[nSLUG] Keep loosing internet connection

Rich budman85 at eastlink.ca
Thu Feb 9 10:40:33 AST 2006

On Thu, 2006-02-09 at 08:57 -0400, J. Paul Bissonnette wrote:
> Rich wrote:
> >On Wed, 2006-02-08 at 18:43 -0400, J. Paul Bissonnette wrote:
> >  
> >
> >>I have a "Devolo Microlink Lan Router" connected to Eastlinks cable modem. I
> >>have been loosing the internet connection more often than I think is 
> >>warranted, some days
> >>like 2 - 3 times, then maybe not for a day or so. . Eastlink claims that 
> >>their cable modem tests good and
> >>that the problem probably is with my router.
> >>
> >>Is there anyway of testing this?
> >>
> >>    
> >>
> >
> >
> >It could be a couple of things:
> >
> >Need to isolate if its internal or external.
> >
> >Are any other internal machines dropping
> >     check your logs on the machine, how old is the nic driver
> >     sometimes there are bugs that get fixed, auto negotation was
> >     a nightmare on the intel cards at work, but a new driver fixed it.
> >  
> >
> No the switch side of the router has never failed
> >Does the cable modem reset, does the connect light reset
> >     try swapping wires, is the cable connection good at that location
> >     how much excess coaxial do you have from the modem to the wall
> >     try not to coil more than once or twice, after that it becomes  
> >     an antennae. 
> >  
> >
> some time when I loose connection I can reset the cable modem from 
> Mozilla, other times it is not visible, other time I have to physically 
> unplug both router and modem

This may indicate the router is getting hit with a lot of broken
packets.  If you can setup a listening device like a sniffer, or a pc
that can monitor packets coming from the modem to the router, that may

Do you have your router set to renew its DHCP address or is set to never

I agree with Bill in another post, check for firmware updates.
Also, how long between resets, it may be the arp table filling up.

> >If you are the only PC on the LAN, use your PC to connect to the modem.
> >You will need to match the MAC address of the router unless you used the
> >MAC from your PC on the router.  This is so you can connect to Eastlink.
> >
> >  
> >
> there are others, printer, VOIP.
> >Do you have access to a sniffer or the ethereal app in linux?
> >There are other tools like tcpdump and sniffit.
> >  
> >
> As long as the connection is active, I don't think it has ever been 
> dropped. I ran mtr for a few hours, 100%

You need to see packet traffic to see if that is the cause.
I've seen a lot of denials on my connection, so its probably not
uncommon to get dropped.  From what I can remember the repeaters the
cable companies use share the bandwidth for all connections, if there is
a user that gets hammered, that repeater will get saturated causing
other ports to drop or timeout - sort of like a shared hub compared to a
switched hub.  The problem may not even be yours, it may be someone who
shares your repeater.

> >Need to see if you are getting hit with packets storms, or DOS attacks.
> >Or worse yet, your IP was used for someone else causing duplicate
> >connections.  Seen it before.. 

When you connect to the modem, you initially gave them your MAC address
from one PC or the router, then then enter that into their DHCP table as
a reserved connection and it gets an IP assigned.  Problem is, the
addresses are prone to typing errors by their staff.  You may have a
good connection for a year, then one day, erratic behavior, drops, weird
stuff, timeouts, then you are okay for a while, then it occurs again.
This usually turns out that there was a typo in the entry table causing
two machines trying to share the same IP. 

If all else fails, I would call Eastlink to have them recycle your IP,
tell them you are seeing random drops and suspect a duplicate IP.  They
will check it.  It happened to me a few months back, new staff equals
new errors. :)


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