Re: [mdnsext] mDNSext features/requirements rollup

[David Farmer <[e-mail]>]

On 1/28/13 11:34 , Andrew Sullivan wrote:
> On Mon, Jan 28, 2013 at 11:51:02AM -0500, RJ Atkinson wrote:
>
>> Some of us would like to see mDNS support multiple IP subnets
>> (e.g. multiple buildings, multiple groups, multiple (V)LANs)
>> within a single administrative domain (e.g. university campus,
>> corporate campus).
>>
>>    This implies having a straight-forward way to configure
>>    networking devices (e.g. firewalls, routers) at the edge
>>    of one's administrative domain to exclude certain interfaces
>>    (e.g. exterior uplink interfaces) from all mDNS traffic
>>    of the administrative domain using mDNS.
>
> I still do not understand why this sort of thing isn't better handled
> by vastly improved tools for real DNS management.  It seems to me that
> people are asking for a single, unifed namespace outside the
> link-local context, and we invented a mechanism for that many years
> ago.  The problem is that the support tools for that mechanism sort of
> suck.  Instead of inventing a new protocol which, by definition, is
> going to run into conflicts with the existing protocols in this space,
> why wouldn't it be better to take that energy and expend it on the
> missing tools?

If you mean an implementation of Wide-Area DNS Services Discovery then 
yes, but most of the zero-conf implementations and the applications 
using this have ignored anything but mDNS and Link-Local DNS Services 
Discovery.

The real issue is that end-users and even IT Executives (CIOs, etc...) 
don't see why there should be any difference between what they can do 
and use at home and in the office.  If they can do wiz-bang-thing at 
home they want to do it in the office.  Right now mDNS and Link-Local 
DNS Services Discovery are critical to how many of these consumer 
devices, or the Internet-of-things that some people call it, make the 
wiz-bang-things work.

I apologize to Apple, but to really make this clear I have to call them 
out.  The driver behind the petition is a specific case of what I 
generically described above.  Users and IT Executives in Higher Ed 
wanted to be able to use AirPlay Screen Mirroring to Apple TVs from iOS 
and now Mountain Lion Laptops on the campus network.  Not only was this 
an idea they came up with but, Apple even had an TV ad campaign 
promoting the idea.  To be honest as a network engineer its very much an 
uphill battle when your arguing against a multi-million dollar TV ad 
campaign. :(

So you hear a bunch of us pushing to solve this with network hacks, or 
mDNS hacks.  Not because we think it is really the right way, but 
because the network is what we can effect, its the levers we can 
control.  The applications and wiz-bang-thing devices are out of our 
control and, right or wrong, we have had exceptions placed on us to make 
them work on our networks.

So, while it may not be the right thing, I need a way to make normal 
mDNS and Link-Local DNS Services Discovery work on my network.  Which 
consists of multiple segments and the services the users want may or may 
not exist on the same segment.  Fundamentally, this is either a symptom 
of the success of mDNS and Link-Local DNS Services Discovery or a 
failure to think through the consequences of not including broader 
scalability in the original solution, take your pick.

So while we need the better DNS tool you refer to, we also need 
solutions that work with the applications and wiz-bang-thing devices 
that are out there now.

-- 
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David Farmer               Email: [e-mail]
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