alt Hacker NewsI'm confused by the argument that replacing equipment is something that is always possible. It doesn't matter that it's easy to support by updating or replacing the hardware - a lot of hardware isn't going to be updated or replaced.
I'm confused by the argument that replacing equipment is something that is always possible. It doesn't matter that it's easy to support by updating or replacing the hardware - a lot of hardware isn't going to be updated or replaced.
ISPs are used to this though, and tunnel a lot of packets. If you have DSL at home, your ISP doesn't have a router in every edge cabinet - your DSL router sets up a layer-2 point-to-point tunnel to the ISP's nearest BRAS (broadband remote access server) in a central location. All IP routing happens there. Because it's a layer-2 tunnel it looks like your router is directly connected to the BRAS, even though there are many devices in between. I don't know how it's done on CATV and fiber access networks.
If an ISP uses an MPLS core, every POP establishes a tunnel to every other POP. IP routing happens only at the source POP as it chooses which pre-established tunnel to use.
If an ISP is very new, it likely has an IPv6-only core, and IPv4 packets are tunneled through it. If an ISP is very old, with an IPv4-only core, it can do the reverse and tunnel IPv6 packets through IPv4. It can even use private addresses for the intermediate nodes as they won't be seen outside the network.