Subject: Re: [alto] [dnsext] RFC 3484 section 6 rule 9 causing more operational problems

From: Nicholas Weaver <[email-masked]>
Date: Wed, 4 Mar 2009 08:31:04 -0800

I've added the ALTO mailing list to this discussion:

What it comes down to is you want "localization", not RFC 3484.

On Mar 4, 2009, at 8:05 AM, Ondřej Surý wrote:

>
>
> On Wed, Mar 4, 2009 at 4:17 PM, Paul Vixie <[email-masked]> wrote:
>> dns-based load balancing is an unfortunate overloading and
>> should never be done.
>
> Here I agree.

>
>> RFC 3484 is correct as it is.
>
> Here I don't. The idea behind is good, the implementation is not.
> Client would have to know BGP path to DA + DB and decide on
> basis of routing protocol. Selection based on longest matching
> prefix will work in only very small percent of case, all other cases
> are based on pure luck.

If a localization service is available, querying it to get the "Best  
match" would be most appropriate.  the ALTO group in the IETF is  
looking at such issues, primarily with respect to P2P, but elsewhere  
as well [1].

In the absence of localization, probably the best is "If prefix is  
almost identical, use it, otherwise select random", because address is  
almost irelevent for localization beyond the current network these  
days, but having the standard specify "select randomly" has some  
general benefits when localization is not available.

[1] In retrospect, I take back my comment about "should focus on P2P",  
localization may very well indeed be a more generic primitive.