Internet dies if GPS dies?

[Tyler Durden]

Variola wrote...

"[If GPS dies] "Internet activity would slow to a crawl, because many
  backbone operators rely on precise GPS time stamps to route data. "
http://www.wired.com/wired/archive/11.05/start.html?pg=6

Sounds like bullshit to me, data clocks should be able to run without
being fully synched externally, constantly.
Maybe very occasional minor glitches at boundaries of clock domains.

Any SONET Gurus wanna comment?"

Sure, but I don't know enough about IP to tell you.

SONET networks derive their timing from a STRATUM1 clock, which used to be 
Cesium but which are increasingly GPS-based.
If the STRATUM1 clock "dies", the network can look for another high-quality 
clock. If it doesn't find one, each NE will go into hold-over, and time of 
of the internal STRATUM (likely 2e) clock until a good clock reappears.

But the time stamps for SONET clocks are in the DS1 overhead, so the packets 
in the (other) DS1s/DS3s, etc...never "see" that timestamp, unless that 
timestamp is somehow read by a router and then put into the packets. But 
does a router  even GET timing? (ie, is there a BITS interface on a router? 
I don't think so.)

In any event, if the router gets its timing from the SONET network then 
there's no problem. If they don't get their timing from SONET, I doubt they 
get it directly from a GPS.

So it sounds like bullshit to me.

-TD

>From: "Major Variola (ret)" <mv at cdc.gov>
>To: "cypherpunks at lne.com" <cypherpunks at lne.com>
>Subject: Internet dies if GPS dies? Date: Sun, 20 Apr 2003 21:35:43 -0700
>
>[If GPS dies] "Internet activity would slow to a crawl, because many
>   backbone operators rely on precise GPS time stamps to route data. "
>http://www.wired.com/wired/archive/11.05/start.html?pg=6
>
>Sounds like bullshit to me, data clocks should be able to run without
>being fully synched externally, constantly.
>Maybe very occasional minor glitches at boundaries of clock domains.
>
>Any SONET Gurus wanna comment?
>
>[The article is full of hysterics like this.  What it *doesn't* say
>is that the rockets have been used to launch OsamaSat, HusseinSat,
>etc., none of which exist of course, no such hardware here]
>
>---
>Number theory makes my brain hurt.


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