U.S. patent application number 13/690977 was filed with the patent office on 2013-05-02 for method and system for energy efficient communication among one or more interfaces in a communication path.
This patent application is currently assigned to Broadcom Corporation. The applicant listed for this patent is Broadcom Corporation. Invention is credited to Wael William Diab.
Application Number | 20130111240 13/690977 |
Document ID | / |
Family ID | 42131331 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130111240 |
Kind Code |
A1 |
Diab; Wael William |
May 2, 2013 |
Method And System For Energy Efficient Communication Among One Or
More Interfaces In A Communication Path
Abstract
Network devices coupled via serial and/or parallel interfaces
may determine a power level mode of operation according to an
energy efficient network communication control policy and may
configure one or more of the interfaces for the lower power mode.
The network devices may comprise a PHY, a MAC and/or higher layer
devices. The interfaces may comprise a XGMII extender, a XAUI
and/or a XFI device. The interfaces may comprise a backplane PHY,
for example, a 10GBASE-KR, a 10GBASE-KX4 and/or a 1GBASE-KX PHY
which may perform FEC. The interfaces may comprise direct attach
copper such as SFP+ and/or InfiniBand and/or 10GBASE-CX4 PHYs. The
interfaces may comprise a pluggable transceiver module. Energy
efficient network control data may be communicated to and/or from
the network devices which may enter and/or exit a lower power mode
of operation.
Inventors: |
Diab; Wael William; (San
Francisco, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Broadcom Corporation; |
Irvine |
CA |
US |
|
|
Assignee: |
Broadcom Corporation
Irvine
CA
|
Family ID: |
42131331 |
Appl. No.: |
13/690977 |
Filed: |
November 30, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12478320 |
Jun 4, 2009 |
8356190 |
|
|
13690977 |
|
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|
|
61111653 |
Nov 5, 2008 |
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Current U.S.
Class: |
713/320 |
Current CPC
Class: |
G06F 1/3234 20130101;
Y02D 50/42 20180101; H04L 12/12 20130101; Y02D 50/40 20180101; Y02D
30/30 20180101; Y02D 30/32 20180101; Y02D 30/00 20180101; Y02D
30/50 20200801 |
Class at
Publication: |
713/320 |
International
Class: |
G06F 1/32 20060101
G06F001/32 |
Claims
1. A network device, comprising: a backplane; a first module that
includes a first physical layer device and a second physical layer
device, said first physical layer device being configured for
communication with an external second network device via a network
cable; a second module that includes a third physical layer device,
said third physical layer device being configured for communication
with said second physical layer device via said backplane; and an
energy efficiency control policy module, said energy efficiency
control policy module being configured to determine a need to
transition said first physical layer device from a first operating
mode to a second operating mode, wherein a plurality of interfaces
in a communication path that extends in a direction upstream from
an interface between said first physical layer device and said
network cable are configured to transition to an energy saving mode
in response to said determined need to transition said first
physical layer device to said second operating mode.
2. The network device of claim 1, wherein said energy efficiency
control policy module is in said first physical layer device.
3. The network device of claim 1, wherein said plurality of
interfaces includes an interface between said first physical layer
device and a media access controller device.
4. The network device of claim 1, wherein said plurality of
interfaces includes an XGMII extender interface.
5. The network device of claim 1, wherein said plurality of
interfaces includes said second physical layer device and/or said
third physical layer device.
6. The network device of claim 1, wherein said plurality of
interfaces transitions substantially at the same time as said
transition of said first physical layer device.
7. The network device of claim 1, wherein said plurality of
interfaces transitions at a later time than said transition of said
first physical layer device.
8. The network device of claim 1, wherein said first module is a
line card and said second module is a supervisor module having a
switch chip.
9. The network device of claim 1, wherein said plurality of
interfaces are controlled using a control packet that is
communicated over said plurality of interfaces.
10. The network device of claim 1, wherein said plurality of
interfaces are controlled using a control signal communicated
within an inter-packet gap over said plurality of interfaces.
11. A method, comprising: determining, by an energy efficiency
control policy in a network node, a need to transition a first
physical layer device in a first module in said network node from a
first power mode to a second power mode; and communicating, by said
network node, one or more energy efficiency control signals to one
or more additional physical layer devices in a communication path
that extends in a direction upstream from an interface between said
first physical layer device and said network cable, wherein said
one or more energy efficiency control signals enables said one or
more additional physical layer devices in said communication path
to transition to an energy saving mode.
12. The method of claim 11, wherein one of said additional physical
layer devices is in a second network node.
13. The method of claim 11, wherein said determining comprises
determining by an energy efficiency control policy in said first
physical layer device.
14. The method of claim 11, wherein said communicating comprises
communicating within a packet preamble.
15. The method of claim 11, wherein said communicating comprises
communicating within an inter-packet gap.
16. The method of claim 11, wherein said communicating enables
transitioning an interface between one of said additional physical
layer devices and a media access controller device.
17. The method of claim 11, wherein said communicating enables
transitioning an XGMII extender interface into an energy saving
mode.
18. The method of claim 11, wherein said communicating enables
transitioning a backplane interface between two backplane physical
layer devices.
19. The method of claim 11, wherein said communicating enables
transitioning said one or more additional physical layer devices
substantially at the same time as a transition of said first
physical layer device to said second power mode.
20. The method of claim 11, wherein said communicating enables
transitioning said one or more additional physical layer devices at
a later time than a transition of said first physical layer device
to said second power mode.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY
REFERENCE
[0001] This application is a continuation of Non-Provisional
application Ser. No. 12/478,320, filed on Jun. 4, 2009, which
claims priority to, and claims the benefit of U.S. Provisional
Application Ser. No. 61/111,653, filed on Nov. 5, 2008.
[0002] This application makes reference to:
[0003] U.S. patent application Ser. No. 12/471,861 (Attorney Docket
No. 20367US02) filed on May 26, 2009;
[0004] U.S. patent application Ser. No. 12/470,785 (Attorney Docket
No. 20368US02) filed on May 22, 2009;
[0005] U.S. patent application Ser. No. 12/470,970 (Attorney Docket
No. 20369US02) filed on May 22, 2009;
[0006] U.S. patent application Ser. No. 12/474,557 (Attorney Docket
No. 20370US02) filed on May 29, 2009;
[0007] U.S. patent application Ser. No. 11/685,554 (Attorney Docket
No. 18031US01) filed Mar. 13, 2007; and
[0008] U.S. patent application Ser. No. 11/473,205 (Attorney Docket
No. 17396US02) filed Jun. 22, 2006.
[0009] Each of the above stated applications is hereby incorporated
herein by reference in its entirety.
FIELD OF THE INVENTION
[0010] Certain embodiments of the invention relate to networking.
More specifically, certain embodiments of the invention relate to a
method and system for energy efficient communication among one or
more interfaces in a communication path.
BACKGROUND OF THE INVENTION
[0011] Communications networks and in particular Ethernet networks,
are becoming an increasingly popular means of exchanging data of
various types and sizes for a variety of applications. In this
regard, Ethernet networks are increasingly being utilized to carry
voice, data, and multimedia traffic. Accordingly more and more
devices are being equipped to interface to Ethernet networks.
