Hello Elazar,
you had already a thread about this.
Where you have received useful suggestions.
However, in this new thread you have provided more info in the initial post.
You would like to have traffic to and from network XXX.XX.188.0 to use ISP2.
You would like to have traffic to and from other networks to use already existing ISP1.
BGP has a rich set of tools but it is still a destination oriented protocol.
you can achieve control on what path traffic uses to come back to your company with BGP.
For doing this as it has been explained in the other thread you need to use route filters so that you send only net XXX.XX.188.0 to ISP2 and all other prefixes to ISP1.
You can do this with route-maps or with prefix-lists or access-lists.
Let's go to the outbound traffic.
But to control how traffic is sent to the internet BGP is not enough.
First of all, you receive just two BGP default routes or at least you accept only them.
to perform outbound routing based on source address you need to add PBR in your scenario.
so you need the following
access-list 11 permit XXX.XX.188.0 0.0.0.255
you will prefer default route received by ISP1 by using
router bgp ASN_NUMBER
neighbor XX.XXX.152.5 weight 500
neighbor XX.XXX.152.5 local-preference 400
now you need a route-map to divert to ISP2 traffic specified in ACL 11
route-map PBRtoISP2 permit 10
match ip address 11
set ip next-hop XX.XXX.237.9
you need to apply this on internal interface(s) that receive traffic directed to the internet
let's suppose it is gi0/0
int gi0/0
ip policy route-map PBRtoISP2
This should complete your configuration.
For BGP filtering refers to the other thread or use the following
ip prefix-list only188 permit XXX.XX.188.0/24
! check the syntax of the following line
ip as-path access-list 1 permit ^$
route-map toISP2 permit 10
match ip address prefix-list only188
for ISP1
route-map toISP1 deny 10
match ip address prefix-list only188
route-map toISP1 permit 20
match ip as-path 1
router BGP ASN_NUMBER
neighbor XX.XXX.152.5 route-map toISP1 out
neighbor XX.XXX.237.9 route-map toISP2 out
Hope to help
Giuseppe
