PoE module provides
the second supply voltage to one of the one or more Ethernet
ports.
3. The interface module of claim 1, wherein the second supply
voltage is greater than the first supply voltage.
4. The interface module of claim 1, wherein the PoE module supports
powered devices coupled to the one or more Ethernet ports.
5. The interface module of claim 4, wherein the digital system does
not include a PoE subsystem to support powered devices coupled to
the one or more Ethernet ports.
6. The interface module of claim 1, wherein the first connector
element is configured to be inserted into a corresponding connector
element on a backplane of the Ethernet switch.
7. An interface module for an Ethernet switch comprising: a printed
circuit board having a first connector element that receives a
first supply voltage, and a second connector element configured to
receive a daughterboard containing a power over Ethernet (PoE)
module; a digital system on the printed circuit board, wherein the
digital system is powered by the first supply voltage; and one or
more Ethernet ports, each coupled to the digital system and the
second connector element by the printed circuit board.
8. The interface module of claim 7, further comprising a
daughterboard including a PoE module inserted into the second
connector element of the printed circuit board.
9. The interface module of claim 8, wherein the first connector
element also receives a second supply voltage, wherein the PoE
module is powered by the second supply voltage received by the
first connector element.
10. The interface module of claim 9, wherein the PoE module
provides the second supply voltage to one of the one or more
Ethernet ports.
11. The interface module of claim 9, wherein the second supply
voltage is greater than the first supply voltage.
12. The interface module of claim 8, wherein the PoE module
supports powered devices coupled to the one or more Ethernet
ports.
13. The interface module of claim 7, wherein the first connector
element is configured to be inserted into a corresponding connector
element on a backplane of the Ethernet switch.
14. A method of constructing an interface module for an Ethernet
switch comprising: providing an interface module having one or more
Ethernet ports, wherein the interface module only supports
non-power over Ethernet (non-PoE) devices coupled to the one or
more Ethernet ports, wherein the interface module includes a
connector element; and inserting a power over Ethernet (PoE) module
into the connector element of the interface module, wherein the PoE
module supports powered devices coupled to the one or more Ethernet
ports.
15. An Ethernet switch comprising: a first interface module having
a plurality of Ethernet ports, wherein the first interface module
only supports non-power over Ethernet (non-PoE) devices; a second
interface module having a plurality of Ethernet ports, wherein the
second interface module supports power over Ethernet (PoE) devices,
and wherein the second interface module is identical to the first
interface module, except for a PoE module that is inserted into a
connector element of the second interface module.
16. The Ethernet switch of claim 15, wherein the first and second
interface modules each include a connector element for receiving a
PoE module.
17. The Ethernet switch of claim 16, further comprising: a first
power supply module that provides a first supply voltage to the
first and second interface modules, wherein the first interface
module is powered by the first supply voltage; and a second power
supply module that provides a second supply voltage to the first
and second interface module, wherein the PoE module of the second
interface module is powered by the second supply voltage.
18. The Ethernet switch of claim 17, wherein the PoE module
provides the second supply voltage to one or more of the Ethernet
ports of the second interface module.
19. The Ethernet switch of claim 17, wherein the second supply
voltage is greater than the first supply voltage.
20. The Ethernet switch of claim 17, wherein a portion of the
second interface module is powered by the first supply voltage.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/420,458 filed May 25, 2006, entitled "Power
Supply Status Driven Enabling And Disabling Of Power Over Ethernet
Software Subsystem" as amended to be entitled "Enabling/Disabling
Power-Over-Ethernet Software Subsystem In Response To Power Supply
Status".
FIELD OF THE INVENTION
[0002] The present invention relates to a power over Ethernet (PoE)
system. More specifically, the present invention relates a method
for enabling and disabling a PoE software subsystem in response to
the status of an associated power supply.
RELATED ART
[0003] In a power over Ethernet (PoE) system, one or more Ethernet
devices connected to an Ethernet network are powered over the
network cables. Power sourcing equipment located in an Ethernet
switch is used to supply the power on the network cables. Ethernet
devices which are configured to operate in response to the power
supplied on the network cables are commonly referred to as powered
Ethernet devices, or simply powered devices (PDs). As defined
herein, Ethernet devices which are configured to receive power from
a separate power supply (e.g., a conventional 120 Volt AC outlet)
will be referred to as non-PoE devices.
