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

[Robert Heller]

At Sat, 8 May 2010 04:50:34 -0700 (PDT) Cheryl Handsaker <charlemontwebworks at yahoo.com> wrote:

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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.
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> 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.

Three (different) equally bad routers?  ALL having *exactly* the same
failure pattern?  Hmmm...  This is *probably* not likely (possible,
just not probable).  Even if all three routers were bad, I'd expect
them to have *different* failure patterns, between being different
makes, vintages, etc.  ALL of them failing in exactly the same way
makes no sense. I would check the wires (Ethernet cables, etc.).  Since
the failure mode seems the same, it is more likely to be caused by
something common in your setup: the phone line (despite what Verizon's
support person is saying), the drop cable and anything on it (like
maybe the lighting arrester or voice tap filter thingy, if you have
such a thing and any voice phone wiring, etc. -- maybe some mice have
been chewing on the wire(s) someplace?), the DSL modem itself (how old is
it?), and the cable between the DSL modem and the router.

Oh, are these routers wireless or wired?  Is the problem with wired or
wireless connections?  Both? If wireless, it could be something stupid
like radio interference (did a neighbor fire up his/her wireless
router? -- that could do it also).

Another random thought: it is *possible* you have an infected computer
on your LAN that is shoving lots of traffic though the router(s) and
causing the router(s) to become overwhelmed with the traffic.  If you
have a wireless connection, someone *outside your organization* could
be either leaching your service (and overwhelming your LAN with
traffic) or just massively 'pinging' the router.

> 
> Thanks for reading this all the way through :-). Any ideas?
> 
> Thanks,
> Cheryl 

-- 
Robert Heller             -- 978-544-6933
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