[Hidden-tech] Suggestions on debugging a DSL/ router issue

[David Korpiewski]

The thing that I'm not clear about that you should probably explain to 
us is what you have for a network setup.  You say that you replace the 
router, but a DSL system generally requires that you have a DSL modem 
and then that goes into the router and then the router goes into the 
network.  (DSL Modem <--> Router <--> Network)

Have you tried rebooting the DSL modem?  Does Verizon say anything about 
that being an issue?  If you are getting the same issue with 3 different 
routers, the issue isn't the routers, its something else.

Also too you have to properly set your VPI and VCI within the 
router/modem so that it can properly work on the network.  I set up a 
new Netgear DSL/router combo unit and without the VPI being set to 0 it 
was doing as you mentioned -- things just ground to a halt.

Furthermore, being a seasoned consultant, I have seen cases where the 
network switch was failing on a particular port and would do things 
similar to what you are seeing.  But this would be the more unusual 
situation.

Check your filters too to make sure none of them got unplugged.

Good luck
David




On 5/8/2010 7:50 AM, Cheryl Handsaker wrote:
>     ** Be sure to fill out the survey/skills inventory in the member's area.
>     ** If you did, we all thank you.
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> Hi all,
>
> I am looking for suggestions as to how I might go about debugging a
> puzzling network connectivity issue that began yesterday. Specifically:
>
> 1. Has anyone else experienced these kinds of problems with a similar
> Verizon DSL configuration?
>
> 2. Does anyone have suggestions about how to approach gathering
> additional information or solving the problem? Things to try or
> questions to ask?
>
> The details - and my apologies in advance for the length of this
> description.
>
> I am a Verizon DSL Business customer and have been since DSL became
> available here in Charlemont in 2004 or 2005 (and before you all dump on
> Verizon as an ISP, please know that it is the only game in town). We
> have a router connected to the DSL modem and have been using the same
> set up for years. While we've had intermittent problems before, most
> have been traced to the quality of the phone line and usually occur in
> the rain or snow. Yesterday was dry and sunny for the most part here. To
> their credit, when a Verizon technician actually comes on site, they
> have been very helpful and knowledgeable. Phone support has been
> sometimes excellent and sometimes dreadful.
>
> Beginning yesterday at about 7AM, we began to experience intermittent
> connectivity problems. We begin to notice a degredation in performance
> that gets steadily worse over a 10-15 minute period until the network
> becomes unusable. This appears to be caused by the network setup
> dropping packets - initially 10% packet loss, then 25%, then 50%. At
> about the 50% mark, we reboot the modem and/or the router and the
> network does not come back up and appears not to be able to sync for at
> least 15-20 minutes.
>
> Our initial call to Verizon indicated that our old but very reliable US
> Robotics router had failed. It appeared that all the packet loss was
> happening at the router.
>
> We happened to have another spare but old router in the closet (a
> Linksys, I think). We configured this and the network came up for a
> while and then connectivity died in the same way as before, with us
> showing packet loss at the router about 10AM.
>
> The Verizon phone support person, a good one, suggested maybe both these
> routers needed a firmware upgrade due to their age.
>
> We decided not to mess with that because the network eventually came
> back up (after a couple of reboots and about 20 minutes of attempting to
> sync).
>
> At 1:30, same pattern of network failure occurred again. Rather than
> upgrade the firmware in the older routers, we happened to have access to
> a brand new router that we had purchased for someone else in the fall
> that was not being used, this time a LinksKey. We replaced the router
> yet again.
>
> At about 7:15, the same pattern of failure occured with the new router.
> Verizon tech support, this time a dreadful rep, said she saw no problems
> on the line and that this third router must be bad. While on the phone,
> the sync completed and the network was again restored.
>
> Thanks for reading this all the way through :-). Any ideas?
>
> Thanks,
> Cheryl
>
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-- 
===========================================
David Korpiewski
Software Specialist I
CSCF - Computer Science Computing Facility
Department of Computer Science
Phone: 413-545-4319
Fax:   413-577-2285
===========================================