Abstract:
A method for indicating bandwidth for a virtual network interface card (NIC) includes receiving a bandwidth trigger for a bandwidth of a first virtual NIC operatively connected to a NIC, wherein the NIC is associated with a network bandwidth, obtaining a bandwidth allocation stored in the first virtual NIC in response to the bandwidth trigger, wherein the bandwidth allocation corresponds to the bandwidth of the first virtual NIC, and wherein the bandwidth allocation corresponds to a portion of the network bandwidth, and returning the bandwidth allocation to a component associated with the virtual NIC.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application contains subject matter that may be related to the subject matter in the following U.S. applications filed on Apr. 22, 2005, and assigned to the assignee of the present application: “Method and Apparatus for Managing and Accounting for Bandwidth Utilization Within A Computing System” with U.S. application Ser. No. 11/112,367 (Attorney Docket No. 03226/643001; SUN050681); “Method and Apparatus for Consolidating Available Computing Resources on Different Computing Devices” with U.S. application Ser. No. 11/112,368 (Attorney Docket No. 03226/644001; SUN050682); “Assigning Higher Priority to Transactions Based on Subscription Level” with U.S. application Ser. No. 11/112,947 (Attorney Docket No. 03226/645001; SUN050589); “Method and Apparatus for Dynamically Isolating Affected Services Under Denial of Service Attack” with U.S. application Ser. No. 11/112,158 (Attorney Docket No. 03226/646001; SUN050587); “Method and Apparatus for Improving User Experience for Legitimate Traffic of a Service Impacted by Denial of Service Attack” with U.S. application Ser. No. 11/112,629 (Attorney Docket No. 03226/647001; SUN050590); “Method and Apparatus for Limiting Denial of Service Attack by Limiting Traffic for Hosts” with U.S. application Ser. No. 11/112,328 (Attorney Docket No. 03226/648001; SUN050591); “Hardware-Based Network Interface Per-Ring Resource Accounting” with U.S. application Ser. No. 11/112,222 (Attorney Docket No. 03226/649001; SUN050593); “Dynamic Hardware Classification Engine Updating for a Network Interface” with U.S. application Ser. No. 11/112,934 (Attorney Docket No. 03226/650001; SUN050592); “Network Interface Card Resource Mapping to Virtual Network Interface Cards” with U.S. application Ser. No. 11/112,063 (Attorney Docket No. 03226/651001; SUN050588); “Network Interface Decryption and Classification Technique” with U.S. application Ser. No. 11/112,436 (Attorney Docket No. 03226/652001; SUN050596); “Method and Apparatus for Enforcing Resource Utilization of a Container” with U.S. application Ser. No. 11/112,910 (Attorney Docket No. 03226/653001; SUN050595); “Method and Apparatus for Enforcing Packet Destination Specific Priority Using Threads” with U.S. application Ser. No. 11/112,584 (Attorney Docket No. 03226/654001; SUN050597); “Method and Apparatus for Processing Network Traffic Associated with Specific Protocols” with U.S. application Ser. No. 11/112,228 (Attorney Docket No. 03226/655001; SUN050598). 
         [0002]    The present application contains subject matter that may be related to the subject matter in the following U.S. applications filed on Oct. 21, 2005, and assigned to the assignee of the present application: “Method and Apparatus for Defending Against Denial of Service Attacks” with U.S. application Ser. No. 11/255,366 (Attorney Docket No. 03226/688001; SUN050966); “Router Based Defense Against Denial of Service Attacks Using Dynamic Feedback from Attacked Host” with U.S. application Ser. No. 11/256,254 (Attorney Docket No. 03226/689001; SUN050969); and “Method and Apparatus for Monitoring Packets at High Data Rates” with U.S. application Ser. No. 11/226,790 (Attorney Docket No. 03226/690001; SUN050972). 
         [0003]    The present application contains subject matter that may be related to the subject matter in the following U.S. applications filed on Jun. 30, 2006, and assigned to the assignee of the present application: “Network Interface Card Virtualization Based On Hardware Resources and Software Rings” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/870001; SUN061020); “Method and System for Controlling Virtual Machine Bandwidth” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/871001; SUN061021); “Virtual Switch” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/873001; SUN061023); “System and Method for Virtual Network Interface Cards Based on Internet Protocol Addresses” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/874001; SUN061024); “Virtual Network Interface Card Loopback Fastpath” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/876001; SUN061027); “Bridging Network Components” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/877001; SUN061028); “Method and Apparatus for Containing a Denial of Service Attack Using Hardware Resources on a Virtual Network Interface Card” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/879001; SUN061033); “Virtual Network Interface Cards with VLAN Functionality” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/882001; SUN061037); “Method and Apparatus for Dynamic Assignment of Network Interface Card Resources” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/883001; SUN061038); “Generalized Serialization Queue Framework for Protocol Processing” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/884001; SUN061039); “Serialization Queue Framework for Transmitting Packets” with U.S. application Ser. No. TBD (Attorney Docket No. 03226/885001; SUN061040). 
     
     BACKGROUND 
       [0004]    Network traffic is transmitted from a network, such as the Internet, from a sending system (e.g., a computer system) to a receiving system (e.g., a computer system) via a network interface card (NIC). The NIC is a piece of hardware found in a typical computer system that includes functionality to send and receive network traffic. Typically, network traffic is transmitted in the form of packets, where each packet includes a header and a payload. The header contains information regarding the source address, destination address, size, transport protocol used to transmit the packet, and various other identification information associated with the packet. The payload contains the actual data to be transmitted from the network to the receiving system. 
         [0005]    Each of the packets sent between the sending system and receiving system is typically associated with a connection. The connection ensures that packets from a given process on the sending system reach the appropriate process on the receiving system. Packets received by the receiving system (via a NIC associated with the receiving system) are analyzed by a classifier to determine the connection associated with the packet. 
         [0006]    Typically, the classifier includes a connection data structure that includes information about active connections on the receiving system. The connection data structure may include the following information about each active connection: (i) the queue associated with the connection; and (ii) information necessary to process the packets on the queue associated with the connection. Depending on the implementation, the connection data structure may include additional information about each active connection. Such queues are typically implemented as first-in first-out (FIFO) queues and are bound to a specific central processing unit (CPU) on the receiving computer system. Thus, all packets for a given connection are placed in the same queue and are processed by the same CPU. In addition, each queue is typically configured to support multiple connections. 
         [0007]    Once the classifier determines the connection associated with the packets, the packets are forwarded to a temporary data structure (e.g., a receive ring on the NIC) and an interrupt is issued to the CPU associated with the queue. In response to the interrupt, a thread associated with the CPU (to which the serialization queue is bound) retrieves the packets from the temporary data structure and places them in the appropriate queue. Once packets are placed in the queue, those packets are processed in due course. In some implementations, the queues are implemented such that only one thread is allowed to access a given queue at any given time. 
       SUMMARY 
       [0008]    In general, in one aspect, the invention relates to a method for indicating bandwidth for a virtual network interface card (NIC), comprising receiving a bandwidth trigger for a bandwidth of a first virtual NIC operatively connected to a NIC, wherein the NIC is associated with a network bandwidth, obtaining a bandwidth allocation stored in the first virtual NIC in response to the bandwidth trigger, wherein the bandwidth allocation corresponds to the bandwidth of the first virtual NIC, and wherein the bandwidth allocation corresponds to a portion of the network bandwidth, and returning the bandwidth allocation to a component associated with the virtual NIC. 
         [0009]    In general, in one aspect, the invention relates to a system for indicating bandwidth for a virtual network interface card (NIC), comprising a NIC associated with a network bandwidth, a host, operatively connected to the NIC, comprising a first virtual NIC operatively connected to the NIC, and a bandwidth allocation stored in the first virtual NIC, wherein the host is configured to receive a bandwidth trigger for a bandwidth of the first virtual NIC, obtain the bandwidth allocation stored in the first virtual NIC in response to the bandwidth trigger, wherein the bandwidth allocation corresponds to the bandwidth of the first virtual NIC, and wherein the bandwidth allocation corresponds to a portion of the network bandwidth, and return the bandwidth allocation to a component associated with the virtual NIC. 
         [0010]    In general, in one aspect, the invention relates to a computer usable medium having computer readable code embodied therein for causing a computer system to execute a method for indicating bandwidth for a virtual network interface card (NIC), comprising receiving a bandwidth trigger for a bandwidth of a first virtual NIC operatively connected to a NIC, wherein the NIC is associated with a network bandwidth, obtaining a bandwidth allocation stored in the first virtual NIC in response to the bandwidth trigger, wherein the bandwidth allocation corresponds to the bandwidth of the first virtual NIC, and wherein the bandwidth allocation corresponds to a portion of the network bandwidth, and returning the bandwidth allocation to a component associated with the virtual NIC. 
