[nzlug] Broadband bandwidth drop: WTF?

[Simon Bridge]

On Mon, 2008-01-21 at 19:59 +1300, Daniel Mason wrote:
> I have a feeling it is, As ISP's advertise kBytes and mBytes. While your
> downloads will show kbits and mbits.

Or, possibly, the other way around :) (mBytes I have seen, technically
this means "milli-bytes", but I have seen that notation.) It can get
confusing as the b and B seem to get used interchangeably in consumer
documentation as well as ISP advertising.

This is actually the reason I left it for so long. Reason I wanted to do
a check now was that I just got off the phone from ihug, other problem,
and in the course of troubleshooting I happened to montion my data rate.
The guy was shocked and insisted I should show a higher rate. I *was*
saying "kilo*bytes* and so was he... of course, I cannot rule out
contributary confusion at the other end :/

Lets see.. modem reports:
[thingy: downstream upstream units]
SNR Margin: 11.5 24.0 dB
Line Attenuation: 51.0 31.5 dB
Loss of Signal: 0 0
CRC Errors: 166 60
Data Rate: 2112 160 Kbps
Latency: Interleaved Interleaved

Note: non-SI notation
OK 2112kbps/8 = 264kBps

Test: It has been suggested that I ping the nameserver...

$ ping ns1.ihug.net.nz
PING ns1.ihug.net.nz (203.109.252.7) 56(84) bytes of data.
[snip]
8 packets transmitted, 8 received, 0% packet loss, time 6998ms
rtt min/avg/max/mdev = 54.393/58.276/62.228/2.249 ms

Anyway, 64 byte packets came back (58 \pm 2)ms later so the round trip
data rate is 64000/58 Bps or 110.34 \pm 0.03 Bps.

However, the upload speed is much slower than the download speed. With
the above figures as a guide, upload occupies 2112/2272 of the time, or
56 \pm 2 ms ... so *download* rate comes to 32kBps.

*** Though I imagine the idea was to use ping to check the possibility
of packet loss :) these times must include some processing.

How about ftp download of FreeBSD 6.2 from ftp.nz.freebsd.org

168-206kBps (says fireFTP).

sudo apt-get upgrade says 220-228kBps ... this is just not my night for
demonstrating low speeds.

This is pretty consistent with the "different units" hypothesis.
Similarly, that 7kBps is correct then for a 56k modem. (I think I still
have a box for a modem that says 56KBPS - all caps - nice and
ambiguous.)

My low rate then gets even odder... 
Advertised at 64kbps ... I get a consistent 11kBps, which translates to
88kbps. Perhaps I'd better not tell them?

So I will put this down to confusion.

Reminds me of an ad on Waiheke that offered compost for sale at $30 per
cm^3 ...

Now, with my reputation burrowing eagerly into the sea floor, I go to
bed.