[73437] in North American Network Operators' Group
RE: The strangest cable modem issue
daemon@ATHENA.MIT.EDU (Samuel Petreski)
Mon Aug 23 12:26:22 2004
Reply-To: <petreski@ksu.edu>
From: "Samuel Petreski" <petreski@ksu.edu>
To: "'Drumm, Dan'" <ddrumm@ball.com>, <nanog@trapdoor.merit.edu>
Date: Mon, 23 Aug 2004 11:25:50 -0500
In-Reply-To: <7CC5B2627803D94CBA129798D3205DC60CD907@ballmsg01.cs.ball.com>
Errors-To: owner-nanog-outgoing@merit.edu
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I think your problem was as a result of what happened to Comcast yesterday
http://www.miami.com/mld/miamiherald/news/local/states/florida/counties/brow
ard_county/9457328.htm?1c
Was it only happening yesterday?
Coincidence???
--Samuel
_____
From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] On Behalf Of
Drumm, Dan
Sent: Monday, August 23, 2004 11:10 AM
To: nanog@trapdoor.merit.edu
Subject: The strangest cable modem issue
I thought I'd ask NANOG this, since somebody may be from a large cable
operator and may know. I am a Comcast customer and don't want to call this
in through tech support, as I've tried that before without any success.
I use my cable modem normally - to surf the web, to play a game or two, and
to listen to stream casts. I have a buddy who often needs tech support, so I
use RAdmin (http://www.famatech.com/radmin/) to login to his computer and go
through stuff with him. I use large TCP packets, small UDP packets - ICMP,
ESP - large and small.
RAdmin can transfer files from desktop to desktop. Ethereal reveals this is
a standard TCP based protocol used on the RAdmin port tcp/4899. If I want
him to have a file, I push it that way.
Last night - I decided to start IIS FTP server, and have him use his
SmartFTP (www.smartftp.com <http://www.smartftp.com/> ) client to pull
several larger files from me. I poked a hole in the Linksys router's port
forwarding for FTP and off we went. He grabs the first file, and it's going
along at roughly the correct uplink speed for Cable (20 KB/s or so) and all
is fine. Then, my cable modem reboots. Stops dead. All the lights go off and
start blinking, a full reload. It grabs the same IP address via DHCP and he
restarts. Again, about 15 seconds into the download, it crashes the cable
modem. We do this about 5 times to really make sure it's just FTP doing
this.
I have a DOCSIS 1.1 modem from RCA
(http://www.rca.com/product/viewdetail/0,2588,PI700502-CI700094,00.html?)
I have a Linksys BEFSR81
(http://www.linksys.com/products/product.asp?prid=155
<http://www.linksys.com/products/product.asp?prid=155&grid=5> &grid=5) with
the latest firmware
FTP is the only protocol that does this. Using RAdmin file transfer, I push
files to him over tcp/4899 and it doesn't happen.
The cable modem is somewhat old, perhaps it needs to be flashed with a newer
image, but I am not sure what could cause it.
Ideas?
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<p class=3DMsoNormal><font size=3D3 color=3Dblue face=3D"Times New =
Roman"><span
style=3D'font-size:12.0pt;color:blue'>I think your problem was as a =
result of
what happened to Comcast yesterday </span></font><font size=3D2 =
face=3D"Courier New"><span
style=3D'font-size:10.0pt;font-family:"Courier New"'><a
href=3D"http://www.miami.com/mld/miamiherald/news/local/states/florida/co=
unties/broward_county/9457328.htm?1c">http://www.miami.com/mld/miamiheral=
d/news/local/states/florida/counties/broward_county/9457328.htm?1c</a>
<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;
font-family:"Courier New"'>Was it only happening =
yesterday?<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;
font-family:"Courier New"'>Coincidence??? <o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></font></p>
<div>
<p class=3DMsoNormal><font size=3D2 face=3D"Courier New"><span =
style=3D'font-size:10.0pt;
font-family:"Courier New"'>--Samuel</span></font><font =
color=3Dblue><span
style=3D'color:blue'><o:p></o:p></span></font></p>
</div>
<div>
<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
size=3D3
face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>
<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>
</span></font></div>
<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'>
owner-nanog@merit.edu [mailto:owner-nanog@merit.edu] <b><span =
style=3D'font-weight:
bold'>On Behalf Of </span></b>Drumm, Dan<br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Monday, August 23, =
2004
11:10 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> =
nanog@trapdoor.merit.edu<br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> The strangest =
cable modem
issue</span></font><o:p></o:p></p>
</div>
<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I thought I’d ask NANOG this, since somebody =
may be
from a large cable operator and may know. I am a Comcast customer and
don’t want to call this in through tech support, as I’ve =
tried that
before without any success.<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I use my cable modem normally – to surf the =
web, to
play a game or two, and to listen to stream casts. I have a buddy who =
often
needs tech support, so I use RAdmin (<a =
href=3D"http://www.famatech.com/radmin/">http://www.famatech.com/radmin/<=
/a>)
to login to his computer and go through stuff with him. I use large TCP
packets, small UDP packets – ICMP, ESP – large and =
small.<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>RAdmin can transfer files from desktop to desktop. =
Ethereal
reveals this is a standard TCP based protocol used on the RAdmin port =
tcp/4899.
If I want him to have a file, I push it that way. =
<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Last night – I decided to start IIS FTP server, =
and
have him use his SmartFTP (<a =
href=3D"http://www.smartftp.com/">www.smartftp.com</a>)
client to pull several larger files from me. I poked a hole in the =
Linksys
router’s port forwarding for FTP and off we went. He grabs the =
first
file, and it’s going along at roughly the correct uplink speed for =
Cable
(20 KB/s or so) and all is fine. Then, my cable modem reboots. Stops =
dead. All
the lights go off and start blinking, a full reload. It grabs the same =
IP
address via DHCP and he restarts. Again, about 15 seconds into the =
download, it
crashes the cable modem. We do this about 5 times to really make sure
it’s just FTP doing this.<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I have a DOCSIS 1.1 modem from RCA (<a
href=3D"http://www.rca.com/product/viewdetail/0,2588,PI700502-CI700094,00=
.html">http://www.rca.com/product/viewdetail/0,2588,PI700502-CI700094,00.=
html</a>?)<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>I have a Linksys BEFSR81 (<a
href=3D"http://www.linksys.com/products/product.asp?prid=3D155&grid=3D=
5">http://www.linksys.com/products/product.asp?prid=3D155&grid=3D5</a=
>)
with the latest firmware<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>FTP is the only protocol that does this. Using RAdmin =
file
transfer, I push files to him over tcp/4899 and it doesn’t happen. =
<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>The cable modem is somewhat old, perhaps it needs to =
be
flashed with a newer image, but I am not sure what could cause it. =
<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'>Ideas?<o:p></o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
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