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Certain routers can not be geolocated because they respond to only a few pings or don't respond to them at all. A script vtrace0chk.pl tries to geolocate such routers in the cache and updates the cache accordingly each night.

Both vtracefromchk.pl and vtrace0chk.pl are placed in /afs/slac/package/pinger/tulip/ and executed via trscrontab in pinger.slac.stanford.edu for user pinger.

Design

The tabular traceroute is shown together with the Autonomous System Number (ASN), if known, the router's location coordinates and distance between hops. Clicking on the IP address will take you to the TULIP geolocation utility. Clicking on the ASN will provide information on the ASN. 

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The England to Washington DC is interesting since VTrace, Maxmind and undns (orange line) give very different results for the target. Despite Sofia University advertising itself as being in Palo Alto the web server is actually near Washington DC. Also the route does not go from London to Paris as indicated by Maxmind.

Melbourne to French PolynesiaAustralia detailW Coast US detailundns and Vtrace agree
    
    

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Complementarity of VTrace and MaxMind

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Traceroute
Melbourne to French PolynesiaDetail for AustraliaDetail of VTrace & undns at MelbourneDetail of W. Coast USDetail showing VTrace & undns at SeattleMalaysia to French PolynesiaJapan to French Polynesia
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Maxmind gets the location of the host in French Polynesia. However the route in Australia and the US is badly off. Vtrace and undns agree for Australia and for hops in the US. VTrace does not work for French Polynesia since the underlying TULIP does not attempt to locate a host where the nearest Tier 0 landmark (SLAC) has > 60msec min_RTT. N.b. Australia's route to French Polynesia goes via the U.S. as does Malaysia's, and Japan's. The Japan traceoute is interesting in that undns shows the route as going via Chile. THis requires more investigation. The landmarks in China and Bolivia were unable to make traceroutes.

Miscellaneous

The traceroute from SLAC to UTM, Johor Bahru, Malaysia for MaxMind goes to central US, Japan, then via China and terminates in Sarawak. The VTrace goes from SLAC to Japan (undns confirms this), then to Kuala Lumpur Malaysia, then to Johor Bahru. It then takes an excursion to the Gulf of Thailand (hop 14) and appears to stop there (middle image below). On more detailed inspection (right hand image below), it is seen that it then returns to Johor Bahru and UTM (hops 15-16).

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