I like your solution but given that base is deployable without this, I wonder 
if you could just write this up in a separate draft that was an extension to 
base?


On Sep 20, 2012, at 10:29 , Marc Petit-Huguenin <[email protected]> wrote:

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> In Vancouver we decided[1] to remove the support for
> multicast/anycast/broadcast in the RELOAD spec, following a discussion back in
> Taipei about problems for supporting anycast.
> 
> I thought a bit more about the anycast problem, and I found a solution to this
> problem that is simple and so that would permit to keep the text in -base.
> 
> To summarize the problem, a bootstrap node cannot be directly running on an
> anycast address because the real destination can change at any time, and that
> would break DTLS.  That can be solved by adding the IP address of a bootstrap
> node not running on the anycast address in the PingResponse, but unfortunately
> this is not a compatible change.  There is other problems with this approach,
> related to the fact that the Ping must be sent without DTLS (naked Ping).
> 
> But, as per -base section 6.5.1.4, all RELOAD nodes are also STUN servers, so
> the naked Ping can be replaced by a STUN connectivity check.  The nice thing
> about STUN is that the support for anycast is already there, as a STUN server
> running on an anycast address will respond with a 300 Try Alternate with an
> ALTERNATE-SERVER attribute containing the IP address of the non-anycast node.
> 
> So the whole problem can be solved by just saying in -base that any connection
> to the bootstrap servers must start with a STUN connectivity check.  The first
> IP address to successfully respond (i.e. after processing the 300), is the one
> where the DTLS/TLS connection must be established to start sending the RELOAD
> messages.
> 
> 
> 
> [1] https://www.ietf.org/proceedings/84/minutes/minutes-84-p2psip
> [2] https://www.ietf.org/proceedings/82/minutes/minutes-82-p2psip
> 
> - -- 
> Marc Petit-Huguenin
> Email: [email protected]
> Blog: http://blog.marc.petit-huguenin.org
> Profile: http://www.linkedin.com/in/petithug
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