(resending with nanog-approved address..)
On 18. jan. 2013 01:30, Jeff Kell wrote:
On 1/17/2013 6:50 PM, Owen DeLong wrote:
Vonage will, in most cases fail through CGN as will Skype, Xbox-360,
and many of the other IM clients.
Not sure about Vonage, but Skype, Xbox, and just about everything else
imaginable (other than hosting a server) works just fine over NAT with
default-deny inbound here, and we have several thousand students in the
dorms that bang the heck out of those services. Most applications have
adapted to the SOHO NATing router that is prevalent today on broadband
internet. And if it didn't work, believe me, I'd hear about it :)
Your users must have fairly low expectations :-)
That snide comment aside, a single level of NAT44 works OK now for most
current consumer level applications. But this is about multiple levels
of NAT, where the usual "hacks" with UPNP IGD/NAT-PMP to get inbound
ports are not likely to work. Even if you dont support these tricks on
your end today, its likely that it is supported at the other side. Most
"p2p" traffic like Skype only needs the mapping to work at one end, as
they have to signal/negotiate addresses and portnumbers through some
third party anyway.
So currently, even double NAT at one end, it is likely to work out
(within the current expectations of users.)
When CGN gets to critical mass, where both ends of a connection is
likely to be even more crippled than today*, things change. Now you have
to bounce all the data of some third party, like a DC, maybe not even on
the same continent.
When Skype fails to map ports at both ends today the experience is
pretty horrible actually, at least over here, even with the backing of
Microsofts infrastructure. Also makes me wonder how expensive running
such services will become (Only feasable for Google and Microsoft?)
* Some support for mapping ports at CGN is in development, but requires
new or updated CPE/home gateways, software support/awareness and support
for it in the CGN (riiight.)
