LCA: Vint Cerf on re-engineering the Internet
Posted Jan 25, 2011 5:53 UTC (Tue) by gdt
Parent article: LCA: Vint Cerf on re-engineering the Internet
I stand by the recommendations in the leaflet I wrote.
A 16MB buffer size is appropriate for GbE users and the 0.2s of round-trip delay from the undersea network which attaches Australia to the west coast of the USA. As the leaflet explains, Australia is one of the few countries in the world where users face such a high RTT to their popular Internet resources and can afford such high bandwidth too. Given that odd situation, it isn't surprising that operating systems need some tuning.
When discussing buffer bloat you need to distinguish hosts and routers -- Jim Gettys' complaint was about excessive buffers in routers. The host needs a TCP buffer with a maximum size of the bandwidth-delay product in order to be able to fill the pipe. The routers along that pipe need nowhere near that, rather buffering appropriate for the bandwidth and delay of the next hop, and their buffer scheduling appears to be just as important to TCP throughput as the depth of the buffer. It's fair to say that the academic understanding of router buffering is much less clear than host buffering, and this makes definite recommendations of router buffer sizes difficult, which is one reason why router buffering was not mentioned at all in the leaflet.
On the plus side, I get to add "dissed by Vint Cerf" to my CV :-)
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