Erik Nordmark wrote: >>We haven't really specified the source address selection like this for >>IPv4 either, I believe. Have I missed something? > > > That wasn't what I said. I said that IETF specifications don't > go into details on how to cache things, whether it is for "routing" > or "source address selection". > > I suspect IPv4 implementations which allow more than one IP address > per interface have some mechanism by which the source IP address > is selected, since it can't just be the single IP address assigned to > the outgoing interface. > >
Having implemented this for SCTP I can tell you that normally if more than one address exists for an interface you end up picking the first source address on the interface (assuming it is not restricted i.e. the application has this address in its bound list and the peer knows about the address). This works for both V6 and V4 and scoping must be done for both V4 and V6 addresses... since we have this little ugly thing called NAT in V4.... Generally you do the route lookup and then cache the route. The route has a pointer to the interface and you pick up the first address on the interface.. not complex but it can get tricky when the first address is restricted :-0 >>Routing table lookup is very simple compared to this I think. > > > Conceptually simple, yes. Making it perform, combining the routing table > with the arp/nd cache for performance, etc makes it more complex. > Source address selection is also conceptually simple. And making it > perform well makes life more complex. > You got that right :-0 R > Erik > > -------------------------------------------------------------------- > 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] > -------------------------------------------------------------------- > > -- Randall R. Stewart [EMAIL PROTECTED] 815-342-5222 (cell phone) -------------------------------------------------------------------- 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] --------------------------------------------------------------------
