NNSquad - Network Neutrality Squad
[ NNSquad ] Re: How do I detect connection disruption by my IAP?
People who want to monitor cable modem networks with Wireshark or
similar Ethernet capture tools should be aware of the limitations. On
cable modem networks, upstream and downstream use different RF channels,
and the cable modem itself is not capable of receiving upstream data.
Hence, the only data you will see on the Ethernet side of a cable modem
is downstream traffic and the immediate client's attempted upstream
traffic (which may or may not be transmitted on the cable modem
network.) Hence, it's impossible to say with certainty how busy the
upstream side is at any given time. This means, for example, that any
claims about the load on the Comcast network's upstream side during
periods of upstream traffic shaping are total speculation. Of course,
you can guess about the upstream traffic based on the number of ACKs you
see on the downstream side, but dropped packets are hard to detect.
There are ways to monitor the upstream side of a cable modem on the RF
side, of course, but they require specialized equipment.
RB
Fred Reimer wrote:
> You can download WireShark at www.wireshare.org for a packet
> capture and analysis program. You'd need to know a bit about
> TCP/IP in order to make good use of it, but you can search for
> TCP packets with the RST bit set. That would be a "forced"
> close. You CAN get them from some valid destinations, but they
> should be rare, and should only happen at the end of a connection
> anyway. A normal closure would be the use of the FIN flags.
>
> Fred Reimer, CISSP, CCNP, CQS-VPN, CQS-ISS
> Senior Network Engineer
> Coleman Technologies, Inc.
> 954-298-1697
>
>
>
>
> -----Original Message-----
> From: nnsquad-bounces+freimer=ctiusa.com@nnsquad.org
> [mailto:nnsquad-bounces+freimer=ctiusa.com@nnsquad.org] On Behalf
> Of B.J. Herbison (Mailing lists)
> Sent: Thursday, November 08, 2007 10:08 AM
> To: nnsquad@nnsquad.org
> Subject: [ NNSquad ] How do I detect connection disruption by my
> IAP?
>
> I have Comcast as my Internet access provider. I've been sending
> large messages regularly via Gmail (almost daily for a couple of
> years). I sent a message without problem Monday through
> Wednesday.
>
> This morning I tried to send a message and it failed five times.
> The attachment is large, but a little smaller than yesterday.
> The error was:
>
> Oops... a server error occurred and your email was not sent.
> (#001)
> (Similar error if I try to "save" the message.)
>
> The five send failures and save failure were with Firefox, my
> standard browser. Then I tried from IE and the message was sent.
> Then it failed again from Firefox. (Chance? Coincidence?
> Time-outs somewhere? I'd love to construct a formal experiment
> with multiple computers, different browsers and add-ons, and
> stop-watch controlled timing intervals. Unfortunately, I have a
> life.)
>
> How can I tell whether there is a problem with Google today, some
> issue "out on the Internet", a Firefox problem, or whether
> Comcast is messing with my connections?
>
> Are there any Windows XP tools to monitor my connections (either
> inside or out of Firefox) to see if there was a forced close?
>
>
> Thanks,
> B.J.
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> NNSquad mailing list information:
> http://lists.nnsquad.org/mailman/listinfo/nnsquad
--
Richard Bennett
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People who want to monitor cable modem networks with Wireshark or
similar Ethernet capture tools should be aware of the limitations. On
cable modem networks, upstream and downstream use different RF
channels, and the cable modem itself is not capable of receiving
upstream data. Hence, the only data you will see on the Ethernet side
of a cable modem is downstream traffic and the immediate client's
attempted upstream traffic (which may or may not be transmitted on the
cable modem network.) Hence, it's impossible to say with certainty how
busy the upstream side is at any given time. This means, for example,
that any claims about the load on the Comcast network's upstream side
during periods of upstream traffic shaping are total speculation. Of
course, you can guess about the upstream traffic based on the number of
ACKs you see on the downstream side, but dropped packets are hard to
detect.<br>
<br>
There are ways to monitor the upstream side of a cable modem on the RF
side, of course, but they require specialized equipment.<br>
<br>
RB<br>
<br>
Fred Reimer wrote:
<blockquote
cite="mid98B7739FB65BF04F9B3233AB842EEC950143E72E@EXCHANGE.ctiusa.com"
type="cite">
<pre wrap="">You can download WireShark at <a class="moz-txt-link-abbreviated" href="http://www.wireshare.org";>www.wireshare.org</a> for a packet
capture and analysis program. You'd need to know a bit about
TCP/IP in order to make good use of it, but you can search for
TCP packets with the RST bit set. That would be a "forced"
close. You CAN get them from some valid destinations, but they
should be rare, and should only happen at the end of a connection
anyway. A normal closure would be the use of the FIN flags.
Fred Reimer, CISSP, CCNP, CQS-VPN, CQS-ISS
Senior Network Engineer
Coleman Technologies, Inc.
954-298-1697
-----Original Message-----
From: <a class="moz-txt-link-abbreviated" href="mailto:nnsquad-bounces+freimer=ctiusa.com@nnsquad.org";>nnsquad-bounces+freimer=ctiusa.com@nnsquad.org</a>
[<a class="moz-txt-link-freetext" href="mailto:nnsquad-bounces+freimer=ctiusa.com@nnsquad.org";>mailto:nnsquad-bounces+freimer=ctiusa.com@nnsquad.org</a>] On Behalf
Of B.J. Herbison (Mailing lists)
Sent: Thursday, November 08, 2007 10:08 AM
To: <a class="moz-txt-link-abbreviated" href="mailto:nnsquad@nnsquad.org";>nnsquad@nnsquad.org</a>
Subject: [ NNSquad ] How do I detect connection disruption by my
IAP?
I have Comcast as my Internet access provider. I've been sending
large messages regularly via Gmail (almost daily for a couple of
years). I sent a message without problem Monday through
Wednesday.
This morning I tried to send a message and it failed five times.
The attachment is large, but a little smaller than yesterday.
The error was:
Oops... a server error occurred and your email was not sent.
(#001)
(Similar error if I try to "save" the message.)
The five send failures and save failure were with Firefox, my
standard browser. Then I tried from IE and the message was sent.
Then it failed again from Firefox. (Chance? Coincidence?
Time-outs somewhere? I'd love to construct a formal experiment
with multiple computers, different browsers and add-ons, and
stop-watch controlled timing intervals. Unfortunately, I have a
life.)
How can I tell whether there is a problem with Google today, some
issue "out on the Internet", a Firefox problem, or whether
Comcast is messing with my connections?
Are there any Windows XP tools to monitor my connections (either
inside or out of Firefox) to see if there was a forced close?
Thanks,
B.J.
</pre>
<pre wrap="">
<hr size="4" width="90%">
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</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Richard Bennett
</pre>
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