         [0011]    Other aspects of the invention will be apparent from the following description and the appended claims. 
     
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  shows a schematic diagram of a system in accordance with one or more embodiments of the invention. 
           [0013]      FIGS. 2-3  show flow charts in accordance with one or more embodiments of the invention. 
           [0014]      FIG. 4  shows a computer system in accordance with one or more embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Specific embodiments of the invention will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency. 
         [0016]    In the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. 
         [0017]    In general, embodiments of the invention provide a method and apparatus to report link speeds associated with virtual network interface cards (NICs). In one or more embodiments of the invention, multiple virtual NICs are associated with a single physical NIC, where the single physical NIC is associated with a network bandwidth. The virtual NICs share the network bandwidth of the single physical NIC. In some cases, each virtual NIC is assigned a bandwidth. 
         [0018]    Further, embodiments of the invention provide a method and apparatus to report link speeds for virtual NICs based on the allocated bandwidth for the virtual NICs. Instead of reporting the link speed of the physical NIC as the link speed of a virtual NIC connected to the physical NIC, embodiments of the invention report the link speed of a virtual NIC as the bandwidth allocation of the virtual NIC. In addition, embodiments of the invention allow changes in bandwidth allocation of a virtual NIC to be reported to the network stack associated with the virtual NIC. IN such embodiments, any applications or virtual machines connected to the network stack would subsequently receive a notification regarding the change in bandwidth allocation of the associated virtual NIC. In one or more embodiments of the invention, bandwidth and link speed are synonymous terms for data transfer rate. 
         [0019]      FIG. 1  shows a schematic diagram of a system in accordance with one or more embodiments of the invention. As shown in  FIG. 1 , the system includes a host ( 100 ), a network interface card (NIC) ( 105 ), a network ( 110 ), multiple virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )), multiple virtual machines (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )), and multiple pieces of management software (e.g., management software  1  ( 130 ), management software  2  ( 135 ), management software  3  ( 140 )). Each of these components is described below. 
         [0020]    The NIC ( 105 ) provides an interface between the host ( 100 ) and a network ( 110 ) (e.g., a local area network, a wide area network, a wireless network, etc.). More specifically, the NIC ( 105 ) includes a network interface (NI) (i.e., the hardware on the NIC used to interface with the network ( 110 )). For example, the NI may correspond to an RJ-45 connector, a wireless antenna, etc. The packets received by the NI are then forwarded to other components on the NIC ( 105 ) for processing. In one embodiment of the invention, the NIC ( 105 ) includes one or more receive rings (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )). In one embodiment of the invention, the receive rings (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )) correspond to portions of memory within the NIC ( 105 ) used to temporarily store packets received from the network ( 110 ). Further, in one embodiment of the invention, a ring element of the receive rings (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )) may point to host memory. 
         [0021]    In one or more embodiments of the invention, the host ( 100 ) may include a device driver (not shown) and one or more virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )). In one embodiment of the invention, the device driver provides an interface between the receive rings (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )) and the host ( 100 ). More specifically, the device driver (not shown) exposes the receive rings (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )) to the host ( 100 ). In one embodiment of the invention, each of the virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is associated with one or more receive rings (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )). In other words, a virtual NIC (e.g., virtual NIC  1  ( 130 ), virtual NIC  2  ( 135 ), virtual NIC  3  ( 140 )) receives incoming packets from the corresponding receive ring (e.g., receive ring  1  ( 115 ), receive ring  2  ( 120 ), receive ring  3  ( 125 )). 
         [0022]    In one or more embodiments of the invention, the virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) are operatively connected to virtual machines (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) via virtual network stacks (not shown). The virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) provide an abstraction layer between the NIC ( 105 ) and the virtual machines (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) on the host ( 100 ). More specifically, each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) operates like a NIC ( 105 ). For example, in one embodiment of the invention, each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is associated with one or more Internet Protocol (IP) addresses, one or more ports, and configured to handle one or more protocol types. Thus, while the host ( 100 ) may be operatively connected to a single NIC ( 105 ), virtual machines (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) executing on the host ( 100 ) operate as if the host ( 100 ) is bound to multiple NICs. Further, each virtual machine (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) has no knowledge of the other virtual machines residing on the host. To each virtual machine (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )), the corresponding virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is indistinguishable from a physical NIC ( 105 ). Further, each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) includes properties of a physical NIC, such as link speed, Media Access Control (MAC) address, etc. 
