perfsonar development work

[Nicolas Simar <>]

Hi Nina and Maciej,

Nina Jeliazkova wrote:
> Hi Nicolas,
>
>
> Nicolas Simar 
> <>
>  wrote:
>
>
> > > > > > Several groups of users have been complaining that there 
> > > > > > isn't any discovery of
> > > > > > MAs and they'd like to skip the pSUI
> > > > > > selection step.
> > > > > >      
> > >
> > > As a side note: the user can have all MA selected , psUI will find the 
> > > correct ones anyway.
> >
> > It is quite time consuming. People have been put off from pSUI because 
> > of that feature inter-acting with either too slow MAs or no MA. It was 
> > taking 4 minutes in some case.
>
>
> OK. We have yet to find out how time consuming will be the proposed gLS
> approach.

Could you please make a rough estimate of the time the process of using 
the gLS by a client would take to get the URL of the MA we are looking 
for (using the current time it takes to get some information from an 
LS). Please describe the different steps.

(e.g. (1) for a list of 12 IP addresses (a traceroute), getting the 
domain name from the DNS would take so much time (Nina can help to get 
those value if you can't find them). Then requesting the LS URL for the 
domain to the gLS would take so much time (estimate). The request to the 
LS would take so much time (from experience). So the total when 
searching for 12 IP addresses would take so much time.
(2) If now we are assuming that 50% of the domains from the 12 IP 
addresses addresses are not covered in the gLS - e.g. campuses, etc) how 
much time would it take?
(3) how is foreseen the handeling of an IP address of an access being 
part of a domain and being configured and monitored on a router from 
another domain? (e.g. dfn-gw.rt1.fra.de.geant2.net [62.40.124.34] is a 
GEANT IP addresses configured on a DFN router, and thus part of the DFN 
domain)

> > > The steps are more or less clear:
> > > - get domain name of the IP
> >
> > That's my main point of interrogation. How can it be done?
> > Whois to get the domain or AS name?
> > In that case, it is important that the deployer of the LS register the 
> > same name as the one used in the reference methodology to map IP 
> > addresses to domain name/AS name.
>
>
> This is what DNS is for :)  It is straightforward to query DNS by Java code
> and get IP - host name mapping.

OK, so domain name is the way to go forward.

>         InetAddress[] addrs = InetAddress.getAllByName ("62.40.125.66");
>         for ( int i=0; i<addrs.length; i++ )   {
>               System.out.println( "IP Address : " + addrs[i].getHostAddress()
> );
>               System.out.println( "hostname   : " + addrs[i].getHostName() );
>               System.out.println();
>            }
>
>
> and the output in this case will be
> IP Address : 62.40.125.66
> hostname   : istf2-gw.rt1.bud.hu.geant2.net
>
> From the host name the domain eventually should be  "rt1.bud.hu.geant2.net"
>
>
> Some time ago (for a different project) I've used DNSJava library
> (http://www.dnsjava.org/), which provides finer control, async calls, etc.
> Please note DNS queries can be time consuming as well.
>
>
> For autonomous system number I can indeed think only of whois, but why we
> would need AS -IP mapping instead of IP-name mapping ?

I think AS numbers are less needed as the domain name can easily be found.

Cheers,
Nicolas

> Best regards,
> Nina
>
>
> > Cheers,
> > Nicolas
> >
> >
> > > - send it to gLS
> > > - receive URL of LS
> > > -query LS for the IP
> > > -get MA URL
> > > -query MA as usual

--
Nicolas
______________________________________________________________________

Nicolas Simar
Network Engineer

DANTE - www.dante.net

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