Mon, 01 Jul 2013
The times when the Internet was considered a transparent network, which relayed any kind of Layer 4 frames, as long as they were properly encapsulated in Layer 3 - the Internet Protocol version 4 (and version 6, recently) - are apparently gone forever.
The Network is not even supposed to look inside the Layer 3 payload, yet some core switches apparently handle a particular L7 protocol in a special way. I wonder whether we are now in state of TCP, UDP, and ICMP being cast in stone, and no way of deploying a whole new L4 protocol, or a substantial modification of current L4 protocols (do you remember TCP ECN fiasco, anyone?).
With NATs and firewalls being the integral part of the Internet, the situation is probably even worse. Not only L3 and L4 are cast in stone, but application protocols as well. These times, everybody seems to tunnel their data over HTTP, as this is the only protocol, which can be expected to pass over this mess of NATs and prohibitedly configured firewalls.
So let's hold a minute of silence for the end-to-end transparent Internet, which is apparently gone forever.