Re: proposal for a compromise on DNS discovery

[Mohsen Souissi <Mohsen.Souissi@nic.fr>]

If this tradeoff proposal can help us move quickly to an operational
solution which maybe quickly implemented and shipped in OS's, I fully
support it.

My concern is that while having this endless religious debate (thanks
Tim for the word), people who want to deploy real and credible IPv6
networks still lack this critical feature (recursive name server
discovery).

Mohsen.

On 16 Jul, Alain Durand wrote:
| I have circulated this among several people yesterday and it may be time
| to bring this to the list.
| 
| Our community is basically divided in two camps,
| the "conservatives", coming from v4 where the operational practice
| is to use DHCP for DNS discovery and would like to operate the same way
| for v6, and the "liberals", coming from v6 where the autoconfiguration
| story is build on Neighbor Discovery and RA/RS, and who would like to
| expand on this.
| 
| As I explain in an earlier mail, the differences in the mode of 
| operation are:
| - DHCPv6 can also pass the address of the NTP server
| - RA/RS have the unsolicited multicast provision that helps save 
| bandwidth
|    when a large number of nodes are autoconfiguring at the same time.
| 
| The compromise solution I'd like to bring forward is to optionally 
| piggy back the
| unsolicited multicast mode to DHCPv6-lite.
| 
| More specifically, this would work the following way:
| 
| At boot time, the client wait a bit (random 0..MAX1 seconds) and listen
| to unsolicited DHCPv6 DNS recursive server advertisements sent to the
| link-local-all-node multicast address.
| If noting comes, it send a DHCPv6 request.
| The DHCPv6 server answer to the unicast address of the requester
| and, if configured to do so (this would be optional), send the same 
| thing to the
| link-local-all-node multicast address.
| Those multicast responses will be rate limited by the server,
| that is, if a second request come within MAX2 seconds,
| only the unicast answer will be sent.
| 
| I'm sure there would be many details to work out.
| 
| 	- Alain.
| 
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| 

-- 
Mohsen Souissi

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