Distributed dynamic load balancing in network systems
A source switching device in a switching system receives information measured by a target switching device in the switching system. The information is indicative of an amount of data received in a given amount of time by the target switching device via each of two or more first links coupled to the target switching device. The source switching device determines, based at least in part on the information received from the target device, a path, from among multiple paths from the source switching device to the target switching device, for transmission of a packet flow directed to the target switching device. The source switching device transmits, via the determined path for transmission of the packet flow to the target device, one or more packets belonging to the packet flow.
1. A method for balancing traffic load in a network system, the method comprising:
receiving, at a source device, information measured by a target device, the information indicative of respective total amounts of data received in a given sampling time interval by the target device via respective ones of two or more first links coupled to the target device, the data having been transmitted to the target device by multiple source devices in the network system;
determining, by the source device, a path from among multiple paths from the source device to the target device, the path for transmission of a packet flow directed to the target device, including determining the path based at least in part on calculations that utilize share metrics indicative of respective shares of the packet flow with respect to multiple packet flows being transmitted using links included in respective paths among the multiple paths from the source device to the target device, the share metrics calculated based on the respective total amounts of data received in the given sampling time interval via the respective ones of the two or more first links coupled to the target device, the respective total amounts of data indicated by the information received at the source device from the target device; and
transmitting, by the source device, one or more packets belonging to the packet flow, the one or more packets being transmitted via the determined path for transmission of the packet flow to the target device.
2. The method of claim 1 , wherein determining the path comprises determining the path further based on information indicative of an amount of data transmitted by the source device on each of two or more second links coupled to the source device.
3. The method of claim 1 , wherein determining the path comprises determining the path further based on a bandwidth of the packet flow.
4. The method of claim 1 , wherein determining the path includes
determining a set of share metrics for the packet flow, respective share metrics in the set of share metrics indicative of a share of the packet flow on respective paths of the two or more paths with respect to all packet flows being transmitted using links included in the respective paths, and
determining the path based at least in part on the set of share metrics, including determining the path such that share of the packet flow on the determined path is greater than share of the packet flow on a path that is currently being used by the source device for transmission of the packet flow.
5. The method of claim 4 , wherein
the method further comprises determining, by the source device based on the set of share metrics, a set of gain metrics, respective gain metrics in the set of gain metrics indicating respective potential gains in share of the packet flow if the packet flow is redirected (i) from the path currently being used by the source device for transmission of the packet flow to (ii) respective ones of other paths of the two or more paths from the source device and the target device, and
determining the path comprises determining the path based at least in part on the set of gain metrics.
6. The method of claim 1 , wherein determining the path for transmission of the packet flow comprises determining a second link from among two or more second links coupled to the source device, the second link being associated with the path.
7. The method of claim 1 , wherein the packet flow is a first packet flow being processed by the source device, and wherein the method further comprises determining, based at least in part on the information received from the target device, a second path for transmission of a second packet flow being processed by the source device.
8. The method of claim 1 , wherein receiving the information indicative of the respective total amounts of data received in the given sampling time interval by the target device via respective ones of the two or more first links coupled to the target device comprises receiving the information in a control message transmitted by the target switching device directly to the source device.
9. The method of claim 1 , wherein transmitting the packet to the target device comprises transmitting the packet to the target device via a switching device of an interconnect switching stage of the network system.
10. The method of claim 9 , wherein receiving the information from the target device includes receiving information indicative of a total amount of data received in the given sampling time interval by the target device via a particular one of the two or more first links coupled to the target device, the data having been transmitted by the multiple source devices in the network system.
11. A source device for operation in a network system, comprising:
a plurality of ports to couple the source device to respective links in the network system;
a load balancer device configured to
receive information measured by a target device in the network system, the information indicative of respective total amounts of data received in a given sampling time interval by the target device via respective ones of two or more first links coupled to the target device, the data having been transmitted to the target device by multiple source devices in the network system, and
determine a path from among multiple paths from the source device to the target device, the path for transmission of a packet flow directed to the target device, including determining the path based at least in part on calculations that utilize share metrics indicative of respective shares of the packet flow with respect to multiple packet flows being transmitted using links included in respective paths among the multiple paths from the source device to the target device, the share metrics calculated based on the respective total amounts of data received in the given sampling time interval via the respective ones of the two or more first links coupled to the target device, the respective total amounts of data indicated by the information received at the source device from the target device; and
a packet processor device configured to transmit one or more packets belonging to the packet flow, the one or more packets being transmitted via a port of the plurality of ports, the port corresponding to the determined path for transmission of the packet flow to the target device.
12. The source device of claim 11 , wherein the load balancer device is configured to determine the path further based on information indicative of an amount of data transmitted by the source device on each of two or more second links coupled to the source device.
13. The source device of claim 11 , wherein the load balancer device is configured to determine the path further based on a bandwidth of the packet flow.
14. The source device of claim 11 , wherein the load balancer device is configured to determine the path at least by:
determining a set of share metrics for the packet flow, respective share metrics in the set of share metrics indicative of share of the packet flow on respective paths of the two or more paths with respect to all packet flows being transmitted using links included in the respective paths, and
determining the path based at least in part on the set of share metrics, including determining the path such that share of the packet flow on the determined path is greater than share of the packet flow on a path that is currently being used by the source device for transmission of the packet flow.
15. The source device of claim 14 , wherein the load balancer device is further configured to:
determine, based on the set of share metrics, a set of gain metrics, respective gain metrics in the set of gain metrics indicating respective potential gains in share of the packet flow if the packet flow is redirected (i) from the path currently being used by the source device for transmission of the packet flow to (ii) respective ones of other paths of the two or more paths from the source device and the target device, and
determine the path based at least in part on the set of gain metrics.
16. The source device of claim 14 , wherein the load balancer device is configured to determine the path at least by determining a second link from among two or more second links coupled to the source device, the second link being associated with the path.
17. The source device of claim 16 , wherein the packet flow is a first packet flow being processed by the source device, and wherein the load balancer device is further configured to determine, based on at least in part on the information received from the target device, a second path for transmission of a second packet flow being processed by the source device.
18. The source device of claim 11 , wherein the information indicative of the respective total amounts of data received in the given sampling time interval by the target device via respective ones of the two or more first links coupled to the target is received by the source device in a control message transmitted by the target device directly to the source device.
19. The source device of claim 11 , wherein
the network system comprises at least a first switching stage and a second switching stage, with devices of the first switching stage being interconnected via switching devices of the second switching stage, and
the source device is a switching device of the first switching stage,
the target device is a switching device of the first switching stage, and
the packet processor is configured to transmit the packet to the target device via a switching device of the second switching stage.
20. The source device of claim 19 , wherein the information received from the target device includes information indicative of a total amount of data received in the given sampling time interval by the target device via a particular one of the two or more first links coupled to the target device, the data being having been transmitted by the multiple source devices in the network system.