BGP Backup

RouterOS Forwarding Protocols
1

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

2

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?

3

I try to explane :smiley:

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 :smiley: )

4

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

5

can you explane my how to made it ?

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

6

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

7

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

8

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

just decide exactly what you want to do