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Re: [RRG] Re: [RAM] Different approaches for different protocols
On 21/12/2007, Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
> On 2007-12-20 20:27, Victor Grishchenko wrote:
> >> Specifically, the thought of having to manage multiple addresses at
> >> each and every host is NOT something that we automated in v6. Also,
> >> Dave Thaler might provide us with some entertainment at the mere
> >> mention of host changes. ;-)
> > That host changes might not be mandatory. v1 hosts get 1 address, v2 hosts
> > get a bunch.
> IPv6 has always supported multiple addresses per interface. What we
> are talking about is really whether an address selection algorithm
> like RFC 3484 is sufficient to handle multiple addresses, or whether
> something more sophisticated like shim6 (or SCTP) is required.
RFC 3484 R. Draves Microsoft Research
"...Well-behaved applications SHOULD iterate through the list of
addresses returned from getaddrinfo() until they find a working
address...
...all else being equal prefer address pairs having the longest
possible common prefix..."
Seems good enough. In the bunch-to-the-host scenario
longest-common-prefix might be the best simple strategy.
In the context of an IP connection, keeping it open while a site
rehomes is hardly critical in the common case. Intuitively, an
ordinary topology change will affect just part of a bunch, so the rest
remains functional and applications may re-connect.
So, my point holds. Further sophistication is useful but it is hardly
mandatory. May always sell it as v2.0 / mobile extensions / pervasive
load balancing / etc
BTW, regarding D.Meyer's remark in IETF Journal Oct 2007.
> It has been proposed that the Domain Name System [DNS] would be
> used to find the destination address, but then how does one find the
> address of the DNS servers?
Supporting (routing to) the root DNS server farms might be obligatory
for those "Large Structures" (i.e. owners of root prefixes). Thus,
addresses of the root DNS servers will be short and immutable.
--
Victor