[mdnsext] mDNSext features/requirements rollup

[Alf Watt <[e-mail]>]

I've worked back through the mail log and assembled all the common features and requirements that I could identify, there's likely some personal bias in this list as I have preferences on how to implement some of these, but hopefully it's enough to get our BoF in the air:

Multicast Domain Bridging (Bonjour Bridge)

	- this is the feature that multiple vendors are currently working on, briefly:
		Bonjour packets are proxied between two multicast domains, optionally with filters.

Multicast to Unicast Proxy/Relay/Middlebox

	- proposed feature where local services can be browsed via unicast dns for efficiency or to cover a wider area
	- functionally looks like a DYN-DNS server but updates via mdns queries instead of registration by clients
	- resolve namespace collision issues (each multicast domain may need a separate .local or .site subdomain)
	- support for long-lived unicast queries to the proxy

Improved performance

	- multicast on wireless links is expensive, move as much traffic as possible to unicast 
	- use multicast to discover the local proxy (or lack thereof) and switch to unicast if present

Administrative & Security Features

	- suppression of some or all bonjour activity, selected services or other filters (e.g. browse-only domains)
	- redirection to a Bonjouor proxy or other alternate service discovery mechanism (see above)
	- this 'breaks' some features but is better than complete suppression which is currently common
	- validation of service advertisements and resolution (prevent resolution spoofing)
	- Users and devices are only authorized to advertise certain services
	- Service advertisements are only delivered to authorized recipients
	- ensure that service resolution is authoritative for the advertisement, whether it is an original or proxy advertisement"


I'm sure I missed a few, please feel free to fill in the list.

Best,
Alf