Abstract:
A system including a first interface module, a second interface module, and a first physical layer device. The first interface module is configured to interface to a copper medium. The second interface module is configured to interface to a fiber-optic medium. The second interface module is configured to interface to the fiber-optic medium via a small form-factor pluggable (SFP) interface module. The first physical layer device is configured to detect when a link is being established over the copper medium via the first interface module and, in response to detecting that the link is established over the copper medium via the first interface module, to deactivate (i) the second interface module and (ii) the SFP interface module.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 12/906,934, filed on Oct. 18, 2010, which is a continuation of U.S. patent application Ser. No. 11/200,659 (now U.S. Pat. No. 7,817,661), filed on Aug. 10, 2005, which claims the benefit of U.S. Provisional Application No. 60/656,661, filed on Feb. 24, 2005. The entire disclosures of the above referenced applications are incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to dual-media network interfaces, and more particularly to dual-media network interfaces that include small form-factor pluggable (SFP) interface modules. 
     BACKGROUND OF THE INVENTION 
     Dual-media network interfaces support two separate interfaces for a single port of a network device. For example, a single port of an Ethernet network interface may include a first interface for a copper medium and a second interface for a fiber optic medium. However, both interfaces may also support the same types of media. Dual-media network interfaces allow flexibility by providing a user with an option between two potentially different media. Additionally, dual-media network interfaces allow users to utilize redundant network connections. For example, if a first interface of a dual-media network interface fails, the dual-media network interface may be programmed to automatically switch to a second interface that includes a redundant network connection. Such redundant network connections reduce network downtime. 
     Some dual-media network interfaces include small form-factor pluggable (SFP) interfaces that support SFP modules. SFP modules are interchangeable plug-in transceivers that are typically hot-swappable and provide interfaces for desired media. For example, SFP modules commonly provide interfaces for high-speed fiber optic media. However, SFP modules provide interfaces for other media such as copper media. SFP modules allow a user to quickly and inexpensively repair or upgrade a network device. For example, if an SFP module fails, the SFP module can be replaced without soldering components. Simultaneous active links for a single port of a dual-media network interface can cause significant network disruption and/or downtime including a total network failure. Therefore, only one interface of a dual-media network interface is active at a time. 
     Referring now to  FIG. 1 , a dual-media network interface  10  includes a medium access control (MAC) device  12  that communicates with a physical layer device  14  (or PHY). The physical layer device  14  communicates with first and second interfaces  16  and  18 . The first interface  16  is an SFP interface between the physical layer device  14  and an SFP module  20 . The second interface  18  is illustrated as a medium dependent interface (MDI) such as a copper media interface, although the second interface  18  may be another type of interface. For example, the second interface  18  may be hard-wired and controlled by the physical layer device  14 . Conversely, the SFP module  20  includes an independent physical layer device  22  that controls network communications between the SFP module  20  and external devices. 
     As discussed above, it is undesirable for the first and second interfaces  16  and  18 , respectively, to simultaneously establish links between the physical layer device  14  and external devices. In one approach, the physical layer device  14  utilizes link monitoring software to determine when either the first or second interface  16  or  18 , respectively, establishes a link. For example, a processor  23  may execute the link monitoring software and communicate with the physical layer device  14  via management data input/output and management data clock (MDC/MDIO) signals. 
     The processor  23  is capable of reading registers in the physical layer device  14  via the MDC/MDIO signals in order to monitor links between the physical layer device  14  and external devices. For example, the link monitoring software may periodically poll the first and second interfaces  16  and  18  to detect when one of the first or second interfaces  16  or  18 , respectively, establishes a link. When a link is detected at one of the first or second interfaces  16  or  18 , respectively, the link monitoring software ceases communications via the other of the first or second interfaces  18  or  16 , respectively. For example, the link monitoring software may cease communications via an interface  16  or  18  by disabling an internal module that is dedicated to the particular interface  16  or  18 . 
