Re: [homenet] Status of draft-tldm-simple-homenet-naming CFA

[Toke Høiland-Jørgensen <[e-mail]>]

Ted Lemon <[e-mail]> writes:

> El 15 ag 2017, a les 15:38, Toke Høiland-Jørgensen <[e-mail]> va escriure:
>>> I think we are wandering off into nonsense territory here.   Have you
>>> observed this sort of problem in the field?   If so, can you describe
>>> what happened?   If not, why would we optimize for it?
>> 
>> If you consider flaky ISP DNS servers to be "nonsense" you are clearly
>> more fortunate with your ISPs than me. And that's before even going into
>> the DNS censorship issue; in my part of the world ISP DNS servers are
>> broken *by design*.
>
> In both of these cases, you are better off doing what we discussed
> earlier and setting up your own DNS cache, possibly with a whitelist
> for domains you want to send to the ISP forwarder.

Sure, and that's what I usually do. But if we can't specify that
behaviour for homenet, at least trying all upstream DNS servers gives a
better chance of finding one that works.

>>>> Right, so if this is the case, how about we specify that routers MAY (or
>>>> maybe even SHOULD) support MPvD-specific resolver addresses, and
>>>> advertise the fact over HNCP. And that if a router receives such an
>>>> announcement from another router it MUST announce the MPvD-specific
>>>> resolver addresses over DHCP/RA. This way we ensure that *if* a router
>>>> on the network implements MPvD it is going to work for the whole
>>>> network; but routers can still opt to not implement the functionality
>>>> itself if the implementer doesn't want to pay the implementation cost.
>>> 
>>> Can you describe for us what this implementation cost is that you want
>>> to avoid?
>> 
>> Can you describe for us how multiplying the number of resolvers by N (or
>> MxN if we follow your suggestion of running a full set of resolvers on
>> every router) is *not* going to incur a significant implementation and
>> debugability cost?
>
> It's just a bunch of ports/address pairs, with one thing listening on
> all of them, and using the port/address pair as a behavioral selector.
> I'm not going to say that it's zero effort, but it's not hard.
> Honestly, every home router right now has some kind of DNS proxy or
> DNS resolver in it; this is not a big change. Compared to, say,
> implementing HNCP or DNSSD, it's utterly trivial.

You may be right that hacking up a working prototype isn't that hard.
But the failure modes change from "the internet is down" or may "I
cannot access site A", to "site A is working every third attempt, except
it is entirely broken on device X" maybe even with an added "ah, but
it works on device X if I go into the kitchen".

Hmm, while writing this is occurred to me that it might make sense to
just export the ISP DNS server(s) directly in the MPvD-only RAs?

-Toke