DYNAMIC BANDWIDTH THROTTLING

• US 20110066752A1
• Filed: 09/09/2010
• Published: 03/17/2011
• Est. Priority Date: 09/14/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Goodrow, Dennis Sidney, Lincroft, Peter James, LIPPINCOTT, Lisa Ellen
• Granted Patent: US 8,966,110 B2
• Time in Patent Office: Days
• US Class Current: 709/233
• CPC Class Codes: H04L 12/12 Arrangements for remote connection or disconnection of substations or of equipment thereof
• CPC Class Codes: H04L 43/0894 Packet rate
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps
• CPC Class Codes: H04L 45/122 by minimising distances, e.g. by selecting a route with minimum of number of hops
• CPC Class Codes: H04L 45/64 using an overlay routing layer
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions

Abstract

An approximation of the bandwidth of the narrowest link in a network is determined by watching how fast data gets to the other end and then back again. The rate of data transmission is limited according to this approximation. Dynamic capacity of the link, i.e. the amount of data that can be in-flight at the same time, neglecting any buffers, is also tracked. The technique looks at how much data is in-flight and, if there is more data in flight than the dynamic capacity of the network, the data transmission rate is slowed down.

Claims

1. A computer implemented method for dynamic bandwidth throttling, comprising the steps of:

a sender configured to track an approximation of network bandwidth by watching how fast data gets to a receiver at an other end of the network from said sender and back again, said approximation comprising a metric determined according to the processor implemented steps of;

sending time-stamped information from said sender to said receiver;

said receiver time-stamping said information and returning said information to said sender;

said sender calculating a baseline value for bandwidth from said information based upon said sender'"'"'s time stamp and said receiver'"'"'s time stamp; and

said sender sending additional time-stamped information to a receiver to determine network bandwidth relative to said baseline and to generate a metric therefrom which comprises said bandwidth approximation; and

said sender limiting a rate of data transmission according to said approximation.

2. The method of claim 1, further comprising the step of:

said sender using said approximation to determine a lateness metric.

3. The method of claim 1, further comprising the step of:

said sender using said approximation to determine a penalty.

4. The method of claim 1, further comprising the step of:

examining how much data is in-flight and, if more data is in flight than dynamic capacity of the network, slowing said data transmission rate to avoid having more data in flight than the dynamic capacity of the network.

5. The method of claim 1, further comprising the step of:

adjusting the size of blocks of data transferred to optimize a transfer rate, wherein when blocks of data are received in their entirety, transmission of larger blocks is attempted; and

when blocks of data are received in different sizes than they were sent, smaller blocks are sent.

6. The method of claim 1, further comprising the step of:

determining lateness of data by looking at increments of data that were sent out, making an estimate of when the data is expected to arrive, and measuring a difference between when the data is expected to arrive and when the data actually arrives;

wherein if lateness goes up significantly, indicating that there is heavy traffic on the network, responding by sending data more slowly.

7. The method of claim 6, further comprising the steps of:

determining outbound lateness and inbound lateness by comparing two or more different transit times to see how much later one was than the other, wherein transit time comprises a time a particular unit of data was sent and a time that it was received; and

comparing a difference in transit times for each transmission to a baseline to determine whether the network is slower or faster relative to the baseline, and thus provide a metric on network congestion.

8. The method of claim 6, further comprising the step of:

using lateness to throttle data transmission by assigning various penalties to local transmissions.

9. The method of claim 8, further comprising the steps of:

determining a penalty by dividing an amount of data to be sent by bandwidth and calculating an amount of time that is designated as a sending penalty.

10. The method of claim 8, further comprising the step of:

determining said penalty based upon the following;

whether or not to send data based upon bandwidth;

trying to send data and failing because buffers on a local system are full;

something else is sending data on a same system and a local system is unable to get data onto the network quickly enough;

stalling, where a receiver completely stops receiving data; and

when data arrives late, assigning a penalty for late arrival.

11. A dynamic bandwidth throttling apparatus, comprising:

a sender configured to track an approximation of network bandwidth by watching how fast data gets to a receiver at an other end of the network from said sender and back again;

a processor for determining said approximation by;

sending time-stamped information from said sender to said receiver;

wherein said receiver time-stamps said information and returns said information to said sender;

said sender calculating a baseline value for bandwidth from said information based upon said sender'"'"'s time stamp and said receiver'"'"'s time stamp; and

said sender sending additional time-stamped information to a receiver to determine network bandwidth relative to said baseline and to generate a metric therefrom which comprises said bandwidth approximation; and

said sender limiting a rate of data transmission according to said approximation.

12. The apparatus of claim 11, said processor configured to provide parameters that can be used to control bandwidth, said parameters comprising any of:

a maximum control parameter that allows a user to set a maximum bandwidth to consume, wherein said parameter delays sending so that bandwidth use never exceeds said maximum;

a minimum control parameter that allows a user to set a minimum bandwidth to consume, wherein said attempts to not go below said minimum bandwidth, even if there is competing traffic; and

a percentage control parameter that allows a user to set a percentage of bandwidth to consume, wherein said parameter delays sending to stay below a maximum percentage of available bandwidth, wherein if sending starts to interfere with said available bandwidth, sending is slowed down further, and wherein once competing traffic subsides, the sending is increased back up to said percentage.