kre, >> Brian E Carpenter wrote: >> Nevertheless, it is not architecturally forbidden to subnet at >> /124 if you really want to
> Robert Elz wrote: > No, and it can be a good thing to do No, but I am not so sure about it being a good thing. > - if I have a lot of P2P links that I am going to number as 1 and > 2 at the two ends (for lots of reasons I don't want unnumbered most > times) > If I have just a couple of dozen of them, then sure, burning numbers > out of the subnet number space between /48 and /64 should be fine. > But if I have hundreds, or perhaps even tens of thousands, then using > some of those 62 padding 0's to number all of these P2P's, and > consuming just one subnet number for the lot of them makes a lot of > sense. Id does make sense in IPv4. However, IPv6 has been designed with an explicit trade-off between simplicity and allocation efficiency. Let me make a comparison with Novell IPX: an IPX address is 80 bits, which are 32 bits for the network, and 48 bits for the host (actually, the MAC address most of the time). So, a /32 in IPX would be the equivalent of a /64 in IPv6 (vaguely). There is a Novell animal called the IPX internal network, which is basically a loopback interface that is routable. I have never heard anyone complaining that the IPX internal net, which uses an entire "subnet" for only one network address, was a problem because it was wasting address space. > The answer to the original question is that nothing should assume > anything about the internal structure of the 128 bits, except where > actually required by some standard (such as auto-conf). I concur that it would not be wise to assume anything, but saving IPv6 addresses does not strike me as good idea if it brings more complexity and does not bring anything else than allocation efficiency. Michel. -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
