Hi!

I have a problem.
I'm an AS internet provider and i have my public IPs.
I have two internet "backbone" and i can use my public IPs on these two.
But i have to use the first's backbone only for a range of my IPs ( from 1 to 100 ) and use the second's for the other IP ( from 101 to 254 ).
I have a routed network with ospf for "intra-routing" and BGP for routing with the other AS.
I have a router that divide my network from the two backbone and i use policy routing for choose the correct. I have some other router from this gateway and the other provider.
Now i have to make an automatic system for route to the available backbone if one of this go down.


Thank's

But i have to use the first's backbone only for a range of my IPs ( from 1 to 100 ) and use the second's for the other IP ( from 101 to 254 ).

so, does that setup work, or you just use policy routing for upload traffic, but download comes via one of your ISPs?..

what's your current config?

I try to explane

My network use OSPF

MY_NET ( OSPF ) <-> CORE ROUTER ( OSPF ) <-> ROUTER1(OSPF) <-> BGP1_ROUTER ( OSPF & BGP )
MY_NET ( OSPF ) <-> CORE ROUTER ( OSPF ) <-> ROUTER2(OSPF) <-> BGP2_ROUTER ( OSPF & BGP )



So i like that my ip from .1 to .100 are annunciated on internet from the BGP1_ROUTER and my ip from .101 to .254 on the BGP2_ROUTER. This for upload and for download.But if the BGP1_ROUTER is unreacheble (or BGP2_ROUTER) i like that the first range ( .1 to .100 ) are annunciated from the BGP2_ROUTER.

(BGP1_ROUTER and BGP2_ROUTER are connected to internet by two different provider)


(Sorry for my bad english )

you should use routing filters to announce backup routes with some prepend - so they will be used only when main route is off

you should use routing filters to announce backup routes with some prepend - so they will be used only when main route is off

can you explane my how to made it ?

I have to use a script to disable the routing filter ?

do you have only a /24? in this case is difficult to announce only half to one ISP and the other half on the other, becouse prefix< 24 are filtered and dropped!!

if you have a /23 or >, you can split the announcement and announce the full /23 on both isp and a /24 for ISP; in this way the /24 is smaller and have precedence; if the isp will fall down, the /24 will not be announced and the whole /23 take priority!

this is the simple way!

for outgoing traffic you can use the route marking!

Michele P

do you have only a /24? in this case is difficult to announce only half to one ISP and the other half on the other, becouse prefix< 24 are filtered and dropped!!

if you have a /23 or >, you can split the announcement and announce the full /23 on both isp and a /24 for ISP; in this way the /24 is smaller and have precedence; if the isp will fall down, the /24 will not be announced and the whole /23 take priority!

this is the simple way!

for outgoing traffic you can use the route marking!

Michele P

But this on the core router or on the two BGP routers?

on your BGP routers (BTW, why two?.. one is enough...)

just decide exactly what you want to do