Codice:

Main/Backup link setup
After chains are specified we can accept our networks and drop everything else as we are not transit provider. As you know one of the BGP attributes that influence best path selection is AS Path length (shorter AS Path is more preferred). So as we want ISP2 to be backup only, we will use BGP AS prepend (increase length of AS path) to force incoming traffic through ISP1.


Outgoing filters to ISP1:

/routing filter
#accept our networks
add chain=isp1-out prefix=10.1.1.0/24 action=accept
add chain=isp1-out prefix=10.1.2.0/24 action=accept
#discard the rest
add chain=isp1-out action=discard


Outgoing filters to ISP2:

/routing filter
#accept our networks and prepend AS path three times
add chain=isp2-out prefix=10.1.1.0/24 action=accept set-bgp-prepend=3
add chain=isp2-out prefix=10.1.2.0/24 action=accept set-bgp-prepend=3
#discard the rest
add chain=isp2-out action=discard


We also do not need any routes from both ISPs, because default route is used to force outgoing traffic through ISP1 and leave ISP2 as backup.

/routing filter
add chain=isp1-in action=discard
add chain=isp2-in action=discard

/ip route
add gateway=192.168.1.1 check-gateway=ping
add gateway=192.168.2.1 distance=30 check-gateway=ping