     Since the second interface  18  is controlled by the physical layer device  14 , the link monitoring software is capable of quickly and completely ceasing communications via the second interface  18  when a link is detected at the first interface  16 . However, it is possible for the independent physical layer device  22  to retain a link with an external device even after the link monitoring software ceases communications via the first interface  16 . For example, in order to disable the SFP module  20 , the processor  23  may first transmit a signal to the MAC device  12 , which is then forwarded to a disable pin  24  of the SFP module  20  (identified as TX_DIS in  FIG. 1 ). In this case, an appreciable delay occurs from the time when the processor  23  first detects a link at the second interface  18  to the time when the MAC device  12  disables the SFP module  20  via the disable pin  24 . 
     Additionally, the delay may be further extended when the processor  23  is busy processing other data unrelated to the dual-media network interface  10 . For example, a network device  25  that includes the dual-media network interface  10  may include a large number of ports. In this case, the external device may still detect a link with the dual-media network interface  10  and attempt to send packets, which may create a disruptive renegotiation loop or other network congestion when the external device does not detect a response. Also, during the period of time both the first and second interfaces  16  and  18 , respectively, are capable of establishing links on the same port, which can cause significant network disruption. 
     SUMMARY OF THE INVENTION 
     A dual-media network interface according to the present invention includes a physical layer device. A first interface module communicates with the physical layer device via a medium dependent interface. A small form-factor pluggable (SFP) interface module communicates with the physical layer device. A link indicator indicates a communications link with the physical layer device via the first interface module. The physical layer device transmits a link indication signal to the link indicator and the SFP interface module when the physical layer device establishes a communications link via the first interface module. The link indication signal activates the link indicator and disables the SFP interface module. 
     In other features, the dual-media network interface is a single-port network interface and only one of the first interface module or the SFP interface module is active at a time. The first interface module is a copper media interface module. The copper media interface module interfaces with media that is compliant with at least one of 1000BASE-T, 100BASE-TX, and/or 10BASE-T standards. The SFP interface module interfaces with media that is compliant with at least one of 100BASE-FX, 10BASE-T, 100BASE-T, and/or 1000BASE-T standards. 
     In still other features of the invention, the SFP interface module is one of a copper media interface module or a fiber optic media interface module. The SFP interface module communicates with the physical layer device via at least one of a serial gigabit medium independent interface (SGMII), a 4-byte/5-byte (4B/5B) local fiber interface, and/or a serializer/deserializer (SERDES) interface. The physical layer device includes an SFP control module. The physical layer device disables the SFP control module when the physical layer device establishes a communications link via the first interface module. The physical layer device includes a copper control module. The physical layer device disables the copper control module when the physical layer device establishes a communications link via the SFP interface module. A medium access control (MAC) device communicates with the physical layer device. 
     In yet other features, the physical layer device includes a link status pin. The physical layer device asserts the link status pin when the physical layer device establishes a communications link via the first interface module. The SFP interface module includes a disable pin that communicates with the link status pin. The SFP interface module is disabled when the physical layer device asserts the link status pin. The link indicator communicates with the link status pin. The link indicator is activated when the physical layer device asserts the link status pin. The link indicator is a light-emitting diode (LED). A network device comprises the dual-media network interface. 
     A dual-media network interface according to the present invention includes a first copper media interface module. A physical layer device includes a copper link status pin and asserts the copper link status pin when the physical layer device establishes a communications link via the first copper media interface module. A copper link indicator indicates a communications link with the physical layer device via the first copper media interface module and communicates with the copper link status pin. A small form-factor pluggable (SFP) interface module includes an SFP disable pin. The SFP disable pin communicates with the copper link status pin. The copper link indicator is activated and the SFP interface module is disabled when the physical layer device asserts the copper link status pin. 
