1 / 12

Enhanced ECMP and Large Flow Aware Transport draft-yong-pwe3-enhance-ecmp-lfat

Enhanced ECMP and Large Flow Aware Transport draft-yong-pwe3-enhance-ecmp-lfat. {lucyyong,yangpeilin}@huawei.com. Why Enhanced ECMP. Internet Traffic show the traffic pattern as Very small % top large flows take up large portion of network capacity

oprah
Download Presentation

Enhanced ECMP and Large Flow Aware Transport draft-yong-pwe3-enhance-ecmp-lfat

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Enhanced ECMP and Large Flow Aware Transportdraft-yong-pwe3-enhance-ecmp-lfat {lucyyong,yangpeilin}@huawei.com IETF77, Anaheim CA

  2. Why Enhanced ECMP • Internet Traffic show the traffic pattern as • Very small % top large flows take up large portion of network capacity • Huge amount of small flows consume the rest of network capacity • Hash based ECMP can not evenly disperse traffic flows over ECMP paths under such traffic pattern • Hashing preserves the order of packets that belongs to individual flows within the aggregated flows • Hashing dispersion is simple and stateless, if flow IDs are random enough, it evenly disperses the number of flows on paths • But it does not mean the even traffic volume on the paths • Simulation shows uneven load for internet traffic • Unbalanced load over ECMP paths results • Congestion on some path while other are partially used • Enforce carrier to deploy more capacity in order to maintain the performance -> lower network utilization and increase service cost • Hash based distribution are popularly used, because simple and scale IETF77, Anaheim CA

  3. Enhanced ECMP Proposal • Apply different treatments on small flows and large flows • Use hash to disperse all small flows over ECMP paths • Use a table to map a small set of large flows to ECMP paths • Simple load balance algorithm can effectively compensate unbalanced paths caused by hashing • Mapping table automatically refresh to remove non-live flows • A very small set of large flows will not give BIG burden to device and not cause scalability concern IETF77, Anaheim CA

  4. Simulation Result • We analyzed Internet Traffic captured by Caida (http://www.caida.org/data/monitor) • Program a traffic generator that generate • 2% large flows that take up 30% of traffic volume • 98% small flows that take up 70% of traffic volume • Flow rate for small or large flows are randomly generated • Apply generated traffic to 4 ECMP paths by using existing ECMP and enhanced ECMP approach, respectively • Run it again over 10 ECMP paths IETF77, Anaheim CA

  5. Result for Four ECMP Paths ECMP can get ~10% volume difference between paths Enhanced ECMP obtains <1% volume difference between paths IETF77, Anaheim CA

  6. Result for Ten ECMP Paths ECMP can get ~15% volume difference between paths The more ECMP paths, the worse Hash perform Enhanced ECMP obtains <1% volume difference between paths IETF77, Anaheim CA

  7. Ingress PE Process • Insert flow label for each received packet • Perform Large Flow Recognition • Large flow criteria can be configured by operator • Insert large flow indication in the packets for the large flow • Set the default as a small flow • Egress PE trims off the flow label before forwarding to AC • Same process as described in FAT-PW IETF77, Anaheim CA

  8. Enhanced ECMP Process at P • Inspect large flow indication on each received packets • Use hash to disperse small flow packets • Forward large flow packets based on the mapping table • For an existing flow • Forward the packet to the path indicated in table • For a new flow • Select the least loaded path for the new flow • Add an entry in table for the new flow • Remove the flow entry when the flow transport completed IETF77, Anaheim CA

  9. Congestion Control • When congestion happens, P node selects some large flows to be dropped, rerouted, or cached • Dramatically reduce the number of impacted services • Reduce network convergence time (only few flow impacted) -> Large flow indication brings an advantage in congestion control IETF77, Anaheim CA

  10. Full Backward Compatibility • When ingress PE does not support Large Flow Recognition, it SHALL set F bit to 0 • All packets will be treated as small flow at the P nodes that implement enhanced ECMP • When ingress PE supports Large Flow Recognition, P node does not support • P node will not check the large flow indication and treat all packets as small flow packets • Enhanced ECMP can co-exist with existing ECMP • Some LSRs with enhanced ECMP and some with ECMP • What a great help in network migration! IETF77, Anaheim CA

  11. Applicability • A single large flow in PW • IP packets • LSP traffic with entropy label or application label • Transport over LAG • MS-PW IETF77, Anaheim CA

  12. Acknowledgement Authors like to thank Stewart Bryant, Frederic Jounay, Simon Delord, Raymond Key for their review and comments Next Step We like to hear people comments and advices in moving to next step IETF77, Anaheim CA

More Related