At 6:11 PM -0400 10/2/02, Rob Austein wrote: >At Wed, 2 Oct 2002 15:07:55 -0700, Steve Deering wrote: > > > > In a response to that message, Rob asked me if I had forgotten about > > unnumbered point-to-point links. I answered as follows: > > > > >Yes, I did forget about them, but I think it's obvious how to handle them: > > >they are not part of a subnet that exists on any other link, so subnet- > > >scope multicasts would not be forwarded to or from an unnumbered link. > >Assuming that one suspends disbelief about the whole multi-link subnet >thing in the first place, it's far from obvious to me that unnumbered >links aren't part of a subnet that exists on other links.
So which is it? Either we're talking about the case where multilink subnets are not employed (no need to believe in them), in which case my statement holds. Or we are venturing into the oh-so-scary land of multilink subnets, in which case the routers know (are required to know, in order to make unicast routing work) that they are extending the span of a subnet across more than one link, possibly including point-to-point links, so know which links are part of the same subnet, and can therefore do subnet-scope boundary enforcement as necessary. What am I missing here? >The most common use I've seen of proxy ARP in IPv4 has been to extrude >small numbers of IP addresses across PPP links. Yes, proxy ARP is an (undocumented) special case of multilink subnetting. Steve -------------------------------------------------------------------- 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] --------------------------------------------------------------------
