[Cerowrt-devel] Bufferbloat at upcoming LUG talk

Michael Richardson mcr at sandelman.ca
Mon Nov 26 07:26:40 EST 2012

>>>>> "Richard" == Richard Brown <richard.e.brown at dartware.com> writes:
    Richard> - I can see how the CeroWrt de-bloating algorithms help
    Richard> protect against bad latency when I'm *uploading* big
    Richard> files. I'm not sure whether using CeroWrt with its
    Richard> CoDel/FQ/SFQ/etc. helps when I'm downloading big files,
    Richard> though. What can I say about this? 

If the link from the broadband to the laptop is wireless, than it's
quite possible that the wireless link experiences bufferbloat. 
This would be true:
     - if the laptop is far from the base station the rate could be
       lower than the broadband download link. (Especially now that
       cable offers 50Mb/s downlinks...)
     - if the wireless is bridged to wired, and there are many windows
       boxes, broadcasting a lot, then the wireless link may be
       otherwise saturated

bad uplink latency will affect TCP ACKs, and can totally ruin your
interactive ssh day too.

But, in general, either the ISP has to debloat too, or it has to rate
limit to below the actual bandwidth.

    Richard> - I believe the default DNS server in Sugarland is dnsmasq,
    Richard> not bind. Is DNSSEC enabled by default? Also: there's a
    Richard> report (Bug #411) that says that DNS is leaking internal
    Richard> names to the outside world. What's the best advice for
    Richard> closing this? ("list notinterface 'ge00'" is one
    Richard> recommendation…) 

(In general, leaking names is really not that much of a worry...)

    Richard> My plan is to give a little of the science behind
    Richard> bufferbloat mitigation and also put in a plug for
    Richard> CeroWrt. Any topics I haven't already mentioned that I
    Richard> should? Thanks! 

Use the fountain images that Van Jacobson used at IETF84.

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]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
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