Brian, I would be also interested in the conditionals in this which is best case 3 machine instructions too. And what the conditionals did to the complexity of the code and future maintance. Of course I am not clear implementation details interest many these days in our decision process. Its like we infinite time and infinite resources to do IPv6.
/jim [Have you ever seen the rain coming down on a sunny day] > -----Original Message----- > From: Brian Haberman [mailto:bkhabs@;nc.rr.com] > Sent: Wednesday, October 30, 2002 9:08 PM > To: Ole Troan > Cc: Jun-ichiro itojun Hagino; Richard Draves; [EMAIL PROTECTED] > Subject: Re: Limiting the Use of Site-Local > > > > > Ole Troan wrote: > >>>>A router might (and probably should) be hard-coded not to > >>>>forward link-local packets, as there is no reason to ever > >>>>forward them. > >>>> > >>>>However, a router that might ever need have multiple > >>>>interfaces in a single site can't be hard-coded not to > >>>>forward site-locals. Whether or not they will be forwarded is > >>>>the result of configuration. > >>> > >>>Actually, a router can forward link-locals between > interfaces on the > >>>same link. In particular, a router can forward a packet with > >>>link-local dest and/or source back out the interface from which it > >>>arrived (and presumably generate a Redirect too). > >>> > >>>If you are implementing link-locals properly, it's really > very little > >>>additional code to support site-locals. At least that's my > >>>experience. > >> > >> could you comment on routing code? (RIPng, OSPFv3) i > still think > >> it's way too tough to support multi-sited node. > > > > > > RIPng is relatively simple. link-state protocols require congruent > > areas and sites. there are some open issues with regards to > multicast > > and PIM I believe. routing protocol support is required in any case > > for VPNs. > > The actual routing protocol changes in RIPng is dependent on > how you structure your RIBs. I hacked RIPng to make an SBR > using a monolithic RIB with an additional index (the zone > id). It was an additional 800-900 lines of code to deal with > figuring out which RIB entries needed to be advertised on > each interface. > > Then there are the changes to configure and maintain the zone IDs. > > The biggest hit is actually in the forwarding. Each packet > gets at least one additional table lookup (for the incoming > zone id). Then there are the checks to ensure that the > source address is valid (e.g. a site-local SA and global DA > trying to cross a site border). > > The extra cost? Performance drops around 25-30% for a SBR > between 3 sites. Of course, this was all software based, but > even a hardware-based solution will take the extra lookup hits. > > Brian > > -------------------------------------------------------------------- > 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] > -------------------------------------------------------------------- > -------------------------------------------------------------------- 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] --------------------------------------------------------------------
