Thanks, Ken. I had not realized that the cables and plugs were so common
that this could occur. Thanks for the education on the subject.
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Ken Norton" <ken@xxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Thursday, April 11, 2013 1:20 PM
Subject: Re: [OM] Question for Ken
>> Talking to the technician, I found that they believe someone hooked up a
>> set-top box to a router "backwards", sending a stray signal back to the
>> system. It interfered with customers on opposite sides of town. They
>> have not yet located the source, but took down a bunch of customers in
>> their efforts to track it down. I concluded that the reason I got quick
>> response to my call was that they suspected I might be at the source of
>> their problem. Once they found everything at my end in proper shape,
>> they went on their way.
>>
>> Have you ever encountered this sort of thing?
>
> This can happen if somebody attaches a router to the network with the
> routing tables screwed up (usually with an incorrect gateway setting)
> and the private side hooked up to the public side. This is much more
> common when the provider is using NAT (network address translation)
> which effectively gives you a private network hanging off of a private
> network with no true global IP address. I've seen it where the ISP
> provided addresses in the common 172.x.x.x pool which can provide
> confusion because those same address numbers are used on the private
> side of your router. If you have both sides set to the same network
> and you reverse the connections, ugly things can happen. To one extent
> or another, almost all ISPs have gone to NAT because of IPV6.
>
> However, this also points to a technical flaw in the implementation of
> the FTTH deployment there. In a traditional DSL deployment, we use a
> form of ATM technology (not the banking machines) that is what we call
> a "Layer-2" Technology, which keeps your Ethernet connection isolated
> from everybody else's all the way to the router. Each stream is
> terminated at a common point right where the brains are. Almost every
> other form of broadband to the home works in what I lovingly call
> "Layer 2.5" or even "Layer-3". In this environment, you are basically
> in a community-wide local-area-network. There are even deployments
> where you can actually see your neighbors' computers! not so much any
> more, but these types of networks still exist.
>
> As is usual, the technology itself is fine and 99.999% reliable.
> Unfortunately, all it takes is for the human element to bring
> everything crashing down. You saw it happen in your neighborhood. It
> happens with pretty high frequency on the NNI (network to network
> interface) level too. When that happens with incorrectly programmed
> border routers, it can affect hundreds of thousands of users or
> websites. It doesn't take much to bring an entire server farm down. My
> conservative guessimate is that we average every user or website
> around the world being affected by this up to four times a year. I
> subscribe to a couple monitoring services for Zone-10 and can see how
> often it is affected. You know it's this kind of error because one
> monitor will catch it, but another will be fine. Meanwhile, I've had
> people email me saying my website was down when I can get to it fine
> and so forth.
>
> After all these years, it's pretty easy to identify the problem and
> also pretty quick to isolate and repair it. When it happens on the NNI
> level, there are software tools that monitor for this and generally
> squelch it in a hurry. But when it happens within an ISP's own
> network, it can take a little while for all the routers to get their
> routing tables sorted back out again. The biggest impact is when DNS
> is messed up. Between routing tables and DNS databases, it can take 12
> hours to purge the misroutes out of the system.
>
> When all else fails, turn everything off and back on.
>
> --
> Ken Norton
> ken@xxxxxxxxxxx
> http://www.zone-10.com
> --
> _________________________________________________________________
> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
> Themed Olympus Photo Exhibition: http://www.tope.nl/
>
>
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|