Broadband connectivity including internet, cable, phone and VOIP
offered by service providers has led to increased traffic and more
recently, migration to Ethernet networking. Much of the demand for
Ethernet connectivity is driven by a shift to electronic lifestyles
involving desktop computers, laptop computers, and various handheld
devices such as smart phones and PDA's. Applications such as search
engines, reservation systems and video on demand that may be
offered at all hours of a day and seven days a week, have become
increasingly popular.
[0012] These recent developments have led to increased demand on
datacenters, aggregation, high performance computing (HPC) and core
networking. As the number of devices connected to data networks
increases and higher data rates are required, there is a growing
need for new transmission technologies which enable higher data
rates. Conventionally, however, increased data rates often results
in significant increases in power consumption. In this regard, as
an increasing number of portable and/or handheld devices are
enabled for Ethernet communications, battery life may be a concern
when communicating over Ethernet networks. Accordingly, ways of
reducing power consumption when communicating over Ethernet
networks may be needed.
[0013] Further limitations and disadvantages of conventional and
traditional approaches will become apparent to one of skill in the
art, through comparison of such systems with the present invention
as set forth in the remainder of the present application with
reference to the drawings.
BRIEF SUMMARY OF THE INVENTION
[0014] A system and/or method for energy efficient communication
among one or more interfaces in a communication path, substantially
as shown in and/or described in connection with at least one of the
figures, as set forth more completely in the claims.
[0015] Various advantages, aspects and novel features of the
present invention, as well as details of an illustrated embodiment
thereof, will be more fully understood from the following
description and drawings.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0016] FIG. 1 is a block diagram illustrating an exemplary Ethernet
connection between two network devices, in accordance with an
embodiment of the invention.
[0017] FIG. 2 is a block diagram illustrating an exemplary Ethernet
over twisted pair PHY device architecture comprising a multi-rate
capable physical block, in accordance with an embodiment of the
invention.
[0018] FIG. 3 is a block diagram illustrating an exemplary PHY
device that is enabled to implement energy efficient networking, in
accordance with an embodiment of the invention.
[0019] FIG. 4 is a block diagram illustrating an exemplary XGMII
extender that is capable of energy efficient modes of operation, in
accordance with an embodiment of the invention.
[0020] FIG. 5A is a block diagram illustrating an exemplary
backplane PHY that is capable of energy efficient modes of
operation, in accordance with an embodiment of the invention.
[0021] FIG. 5B is a block diagram illustrating an exemplary
implementation of cascading energy efficient mode over a plurality
of interfaces in a communication path, in accordance with an
embodiment of the invention.
[0022] FIG. 6 is a block diagram illustrating an exemplary direct
attached copper interface that is capable of energy efficient modes
of operation, in accordance with an embodiment of the
invention.
[0023] FIG. 7 is a flow chart illustrating exemplary steps for
implementing an energy efficient network control policy in a
plurality of interfaces of a communication path, in accordance with
an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Certain embodiments of the invention can be found in a
method and system for energy efficient communication among one or
more interfaces in a communication path. In this regard, one or
more of a plurality of network devices may be communicatively
coupled via one or more serial and/or parallel interfaces. One or
more circuits within the network devices may be operable to
determine a power level mode of operation for the one or more
interfaces and/or devices according to an energy efficient network
communication control policy. The one or more circuits may
configure the interfaces for the determined power level mode. In
this regard, configuration in various interfaces may occur at one
time instant or configuration may be cascaded sequentially through
a plurality of interfaces. The plurality of network devices may
comprise a physical layer device (PHY), a media access controller
(MAC) and/or one or more higher OSI layer devices. The one or more
of the interfaces may comprise a XGMII extender, for example, a
XAUI and/or a XFI device. Moreover, the one or more interfaces may
comprise a back plane PHY, for example, a 10GBASE-KR, a 10GBASE-KX4
and/or a 1GBASE-KX PHY. The backplane PHY may be operable to
perform forward error control (FEC). The one or more interfaces may
comprise a direct attached copper PHY, for example, SFP+ and/or may
comprise InfiniBand and/or 10GBASE-CX4. Furthermore, the one or
more serial interfaces may comprise a pluggable transceiver module
comprising a direct attached copper PHY. Energy efficient network
control data may be communicated to and/or from one or more of the
plurality of network devices. The one or more plurality of network
devices may enter or exit a lower power mode of operation based on
the communicated energy efficient network control data. In some
instances, the one or more plurality of network devices may buffer
packets pending transmission by the interfaces while the interfaces
and/or other components transition to the determined power level
mode of operation.
[0025] FIG. 1 is a block diagram illustrating an exemplary Ethernet
connection between a two network devices, in accordance with an
embodiment of the invention. Referring to FIG. 1, there is shown a
system 100 that comprises a network device 102 and a network device
104. In addition, there is shown two hosts 106a and 106b, two MAC
controllers 108a and 108b, two PHY devices 110a and 110b, two
interface controllers 114a and 114b, two bus controller interfaces
116a and 116b and a link 112
[0026] The network devices 102 and 104 may communicate via the link
112. The Ethernet link 112 is not limited to any specific medium
and may utilize any suitable medium. Exemplary Ethernet link 112
media may comprise copper, optical and/or backplane technologies.
For example, a copper medium such as STP, Cat3, Cat 5, Cat 5e, Cat
6, Cat 7 and/or Cat 7a as well as ISO nomenclature variants may be
utilized. Additionally, copper media technologies such as SFP+,
CX4, InfiniBand, ribbon and backplane may be utilized. With regard
to optical media for the Ethernet link 112, single mode fiber as
well as multi-mode fiber may be utilized.
[0027] In an exemplary embodiment of the invention, the link 112
may comprise up to four or more physical channels, each of which
may, for example, comprise an unshielded twisted pair (UTP). The
network device 102 and the network device 104 may communicate via
two or more physical channels comprising the link 112. For example,
Ethernet over twisted pair standards 10BASE-T and 100BASE-TX may
utilize two pairs of UTP while Ethernet over twisted pair standards
1000BASE-T and 10GBASE-T may utilize four pairs of UTP. In this
regard, however, aspects of the invention may enable varying the
number of physical channels via which data is communicated.
[0028] In an exemplary embodiment of the invention, the network
devices 102 and/or 104 may comprise a twisted pair PHY capable of
operating at one or more standard rates such as 10 Mbps, 100 Mbps,
1 Gbps, and 10 Gbps (10BASE-T, 100GBASE-TX, 1GBASE-T, and/or
10GBASE-T); potentially standardized rates such as 40 Gbps and 100
Gbps; and/or non-standard rates such as 2.5 Gbps and 5 Gbps.
[0029] In another exemplary embodiment of the invention, the
network devices 102 and/or 104 may comprise a backplane PHY capable
of operating at one or more standard rates such as 10 Gbps
(10GBASE-KX4, 10GBASE-KX and/or 10GBASE-KR); and/or non-standard
rates such as 2.5 Gbps and 5 Gbps.
[0030] In another exemplary embodiment of the invention, the
network devices 102 and/or 104 may comprise an optical PHY capable
of operating at one or more standard rates such as 10 Mbps, 100
Mbps, 1 Gbps, and 10 Gbps; potentially standardized rates such as
40 Gbps and 100 Gbps; and/or non-standardized rates such as 2.5
Gbps and 5 Gbps. In this regard, the optical PHY may be a passive
optical network (PON) PHY.
