[Berlin-wireless] Fwd: Re: [DIY-ISP] ipv6: multiple prefixes+gateways

[Daniel Paufler]

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Hallo

Ich hab für morgen 20h ipv6 concepts im Kalender. Mir passts.

Können wir aber von mir aus auch 2 Wochen verschieben - nächste Woche
ist ja wieder MABB.

Daniel

On 15/07/14 17:27, André Gaul wrote:
> fyi!
> 
> btw: wir wollten ja morgen eigentlich ein treffen machen um das 
> netzkonzept zu diskutieren. leider kann ich nicht teilnehmen bzw. 
> vermutlich erst sehr spaet. wie sieht es bei den anderen aus? passt
> das sonst allen oder wollen wir einen anderen termin erdoodlen?
> 
> ciao, andré
> 
> 
> -------- Original-Nachricht -------- Betreff: Re: [DIY-ISP] ipv6:
> multiple prefixes+gateways Datum: Tue, 15 Jul 2014 23:43:30 +0900 
> Von: Baptiste Jonglez <bjonglez at illyse.org> Antwort an: Baptiste
> Jonglez <bjonglez at illyse.org> An: diy-isp at lists.ffdn.org
> 
> On Tue, Jul 15, 2014 at 04:00:55PM +0200, André Gaul wrote:
>> In the meantime, Henning Rogge (OLSR) announced on the Freifunk
>> Berlin list (in German, see [1]), that he will implement source
>> specific routing in OLSRv2. As soon as it's available, I'll test
>> it and I can share the results here if you like.
> 
> Good to hear :)
> 
>> Example: * GW_A is one of our BGP routers and takes care of
>> subnet A (e.g., 2001:bf7:750::/44 for Berlin) * GW_B is a gateway
>> connected to DSL line and is assigned the subnet B by the DSL
>> provider (e.g. 2001:470:815::/48) * Now a client sends an IP
>> packet with a source address from subnet A and some destination
>> address outside the mesh to its default gateway. The default
>> gateway runs OLSR and sees 2 gateways (GW_A and GW_B) for ::/0.
>> Maybe GW_B is closer and the packet is therefore routed through
>> GW_B.
> 
> Just to make things clear, with this setup, you need to announce
> *two* different default routes.  With a (dest-prefix,
> source-prefix) notation:
> 
> - announce (::/0, 2001:bf7:750::/44) from GW_A - announce (::/0,
> 2001:470:815::/48) from GW_B
> 
> The gateway of the client will know about both routes (both being 
> installed in the kernel as source-specific).  Assume your client
> is 2001:bf7:750::42, then its gateway will forward the packets
> towards GW_A using the first route, because the source address of
> the packets matches the source-specific prefix of the route.
> 
> 
> It depends on the implementation, but you will probably need *all*
> OLSR routers to run the new source-specific version (or they should
> at least form a connected graph between GW_A, GW_B and the
> client).
> 
> There are a number of other solutions, which might be easier to
> deploy:
> 
> 1/ simply don't announce ::/0 from GW_B :)
> 
> 2/ build tunnels between your border routers (either through the
> Internet, or through the wireless network itself), and perform
> source-specific routing only between border routers, statically.
> 
> For instance, when GW_B receives a packet with a source address in 
> 2001:bf7:750::/44, it will forward it to GW_A through the tunnel.
> This generalises to a greater number of border routers, but
> managing the static source-specific routes will become
> complicated.
> 
> 3/ same as the above, but with dynamic source-specific routing
> between the border routers.  You could actually use source-specific
> Babel for this, as it also handles tunnels quite well :) You can
> even build tunnels *both* over the wireless network and over the
> Internet, and let the RTT-based metric decide which one is better.
> 
> 
>> Anyway, I'm pleased to hear that it's already implemented in
>> babel. Although it may be unstable right now in certain cases,
>> it's definitely worth a shot to test it.
>> 
>> Let's keep us mutually updated on this topic! ;)
> 
> Definitely!
> 
> 
> 
> _______________________________________________ Berlin mailing
> list Berlin at berlin.freifunk.net 
> http://lists.berlin.freifunk.net/cgi-bin/mailman/listinfo/berlin
> 

- -- 
Dipl. Inf. (FH) Daniel Paufler
Angewandte Informatik - Computer Aided Facility Management

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