Re: Persistent loops when mixing rtgwg-enterprise-pa-multihoming and rtgwg-dst-src-routing

[Matthieu Boutier <[e-mail]>]

> Actually, I don't. I can produce cases in which source first gives the wrong route, and in which destination first gives the wrong route.

Interesting! (but I'm lost with the example below)

> The only way I see to make doing either one first *always* gives the right result is if a small set of routes is duplicated.

Did you mean: it any cases, the administrator himself will have to
duplicate routes to achieve its goals?

> The issue is when prefixes overlap. If you have sources S1 and S2, destinations D1 and D2, D1 is a more specific of D2, and D1 is advertised by S1 but not S2, and D2 is advertised by S2. If you are looking from S1, you should find S1->D1, and if you are looking from S2, you should find S2->D2. If you look destination first, and happen to be looking from S2, I think you wind up trying to find S2->D1, which doesn't exist.

I'm lost somewhere.  I'm unable to draw this example, being confused with
"who announces what?".  For example, when you say "D1 is advertised by S1
but not S2", does that mean that S1 wants to announce a route for the
destination D1 and for all sources except S2?  or S1 announces (D1, S1)
but not (D1, S2) ?  The first solution would give:

     (D1, ¬S2)
---.  <--     
S1 |----------
---'

:/

> This is the reason I have suggested a PATRICIA algorithm or something like it that looks up both addresses at the same time.

I should have missed the reference.  Could you please resend?  I guess you
first complete tables and then do the lookup, right?

Thanks,
Matthieu