[0031] In addition, the network devices 102 and/or 104 may support
multi-lane topologies such as 40 Gbps CR4, ER4, KR4; 100 Gbps CR10,
SR10 and/or 10 Gbps LX4 and CX4. Also, serial electrical and copper
single channel technologies such as KX, KR, SR, LR, LRM, SX, LX,
CX, BX10, LX10 may be supported. Non standard speeds and
non-standard technologies, for example, single channel, two channel
or four channels may also be supported. More over, TDM technologies
such as PON at various speeds may be supported by the network
devices 102 and/or 104.
[0032] The network device 102 may comprise a host 106a, a medium
access control (MAC) controller 108a, and a PHY device 104a. The
network device 104 may comprise a host 106b, a MAC controller 108b,
and a PHY device 110b. Notwithstanding, the invention is not
limited in this regard. In various embodiments of the invention,
the network device 102 and/or 104 may comprise, for example,
computer systems or audio/video (NV) enabled equipment. In this
regard, NV equipment may, for example, comprise a microphone, an
instrument, a sound board, a sound card, a video camera, a media
player, a graphics card, or other audio and/or video device.
Additionally, the network devices 102 and 104 may be enabled to
utilize Audio/Video Bridging and/or Audio/video bridging extensions
(collectively referred to herein as audio video bridging or AVB)
for the exchange of multimedia content and associated control
and/or auxiliary data.
[0033] The PHY devices 110a and 110b may each comprise suitable
logic, circuitry, and/or code that may enable communication, for
example, transmission and reception of data, between the network
device 102 and the network device 104. The PHY device 110a and/or
the PHY device 110b may support, for example, Ethernet over copper,
Ethernet over fiber, and/or backplane Ethernet operations. In an
exemplary embodiment of the invention, one or both of the PHY
devices 110a and 110b may comprise pluggable modules. Exemplary
form factors for the pluggable modules may comprise SFP, SFP+,
XENPAK, X2, XFP and XPAK modules. For example, the PHY devices 110a
and/or 110b may support SFP+ direct attach copper. The PHY devices
110a and 110b may enable multi-rate communications, such as 10
Mbps, 100 Mbps, 1000 Mbps (or 1 Gbps), 2.5 Gbps, 4 Gbps, 10 Gbps,
or 40 Gbps, for example. In this regard, the PHY devices 110a and
110b may support standard-based data rate limits and/or
non-standard data rate limits. Moreover, the PHY devices 110a and
110b may support standard Ethernet link lengths or ranges of
operation and/or extended ranges of operation. The PHY devices 110a
and 110b may enable communication between the network device 102
and the network device 104 by utilizing a link discovery signaling
(LDS) operation that enables detection of active operations in the
other network device. In this regard the LDS operation may be
configured to support a standard Ethernet operation and/or an
extended range Ethernet operation. The PHY devices 110a and 110b
may also be operable to support autonegotiation, which may for
example, be utilized to identify and/or select communication
parameters such as speed and duplex mode.
[0034] In various embodiments of the invention, the PHY devices
110a and 110b may comprise suitable logic, circuitry, and/or code
that may enable transmission and/or reception at a high(er) data in
one direction and transmission and/or reception at a low(er) data
rate in the other direction. For example, the network device 102
may comprise a multimedia server and the network device 104 may
comprise a multimedia client. In this regard, the network device
102 may transmit multimedia data, for example, to the network
device 104 at high(er) data rates while the network device 104 may
transmit control or auxiliary data associated with the multimedia
content at low(er) data rates.
[0035] The data transmitted and/or received by the PHY devices 110a
and 110b may be formatted in accordance with the well-known OSI
protocol standard. The OSI model partitions operability and
functionality into seven distinct and hierarchical layers.
Generally, each layer in the OSI model is structured so that it may
provide a service to the immediately higher interfacing layer. For
example, layer 1, or physical layer, may provide services to layer
2 and layer 2 may provide services to layer 3. The data transmitted
may comprise frames of Ethernet media independent interface (MII)
data which may be delimited by start of stream and end of stream
delimiters, for example.
[0036] In an exemplary embodiment of the invention illustrated in
FIG. 1, the hosts 106a and 106b may implement OSI layer 3 and
above, the MAC controllers 108a and 108b may implement OSI layer 2
and above and the PHY devices 110a and 110b may implement the
operability and/or functionality of OSI layer 1 or the physical
layer. In this regard, the PHY devices 110a and 110b may be
referred to as physical layer transmitters and/or receivers,
physical layer transceivers, PHY transceivers, PHYceivers, or PHY,
for example. The hosts 106a and 106b may comprise suitable logic,
circuitry, and/or code that may enable operability and/or
functionality of the five highest functional layers for data
packets that are to be transmitted over the link 112. Since each
layer in the OSI model provides a service to the immediately higher
interfacing layer, the MAC controllers 108a and 108b may provide
the necessary services to the hosts 106a and 106b to ensure that
packets are suitably formatted and communicated to the PHY devices
110a and 110b. During transmission, each layer may add its own
header to the data passed on from the interfacing layer above it.
However, during reception, a compatible device having a similar OSI
stack may strip off the headers as the message passes from the
lower layers up to the higher layers.
[0037] The PHY devices 110a and 110b may be configured to handle
physical layer requirements, which comprise, but are not limited
to, packetization, data transfer and serialization/deserialization
(SERDES), in instances where such an operation is required. Data
packets received by the PHY devices 110a and 110b from MAC
controllers 108a and 108b, respectively, may include data and
header information for each of the above six functional layers. The
PHY devices 110a and 110b may be configured to encode data packets
that are to be transmitted over the link 112 and/or to decode data
packets received from the link 112.
[0038] The MAC controller 108a may comprise suitable logic,
circuitry, and/or code that may enable handling of data link layer,
layer 2, operability and/or functionality in the network device
102. Similarly, the MAC controller 108b may comprise suitable
logic, circuitry, and/or code that may enable handling of layer 2
operability and/or functionality in the network device 104. The MAC
controllers 108a and 108b may be configured to implement Ethernet
protocols, such as those based on the IEEE 802.3 standard, for
example. Notwithstanding, the invention is not limited in this
regard.
[0039] The MAC controller 108a may communicate with the PHY device
110a via an interface 114a and with the host 106a via a bus
controller interface 116a. The MAC controller 108b may communicate
with the PHY device 110b via an interface 114b and with the host
106b via a bus controller interface 116b. The interfaces 114a and
114b correspond to Ethernet interfaces that comprise protocol
and/or link management control signals. The interfaces 114a and
114b may be multi-rate capable interfaces and/or media independent
interfaces (MII). The interfaces 114 and/or 114b may comprise
parallel and/or serial links between the MAC controller and PHY
device. For example, the interfaces 114a and/or 114b may comprise
an MII, XGMII, SGMII, XAUI or XFI interface. The bus controller
interfaces 116a and 116b may correspond to PCI or PCI-X interfaces.
Notwithstanding, the invention is not limited in this regard.
[0040] In operation, exemplary PHY devices 110a and 110b may
comprise direct attached copper interfaces that may comprise four
duplex copper wires. The PHY devices 110a and 110b may transmit
data via a fixed number of physical channels having a fixed data
rate limit which may result in network links being underutilized
and transmitting IDLE symbols for significant portions of time. In
this regard, when the network devices 102 and 104 initiate a
connection, they may exchange some preliminary information and/or
training signals. In this regard, the network devices 102 and 104
may negotiate a data rate limit and duplex mode (e.g., full-duplex)
for communicating with each other. Additionally, in order to
establish reliable communications, each of the network devices 102
and 104 may need to "train" or adjust various parameters and/or
circuitry in a network device to account for variables such as the
type of cabling over which data is being communicated and the
environmental conditions (e.g. temperature) surrounding the
cabling.