[0004] FIG. 1 is a block diagram of a conventional Ethernet switch
100, which is capable of operating in a PoE system. Ethernet switch
100 includes power sourcing module 101, switch management module
102, backplane 110 and Ethernet interface modules 111-114. As
described in more detail below, each of Ethernet interface modules
111-114 includes an integrated PoE subsystem. Backplane 110
provides the desired electrical connections between the various
modules 101-102 and 111-114. Backplane 110 typically includes
female connector elements for receiving corresponding male
connector elements on modules 101-102 and 111-114. Backplane 110
further includes electrical conductors and devices which facilitate
signal and power transfer between modules 101-102 and 111-114.
Backplane 110 is typically supported by a rack (not shown), which
includes a plurality of slots that are sized and positioned to
receive and hold modules 101-102 and 111-114.
[0005] Power sourcing module 101 is designed to supply a known
voltage, typically 48 Volts. A 48-Volt power supply is selected
because any powered device coupled to Ethernet interface modules
111-114 must be supplied from a 48-Volt source. Thus, switch
management module 102 and Ethernet interface modules 111-114 are
configured to operate in response to the 48-Volt power sourcing
module 101.
[0006] However, switch management module 102 and Ethernet interface
modules 111-114 include internal digital circuitry that must be
operated in response to a 12-Volt source. Switch management module
102 and Ethernet interface modules 111-114 must therefore include
48-Volt to 12-Volt step down circuitry.
[0007] FIG. 2 is a schematic diagram of Ethernet interface module
111 (which is identical to Ethernet interface modules 112-114).
Ethernet interface module 111 is a motherboard that includes
printed circuit board 200, 12-Volt internal digital system 201,
48-Volt integrated PoE subsystem 202, 48-Volt to 12-Volt step down
converter 205, male connector element 210, and Ethernet port access
panel 220. Male connector element 210 is inserted into a
corresponding female connector element on backplane 110, thereby
coupling Ethernet interface module 111 to 48-Volt power sourcing
module 101. The printed circuit board 200 routes the 48-Volt supply
voltage to integrated PoE subsystem 202 and step down converter
205. Step down converter 205 provides a 12-Volt output signal in
response to the 48-Volt supply voltage. This 12-Volt output signal
is used to power internal digital system 201.
[0008] Both internal digital system 201 and integrated PoE
subsystem 202 are coupled to Ethernet port access panel 220. In the
described example, Ethernet port access panel 220 has 24 Ethernet
ports, including Ethernet port 225. If a powered device is coupled
to Ethernet port 225, PoE subsystem 202 supplies the received
48-Volt supply voltage to Ethernet port 225 (and thereby supplies
power to the powered device).
[0009] Conversely, if a non-PoE device is coupled to Ethernet port
225, the 48-Volt supply voltage received by integrated PoE
subsystem 202 is not used to power Ethernet port 225. Rather,
signaling on Ethernet port 225 is implemented entirely by the
12-Volt internal digital system 201.
[0010] As described above, both internal digital system 201 and
integrated PoE subsystem 202 are powered by 48-Volt power sourcing
module 101. Using this design, if internal digital system 201 is
available for access, then integrated PoE subsystem 202 is also
available for access.
[0011] However, this conventional system design is not
cost-effective from a hardware perspective, because each of the
Ethernet interface modules 111-114 must include a PoE subsystem,
regardless of whether the end user wants or uses the PoE subsystem.
Users not using the PoE subsystem will still have to pay for the
presence of this subsystem indirectly.
[0012] This conventional system design also requires that Ethernet
interface modules 111-114 be powered by a 48-Volt power sourcing
module, even if none of the ports of Ethernet interface modules
111-114 are coupled to a powered device. Note that if there are no
powered devices coupled to Ethernet interface modules 111-114,
Ethernet switch could theoretically be operated in response to a
12-Volt power sourcing module. In this case, hardware
inefficiencies may exist with respect to the 48-Volt power sourcing
module 101 and the step down converters required on each of the
Ethernet interface modules 111-114 and the switch management module
102.
[0013] It would therefore be desirable to have an improved
apparatus and method for implementing an Ethernet switch using
Ethernet interface modules, which remedies the above-described
deficiencies of the prior art.
SUMMARY
[0014] Accordingly, the present invention provides an improved
method for implementing a PoE subsystem in an Ethernet interface
module. More specifically, the present invention provides an
Ethernet interface module motherboard that does not include an
integrated PoE subsystem, but rather, includes a connection
structure configured to receive a separate PoE module daughter
card, which includes a PoE subsystem. Thus, the user can decide
whether each Ethernet interface module includes a PoE subsystem by
attaching (or not attaching) a corresponding PoE module to the
Ethernet interface module.
