3 ms·

i'm confused (which is not too surprising as i am no expert on this). why can't they hole-punch through nats? then they would avoid the extra bounce-through-s

i'm confused (which is not too surprising as i am no expert on this). why can't they hole-punch through nats? then they would avoid the extra bounce-through-server latency and would hugely reduce the load on servers. i thought that was how skype worked, for example. (i realise this doesn't stop their "fastest first" idea being useful - i got kind of sidetracked by the explanation of how servers are used near the start of the post). [ah, ok. thanks for the explanation.]

moxie 14y ago
Your NAT traversal strategy is limited by the type of NAT being employed. Traditionally, the worst case scenario for NAT traversal is "symmetric NAT." Symmetric NAT means that each tuple of (source_ip, source_port, destination_ip, _destination_port) gets its own unique (external_ip, external_port) tuple. This is bad because it means that STUN is ineffective: your STUN server will see a different external port than what your actual destination would see. Mobile data networks are actually worse than symmetric NAT. Not only will your external port change based on your target, but your external IP likely will as well. This makes NAT traversal, AFAIK, basically impossible.
- vy8vWJlco 14y ago
  And there's no real reason to do it either given the availability of global IPv6 addresses and any of the free tunnel brokers/teredo/etc, other than the simple lack of adoption/momentum. Most ISPs will need a push, but from an infrastructure perspective it just boils down to a new gateway router or a firmware upgrade. It doesn't even need replacing the end-user equipment if ISPs simply set up a tunnel server for their own customers as a transitional measure.