[0041] Once the network devices are "trained", they may initially
transmit the data via the direct attached copper in low voltage
differential signaling via the four copper wires in the link 112.
Transfer rates of 2.5 Gbps, 5 Gbps and/or 10 Gbps may be utilized
depending on clocking methods, for example. In this regard,
conventional PHY devices may distribute traffic evenly over all
available physical channels and may continuously transmit IDLE
symbols between packets of actual data. However, based, for
example, on link utilization, past or present traffic statistics,
and/or available resources (e.g., power, buffer space, processor
time, etc.), it may be determined that 2.5 Gbps, 5 Gbps and/or 10
Gbps may be higher than necessary or desired.
[0042] In other embodiments of the invention, PHY 110a and 110b may
comprise a backplane physical layer that may comprise suitable
logic, circuitry, interfaces and/or code that are operable to
improve energy efficiency. In this regard, the backplane PHYs 110a
and 110b may be adapted to transition from a high(er) power mode of
operation to a low(er) power mode of operation and/or vice
versa.
[0043] Controlling the data rate limit of the connection between
the network devices 102 and 104 may enable the network devices 102
and 104 to communicate in a more energy efficient manner. Moreover,
while the data rate limit on the link 112 may be low(er), higher
layer functions and/or resources, such as portions of the MAC
controller may be placed into a low(er) power mode. The data rate
limit may be controlled by, for example, controlling a number of
physical channels utilized to communicate data, controlling the
signal constellation utilized for representing data on the link,
controlling a rate at which symbols are transmitted, and
controlling the length of time between frames (the inter-frame
gap). In this manner, aspects of the invention may enable network
designers and/or administrators to control, with fine precision via
a plurality of data rate variables, a data rate limit. At any given
time instant, the data rate limit may determine the maximum data
rate which the link may support at that instant. In instances that
the actual data rate on the link is less than the data rate limit,
the difference between the data rate limit and the actual data rate
may correspond to wasted energy on the link and/or in network
devices communicatively coupled to the link. Accordingly, the
increased resolution with which the data rate limit may be
controlled, via the plurality of variables, may enable reducing the
difference between the data rate limit and the actual data rate;
thus improving energy efficiency of the link and/or network devices
communicatively coupled to the link.
[0044] FIG. 2 is a block diagram illustrating an exemplary Ethernet
over twisted pair PHY device architecture comprising a multi-rate
capable physical block, in accordance with an embodiment of the
invention. Referring to FIG. 2, there is shown a network device 200
which may comprises an Ethernet over twisted pair PHY device 202, a
MAC controller 204, a host 206, an interface 208, and a bus
controller interface 210. The PHY device 202 may be an integrated
device which may comprise a multi-rate capable physical layer block
212, one or more transmitters 214, one or more receivers 220, a
memory 216, a memory interface 218, and one or more input/output
interfaces 222.
[0045] The PHY device 202 may be an integrated device that
comprises a multi-rate capable physical layer block 212, one or
more transmitters 214, one or more receivers 220, a memory 216, a
memory interface 218, and one or more input/output interfaces 222.
The operation of the PHY device 202 may be the same as or
substantially similar to that of the PHY devices 110a and 110b
disclosed in FIG. 1. In this regard, the PHY device 202 may provide
layer 1 (physical layer) operability and/or functionality that
enables communication with a remote PHY device. Similarly, the
operation of the MAC controller 204, the host 206, the interface
208, and the bus controller 210 may be the same as or substantially
similar to the respective MAC controllers 108a and 108b, hosts 106a
and 106b, interfaces 114a and 114b, and bus controller interfaces
116a and 116b as described in FIG. 1. The MAC controller 204 may
comprise a multi-rate capable interface 204a that may comprise
suitable logic, circuitry, and/or code to enable communication with
the PHY device 202 at a plurality of data rates via the interface
208.
[0046] The multi-rate capable physical layer block 212 in the PHY
device 202 may comprise suitable logic, circuitry, and/or code that
may enable operability and/or functionality of physical layer
requirements. In this regard, the multi-rate capable physical layer
block 212 may enable generating the appropriate link discovery
signaling utilized for establishing communication with a remote PHY
device in a remote network device. The multi-rate capable physical
layer block 212 may communicate with the MAC controller 204 via the
interface 208. In one aspect of the invention, the interface 208
may be a media independent interface (MII) or an XGMII and may be
configured to utilize a plurality of serial data lanes for
receiving data from the multi-rate capable physical layer block 212
and/or for transmitting data to the multi-rate capable physical
layer block 212. However, the invention is not so limited and may
utilize any suitable interface. For example, the interface 208 may
comprise a XAUI implemented via traces between chips on a circuit
board and/or a XFI interface for an optical transceiver. In this
regard, the number of lanes between the MAC controller 204 and the
PHY device 202 may be reduced and the distance between them may be
extended.
[0047] The multi-rate capable physical layer block 212 may be
configured to operate in one or more of a plurality of
communication modes, where each communication mode may implement,
for example, a different communication protocol. These
communication modes may include, but are not limited to, Ethernet
over twisted pair standards 10BASE-T, 100BASE-TX, 1000BASE-T,
10GBASE-T, and other similar protocols that utilize multiple
physical channels between network devices. The multi-rate capable
physical layer block 212 may be configured to operate in a
particular mode of operation upon initialization or during
operation. For example, auto-negotiation may utilize the FLP bursts
to establish a rate (e.g. 10 Mbps, 100 Mbps, 1000 Mbps, or 10 Gbps)
and mode (half-duplex or full-duplex) for transmitting information.
Although FIG. 2 is described with respect to a twisted pair PHY
device 202, the invention is not limited in this regard. For
example, the PHY device 202 may comprise a direct attached copper
interface such as CX4 and the physical channels 224a, 224b, 224c
and 224d may comprise InfiniBand copper cables. In addition, the
PHY device 202 may comprise a pluggable module for example, SFP+,
XENPAK and/or X2.
[0048] The multi-rate capable physical layer block 212 may be
coupled to memory 216 through the memory interface 218, which may
be implemented as a serial interface or a bus. The memory 216 may
comprise suitable logic, circuitry, and/or code that may enable
storage or programming of information that includes parameters
and/or code that may effectuate the operation of the multi-rate
capable physical layer block 212. The parameters may comprise
configuration data and the code may comprise operational code such
as software and/or firmware, but the information need not be
limited in this regard. Moreover, the parameters may include
adaptive filter and/or block coefficients for use, for example, by
the multi-rate capable physical layer block 212 and/or the hybrids
226.
[0049] Each of the transmitters 214a, 214b, 214c, 214d may comprise
suitable logic, circuitry, interface and/or code that may enable
transmission of data from the network device 200 to a remote
network device via, for example, the link 112 in FIG. 1. The
receivers 220a, 220b, 220c, 220d may comprise suitable logic,
circuitry, interface(s) and/or code that may enable receiving data
from a remote network device. Each of the transmitters 214a, 214b,
214c, 214d and receivers 220a, 220b, 220c and 220d in the PHY
device 202 may correspond to a physical channel that may comprise
the link 112. In this manner, a transmitter/receiver pair may
interface with each of the physical channels 224a, 224b, 224c and
224d. In this regard, the transmitter/receiver pairs may be enabled
to provide the appropriate communication rate and mode for each
physical channel.
