Applying policies to schedule network bandwidth among virtual machines

A computer system capable of metering a rate at which packets from a virtual machine are injected into a network utilizing one or more policies specified by tenants of a data center, the computer system comprising a computer storage medium having a plurality of computer software components embodied thereon, the computer software components comprising:

• a first VM instantiated on a physical node;
• a second VM instantiated on the physical node;
• a first token-bucket queue assigned to the first VM;
• a second token-bucket queue assigned to the second VM, wherein the first token-bucket queue and the second token-bucket queue represent distinct memory buffers located on the physical node;
• and
• a scheduler that reads a first-client contract and a second-client contract associated with the first VM and the second VM, respectively, that deposits a first amount of tokens into the first token-bucket queue as a function of the one or more policies within the first-client contract, and that deposits a second amount of tokens into the second token-bucket queue as a function of the one or more policies within the second-client contract,
• wherein the first amount of tokens and the second amount of tokens each represent a portion of network bandwidth that is allocated to the first VM and the second VM, respectively,
• wherein the first amount and the second amount of tokens differ in value,
• wherein the first VM transmits a first data flow of packets to the first token-bucket queue prior to the packets of the first data flow being released from the physical node,
• wherein the second VM transmits a second data flow of packets to the second token-bucket queue prior to the packets of the second data flow being released from the physical node,
• wherein, upon receiving the first data flow, the first token-bucket queue deducts a prescribed amount of tokens deposited therein for each packet within the first data flow,
• wherein, upon receiving the second data flow, the second token-bucket queue deducts a prescribed amount of tokens deposited therein for each packet within the second data flow;
• and
• a routing component that accesses a mapping between the first VM and the first token-bucket queue when the first VM is attempting to transmit the first data flow to an endpoint external to the physical node, and that routes the first data flow to the first token-bucket queue based on the mapping, wherein the routing component routes the first data flow from first VM to the second VM without passing through the first token-bucket queue when the first VM is attempting to transmit the first data flow directly to the second VM.

A computerized method for imposing a limit on a rate of data flowing from a subject virtual machine (VM), the method comprising:

• accepting a first deposit of tokens from a scheduler, wherein an amount of tokens provided within the first deposit is based on determining whether the subject VM is in an active state, based on a depletion of the first deposit of tokens, or an idle state, based on a lack of usage of the first deposit of tokens, wherein, when in the active state, a token-bucket queue of the subject VM is reloaded as a function of a portion of the first deposit of tokens remaining in the first token-bucket queue, and wherein, when in the idle state, the token-bucket queue is reloaded with a minimal amount of tokens reserved for the subject VM;
• consuming the tokens according to a rate of the data flow from the subject VM;
• and
• dynamically metering the data-flow rate upon substantially depleting the tokens, wherein metering comprises:
• (a) forwarding to a network interface component packets within the data flow that are received prior to the tokens being substantially depleted from the token-bucket queue;
• (b) enqueueing packets within the data flow that are received subsequent to the tokens being substantially depleted from the token-bucket queue;
• and
• (c) forwarding the enqueued packets to the network interface component upon the token-bucket queue accepting a second deposit of tokens from the scheduler.