I don't think we should amending rule 7 in such a way. in fact , i think this will make the rule 8 unworkable. according to RFC3484,when at last we have two source address available,both can pass rule1-rule7,then,the rule 8 will chose the longest match prefix.but if we amend rule 7 and prefer manul-configured address,some thing changed,for example: address A is autoconfigured and belong to ISP1,host use it to access network of ISP1. address B is manuconfigured and belong to ISP2,host use it to access network of ISP2. then if we prefer manuconfigured address ,we will chose address B as source when we access ISP1,that maybe refused by the PE router of ISP1 for the reason of soure address filter.
Best regards, Lawrence >-----Original Message----- >From: James Carlson [mailto:[EMAIL PROTECTED] >Sent: Wednesday, October 25, 2006 3:52 AM >To: ipv6@ietf.org >Subject: address selection and DHCPv6 > >I've done quite a bit of searching over the archives and over >various web resources, but I haven't seen this issue addressed >directly. >Apologies if I've just missed it. > >RFC 3484 ("Default Address Selection for Internet Protocol version 6 >(IPv6)") section 5 gives a set of ordered comparisons for >source address selection. However, missing from this list is >a distinction implied by RFCs 2461 and 2462: some systems may >have a mix of addresses acquired by stateless address >autoconfiguration, stateful >(DHCPv6) configuration, and manual addressing. How are these >distinguished? > >Rule 7 does address the temporary (RFC 3041) addresses, but >what about these other flavors of addresses? Are they >distinguished only by scope? > >Was this issue addressed and intentionally omitted from the >RFC? (If so, I don't see it in the archives.) > >I suspect that some clients may need to distinguish among the >various flavors here. I'd suggest amending Rule 7 to read: > > Rule 7: Prefer stable, public addresses. > If SA is a manually-configured address and SB is automatic or > temporary, then prefer SA. If SA is automatically configured via > stateful (DHCPv6) methods and SB is automatically configured via > stateless methods or temporary, then prefer SA. If SA is > automatically configured via stateless methods and SB is temporary, > prefer SA. > > Similarly, if SB is a manually-configured address and SA is not, > then prefer SB. If SB is stateful and SA is stateless or > temporary, prefer SB. If SB is stateless and SA is temporary, > prefer SB. > > When the application has the "prefer temporary address" flag > enabled, all temporary addresses are (within this rule) elevated in > preference above manually-configured addresses. The other > preferences are unaltered. (In other words, the preference order > with this flag set becomes temporary first, then manual, stateful, > and stateless last.) > >... or, to simplify, defining a "stability_of_address(A)" >function that can work here. > >-- >James Carlson, KISS Network ><[EMAIL PROTECTED]> >Sun Microsystems / 1 Network Drive 71.232W Vox +1 >781 442 2084 >MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 >781 442 1677 > >-------------------------------------------------------------------- >IETF IPv6 working group mailing list >ipv6@ietf.org >Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 >-------------------------------------------------------------------- > -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