     In other features, the dual-media network interface is a single-port network device and only one of the first copper media interface module or the SFP interface module is active at a time. The first copper media interface module interfaces with media that is compliant with at least one of 1000BASE-T, 100BASE-TX, and/or 10BASE-T standards. The SFP interface module interfaces with media that is compliant with at least one of 100 BASE-FX, 10BASE-T, 100BASE-T, and/or 1000 BASE-T standards. The SFP interface module is one of a second copper media interface module or a fiber optic media interface module. The first copper media interface module communicates with the physical layer device via a medium dependent interface (MDI). The SFP interface module communicates with the physical layer device via at least one of a serial gigabit medium independent interface (SGMII), a 4-byte/5-byte (4B/5B) local fiber interface, and/or a serializer/deserializer (SERDES) interface. 
     In still other features of the invention, the physical layer device includes an SFP control module. The physical layer device disables the SFP control module when the physical layer device establishes a communications link via the first copper media interface module. The physical layer device includes a copper control module. The physical layer device disables the copper control module when the physical layer device establishes a communications link via the SFP interface module. A medium access control (MAC) device communicates with the physical layer device. The copper link indicator is a light-emitting diode (LED). A network device comprises the dual-media network interface. 
     A method for operating a dual-media network interface according to the present invention includes providing a first interface module that communicates with a physical layer device via a medium dependent interface. A small form-factor pluggable (SFP) interface module is provided that communicates with the physical layer device. A communications link is established via the first interface module. A link indication signal is transmitted to a link indicator and the SFP interface module. The link indication signal activates the link indicator and disables the SFP interface module. 
     In other features, the dual-media network interface is a single-port network interface and only one of the first interface module or the SFP interface module is active at a time. The first interface module is a copper media interface module. The copper media interface module interfaces with media that is compliant with at least one of 1000BASE-T, 100BASE-TX, and/or 10BASE-T standards. The SFP interface module interfaces with media that is compliant with at least one of 100BASE-FX, 10BASE-T, 100BASE-T, and/or 1000BASE-T standards. 
     In still other features of the invention, the SFP interface module is one of a copper media interface module or a fiber optic media interface module. The SFP interface module communicates with the physical layer device via at least one of a serial gigabit medium independent interface (SGMII), a 4-byte/5-byte (4B/5B) local fiber interface, and/or a serializer/deserializer (SERDES) interface. A communications link is established via the first interface module. An SFP control module in the physical layer device is disabled. A communications link is established via the SFP interface module. A copper control module in the physical layer device is disabled. A medium access control (MAC) device communicates with the physical layer device. 
     In yet other features, a communications link is established via the first interface module. A link status pin is asserted. The SFP interface module is disabled during the asserting step. The SFP interface module includes a disable pin that communicates with the link status pin. The link indicator is activated during the asserting step. The link indicator communicates with the link status pin. The link indicator is a light-emitting diode (LED). The dual-media network interface is integrated into a network device. 
     A method for operating a dual-media network interface according to the present invention includes providing a first copper media interface module that communicates with a physical layer device. A communications link is established via the first copper media interface module. A copper link status pin is asserted. A small form-factor pluggable (SFP) interface module is provided that includes an SFP disable pin. A copper link indicator is activated and the SFP interface module is disabled during the asserting step. The SFP disable pin and the copper link indicator communicate with the copper link status pin. 
     In other features, the dual-media network interface is a single-port network device and only one of the first copper media interface module or the SFP interface module is active at a time. The first copper media interface module interfaces with media that is compliant with at least one of 1000BASE-T, 100BASE-TX, and/or 10BASE-T standards. The SFP interface module interfaces with media that is compliant with at least one of 100BASE-FX, 10BASE-T, 100BASE-T, and/or 1000BASE-T standards. The SFP interface module is one of a second copper media interface module or a fiber optic media interface module. The first copper media interface module communicates with the physical layer device via a medium dependent interface (MDI). The SFP interface module communicates with the physical layer device via at least one of a serial gigabit medium independent interface (SGMII), a 4-byte/5-byte (4B/5B) local fiber interface, and/or a serializer/deserializer (SERDES) interface. 
