Re: [SLUG] DSL on different OSes

From: cpace@tampabay.rr.com
Date: Thu Jul 31 2003 - 16:33:29 EDT


I have a couple of points to add to this. I worked
for RR Tech Support for over a year and a half and
had to deal with multiple issues concerning this and
in some cases its something on the RR side, other
times it is not. Here are two things to note and it
should help in diagnosing the issue.

The cable modem actually requests for an IP from the
router and then marries the MAC address of the NIC
to the IP address that it is assigned. If you
decide to plug a different PC/device with a
different MAC address there is a highly probable
chance it will not work due to the IP address
already being assigned to the previous MAC. The
modem knows that you are only allowed to have X
number of IP addresses (where X is how many are
allowed according to the terms of your service) and
the modem will not give out anymore. There is also
a condition where the router still believes that the
modem is still using the IP address and that the
lease has not expired, therefore it will not issue
another one. This condition occurs on the network
and basically keeps you from receiving a new IP
until A) the lease expires (usually 24hr duration)
or B) the router forgets your modem exists.

If the IP is bound by MAC and you switch devices
just power down the modem for about 2 mins and bring
back up. This in effect should clear the modems
cache and allow the new device. If, on the other
hand, the router believes you have the IP then it
gets a little trickier. You will need to leave the
modem powered down for approximately 4hrs and then
power back up and should work correctly. The reason
for the 4hrs is due to the router flushing one of
its internal cache tables (this is what was told to
me by a router tech). The routers update modem
cache tables every 4 hours and if there is no
response from the modem it will forget it even
exists. When the modem is powered back on, the
router will believe it is a new device and reassign
all IP's. This is why when you leave your modem off
for over 4 hours your IP will sometimes change.

One more thing that I have verified both over the
phone and actually physically in front of the box is
Windows XP. There is a condition that exists where
WinXP absolutely refuses to pull an IP address. I
have encountered this on 4 different occasions and
verified that it is definately something within
WindowsXP. On 2 of the systems I booted to Knoppix
and pulled an IP all day long. On the phone with a
customer who told me I was lying I asked if he had
another system we could try and he said he had his
current system dual booted with XP and 2000. I had
him boot to 2000 and worked perfectly fine, booted
to XP and still refused to pull an IP so just be
aware that if they are on WinXP there is a
possibility they could be encountering this issue.
It will eventually pull an IP address which leads me
to wonder if this may have something to do with a
possible error in lease duration or something.
Since there is no access to their source code I
guess none of us will ever know.

I'm no expert on anything, these are just
observations and issues I and others have personally
experienced. Hope some of this helps.

Pace

----- Original Message -----
From: "Timothy L. Jones" <tim@timjones.com>
Date: Thursday, July 31, 2003 12:43 pm
Subject: Re: [SLUG] DSL on different OSes

> It is THEIR problem! I just saw these exact same symptoms on
> Monday on my
> sister-in-law's computer, but (get this) it was Road Runner that
> gave me this
> nonsense, not VZ.
>
> Let me explain - her MB and CPU got fried 2 months ago (on an
> Emachines
> T2460), and she has been fighting with Best Buy to get it fixed
> under
> warranty. Despite being a new machine, they just would not honor
> it. So she
> finally brought it to me. I put in the new MB and CPU, had to re-
> install XP
> (Microsoft didn't approve the install ID that was generated by the
> old
> installation on the new MB). I did all this at my house, meaning
> it grabbed
> a 10.0.0.x address from my firewall's DHCP server. I downloaded
> all the
> Win32 OSS goodies (Open Office, Mozilla, etc), tightened a few
> things (what
> little I know about Windoze anymore - I never use it myself
> anymore), and
> make a 10G Debian partition too (for my sanity). So, I sent it
> home to her,
> figuring she would just plug it in and it would "just work".
>
> But it didn't... I went to HER house, and looked around. The
> symptoms were
> the same under Linux and WinXP: packets were being sent and
> received by the
> network interface (an all-in-one MB), yet there were no
> DHCPOFFERS. There
> was about 200 unsolicited bytes/second being received, but I had
> not
> installed a packet sniffer, so I could not tell what these packets
> were. And
> of course, with the interface lacking an IP address, I could not
> download one
> either. So I give up, tell her it is RoadRunner network, and she
> calls them,
> and of course is told to reboot, reinstall, get rid of Linux, get
> a new
> ethernet card, all of which is totally BS.
>
> The next day, she called to tell me that her computer now had an
> IP address of
> 169.254.45.121, with the same 255.255.0.0 netmask. Knowing that
> IP addresses
> have to come from SOMEWHERE under DHCP, I knew for sure something
> was wrong
> with RR's network. I could not get over there on that day, so I
> didn't get
> to look at it any further.
>
> But the THIRD day, I hear a report from her that everything is
> WORKING...
> DHCP, DNS, fast downloads, all the Windoze virusware working. And
> I had not
> even been there, and no one else had been at her computer.
>
> The troubling thing for me, is that you said you're on VZ DSL.
> The problem I
> saw was on RoadRunner (Temple Terrace area).
>
> tlj
>
> El Mié 30 Jul 2003 09:50 PM, Russell Hires escribió:
> > Hello all...
> >
> > I'm having trouble w/ my Verizon DSL at the moment.
> Interestingly, when I
> > called tech support, they ultimately told me that I have a hardware
> > problem, probably w/ my ethernet card. Okay. I don't believe it,
> since I
> > can connect to my other Macs via this ethernet card while in the
> Mac OS,
> > although I can't connect via dhcp to the rest of the world. Part
> of the
> > troubleshooting relating to this included me going to my Mac OS
> TCP/IP> control panel, and looking at the IP info that it
> presents: IP, Subnet,
> > router. Since mine isn't working, I get an IP of 169.254.x.x.
> The subnet is
> > 255.255.0.0, and no router. They tell me that this is an
> indication that my
> > ethernet card is messed up.
> >
> > What has this to do with Linux? I figure that since I have more
> tools> available to me in Linux, I should be able to get this same
> information> (and more), in Linux, but I don't have a clue about
> how to go about it,
> > beyond the usual ifconfig command, and using a utility like pump.
> >
> > Anybody got any ideas?
> >
> > Russell
>
>
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