Prioritising default routes

[Michael Ludvig]

Hi guys

Any thoughts on the question I posted 3 weeks ago? I'm sure it can be 
done in something as flexible as Bird is. Just don't know how...

Thanks!

Michael

On 28/02/14 15:49, Michael Ludvig wrote:
> Hi
>
> Short version: Can I assign different priorities (metrics?) to the 
> same route inserted by Bird into different routing tables?
>
> Long version:
> I've got a main office router with these uplinks:
>
> - 1x SDSL with BGP, receives national routes
> - 1x ADSL with OSPF Cisco modem that advertises default route
> - 2x OpenVPN tunnel to our Datacentre (one over each physical 
> connection) with OSPF that's primarily for internal nets.
>
> The SDSL and Datacentre are with the same ISP and I can propagate our 
> DMZ subnets over BGP from either location.
>
> Then I've got two routing tables - one for internal LAN and one for 
> DMZ which has different rules.
>
> In normal circumstances the LAN traffic goes out over ADSL unless 
> there is a better route learnt from BGP in which case it'd go out over 
> SDSL. The DMZ traffic (public IPs) always goes out over SDSL, and the 
> DMZ routing table has a static default rule in that sense.
>
> Now if SDSL goes down - as it did yesterday after a fibre cut down the 
> road...
> - all LAN traffic goes out over ADSL, that's good
> - DMZ subnet advertised from DC router over BGP and incoming traffic 
> arrives over the OpenVPN tunnel (which still works over ADSL).
> - all DMZ egress is blocked though until I replace the default route 
> in DMZ routing table to go via the tunnel to datacentre and from there 
> to the internet.
>
> If ADSL goes down...
> - LAN traffic is restricted to BGP learned routes (national traffic) 
> until I add a static default route via SDSL
> - DMZ is fine
>
> What I want is an automatic fail over for both LAN and DMZ if any one 
> of the links fails.
>
> My idea is to advertise a default route over all the uplinks and for 
> the LAN routing table use them in this order of preference:
> 1. ADSL (OSPF), 2. SDSL (BGP), 3. one of the tunnels (unlikely if both 
> physical links are down)
> For DMZ routing table do this order:
> 1. SDSL (BGP), 2. tunnel over ADSL (OSPF), 3. plain ADSL (OSPF)
>
> I know I can manage different routing tables from Bird but how do I 
> assign different priorities (metrics?) for the same route going into 
> different tables?
>
> Thanks!
>
> Michael
>
>
>
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