     In still other features of the invention, a communications link is established via the first copper media interface module. An SFP control module in the physical layer device is disabled. A communications link is established via the SFP interface module. A copper control module in the physical layer device is disabled. A medium access control (MAC) device communicates with the physical layer device. The copper link indicator is a light-emitting diode (LED). The dual-media network interface is integrated into a network device. 
     A dual-media network interface according to the present invention includes communications configuring means for specifying a data communications configuration. First interfacing means communicates with the communications configuring means via a medium dependent interface. Pluggable interfacing means communicates with the communications configuring means. Link indicating means indicates a communications link with the communications configuring means via the first interfacing means. The communications configuring means transmits a link indication signal to the link indicating means and the pluggable interfacing means when the communications configuring means establishes a communications link via the first interfacing means. The link indication signal activates the link indicating means and disables the pluggable interfacing means. 
     In other features, the dual-media network interface is a single-port network interface and only one of the first interfacing means or the pluggable interfacing means is active at a time. The first interfacing means is a copper media interface module. The copper media interface module interfaces with media that is compliant with at least one of 1000BASE-T, 100BASE-TX, and/or 10BASE-T standards. The pluggable interfacing means interfaces with media that is compliant with at least one of 100BASE-FX, 10BASE-T, 100BASE-T, and/or 1000BASE-T standards. 
     In still other features of the invention, the pluggable interfacing means is one of a copper media interface module or a fiber optic media interface module. The pluggable interfacing means communicates with the communications configuring means via at least one of a serial gigabit medium independent interface (SGMII), a 4-byte/5-byte (4B/5B) local fiber interface, and/or a serializer/deserializer (SERDES) interface. The communications configuring means includes pluggable controlling means for configuring the pluggable interfacing means. The communications configuring means disables the pluggable controlling means when the communications configuring means establishes a communications link via the first interfacing means. The communications configuring means includes interface controlling means for configuring the first interfacing means. The communications configuring means disables the interface controlling means when the communications configuring means establishes a communications link via the pluggable interfacing means. Medium controlling means for controlling use of a medium communicates with the communications configuring means. 
     In yet other features, the communications configuring means includes link communicating means for communicating link status. The communications configuring means asserts the link communicating means when the communications configuring means establishes a communications link via the first interfacing means. The pluggable interfacing means includes disabling means for disabling the pluggable interfacing means that communicates with the link communicating means. The pluggable interfacing means is disabled when the communications configuring means asserts the link communicating means. The link indicating means communicates with the link communicating means. The link indicating means is activated when the communications configuring means asserts the link communicating means. The link indicating means is a light-emitting diode (LED). A network device comprises the dual-media network interface. 
     A dual-media network interface according to the present invention includes first copper interfacing means for interfacing with copper media. Communications configuring means for specifying a data communications configuration includes link communicating means for communicating link status and asserts the link communicating means when the communications configuring means establishes a communications link via the first copper interfacing means. Link indicating means for indicating a communications link with the communications configuring means via the first copper interfacing means communicates with the link communicating means. Pluggable interfacing means for communicating with the communications configuring means includes disabling means for disabling the pluggable interfacing means. The disabling means communicates with the link communicating means. The link indicating means is activated and the pluggable interfacing means is disabled when the communications configuring means asserts the link communicating means. 
     In other features, the dual-media network interface is a single-port network device and only one of the first copper interfacing means or the pluggable interfacing means is active at a time. The first copper interfacing means interfaces with media that is compliant with at least one of 1000BASE-T, 100BASE-TX, and/or 10BASE-T standards. The pluggable interfacing means interfaces with media that is compliant with at least one of 100BASE-FX, 10BASE-T, 100BASE-T, and/or 1000BASE-T standards. The pluggable interfacing means is one of second copper interfacing means or fiber optic interfacing means for interfacing with fiber optic media. The first copper interfacing means communicates with the communications configuring means via a medium dependent interface (MDI). The pluggable interfacing means communicates with the communications configuring means via at least one of a serial gigabit medium independent interface (SGMII), a 4-byte/5-byte (4B/5B) local fiber interface, and/or a serializer/deserializer (SERDES) interface. 
