Re: [Int-area] Discovering a Location Server in the Access Network

On Fri, 14 Sep 2007, Hannes Tschofenig wrote:
> In short, the current proposal (see 
> http://tools.ietf.org/html/draft-thomson-geopriv-lis-discovery-02.txt; 
> ignoring Section 2 which defines the DHCP portion) essentially does the 
> following:
>
> * Discover the public IP address of the end point
> * Perform a reverse DNS lookup to learn the domain
> * Lookup the LIS for that domain
> * Contact the LIS

2-3 years ago we had the similar problem with IPv6-in-IPv4 tunnel 
endpoint discovery, only that the endpoint could reside outside the 
L2/L3 network as well.  The approaches identified then were described 
at:

http://tools.ietf.org/html/draft-palet-v6ops-tun-auto-disc-03

Personally, I thought anycast made most sense.

Some other folks preferred reverse DNS population (e.g. [1]), but that 
also has problems with private address use of a more recent approach 
to try to push the NAT boxes to act as authoritative for private 
address spaces [2] in which case the ISP could not populate its DNS 
resolvers for private addresses either.

In your case where the L2/L3 provider is required to provide this 
information in order for the methodology could work, though personally 
I'm somewhat concerned about 1) how reliable the public IP address 
discovery could be, 2) what happens if the ISP doesn't provide reverse 
DNS entry for the public IP, and 3) whether the operator who's 
providing L3 service and public IP does in fact even know where the 
user is located (if the user's ADSL session is provided by a L2 
provider and just tunneled - in bulk - using L2TP to L3 provider).

The last issue is probably the biggest and you may need to consider in 
more detail how such "L2 different from L3" network would work. 
Realistically any solution I could think of that doesn't involve DHCP 
or PPP is likely to require coordination in this case.  Would it 
required that the local regular requires L3 provider to also keep 
track of the physical location?

[1] http://tools.ietf.org/html/draft-yamamoto-naptr-service-discovery-01 
[2] http://tools.ietf.org/html/draft-ietf-dnsop-default-local-zones-02

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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