[0050] The input/output interfaces 222 may comprise suitable logic
circuitry, and/or code that may enable the PHY device 202 to
impress signal information onto a physical channel, for example a
twisted pair of the link 112 disclosed in FIG. 1. Consequently, the
input/output interfaces 222 may, for example, provide conversion
between differential and single-ended, balanced and unbalanced,
signaling methods. In this regard, the conversion may depend on the
signaling method utilized by the transmitter 214, the receiver 220,
and the type of medium of the physical channel. Accordingly, the
input/output interfaces 222 may comprise one or more baluns and/or
transformers and may, for example, enable transmission over a
twisted pair. Additionally, the input/output interfaces 222 may be
internal or external to the PHY device 202. In this regard, if the
PHY device 202 comprises an integrated circuit, then "internal"
may, for example, refer to being "on-chip" and/or sharing the same
substrate. Similarly, if the PHY device 202 comprises one or more
discrete components, then "internal" may, for example, refer to
being on the same printed circuit board or being within a common
physical package.
[0051] In operation, the PHY device 202 may be enabled to transmit
and receive simultaneously over up to four or more physical links.
Accordingly, the network device 200 may comprise a number of
hybrids 226 corresponding to the number of physical links. Each
hybrid 226 may comprise suitable logic, circuitry, interface and/or
code that may enable separating transmitted and received signals
from a physical link. For example, the hybrids may comprise echo
cancellers, far-end crosstalk (FEXT) cancellers, and/or near-end
crosstalk (NEXT) cancellers. Each hybrid 226 in the network device
300 may be communicatively coupled to an input/output interface
222.
[0052] In operation, the network device 200 may communicate with a
remote partner via the link 112. For example, for 10 Gbps Ethernet,
the network device 200 may transmit data to and receive data from a
remote partner via the physical channels 224a, 224b, 224c, and
224d. When there is no data for the network device 200 to transmit,
then it may transmit IDLE symbols to keep itself and/or the remote
partner "trained". In this manner, power consumption of a network
may be largely independent of the amount of actual data being
transmitted over the network. Accordingly, controlling the data
rate limit on the link 112 may enable the network devices 200 to
transmit fewer IDLE symbols and thus communicate in a more energy
efficient manner.
[0053] The network device 200 may disable, or put into a low(er)
power state, one or more of the physical channels 224, when those
one or more physical channels are not required to meet current
and/or future demand of the link. In this manner, transmitters 214,
receivers 220, hybrids 226, and/or portions of the multi-rate
capable PHY block 212 associated with the unused physical channels
may be disabled. A channel in a low(er) power state a may operate
in one or more ways. For example, one or more channels may convey
little or no data, may be silent, may convey IDLE symbols and/or
convey other energy. In some instances, all channels of a link may
be placed into a low(er) power state. Furthermore, the PHY device
202 as well as the MAC controller 204 may be put to sleep.
[0054] The PHY device 202 and/or one or more components
implementing the layers above the PHY layer may be placed in a low
power idle mode (LPI) wherein the PHY device 202 and/or higher
layer components may be powered down during idle periods. During
power down, the PHY device 202 may maintain various coefficients,
for example, adaptive filter and/or block coefficients and may
maintain synchronization to allow for a more rapid return to an
active state. In addition, during LPI mode, a portion of the
receiver circuitry may be turned off. In asymmetric systems,
devices that handle one direction of communication may be in a
quiet state independent of devices that handle communication in an
opposite direction. In synchronous systems, both directions of a
PHY device may enter and/or leave a quiet state together. Although
a PHY device may operate in a synchronous mode, OSI layers above
the PHY may operate in an asymmetric mode.
[0055] In various embodiments of the invention, a low(er) power
state may be enabled wherein channels of a link may remain active
and a data rate limit on each of the channels may be controlled by
adjusting a signal constellation, PAM levels, an IFG, and/or a
symbol rate.
[0056] FIG. 3 is a block diagram illustrating an exemplary PHY
device that is enabled to implement energy efficient networking, in
accordance with an embodiment of the invention. Referring to FIG.
3, there is shown a block for layers above the MAC layer 306, the
MAC 204 and the PHY device 202. The PHY device 202 may comprise a
physical coding sub-layer (PCS), physical media attachment (PMA)
and/or physical media dependent (PMD) module 308 and an optional
control policy assist module 314. The PCS, PMA and PMD module 308
may comprise a FIFO and/or buffer module 310 and a hardware,
firmware and/or software module 312.
[0057] The MAC 204 and the PHY 202 are described with respect to
FIG. 1 and FIG. 2. The layers above the MAC layer 306 are OSI
layers that may comprise the host 206 layer and/or the interfaces
208 and 210 described with respect to FIG. 1 and FIG. 2, for
example.
[0058] The PHY device 202 may comprise suitable logic, circuitry,
interfaces and/or code that may be operable to improve energy
efficiency for one or more PHY interfaces. In this regard, the PHY
202 may be operable to implement an energy efficient network (EEN)
control policy that may comprise lowering power levels during
periods of little or no data traffic. For example, a PHY may be
operable to enter a low power idle mode (LPI) and/or may lower its
data rate to reduce power consumption. Management of the EEN
control policy implementation and/or decisions regarding when to
enter and/or exit a low(er) power mode may originate from various
parts of the system. Management of the control policy
implementation may comprise approximating and/or monitoring
transmit and/or receive traffic and/or determining when to enter
and/or exit low(er) power modes. In addition, the EEN control
policy may take into consideration latency constraints for various
types of traffic for determining wake and/or sleep periods. Latency
may be introduced while a PHY and/or a MAC controller transition
from a period of low(er) power or a sleep period to a period of
operation at a higher power. For example, in instances when latency
is not tolerable, a series of traffic bursts may be buffered for an
acceptable amount of time before waking the PHY device 202 and/or
MAC controller 204 for delivery of the accumulated traffic
bursts.
[0059] In various embodiments of the invention, the PHY device 202
may be operable to receive control policy management signals
indicating when to go into a reduced power mode and/or when to exit
the reduced power mode. The signals may be received from one or
more layers above the PHY layer, for example. The signals may be
embedded in an EEN control packet, for example, a "magic" packet,
or may be communicated during an inter-packet gap and/or within a
packet preamble for example. In addition, the signals may be
received from a link partner. In other embodiments of the
invention, the PHY device 202 may comprise the control policy
and/or may control and/or originate the EEN control policy
operations.
[0060] The PHY device 202 may comprise the PCS, PMA and/or PMD
module 308 which may comprise suitable logic, circuitry, interfaces
and/or code that may be operable to perform one or more of physical
encoding and/or decoding, PMA framing and transmitter and/or
receiver operations. In addition, the PHY device 202 may comprise
the hardware, firmware and/or software module 312 that may be
operable to implement a control policy within the PHY device 202.
For example, the hardware, firmware and/or software module 312 may
be operable to monitor and/or parse control signals and/or packets
received by the PHY device 202 that may comprise information about
entering and/or exiting a low(er) power mode and/or about buffering
packets.
