Earlier, Brian Carpenter wrote: % Is it OK if only 95% of telephones can be called, too? Brian,
My guess is that at present my own telephones can reach less than 90% of the total PSTN-connected telephones deployed around the globe. There are several *countries* worth of telephones that simply are not reachable from my telephones, whether for policy reasons (e.g. governmental/political policies) or because there are no inter-connection agreements (equivalent to "peering agreements"), or for other reasons. Similarly, the global Internet has not been fully connected for at least a decade now. I would guess that one would have to go back to EGP days (i.e. before BGP deployment) to have a fully connected Internet, and that was a wildly smaller Internet than we have now. A common reason for lack of complete connectivity is that many IP routing prefixes are only advertised regionally (example: they might be advertised within Asia/Pacific, but are not reachable from or advertised within North America). Other reasons might include political policy (e.g. government regulations on which other countries are authorised to be reachable) in various places, security policy (e.g. firewalls implementing organisation-specific policies), or the deployment of NATs (which can sometimes break reachability on a relatively fine-grained basis). Most people *perceive* the Internet to be fully-connected. I suspect they have this perception for multiple reasons. Two likely reasons are (1) some reachability might temporarily be gone; users can't readily distinguish "never reachable" from "not reachable just now" and (2) the most popular destinations tend to be very highly reachable (although some countries have national policy blocks on their users reaching certain highly popular destination web sites -- example: www.CNN.com is usually not reachable from inside the PRC). CONCLUSIONS: 1) I think that it is beyond the scope of the RG to insist that universal reachability exist in future, given that it does not exist at present. 2) Further, the details of reachability are very likely to be *engineering* details, whilst the RG is only chartered to make an *architectural* recommendation to the IETF (i.e. not a protocol recommendation). Ultimately the IETF will either act upon, ignore partly, or ignore completely whatever recommendation this RG might make. Yours, Ran [EMAIL PROTECTED] -- to unsubscribe send a message to [EMAIL PROTECTED] with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg
