[Bloat] fremont flent node: what's the network setup there?

[Aaron Wood]

I'm comparing some numbers between the fremont node and a friend's Droplet
running netserver.

We've previous noted that we don't see more than a 120Mbps download rate
from the fremont node.

Today I was able to confirm in multiple back-to-back runs that the fremont
node was only giving me about 120Mbps of throughput, while both dslreports
and the droplet were giving me ~180Mbps (and 500ms of latency in the cable
head-end).

However, I noticed when running without SQM on my router here at home that
download latency from the fremont node was virtually non-existent, vs. the
very large latency that I was seeing from both the droplet and dsl-reports.

Box-plots:
https://drive.google.com/file/d/0B1xfqN4OiFEPODI4cEZjZ1NGeGVtc3RKbGJQR3ltaHhyb1Bz/view

That very, very low send latency from the fremont node makes me think that
it might be running BBR as the default congestion control algorithm?  If I
run the cubic-reno test without any SQM, the results look pretty awful, but
without specifying the TCP cc alg, it seems to behave very, very well
(albeit not as much throughput as I think I should get).

Re-enabling cake (at 170Mbps downstream, 12Mbps up), I can't seem to get
much more than that 120Mbps from the router (even though I've tested it at
900Mbps as the netserver host itself).  Am I running into a cpu limitation
in the NAT/forwarding modules?

-Aaron
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