This behavior is implemented in Vista and Windows 7. Can you explain the concern about unpredictability more? The algorithm reacts to the changes in the network - hence there is bound to be unpredictability on the time line of when the packets start getting routed to a different next hop - but given a history of data packets it isn't all that unpredictable. Is the concern about the non-standard mechanism used to detect unreachability?
Thanks Simha -----Original Message----- From: ipv6-boun...@ietf.org [mailto:ipv6-boun...@ietf.org] On Behalf Of Erik Nordmark Sent: Sunday, December 06, 2009 9:23 AM To: IPv6 Maintenance WG Subject: Question on RFC 4191 inconsistency The default router preferences RFC seems to be internally inconsistent on the scope of the "non-reachable router" implications. Section 3.2 contains: using route preference values as a tie-breaker if multiple matching routes have the same prefix length. If the best route points to a non-reachable router, this router is remembered for the algorithm described in Section 3.5 below, and the next best route is consulted. thus it talks about multiple matching routes *with the same prefix length*. Nothing in section 3.5 contradicts this. Yet the example in section 3.6 talks about falling back to the default route (or any route with a shorter match) when all the longest match routes lead to unreachable routers. It is quite odd that the example is the only source of this novel behavior. I'm concerned that going to shorter matching routes isn't only complex to implement, makes the protocol operationally unpredictable (who knows how quickly a host might decide a router is unreachable when there is non-zero packet loss), but also charters completely new territory in terms on longest-match routing. Have this example behavior in section 3.6 been implemented? Do we have any operational experience with it? Erik -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 -------------------------------------------------------------------- -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
