Symptoms of bufferbloat-induced congestion

Once a network is congested, various service protocols (statistically insignificant in terms of additional network load, but mission-critical) can’t do their jobs. Here are some examples

  • DNS - adding hundreds of ms of latencies to turning a website into an IP address is not good. With a typical web page doing dozens, even hundreds of DNS lookups, DNS not getting through in a timely fashion results in vastly slower browsing.
  • NTP - the network time protocol - relies on somewhat timely delivery of packets in order to keep your computer’s clock accurate. Lots of things rely on accurate timekeeping.
  • ARP - the address resolution protocol - also relies on timely resolution in order to even find other devices on your network.
  • DHCP - if these packets are lost or excessively delayed, machines can’t get on the network in the first place.
  • Routing - many routing protocols depend on packet drops as a way of monitoring network health and are time sensitive.
  • VOIP - needs about a single packet per 10ms flow in order to be good, and less than 30ms jitter.
  • Gamers will get fragged a lot more often with latencies above their twitch factor.
  • IPv6 relies on even more specialized packet types for autoconfiguration, e.g. the equivalent of ARP
  • Encapsulated packets (VPNs, X11 over ssh, IPv6 over 6rd/6to4) also suffer.
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