[Babel-users] RTT-aware branch of Babel

[Baptiste Jonglez]

On Thu, Jun 20, 2013 at 03:40:00PM -0700, Dave Taht wrote:
> So it sounds like distinguishing between gigE and 100Mbit won't happen
> with a floor like this until the 100Mbit link gets loaded. How
> unstable does it get with a rtt-min of 1 (or less) ? (100Mbit ethernet
> is common with POE, GigE is almost everywhere else)

This is certainly not a realistic way to distinguish between 100M and
1G links.

For a start, Babel packets are extremely small, let's say around 100
bytes.  The transmission time would be 8 μs at 100M, and less than 1
μs at 1G.  At this scale, the time spent in queues is all but
negligible, and even the physical propagation time can be in the same
order of magnitude.

Also, the size of a Babel message can range from about 20 bytes
(single Hello message) to something like 400 bytes (full route table
dump), which would add way too much noise.


While making this distinction would be interesting, our method is
well-suited for resolutions of about 1 ms (through averaging, the real
resolution for samples is 10 ms) to hundreds of ms.

Regards,
Baptiste
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