Re: NOTE: WG Last Call: draft-ietf-v6ops-mech-v2-01.txt

[Fred Templin <ftemplin@iprg.nokia.com>]

Itojun,

Nodes may act as hosts on some interfaces and routers on other
interfaces. They may also act in different turns as routers and hosts
on the same interface. I see nothing in RFC 2461 that precludes such
"hybrid" nodes from sending RSs and processing RAs.

In fact, the second-to-last paragraph of RFC 2461, section 6.2.7
("Router Advertisement Consistency") says:

  "Note that it is not an error for different routers to advertise
  different sets of prefixes.  Also, some routers might leave some
  fields as unspecified, i.e., with the value zero, while other routers
  specify values.  The logging of errors SHOULD be restricted to
  conflicting information that causes hosts to switch from one value to
  another with each received advertisement."


So, if router A has good reason to believe that router B advertises
a different set of prefixes, I see nothing unusual about A sending
RSs to B (and getting RAs back from B) to discover the different
prefixes.

Fred
ftemplin@iprg.nokia.com


Jun-ichiro itojun Hagino wrote:

> > So, I believe the initial negotiation is necessary and the best mechanism
> > to support this is sending an IPv6 Router Solicitation and getting an IPv6
> > Router Advertisement back. (My writings have talked about using RS/RA
> > exhanges for MTU negotiations among other purposes for a long time now.)
> > Reasons why using the RS/RA mechanism is best:
> >    
>
> 	both end of the tunnel could be router, so it looks weird for me that
> 	a router to send RS/receive and process RA (other than the validation
> 	rule in RFC2462).
>
> itojun
>