[mdnsext] mDNSext features/requirements rollup

[RJ Atkinson <[e-mail]>]

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.

To a first approximation, the facility/capability provided 
by (old) Apple EtherTalk would do very nicely. 

Kindly note that the ability to group a resource into a 
non-topological "zone" within that single administrative domain 
would be most helpful.

Overall bandwidth efficiency is also important as a design
goal.  Some of us have a mixture of different links/subnets
with different technologies and bandwidth limitations --
not everything is running at Gbps speeds, over fibre, or
over uncontested radio spectrum.[1]

Ran

[1] Exempli Gratia:   IEEE 802.11n does NOT operate at full 
    theoretical performance in typical 2.4 GHz deployments,
    because of the widespread use of the 2.4 GHz band for
    a wide range of things -- other 802.11 deployments,
    cordless telephones, and so on.  While the 5 GHz band
    often has less interference at present, that also is
    shared, so interference there will tend to grow over
    time.