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There are two significant type of maintenance issues when we talk about TULIP. The problems we need to address are location change of landmarks and their uptime. The problem with the landmarks being available is discussed in landmarks laundering which is child to TULIP analysis page. The other significant problem is the location update of landmarks. We are getting the location of Planet Lab landmarks using the geoiptool, PingER landmark locations are provided by the site hosts and are manually added to Node Detail database.  We intend to run a nightly cron job to check if there is any host which has changed its position. The script is currently deployed at

 /afs/slac/package/pinger/tulip/maintainPL.pl

We have also discovered problems with geoiptool in some of the hosts. One of the challenging problems were two hosts(planetlab1.pop-mg.rnp.br,planetlab2.pop-rs.rnp.br) in Brazil . We did a ping between the host and got a response of 25~30 ms. Geoip tool showed that the hosts are at the same location which is about the center of brazil. We then inquired further and found the case interesting as the traceroute to both of them was going through different routes i.e. traversing different routers to reach the destination.After confirming the actual latititde and longitude from thier websites we updated the database manually. To cater for the problems like these the hash named errltln(Error in lat/long in geoiptool) contains the host which are not updated in the database with this script. The sample code is given below

#Error in lat/long in geoiptool
 my %errltln = (
 'planet01.hhi.fraunhofer.de' => '1',
 'planet02.hhi.fraunhofer.de' => '1',
 'planet-lab1.ufabc.edu.br' => '1',
 'cs-planetlab3.cs.surrey.sfu.ca' => '1',
 'planetlab1.pop-mg.rnp.br' => '1',
 'planetlab2.pop-rs.rnp.br' => '1',
 'csplanet02.cs-ncl.net' => '1'
 );

How to Find Latitude and Longitude of a Node Manually

Most of the Tulip landmarks are actually also PingER monitoring hosts. Almost every PingER Host in the NODEDETAIL database has very useful information e.g. Node Name, URL, Full Name of the node etc. If you have to find the Geographic coordinates manually then this information proves to be very useful. You have to follow the following steps to find Latitudes and Longitudes using Google Map or the following link: www.satsig.net/maps/lat-long-finder.htm 

  1. Find the host's site:
    1. You may have visted the site and be able to identify it on a map.
    2. or copy the URL from the NODEDETAILS database, paste it in your web browser. Go to the landmark's site and look for the site's address (steet address, city etc.). You may find this under 'Contact us' link or see the bottom of the page to find the site's address.
    3. or suppose you do not have a URL then use Node Name/Full Name from NODEDETAIL database to find some web site for that landmark's site. If you find the web site, then do same as explained in Step b.
    4. if there is no web site listed for that node then Use City information to go to that city. Use Zoom facility to make a rough guess of the coordinates again using google map or link. Somtimes the lat-long-finder will recognize the site's official name and point you to it.
    5. If you do not find an entry in the NODEDETAILS database for the desired node, then use the Name of the node to find the full name or City of the node using Google help.
  2. Once you have the location information (e.g. street address), find its coordinates on Google map or through link (Given above).
  3. On the other hand if you have a contact at the landmark's site or there is a contact entry in the NODEDETAILS database, you can contact (e.g. by email) the Contact Person of the host by email to request the Latitude and Longitude.

Results

We have applied this method to find latitude and longitude of the PingER type landmarks. We used the manual method to find coordinates of 14 PingER nodes successfully. e.g. dnsstat.polyn.kiae.su, this node is in Russia. This was because we could not find any contact person in our database for these nodes. Similarly we had sent the mails to the contact persons of other PingER nodes and we have got 60% response (24 Nodes) with server coordinates. This is the most accurate way to find geographical coordinates.

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