[73436] in North American Network Operators' Group
The strangest cable modem issue
daemon@ATHENA.MIT.EDU (Drumm, Dan)
Mon Aug 23 12:10:55 2004
Date: Mon, 23 Aug 2004 10:09:43 -0600
From: "Drumm, Dan" <ddrumm@ball.com>
To: <nanog@trapdoor.merit.edu>
Errors-To: owner-nanog-outgoing@merit.edu
This is a multi-part message in MIME format.
------_=_NextPart_001_01C4892B.99E15FD6
Content-Type: text/plain;
charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
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.
=20
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.
=20
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.=20
=20
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.
=20
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=3D155&grid=3D5) with =
the
latest firmware
=20
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. =20
=20
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.=20
=20
Ideas?
=20
=20
------_=_NextPart_001_01C4892B.99E15FD6
Content-Type: text/html;
charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
<html xmlns:o=3D"urn:schemas-microsoft-com:office:office" =
xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
xmlns=3D"http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=3DContent-Type content=3D"text/html; =
charset=3Dus-ascii">
<meta name=3DGenerator content=3D"Microsoft Word 11 (filtered medium)">
<style>
<!--
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:#606420;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:Arial;
color:windowtext;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.25in 1.0in 1.25in;}
div.Section1
{page:Section1;}
-->
</style>
</head>
<body lang=3DEN-US link=3Dblue vlink=3D"#606420">
<div class=3DSection1>
<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>
</div>
</body>
</html>
------_=_NextPart_001_01C4892B.99E15FD6--
