Subject: RE: Proposed IPv6 DNS Discovery Requirements

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Mon, 29 Apr 2002 18:53:00 +0200

> Server location via anycast means that one is using the 
  > routing system
  > to keep track of the location of the DNS server.  That is, the
  > location of the DNS server is (somehow) injected into the routing
  > system, and the routing system is now responsible for 
  > handing out that
  > information to any client that wants to know.  If the server goes
  > down, moves, whatever, the DNS server becomes unreachable until the
  > routing system converges on a new useful answer,

=> Correct. This is the case for all traffic going 
through a certain 'path' in a network.

 and how 
  > exactly does
  > the routing system know that the DNS server is gone, 
  > anyway?  Does the
  > DNS server now have to speak OSPFv3, or is there some human 
  > sitting at
  > a 24x7 desk somewhere waiting to push a button on failure, or what?

=> There were several mechanisms shown in the analysis
draft to allow this to happen without a human
monitoring the wire.

1. The DNS can inject a route. Do you see problems
   with this?

2. Using Neighbour discovery and periodic solicitations.
   Most people in the DT didn't like this option.

3. The cleanest way: extensions to MLD to allow a node
   to join an anycast group.

Hesham
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From: Rob Austein <[email-masked]>
Date: Mon, 29 Apr 2002 13:37:41 -0400

> 1. The DNS can inject a route. Do you see problems

Well, "the DNS" doesn't do routes, but I assume you meant the DNS
server.  Yes, there are issues:

a) DNS server now has to implement one or more routing protocols,
   which is a lot more code than, say, a stub DHCP server.

b) What's the security model by which the router decides whether to
   accept routing updates from the DNS server?

>    to join an anycast group.

These are both polling approaches, right?  Exactly the same issues Bob
suggested apply to the co-resident DHCP approach apply here: how
tightly coupled does the thing you're polling have to be to the
service you're providing in order for the poll to tell you whether the
service itself is available?
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From: Randy Bush <[email-masked]>
Date: Mon, 29 Apr 2002 22:55:14 +0200

> 1. The DNS can inject a route.

please tell us the rfc or i-d which describes this

randy