--On 19 November 2004 09:40 -0800 Owen DeLong <owen@delong.com> wrote:
If it were true, then I would have to renumber every time I changed telephone companies. I don't, so, obviously, there is some solution to this problem.
But I'm not sure you'd like it applied to the internet. Firstly, in essence, PSTN uses static routes for interprovider routing (not quite true, but nearly - if you add a new prefix everyone else has to build it into their table on all switches). Secondly, IIRC porting works in the UK something like - call delivered to switch of operator who owns the block, marked as ported number, lookup in central porting database (one for all operators), operator port prefix put on dialed number, call sent back out all the way to interconnect, enters new operator network, goes to switch managing ports, further signalling info added to make call go to the correct local switch, call goes to correct local switch, dross removed, call terminated. Roughly speaking this is the internet equivalent of: * Configure all interprovider routes by a static routing config loaded every week or so. * Handle porting by getting ICANN to run a box with a primative gated BGP feed connected to all your distribution routers. Where a packet is delivered to a distribution router and the IP address has changed providers, change the next hop received from the ICANN BGP feed to a GRE tunnel to the appropriate provider's tunnel termination box. * At that tunnel termination box, static route all ported-in IP addresses to the correct distribution router. Yum yum. Sometimes we don't have lessons to learn from the PSTN world, and instead the reverse is true. Alex