         [0023]    In one embodiment of the invention, each virtual network stack (not shown) includes functionality to process packets in accordance with various protocols used to send and receive packets (e.g., Transmission Communication Protocol (TCP), Internet Protocol (IP), User Datagram Protocol (UDP), etc.). Further, each virtual network stack may also include functionality, as needed, to perform additional processing on the incoming and outgoing packets. This additional processing may include, but is not limited to, cryptographic processing, firewall routing, etc. 
         [0024]    In one or more embodiments of the invention, the virtual network stacks correspond to network stacks with network layer and transport layer functionality. In one embodiment of the invention, network layer functionality corresponds to functionality to manage packet addressing and delivery on a network (e.g., functionality to support Internet Protocol, Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), etc.). In one embodiment of the invention, transport layer functionality corresponds to functionality to manage the transfer of packets on the network (e.g., functionality to support TCP, UDP, Stream Control Transmission Protocol (SCTP), etc.). 
         [0025]    As shown in  FIG. 1 , the NIC ( 105 ) is associated with a network bandwidth ( 196 ). In one or more embodiments of the invention, the network bandwidth ( 196 ) relates to the data rate supported by a network connection on the NIC ( 105 ). In other words, the network bandwidth ( 196 ) represents the capacity of the connection between the NIC ( 105 ) and the network ( 110 ). In addition, each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is associated with a virtual NIC bandwidth (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )). In one or more embodiments of the invention, the network bandwidth ( 196 ) is allocated among the virtual NIC bandwidths (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )). Those skilled in the art will appreciate that the network bandwidth ( 196 ) does not need to be completely divided up among the virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )); for example, each of three virtual NICs could share 50% of the network bandwidth ( 196 ), whereas the other 50% of the network bandwidth is left unallocated. 
         [0026]    Each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is also operatively connected to a piece of management software ( 130 ). In one or more embodiments of the invention, the management software ( 130 ) is responsible for creating each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )), changing the properties of each virtual NIC (e.g. MAC address, IP address), assigning bandwidth to each virtual NIC (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )), and listing the virtual NICs on the host ( 100 ). The management software ( 130 ) is also responsible for directing requests for bandwidth from applications (e.g., application  1  ( 175 ), application  2  ( 180 ), application  3  ( 185 )) to the virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )). In addition, the management software ( 130 ) may be responsible for performing changes in bandwidth allocation for each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )), and for sending a notification of a bandwidth reallocation to the virtual network stack (not shown) associated with the virtual NIC. In one or more embodiments of the invention, the management software ( 130 ) acts as an interface that provides virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) configuration services to interested parties, such as applications and administrative tasks. 
         [0027]    In one or more embodiments of the invention, a notification of a bandwidth reallocation is transmitted by a virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) and received by a virtual network stack, which relays the notification to the corresponding virtual machine (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) and any applications (e.g., application  1  ( 175 ), application  2  ( 180 ), application  3  ( 185 )) running on that virtual machine. In one or more embodiments of the invention, a link speed query for a virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is sent by an application (e.g., application  1  ( 175 ), application  2  ( 180 ), application  3  ( 185 )) running within the virtual machine (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) associated with that virtual NIC. 
         [0028]    In one or more embodiments of the invention, the virtual NIC bandwidth (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )) associated with a virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is reported when a link speed query for the virtual NIC is received. The management software ( 130 ) passes the link speed query to the virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )), which reports its bandwidth (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )) to the virtual network stack or virtual machine (e.g., virtual machine  1  ( 160 ), virtual machine  2  ( 165 ), virtual machine  3  ( 170 )) requesting the link speed query. In one or more embodiments of the invention, each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) stores its bandwidth allocation (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )) interally. The management software ( 130 ) is responsible for changing the bandwidth allocation (e.g., virtual NIC  1  bandwidth ( 190 ), virtual NIC  2  bandwidth ( 192 ), virtual NIC  3  bandwidth ( 194 )) and directing requests for bandwidth to the virtual NICs (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )), but the bandwidth allocation is stored in each virtual NIC. Those skilled in the art will appreciate that if the network bandwidth ( 196 ) is reported as the bandwidth of a virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )), the capacity of the virtual NIC will appear to be higher than the actual bandwidth allocation for that virtual NIC. In one or more embodiments of the invention, bandwidth allocation information for each virtual NIC (e.g., virtual NIC  1  ( 145 ), virtual NIC  2  ( 150 ), virtual NIC  3  ( 155 )) is stored inside a Management Information Base (MIB) object. 