[0061] In various embodiments of the invention, the PHY device 202
may comprise the FIFO and/or buffers 310 that may comprise suitable
logic, circuitry, interfaces and/or code that may be operable to
store packets and/or frames prior to transmission. For example, in
instances when the PHY device 202 is waking-up from a low(er) power
mode, packets may be received from higher layers while the PHY
device 202 may need time to transition to an operational state. The
PHY device 202 may store packets in the FIFO and/or buffer 310
until the PHY 202 is able to transmit them across the link.
Similarly, a PHY within a link partner may also need to wake up and
thus data may be buffered long enough for the PHYs in both link
partners to exit LPI mode. In various embodiments of the invention,
the MAC controller 204 may buffer packets.
[0062] The optional control policy assist module 314 may comprise
suitable logic, circuitry, interfaces and/or code that may be
operable assist in implementation of the EEN control policy within
the PHY device 202. For example, the optional control policy assist
module 314 may determine when to buffer packets and when to
transmit and/or to receive. For example, the optional control
policy assist module 314 may comprise timing and/or other
parameters for the length of a sleep or wake cycle. In addition,
the control policy assist module may send and/or receive EEN
control information to and/or from a link partner. For example, the
optional control policy assist module 314 may determine that a
request for entering an LPI mode or a notification of entering an
LPI mode should be sent to a link partner. In addition, the
optional control policy assist module 314 may receive a request or
notification from a link partner for entering into or exiting an
LPI mode.
[0063] In operation, implementation and/or management of the EEN
control policy may occur in various parts of the system 100. For
example, the control policy may be managed by the layers above the
MAC layer 306 and may be communicated to the PHY 202. In this
regard, the layers above the MAC layer 306 may comprise suitable
logic, circuitry, interfaces and/or code to monitor hardware,
firmware, software and/or one or more buses to determine when a
low(er) power mode of operation may be sufficient to handle traffic
flowing through the system 100. Signals that may assert a low(er)
power mode for the PHY device 202 may be communicated from the
layers above the MAC layer 306.
[0064] Management of the EEN protocols and/or techniques may be
based, for example, on management signals of an MDIO interface to
the MAC. For example, the MDIO interface may configure thresholds
such as how long the PHY device 202 should stay in a low(er) power
mode after entering the low(er) power mode, how long a buffer
should be empty before going into a low(er) power mode, and how
full a buffer should be before waking up from a low(er) power mode.
The MDIO interface may also be utilized to configure parameters
pertaining to a link partner. Exemplary parameters comprise how
long the link partner takes to wake up and how much buffering is
available in the link partner's buffers. The MDIO interface may
enable configuration of the control policy by a system designer or
administrator.
[0065] In various exemplary embodiments of the invention, EEN
control signals may by-pass the MAC controller 204 or the PHY
device 202 may control implementation of the EEN control policy
rather than the higher layers. In this manner, an EEN control
policy may be implemented without a costly modification to the MAC
controller 204. In this regard, the PHY device 202 may be
integrated or may be a pluggable transceiver module such as a SFP,
SFP+, XenPak or X2, for example.
[0066] FIG. 4 is a block diagram illustrating an exemplary XGMII
extender that is capable of energy efficient modes of operation, in
accordance with an embodiment of the invention. Referring to FIG.
4, there is shown, a MAC 412, an XGXS 414, an XGXS 416, a PHY 418,
an XGMII extender 420 and XGMII interfaces 422 and 424.
[0067] The PHY 418 may be similar or substantially the same as the
PHY device 202 described, for example, with respect to FIG. 1, FIG.
2 and FIG. 3. The MAC 412 may be similar or substantially the same
as the MAC controller 204 described with respect to, for example,
FIG. 1, FIG. 2 and FIG. 3.
[0068] The XGMII interfaces 422 and/or 424 may be similar or
substantially the same as the interfaces 114 and 203 described with
respect to FIG. 1, FIG. 2 and FIG. 3, for example. The XGMII
interfaces 422 and/or 424 may comprise suitable logic, circuitry
and/or code that may be operable to communicate via parallel pins
and/or traces between the MAC 404 and XGXS 414 and/or between the
XGXS 416 and the PHY 418. In one embodiment of the invention, the
XGMII may comprise a 10 Gbps media independent interface.
[0069] The XGXS modules 414 and/or 416 may each comprise suitable
logic circuitry, interfaces and/or code that may be operable to
communicate via a reduced number of lanes and/or over greater
distances. In various embodiments of the invention, the XGXS
modules 414 and/or 416 may be operable to convert parallel data
received via the XGMII interfaces 422 and/or 424 respectively into
a serial, self clocked data stream. The XGMII extender 420 may
support chip to chip communication via traces on a circuit board.
The XGMII extender 420 may comprise suitable logic circuitry and/or
code to extend the distance between the MAC 412 and the PHY 418
relative to a distance that an XGMII interface may be capable of
achieving. In various embodiments of the invention, the XGMII
extender 420 may comprise a XAUI interface that may be operable to
map the XGMII parallel data to four transmit and receive lanes
wherein each lane may be operable to transmit at 3.125 Gbps based
on 8B10B encoding. In other embodiments of the invention, the XGMII
extender 420 may comprise a XFI interface that may be operable to
map the XGMII parallel data to single lane that may be operable to
run at 10.3125 Gbps based on 64B66B encoding for example.
[0070] In operation, one or more of the interfaces between the MAC
412 and the PHY 418 comprising the XGXS 414, the XGXS 416, the
XGMII extender 420 and/or the XGMII interfaces 422 and 424 may
comprise suitable logic, circuitry, interfaces and/or code that may
be operable to operate in a low(er) power mode according to a
energy efficient network control policy. In this regard, the
control policy may be managed and/or implemented in an OSI layer
above the MAC layer implemented in the MAC 412 and/or may be
implemented in the PHY 418 layer. In this regard, the one or more
interfaces between the MAC 412 and the PHY 418 may be operable to
receive control policy management signals indicating when to go
into a reduced power mode and/or when to exit the reduced power
mode.
[0071] FIG. 5A is a block diagram illustrating an exemplary
backplane PHY that is capable of energy efficient modes of
operation, in accordance with an embodiment of the invention.
Referring to FIG. 5A, there is shown, a supervisor 502 that may
comprise a memory 506, switch chip 510, a MAC 512 and a back plane
PHY 514. In addition, there is shown a line card 504 that may
comprise a backplane PHY 518, a MAC 520, packet processing 524, a
memory 526, a MAC 528 and a PHY 522. There is also shown a
backplane 516 and a link 524.
[0072] The link 524 may be similar to or substantially the same as
the link 112 described with respect to FIG. 1, for example. The MAC
512 and the MAC 520 may be similar and/or substantially the same as
the MAC 108 and/or the MAC 208 described with respect to FIG. 1,
FIG. 2 and FIG. 3, for example. The PHY 522, the backplane PHY 514
and/or the backplane PHY 518 may be similar and/or substantially
the same as the PHY device 110 and/or 202 described with respect to
FIG. 1, FIG. 2 and FIG. 3, for example.
[0073] The backplane 516 may comprise suitable logic, circuitry,
interfaces and/or code that may be operable to handle communication
among a plurality of circuit boards that may be connected to the
backplane. In this regard, the backplane 516 may be operable to
support communication between the backplane PHY 514 and the
backplane PHY 518 based on 10GBASE-KR, 10GBASE-KX4 and/or 1GBASE-KX
Ethernet standards, for example. The 10GBASE-KR and/or 10G BASE-KX4
versions of backplane Ethernet may be implemented with or without
forward error control (FEC). Exemplary applications for the
backplane 516 may comprise switches, routers and blade servers.