     In still other features of the invention, the communications configuring means includes pluggable controlling means for configuring the pluggable interfacing means. The communications configuring means disables the pluggable controlling means when the communications configuring means establishes a communications link via the first copper interfacing means. The communications configuring means includes interface controlling means for configuring the first copper interfacing means. The communications configuring means disables the interface controlling means when the communications configuring means establishes a communications link via the pluggable interfacing means. Medium controlling means for controlling use of a medium communicates with the communications configuring means. The link indicating means is a light-emitting diode (LED). A network device comprises the dual-media network interface. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of a dual-media network interface for a network device according to the prior art; 
         FIG. 2  is a functional block diagram of a dual-media network interface including a physical layer device that automatically disables inactive media according to the present invention; and 
         FIG. 3  is a flowchart illustrating steps performed by the physical layer device of  FIG. 2  when a link is detected at a media interface. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the term module and/or device refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     A dual-media network interface according to the present invention automatically disables interfaces associated with inactive media when a link is established at another interface. The dual-media network interface prevents independent physical layer devices associated with small form-factor pluggable (SFP) modules from establishing or maintaining links with external devices after another interface previously establishes a link. 
     Referring now to  FIG. 2 , an exemplary network device  32  includes a dual-media network interface  34  having a medium access control (MAC) device  36  that communicates with a physical layer device  38  (or PHY). The dual-media network interface  34  includes an SFP interface  40  and a copper interface  42 . The SFP interface  40  communicates with the physical layer device  38  through a serial gigabit medium independent interface (SGMII) or another interface such as a 4-byte/5-byte (4B/5B) local fiber interface or a serializer/deserializer (SERDES) interface. In an exemplary embodiment, the SFP interface  40  supports SFP modules that interface with fiber media according to 100BASE-FX standards. Alternatively or additionally, the SFP interface  40  supports SFP modules that interface with copper media according to 10BASE-T, 100BASE-T, and/or 1000BASE-T standards and/or other current or future Ethernet standards. 
     The copper interface  42  communicates with the physical layer device  38  through a medium dependent interface. For example, the copper interface  42  may be hard-wired and solely controlled by the physical layer device  38 . Additionally, the copper interface  42  may include an RJ-45 connector with or without integrated magnetics (MAG). In an exemplary embodiment, the copper interface  42  interfaces with copper media according to 10BASE-T, 100BASE-TX, and/or 1000BASE-T standards. 
     The physical layer device  38  includes an SFP control module  44  that is associated with the SFP interface  40  and a copper control module  46  that is associated with the copper interface  42 . The physical layer device  38  ceases communications via the SFP interface  40  and/or the copper interface  42  by disabling the SFP control module  44  and/or the copper control module  46 , respectively. For example, the physical layer device  38  may utilize link monitoring software that detects established links at the SFP and copper interfaces  40  and  42 , respectively. The dual-media network interface  34  includes an SFP link indicator  48  and a copper link indicator  50 . For example, the SFP and copper link indicators  48  and  50 , respectively, may be light-emitting diodes (LEDs) or other types of indicators  48  and  50  that indicate the presence of an established link to a user. The physical layer device  38  activates the copper link indicator  50  when a link is established at the copper interface  42 . Likewise, the physical layer device  38  activates the SFP link indicator  48  when a link is established at the SFP interface  40 . 