         [0029]      FIG. 2  shows a flow diagram in accordance with one or more embodiments of the invention. First, a link speed query is received (Step  201 ) for a virtual NIC. The link speed query may be generated by an application residing on a virtual machine associated with the virtual NIC, an application residing on a virtual machine associated with another virtual NIC, or by another application located on another physical host. Next, the link speed query is passed to the relevant virtual NIC (Step  202 ). A determination is then made about whether the network bandwidth is divided among multiple virtual NICs (Step  203 ). In other words, a determination is made about whether the virtual NIC is allocated the entire network bandwidth. If the virtual NIC is allocated the entire network bandwidth, then the network bandwidth is returned (Step  209 ). Otherwise, the virtual NIC looks up its bandwidth allocation (Step  205 ), which is stored internally within the virtual NIC, and returns the bandwidth allocation to the application that requested the bandwidth allocation (Step  207 ). 
         [0030]      FIG. 3  shows a flow diagram in accordance with one or more embodiments of the invention. Initially, a bandwidth reallocation occurs (Step  301 ). In one or more embodiments of the invention, a bandwidth reallocation may occur when a virtual NIC requires more bandwidth than is currently allocated, a new virtual NIC is added to the system, a virtual NIC is removed from the system, etc. In one or more embodiments of the invention, a bandwidth reallocation involves changing field values in a MIB object by a piece of management software operatively connected to the virtual NIC. 
         [0031]    Once the bandwidth reallocation has taken place, a bandwidth reallocation notification is generated (Step  303 ). In one or more embodiments of the invention, a bandwidth reallocation notification is generated by the management software. Alternatively, the virtual NIC generates the bandwidth reallocation notification upon a change in the value of its bandwidth allocation by the management software. Next, the bandwidth reallocation notification is passed to the Media Access Control (MAC) of the host layer (Step  305 ). In one or more embodiments of the invention, the MAC layer corresponds to the data link level MAC layer associated with the virtual NIC and the physical NIC; the MAC layer is responsible for moving data packets between the NIC and virtual NICs, as well as other NICs on other hosts, using MAC protocols. From the MAC layer, the notification is passed to the virtual network stack (Step  307 ) of the virtual machine corresponding to the virtual NIC. There, the bandwidth reallocation notification is relayed to packet destinations connected to the virtual network stack (Step  309 ). In one or more embodiments of the invention, packet destinations include applications or containers running on the virtual machine. 
         [0032]    The invention may be implemented on virtually any type of computer regardless of the platform being used. For example, as shown in  FIG. 4 , a computer system ( 400 ) includes a processor ( 402 ), associated memory ( 404 ), a storage device ( 406 ), and numerous other elements and functionalities typical of today&#39;s computers (not shown). The computer ( 400 ) may also include input means, such as a keyboard ( 408 ) and a mouse ( 410 ), and output means, such as a monitor ( 412 ). The computer system ( 400 ) is connected to a local area network (LAN) or a wide area network (e.g., the Internet) (not shown) via a network interface connection (not shown). Those skilled in the art will appreciate that these input and output means may take other forms. 
         [0033]    Further, those skilled in the art will appreciate that one or more elements of the aforementioned computer system ( 400 ) may be located at a remote location and connected to the other elements over a network. Further, the invention may be implemented on a distributed system having a plurality of nodes, where each portion of the invention (e.g, network interface card, virtual NICs, etc.) may be located on a different node within the distributed system. In one embodiment of the invention, the node corresponds to a computer system. Alternatively, the node may correspond to a processor with associated physical memory. The node may alternatively correspond to a processor with shared memory and/or resources. Further, software instructions to perform embodiments of the invention may be stored on a computer readable medium such as a compact disc (CD), a diskette, a tape, a file, or any other computer readable storage device. 
         [0034]    While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.