[0074] The supervisor 502 may comprise suitable logic, circuitry,
interfaces and/or code that may be operable to manage communication
among one or more line cards such as the line card 504 that may be
connected to the backplane 516. The supervisor 502 may comprise the
switch chip 510. The switch chip 510 may comprise suitable logic,
circuitry, interfaces and/or code that may be operable to
interconnect network nodes via the one or more line cards
communicatively coupled to the backplane 516, such as the line card
504. The switch chip 510 may provide Open Systems Interconnect
(OSI) layer 2 and above operability. The switch chip 510 may
comprise the MAC 512.
[0075] The MAC 512 may comprise suitable logic, circuitry,
interfaces and/or code that may enable handling of data link layer,
layer 2, operability and/or functionality in the switch chip 510.
The MAC 512 may be operable to communicate with the backplane PHY
514 via any suitable interface, for example a GMII, an XGMII and/or
an extended XGMI for example.
[0076] The backplane PHY 514 and the backplane PHY 518 in the line
card 504 may comprise suitable logic, circuitry, interfaces and/or
code that may be operable to communicate via the backplane 516 in
accordance with one or more standard rates such as 10 Gbps, 1 Gbps
and/or at non-standard rates such as 2.5 Gbps and 5 Gbps. For
example, the backplane PHY 514 and/or the backplane PHY 518 may be
operable to communicate based on 10GBASE-KX4, 1GBASE-KX and/or
10GBASE-KR Ethernet standards.
[0077] The line card 504 may comprise suitable logic, circuitry,
interfaces and/or code that may be operable to provide an interface
between the external link 524 and the backplane 516. The line card
504 may be a swappable module that may be upgradable. The line card
504 may comprise the backplane PHY 518 that may communicate via the
backplane 516 with the backplane PHY 514 in the supervisor 502. In
addition, the line card 504 may comprise the PHY 522 that may
communicate with other network nodes via the external link 524. The
MAC 520 and the MAC 528 may be operable to implement OSI layer 2
and above operability in the line card 504 and may communicate with
the backplane PHY 518 and the PHY 522. The packet processing module
may handle OSI layer 3 and/or higher layer processing. The memory
526 may be operable to buffer packet data.
[0078] The backplane PHY 514 and/or the backplane PHY 516 may
comprise suitable logic, circuitry, interfaces and/or code to
implement energy efficient network (EEN) control policies. In this
regard, the backplane PHYs 514 and/or 516 may be adapted to operate
in a low(er) power mode. For example, low power idle and/or
sub-rating, for example, and may be operable to transition from a
low power idle mode to a high(er) power mode of operation and/or
vice versa.
[0079] In operation, the backplane PHYs 514 and/or 518 and one or
more other portions of the supervisor 502 and/or the line card 504
may be operable to transition between a low(er) power mode and a
higher power mode and vice versa based on an EEN control policy.
Traffic communicated across the backplane 516 may be monitored
and/or future traffic may known or estimated. It may be determined
according to the control policy that the backplane PHYs 514 and/or
518 may be placed in a low(er) power mode or in a high(er) power
mode based on pending, current, and/or future traffic. In this
manner energy consumption may be reduced in the backplane PHYs 514
and/or 518.
[0080] The control policy may be managed in the supervisor 502
and/or in the line card 504. For example, one or more of the
backplane PHYs 514 and 518 may control the power level modes of
operation and may send EEN control signals to one or other
component in the supervisor 502 and/or the line card 504 according
to the control policy. In other embodiments of the invention, the
control policy may be managed by layers above the PHY layer, for
example, in the packet processor 524. In this regard, EEN control
policy signals that assert or enable a particular mode of operation
may be communicated to one or more of the backplane PHYs 514 and
518 to in order to implement low(er) and/or high(er) power modes.
The EEN control signals may be embedded in an EEN control packet, a
"magic" packet, or may be communicated during an inter-packet gap
and/or within a packet preamble for example. Packet data that may
be pending transmission may be buffered while one or more of the
backplane PHYs 514 and 518 and/or other components of the
supervisor 502 and/or the line card 504 are transition between
different modes of operation.
[0081] FIG. 5B is a block diagram illustrating an exemplary
implementation of cascading energy efficient mode over a plurality
of interfaces in a communication path, in accordance with an
embodiment of the invention. Referring to FIG. 5B there is shown
the supervisor 502 that may comprise the memory 506, the switch
chip 510, the MAC 512 and the back plane PHY 514. In addition,
there is shown the line card 504 that may comprise the backplane
PHY 518, the MAC 520, the packet processor 524, the memory 526, the
MAC 528 and the PHY 522. There is also shown the backplane 516, the
link 524 and the XGMII extender 420.
[0082] The supervisor 502, the memory 506, the switch chip 510, the
MAC 512, the back plane PHY 514 the line card 504, the backplane
PHY 518, the MAC 520, the packet processor 524, the memory 526, the
MAC 528 and the PHY 522, the backplane 516 and the link 524 are
described with respect to FIG. 5A. The XGMII extender 420 is
described with respect to FIG. 4A.
[0083] The XGMII extender 420 may provide an interface between the
MAC 528 and the PHY 522. In this regard, the XGMII extender 420 may
be a serial or parallel interface and may be part of an IEEE
standard or may be a proprietary interface, for example. For
example, the XGMII extender 420 may be a XAUI or a XFI interface.
In various embodiments of the invention, the MAC 528 and the PHY
522 may be implemented on different pieces of silicon. Moreover,
interfaces between other layer devices may be implemented on
different pieces of silicon. For example, an interface between the
switch chip 510 and the MAC 512 and/or an interface between the PHY
514 and the MAC 512 may be implemented over a plurality of silicon
chips.
[0084] In operation, communication may be established with a link
partner via the PHY device 222 and the link 524. Packets may be
communicated and/or processed via a communication path comprising
one or more devices and/or interfaces within the line card 504, the
backplane 516 and the supervisor 502. For example packets may be
communicated and/or processed along a communication path comprising
the PHY 522, the XGMII extender 420, the MAC 528, the packet
processor 524, the MAC 520, the backplane PHY 518, the back plane
PHY 516, backplane PHY 514, the MAC 512, the switch 510 and the
memory 506. In instances when there is little or no packet data for
communication, a power level mode of operation, for example, a
low(er) power level mode of operation, may be determined for one or
more devices and/or interfaces within the communication path.
[0085] In various embodiments of the invention, the determined
power level mode may be configured within the one or more devices
and/or interfaces along the communication path at one time instant
and/or at different time instants. For example, configuration of
devices and/or interfaces for lower power mode may be cascaded in
succession along the communication path as devices and/or
interfaces finish processing and/or communicating packets. In an
exemplary embodiment of the invention, the PHY 522, the XGMII
extender 422 and the MAC 528 may be transitioned to a low(er) power
mode of operation and the backplane PHY 518, the backplane 516 and
the backplane PHY 514 may subsequently be placed in a lower power
mode of operation. Although a linecard and switch architecture are
shown in FIG. 5A and FIG. 5B, the invention is not so limited and
may comprise other network devices. For example, an exemplary
embodiment of the invention may comprise one or more devices of a
computer, a router, an aggregation switch, a blade server and a
data center switch.