     According to an exemplary embodiment, the physical layer device  38  includes a copper link indication pin  52  and an SFP link indication pin  54 . The physical layer device  38  asserts the copper link indication pin  52  and disables the SFP control module  44  when a link is established at the copper interface  42 . Likewise, the physical layer device  38  asserts the SFP link indication pin  54  and disables the copper control module  46  when a link is established at the SFP interface  40 . For example, disabling the copper control module  46  disables the copper interface  42 . The physical layer device  38  may assert the copper link indication pin  52  and SFP link indication pin  54  by outputting a logical high signal, a logical low signal, or another signal at a specific voltage or within a specific voltage range. 
     The SFP interface  40  supports an SFP module  56  including an independent physical layer device  58 . Therefore, disabling the SFP control module  44  alone does not necessarily prevent the SFP module  56  from establishing a link with an external device. Communications standards typically require that SFP interfaces  40  include a disable pin  60 . The SFP interface  40  and the SFP module  56  are disabled when the disable pin  60  is asserted. For example, the SFP module  56  may include a disable pin  62  that communicates with the disable pin  60  of the SFP interface  40 . According to the present invention, the disable pin  60  of the SFP interface  40  communicates with the copper link indication pin  52 . Therefore, when the physical layer device  38  asserts the copper link indication pin  52 , the SFP interface  40  and the SFP module  56  are automatically and immediately disabled. 
     Since the copper interface  42  is solely controlled by the copper control module  46 , the copper interface  42  is automatically disabled when the physical layer device  38  disables the copper control module  46 . Additionally, the SFP interface  40  and SFP module  56  are automatically disabled when a link is established at the copper interface  42 . Therefore, the present invention avoids problems associated with double linking that can occur when a processor performs link monitoring. For example, in prior art systems, software delays in processors prevent the physical layer device  38  from immediately disabling the SFP module  56  when a link is established at the copper interface  42 . 
     According to the present invention, double linking is avoided in this case because the physical layer device  38  does not wait for the link monitoring software to first detect the link at the copper interface  42  and then take action. Instead, the SFP interface  40  and SFP module  56  are disabled as soon as the physical layer device  38  detects the link at the copper interface  42  and activates the copper link indicator  50 . Therefore, the SFP interface  40  and the SFP module  56  will already be disabled by the time the link monitoring software detects the link at the copper interface  42 . Therefore, there is no longer an overlap in time where the SFP and copper interfaces  40  and  42 , respectively, are capable of simultaneously establishing links. Additionally, the independent physical layer device  58  in the SFP module  56  is unable to retain a link with an external device after a link is established at the copper interface  42 . 
     SFP modules  56  that interface with fiber media will typically shut down automatically and refrain from establishing links with external devices when the physical layer device  38  disables the SFP control module  44 . However, the SFP module  56  may still establish a link with an external device when unintentional signal conditions such as noise occur. Therefore, unintentional links with external devices are avoided by completely disabling both the SFP interface  40  and the SFP module  56  when a link occurs at the copper interface  42 . 
     Referring now to  FIG. 3 , a link detection algorithm begins in step  64 . In step  66 , the physical layer device  38  initializes the SFP interface  40  and the copper interface  42  as inactive. In step  68 , control determines whether a link has been established at either the SFP interface  40  or the copper interface  42 . If false, control loops to step  68 . If true, control proceeds to step  70 . In step  70 , control determines whether the link was established at the copper interface  42 . If false, control proceeds to step  72 . If true, the physical layer device  38  activates the copper link indicator  50  in step  74 . 
     Since the disable pin  60  is tied to the copper link indication pin  52 , the physical layer device  38  also disables the SFP interface  40  by activating the copper link indicator  50 . In step  76 , the physical layer device  38  disables the SFP control module  44  and control ends. In step  72 , the physical layer device  38  activates the SFP link indicator  48 . In step  78 , the physical layer device  38  disables the copper control module  46  and control ends. Since the copper interface  42  is completely controlled by the physical layer device  38 , the copper interface  42  is also disabled in step  78 . 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims.