Tip of the Day: Let's Talk About LEDBAT

Today’s Tip… Let’s Talk About LEDBAT

You may have seen tips on this subject in the past, but let’s see where we are at today!

To Begin With, What is LEDBAT?

LEDBAT (Low Extra Delay Background Transfer) is a latency optimized, network congestion control provider. As a scavenger protocol, it is designed to automatically yield bandwidth to users and applications, while consuming any available bandwidth for background transfers when the network is not in use.

  • When increased latency is detected (indicating that other TCP connections are consuming bandwidth) it reduces its own consumption to prevent interference.
  • When latency decreases LEDBAT ramps up, consuming the unused bandwidth.

In other words, you can transfer SCCM Packages or Microsoft Updates without interfering with critical application traffic.

Things To Remember About LEDBAT

Use Cases

  • LEDBAT can be enabled on a SCCM distribution point running Windows Server 2019.
  • LEDBAT can be configured for WSUS servers using NetTransportFilters (see more below)
  • BITS is also using LEDBAT for background uploads.
  • Current Insider Preview builds have added support for use of LEDBAT by Delivery Optimization.

Configuration Notes

  • LEDBAT can optimize any TCP sender-side workload.  It is not limited to updates!
  • Congestion providers are configured per-flow:
    • LEDBAT provides congestion control for background traffic flows.
    • It does not compete with or replace congestion providers such as CUBIC, which are used for foreground traffic flows.
  • Configure LEDBAT using the Internet Custom template. Never enable LEDBAT using the DataCenter template.
  • LEDBAT has been backported to Windows Server 2016 (kb4132216,4284833)