[0015] During the initial start up phase of the Ethernet switch,
all of the Ethernet interface modules are powered up and
initialized in response to a 12-Volt supply voltage provided by a
12-Volt power sourcing module. Advantageously, the Ethernet
interface modules do not require 48-Volt to 12-Volt converters. The
system software does not attempt to detect or enable any PoE
modules until after the initial start up phase is complete.
[0016] After the Ethernet interface modules have been powered up
and initialized in response to the 12-Volt supply voltage, the
system software determines whether an operational 48-Volt power
sourcing module is enabled within the Ethernet switch. If the
system software detects the presence of an operational 48-Volt
power sourcing module, then (and only then) the system software
attempts to detect the presence of any PoE modules that may be
connected to the Ethernet interface modules. PoE modules can only
be detected when these modules are receiving power from the 48-Volt
power sourcing module.
[0017] Note that when the first 48-Volt power sourcing module
becomes operational in the system, all PoE modules in the system
automatically receive low voltage power required for digital
circuit operation. That is, the received 48-Volt supply voltage is
down-converted within the PoE modules to enable digital circuit
operation within the modules. However, the system software must be
informed that these PoE modules exist and are now receiving the low
voltage power. The system software relies on the first 48-Volt
power sourcing module becoming operational as the event that
triggers the search for the PoE modules and making these PoE
modules fully operational.
[0018] The present invention will be more fully understood in view
of the following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a block diagram of a conventional Ethernet switch,
which includes Ethernet interface modules with integrated PoE
subsystems.
[0020] FIG. 2 is a schematic diagram of an Ethernet interface
module of FIG. 1.
[0021] FIG. 3 is a block diagram of an Ethernet switch in
accordance with one embodiment of the present invention.
[0022] FIG. 4 is a schematic diagram of an Ethernet interface
module and an associated PoE module in accordance with one
embodiment of the present invention.
[0023] FIG. 5 is a state diagram illustrating the operation of the
Ethernet switch of FIG. 3 in response to a pair of 48-Volt power
sourcing modules, in accordance with one embodiment of the present
invention.
DETAILED DESCRIPTION
[0024] FIG. 3 is a block diagram of an Ethernet switch 300, which
is capable of operating in a PoE system in accordance with one
embodiment of the present invention. Ethernet switch 300 includes
12-Volt power sourcing module 301, 48-Volt power sourcing module
302, switch management module 303, backplane 305, Ethernet
interface modules 311-314 and PoE modules 321-322. As described in
more detail below, Ethernet interface modules 311-314 do not
include integrated PoE subsystems. Backplane 305 operates in the
same manner as backplane 110 (FIG. 1) to provide the desired
electrical connections between modules 301-303 and 311-314. Thus,
backplane 305 is supported by a rack (not shown), which in turn,
helps to support modules 301-303 and 311-314.
[0025] Power sourcing modules 301 and 302 are designed to supply
voltages of 12-Volts and 48-Volts, respectively. As described in
more detail below, 48-Volt power sourcing module is only necessary
if one or more of the Ethernet interface modules 311-314 is
connected to a corresponding PoE module. Switch management module
303 and the internal digital system present on each of the Ethernet
interface modules 311-314 are configured to operate in response to
the 12-Volt power sourcing module 301. 48-Volt to 12-Volt step down
circuitry is therefore not necessary in switch management module
303 or Ethernet interface modules 311-314.
[0026] Both internal digital system 401 and PoE module 321 are
coupled to Ethernet port access panel 420. In the described
example, Ethernet port access panel 420 has 24 Ethernet ports,
including Ethernet port 425. If a powered device is coupled to
Ethernet port 425, PoE module 321 supplies the received 48-Volt
supply voltage to Ethernet port 425 (and thereby supplies power to
the powered device). Conversely, if a non-PoE device is coupled to
Ethernet port 425, the 48-Volt supply voltage received by PoE
module 321 is not used to power Ethernet port 425. Rather,
signaling on Ethernet port 425 is implemented entirely by the
12-Volt internal digital system 401.
[0027] FIG. 4 is a schematic diagram of Ethernet interface module
311 (which is identical to Ethernet interface modules 312-314).
Ethernet interface module 311 is a motherboard that includes
printed circuit board 400, 12-Volt internal digital system 401,
male connector element 410, female connector elements 415-416 and
Ethernet port access panel 420. Male connector element 410 is
inserted into a corresponding female connector element on backplane
305, thereby coupling Ethernet interface module 311 to both 12-Volt
power sourcing module 301 and 48-Volt power sourcing module 302 (if
present). The 12-Volt output signal provided by power sourcing
module 301 is used to power internal digital system 401.
[0028] Female connector elements 415-416 of motherboard 400 are
configured to receive corresponding male connector elements 325 and
326 present on PoE module 321, thereby placing PoE module 321 into
electrical contact with Ethernet interface module 311. PoE module
321 is an optional daughter card, which is connected to motherboard
400 to enable Ethernet interface module 311 to support powered
devices connected to Ethernet port access panel 420.
[0029] In the described example, Ethernet interface modules 311 and
312 are coupled to corresponding PoE modules 321 and 322, while
Ethernet interface modules 313 and 314 are not coupled to
corresponding PoE modules. However, it is understood that any, all
or none of the Ethernet interface modules 311-314 can be coupled to
corresponding PoE modules in other embodiments.
[0030] Ethernet switch 300 operates as follows in accordance with
one embodiment of the present invention. Ethernet switch 300 is
initially booted up and initialized when 12-Volt power sourcing
module 301 is present and enabled. During the initialization
process, system software (which is implemented by switch management
module 303) does not attempt to recognize any PoE modules present
in Ethernet switch 300. That is, the initialization process
proceeds as if there are no PoE modules present in Ethernet switch
300. At this time, each of the Ethernet interface modules 311-314
(including each associated internal digital system) is initialized
by the system software, wherein Ethernet switch 300 operates
entirely in response to 12-Volt power supplied by the 12-Volt power
sourcing module 301. The 48-Volt power sourcing module 302 need not
be enabled during this portion of the initialization phase.
[0031] A portion of the system software is responsible for
detecting the presence and health of the power sourcing modules
within Ethernet switch 300. After Ethernet switch 300 is operating
in response to 12-Volt power sourcing module 301, the system
software will generate an event upon detecting the presence and
good health of the first 48-Volt power supply detected in Ethernet
switch 300 (e.g., 48-Volt power sourcing module 302). The PoE
modules are powered up in response to the 48-Volt supply voltage
provided by 48-Volt power sourcing module 302. Note that digital
circuitry on a PoE module may be powered by a 3.3-Volt supply
voltage that is created by stepping down the received 48-Volt
supply voltage.
[0032] The event generated upon detecting the first 48-Volt power
sourcing module is provided to PoE software, which is also
implemented by switch management module 303. This event causes the
PoE software to trigger the execution of an initialization code
that, as part of the initialization process, attempts to detect and
recognize all PoE modules present in Ethernet switch 300. Because
this phase of the initialization process is not initiated until
after 48-Volt power is supplied to Ethernet interface modules
311-314, PoE module detection is guaranteed to succeed if a PoE
module is connected to the associated Ethernet interface module,
and fail if no PoE module is connected to the associated Ethernet
interface module. Any detected PoE modules are initialized and
fully configured by switch management module 303, in response to
corresponding user provided instructions.
[0033] It is important to generate the event indicating that a
48-Volt power supply has been detected before allowing the PoE
software to search for PoE modules, because the PoE software is
incapable of detecting a PoE module in the absence of a 48-Volt
power supply. If the PoE software were to attempt to detect the
presence of PoE modules in the absence of a 48-Volt power supply,
then no PoE modules present in the Ethernet switch 300 would be
detected. Moreover, the system software would be unable to
subsequently detect a PoE module that is not initially detected,
because of a hardware design limitation. That is, the hardware
design typically does not specify an explicit event that can
trigger the software to begin searching for PoE modules, other than
the presence event of the first detected 48-Volt power sourcing
module.
[0034] The present invention enables Ethernet interface modules
(motherboards) and PoE modules (daughter cards) to be manufactured
as separate entities and products. Users purchasing an Ethernet
switch without the PoE feature will receive Ethernet interface
modules that do not include PoE circuitry. Alternately, users
purchasing an Ethernet switch with the PoE feature will receive one
or more Ethernet interface modules, each having an attached
corresponding PoE module. This arrangement provides the
manufacturer full flexibility in manufacturing and maintaining
inventory of the Ethernet interface modules and PoE modules. In
addition, the users realize cost-effectiveness in purchasing
Ethernet interface modules without a PoE feature. Moreover, a user
will also have the ability to upgrade a non-PoE Ethernet switch to
an Ethernet switch capable of supporting PoE functionality, merely
by purchasing and installing a PoE module.
[0035] In accordance with another embodiment of the present
invention, more than one 48-Volt power sourcing module may be
included in an Ethernet switch. The additional 48-Volt power
sourcing modules provide capacity to enable a larger number of
powered devices to be connected to the Ethernet switch. The
operation of Ethernet switch 300, with one additional 48-Volt power
sourcing module, is described below.
[0036] FIG. 5 is a state diagram illustrating the operation of
Ethernet switch 300 in response to a pair of 48-Volt power sourcing
modules. In the initial state 501, the 12-Volt system is
operational, but the PoE modules have not yet been enabled. That
is, the system software has not yet generated an event indicating
the presence of an operational 48-Volt power supply, so the power
allocated to the PoE modules is set to zero. At least one of the
Ethernet interface modules has an attached PoE module, and there
are a total of N powered devices coupled to the ports of these
Ethernet interface modules.
[0037] The system software generates event 1 upon detecting the
presence of a first 48-Volt power sourcing module having a first
capacity, X. The system software increases the available power
capacity of the PoE subsystem to X, which triggers: (a) the
initialization of the PoE modules, (b) the detection of any PoE
modules in the Ethernet interface modules, and (c) the
initialization of PoE drivers in each detected PoE module. The PoE
subsystem uses the PoE drivers to enable Nx powered devices,
thereby placing these powered devices in a powered up state. The
number of powered devices in a denied power state is designated Mx,
wherein Mx=N-Nx. This condition is illustrated as state 502 in FIG.
5. Note that a port will enter a `denied power` state when there is
insufficient power capacity available to meet the powering needs of
the port.
[0038] Processing will return to state 501 from state 502 if the
system software determines that the first 48-Volt power sourcing
module has been disabled or becomes otherwise unavailable. In this
transition, which is illustrated as event 6 in FIG. 5, the system
software detects that the PoE power capacity has been reduced from
X to zero, thereby triggering shutdown of the PoE modules wherein
all allocated system resources (including PoE driver resources) are
cleaned up. The PoE subsystem makes no attempts to access the PoE
hardware, because all of the PoE modules have lost power.
[0039] When in state 502, the system software will generate event 2
upon detecting the presence of a second 48-Volt power sourcing
module having a second capacity, Y. The system software increases
the available power capacity of the PoE subsystem to X+Y, which
triggers the PoE subsystem to enable Ny additional powered devices,
thereby placing these additional powered devices in the powered up
state. The number of powered devices in the powered up state is
designated Nx+y, wherein Nx+y=Nx+Ny. The number of powered devices
in the denied power state is designated Mx+y, wherein Mx+y=N-Nx+y.
This condition is illustrated as state 503 in FIG. 5.
[0040] Note that processing will return to state 502 from state 503
if the second 48-Volt power sourcing module has been disabled or
becomes otherwise unavailable. In this transition, which is
illustrated as event 5 in FIG. 5, the system software reduces the
PoE power capacity from X+Y to X, thereby triggering the PoE
subsystem to disable Ny powered devices for power recovery. At this
time, Nx powered devices are in the power up state and Mx powered
devices are in the denied power state.
[0041] If the second 48-Volt power sourcing module is enabled
before the first 48-Volt power sourcing module (from initial state
501), then the system software generates event 3 (which is similar
to event 1) and proceeds to state 504 (which is similar to state
503). Processing can return to state 501 from state 504 if the
second 48-Volt power sourcing module is disabled. In this case, the
system software generates event 8, which is processed in a manner
similar to event 6.
[0042] Processing can also proceed from state 504 to state 503 if
the first 48-Volt power sourcing module is subsequently enabled. In
this case, the system software generates event 4, which is
processed in a manner similar to event 2. Processing can also
return from state 503 to state 504 if the first 48-Volt power
sourcing module is disabled. In this case, the system software
generates event 7, which is processed in a manner similar to event
5.
[0043] Although the present invention has been described in
connection with various embodiments, it is understood that
variations of these embodiments would be obvious to one of ordinary
skill in the art. Thus, the present invention is limited only by
the following claims.
* * * * *