[0086] FIG. 6 is a block diagram illustrating an exemplary direct
attached copper interface that is capable of energy efficient modes
of operation, in accordance with an embodiment of the invention.
Referring to FIG. 6, there is shown a MAC 604, a PHY 602, a
physical coding sub-layer (PCS) 608, a connector 610 and copper
link 612.
[0087] The MAC 604 may be similar and/or substantially the same as
the MAC 108 and/or the MAC 208 described with respect to FIG. 1,
FIG. 2 and FIG. 3, for example. The PHY 602 may be similar and/or
substantially the same as the PHY devices 110, 202, 418 and/or 522
described with respect to FIG. 1, FIG. 2, FIG. 3, FIG. 4 and/or
FIG. 5 for example.
[0088] The PHY 602 may comprise suitable logic, circuitry,
interfaces and/or code that may be operable to transmit and/or
receive data via a direct attach copper interface and/or a copper
medium, for example, the copper link 612. The MAC 604 may send data
to the PHY 602 that may be formatted according to a suitable
protocol, for example, InfiniBand or QLogic protocol. The PHY 602
may transmit and/or receive serial data via the connector 610. The
connector 610 may be an InfiniBand connector. In this regard, the
serial data may be transmitted via the connector 610 in low voltage
differential signaling via four duplex copper wires in the copper
link 612. In various embodiments of the invention, data may be
transmitted by the PHY 602 at transfer rates of 2.5 Gbps, 5 Gbps,
10 Gbps, for example.
[0089] In various embodiments of the invention the PHY 602 may be
operable to transmit and/or receive data via the copper link 612
based on 10GBASE-CX4 specifications. In this regard, the connector
610 may comprise a Multi-source Agreement (MSA) module to provide
the connectivity to the copper link 612. The PCS 608 may manage
and/or synchronize data flowing among four lanes within the copper
link 612 according to 802.3ae Clause 48 protocol.
[0090] In operation, the PHY 602 may be operable to transition
between a low(er) power level and a higher power level according to
an EEN control policy. The PHY 602 may administer the control
policy and/or may communicate control signals to layers above the
PHY layer and/or to link partners. In various embodiments of the
invention, the PHY 602 may receive control policy management
signals indicating when to go into a reduced power mode and/or when
to exit the reduced power mode. The signals may be received from
one or more layers above the PHY layer, for example, the MAC layer
604 or layers above the MAC 306 described with respect to FIG. 3.
In this regard, the control signals may be embedded in an EEN
control packet, may comprise a "magic" packet, may be communicated
during an inter-packet gap and/or may be communicated within a
packet preamble, for example. In addition, the signals may be
received from a link partner. The PHY 602 may be part of a
communication path wherein a reduced power mode may be implemented
in the PHY 602 as well as other interfaces along the communication
path.
[0091] FIG. 7 is a flow chart illustrating exemplary steps for
implementing an energy efficient network control policy in a
plurality of interfaces of a communication path, in accordance with
an embodiment of the invention. The exemplary steps may begin with
start step 710. In step 712, communication may be established via
one or more interfaces in a communication path that may comprise
two link partners. For example, the interfaces may operate between
the two link partners such as via the PHY to PHY direct attach
copper interface 602 and/or between two PHYs via a backplane such
as between the PHY device 514 and/or the PHY device 518. Moreover,
the interfaces may operate between a MAC and a PHY, for example,
the interfaces may comprise a XAUI or XFI interface. In step 714, a
control policy that may be administered by one or both link
partners may be utilized to determine that a change in power level
is appropriate. For example, a low level of traffic may be detected
by one or both of the link partners that may indicate an
opportunity to reduce energy consumption. In step 716, one or more
of the interfaces within the communication path, for example, one
or more MAC to PHY interfaces and/or PHY to PHY interfaces may
enter and/or exit a low(er) power mode of operation according to
the EEN control policy. Step 718 may be an end of exemplary
steps.
[0092] In an embodiment of the invention, one or more of a
plurality of network devices for example, the MAC 412 and the PHY
418, the PHY 514 and the PHY 518, the MAC 528 and the PHY 522
and/or the PHY 602 and a link partner may be communicatively
coupled via one or more interfaces. In this regard, one or more of
a plurality of network devices may be communicatively coupled via
one or more serial and/or parallel interfaces. One or more circuits
within the network devices may determine a power level mode of
operation for the one or more interfaces according to an energy
efficient network communication control policy. The one or more
circuits may configure the interfaces for the determined power
level mode. In this regard, configuration in various interfaces may
occur at one time instant or configuration may be cascaded
sequentially through a plurality of interfaces.
[0093] The plurality of network devices may comprise a physical
layer device (PHY), a media access controller (MAC) and/or higher
layer devices. The one or more interfaces may comprise a XGMII
extender 420, for example, a XAUI and/or a XFI device. Moreover,
the one or more interfaces may comprise a back plane PHY 514 and/or
518, for example, a 10GBASE-KR, a 10GBASE-KX4 and/or a 1GBASE-KX
backplane PHY. The backplane PHY 514 and/or 518 may perform forward
error control (FEC). The one or more interfaces may comprise a
direct attach copper PHY, for example, SFP+and/or may comprise
InfiniBand and/or 10GBASE-CX4. Furthermore, the one or more
interfaces may comprise a pluggable transceiver module that may
comprise a direct attached copper PHY, for example. Energy
efficient network control data may be communicated to and/or from
one or more of the plurality of network devices. The one or more
plurality of network devices may enter or exit a lower power mode
of operation based on the communicated energy efficient network
control data. In some instances, one or more of the plurality of
network devices may buffer packets pending transmission by the
interfaces while the interfaces, for example, the connector 610
and/or other components transition to the determined power level
mode of operation.
[0094] Another embodiment of the invention may provide a machine
and/or computer readable storage and/or medium, having stored
thereon, a machine code and/or a computer program having at least
one code section executable by a machine and/or a computer, thereby
causing the machine and/or computer to perform the steps as
described herein for a method and system for energy efficient
communication among one or more interfaces in a communication.
[0095] Accordingly, the present invention may be realized in
hardware, software, or a combination of hardware and software. The
present invention may be realized in a centralized fashion in at
least one computer system or in a distributed fashion where
different elements are spread across several interconnected
computer systems. Any kind of computer system or other apparatus
adapted for carrying out the methods described herein is suited. A
typical combination of hardware and software may be a
general-purpose computer system with a computer program that, when
being loaded and executed, controls the computer system such that
it carries out the methods described herein.
[0096] The present invention may also be embedded in a computer
program product, which comprises all the features enabling the
implementation of the methods described herein, and which when
loaded in a computer system is able to carry out these methods.
Computer program in the present context means any expression, in
any language, code or notation, of a set of instructions intended
to cause a system having an information processing capability to
perform a particular function either directly or after either or
both of the following: a) conversion to another language, code or
notation; b) reproduction in a different material form.
[0097] While the present invention has been described with
reference to certain embodiments, it will be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted without departing from the scope of the present
invention. In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the present
invention without departing from its scope. Therefore, it is
intended that the present invention not be limited to the
particular embodiment disclosed, but that the present invention
will include all embodiments falling within the scope of the
appended claims.
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