nanog mailing list archives

Re: Is there a method or tool(s) to prove network outages?


From: Warren Bailey <wbailey () satelliteintelligencegroup com>
Date: Mon, 2 Dec 2013 03:09:13 +0000

Keep in mind that inter web traffic has nothing to do with the overall
health of the radio link. In RF land, we really don¹t care what is going
over that link - just that we have enough RSL hitting the receiver to be
above threshold thus allowing the box to demodulate that signal. If your
radio is sitting at a threshold RSL of -108 and you¹re coming in at -105,
big trouble in little China (3dB fade murdered your link). Stop thinking
like a network engineer.. If your DS-1 was taking hits, an ICMP request
(or lack thereof) would mean little (read: zero) to me as an RF Engineer.
I want to see the BER/PER of the circuit over time so I can correlate
possible trouble with real world issues.

With that being said.. the tidal issue comes up a lot, and more times than
not I see someone who said ³Point that dish over there² and when it
magically works they have earned the title of ³Best RF Engineer in
History² until the tide rolls in and their link suddenly has ³issues². The
invention of cheap wireless has caused many people to believe they have in
depth wireless experience, and that is usually not the case.

Not trying to preach, but I¹ve spent a *TON* of time and other people¹s
money in multi path land.. If someone was responsible for the proper
design of the link multi path would not be a factor as it would be
addressed early on in the link. You are not going to gain much traction
with a wireless company when you call and tell them your pings aren¹t
working.. They are kind of like parents.. They just don¹t understand. ;)

//warren
Ps - I welcome any replies on or off list.. I know how frustrating it can
be to have a link that seems to work well until you look at it, so I
probably have a bit more compassion than others when talking about broken
Microwave/Satellite hops.

On 12/1/13, 5:40 PM, "Dobbins, Roland" <rdobbins () arbor net> wrote:


On Dec 2, 2013, at 6:26 AM, Warren Bailey
<wbailey () satelliteintelligencegroup com> wrote:

I would hold off on considering Multipath as a problem until you see
the RSL. 

Concur. It could also be related to precipitation or other adverse
conditions.

Or, in fact, it could be related to the 'UTM' box and/or something else
on the endpoint network.  It could be a periodic DDoS attack, or traffic
causing an availability hit as an unintended consequence.

It's difficult to say without data.  Since the OP has the ability to
gather IP-level data on his own network, he should utilize whatever
instrumentation and telemetry he can set up in order to diagnose the
issue as accurately as possible.

And the OP should dig out his SLA and see what it says about the
obligations of his upstream.

-----------------------------------------------------------------------
Roland Dobbins <rdobbins () arbor net> // <http://www.arbornetworks.com>

        Luck is the residue of opportunity and design.

                     -- John Milton





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