Hi, On Nov 16, 2009, at 6:08 PM, William Herrin wrote:
On Tue, Nov 10, 2009 at 1:44 PM, Jan Melen <jan.melen at nomadiclab.com> wrote:Of course as we now are talkingabout multiple default routes that are advertised between the routers A, B,C so we need to add source address prefix in to the default route advertisements. Right?Do we? What about routes other than the default? Does it ever make sense for a small ISP to propogate three source address ranges on each link downstream instead of introducing DFZ routes of its own?
Yep, you're right one could also introduce DFZ routes.
We've identified at least two approaches here, tying source and destination together in the route and establishing entirely separate routing domains for each source range. Are there more ways to look at the problem? I think that's a worthwhile question for the problem statement.we need that CS listens to these advertisements and makes up his mind and if it is the CS that has to select the correct next hop router then DHCP is notthe protocol you want to use to configure routes as it is designed todeliver more or less static routes that do not change (at least) during theaddress lease time.How big a concern is that? Won't the higher-level protocols have to deal with dead path detection anyway? Even if you have a legitimate default route, there's no guarantee that all of your ISPs are fully connected right now.
Well it would be nice if one could avoid even trying such a route which is known to be dead, but of course through higher level protocols you can get the the information through time outs but that usually is not desirable as it introduces poor user experience.
Jan
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