Re: [IPv6] Suggestion for multi homed clients without NAT/NPT

[Vasilenko Eduard <[e-mail]>]

PvD has no value for 1)ND, 2)source routing,
That may be needed in a multihoming environment.

But PvD has a value for 3) DNS,
If RDNSS is received from the same router in a situation where it may have a different context (different PIOs).

Strictly speaking, all 3 solutions are needed for a complete multihoming package.

I am not aware of any PvD alternative on how to inform from the same router that "this DNS is for this PIO, but that DNS is for a different PIO".

PS: if the host is receiving different RDNSSes (with respective PIOs) from different routers then PvD is not needed.

Eduard
-----Original Message-----
From: ipv6 [mailto:[e-mail]] On Behalf Of Michael Richardson
Sent: Thursday, January 5, 2023 7:07 PM
To: Philipp S. Tiesel <[e-mail]>; 6man <[e-mail]>
Subject: Re: [IPv6] Suggestion for multi homed clients without NAT/NPT


Philipp S. Tiesel <[e-mail]> wrote:
    > I did my Ph.D. on that topic and called it Happy Eyeballs on Steroids.

    > Most results went into the TAPS WG… maybe have a look at
    > - https://datatracker.ietf.org/doc/draft-ietf-taps-arch/
    > - https://datatracker.ietf.org/doc/draft-ietf-taps-interface/
    > - https://datatracker.ietf.org/doc/draft-ietf-taps-impl/

Very cool.  I will read them. I didn't know TAPS was doing this, and I suspect that few in 6man know either.  Maybe a 5 minute presentation is in order.

Philipp S. Tiesel <[e-mail]> wrote:
    > I am convinced RFC 8028 would also be a great start for clients with
    > multiple default routes, e.g., enabling stuff like multi-path TCP to
    > work correctly, but it will not be sufficient for meaningful
    > multi-homing / source address selection.

Do your IDs explain why?

    > In addition, to avoiding problems with CDNs, it is also  required to
    > separately keep track of DNS on a per-router/PvD basis and only use the
    > matching source addresses for new connections, so RDNSS should also be
    > treated analog to the source address in RFC 8028.

I'm surprised to hear this.  I'm not convinced that PvD are a good idea, I think that they represent IPv4 thinking, and I think that there are better ways to do this in IPv6.  So I'm curious to understand how they are connected.

    > Having tried to manage traffic from within getaddrinfo() I can only
    > recommend to abandon that idea.
    > A lengthly write-up why can be found here in Section 6 of this expired
    > draft:
    > https://datatracker.ietf.org/doc/html/draft-tiesel-taps-socketintents-bsdsockets-02

Thank you. I agree that it can't be done properly in getaddrinfo().

    > The only way forward I see is something like TAPS and Appel’s
    > implementation is already pretty close what it would needs to make use
    > of multi-homing here. They just need a litte more
    > aggressive/opportunistic happy eyeball candidate selection.

Is there a FAQ on how to play with this code?


--
Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide