Transit ISP bgp configuration..Only default route adverisement..!

In this blog, we will see how we will advertise only default route to our transit peer . find the diagram below.

bgp 456

 graceful-restart

 graceful-restart peer-reset

 undo check-first-as

 peer 10.10.1.2 as-number 789

peer 2XXX:XXX:XXX:2::2 as-number 789

 ipv4-family unicast

 peer 10.10.1.2 enable

  peer 10.10.1.2 route-policy ASN-789-IN import

  peer 10.10.1.2 route-policy ASN-789-OUT export

  peer 10.10.1.2 default-route-advertise

ipv6-family unicast

  undo synchronization

  peer 2XXX:XXX:XXX:X::2 enable

  peer 2XXX:XXX:XXX:X::2 route-policy ASN-789-IPv6-IN import

  peer 2XXX:XXX:XXX:X::2 route-policy ASN-789-IPv6-OUT export

  peer 2XXX:XXX:XXX:X::2 default-route-advertise

 

################Downlink IPv4 Route filtering configuration#############

ip ip-prefix ASN-789-OUT index 10 permit 0.0.0.0 0

ip ip-prefix ASN-789-IN index 11 permit 1XX.XXX.XXX.0 23

route-policy ASN-789-OUT permit node 20

 if-match ip-prefix ASN-789-OUT

route-policy ASN-789-IN permit node 20

 if-match ip-prefix ASN-789-IN

################Downlink IPv6 Route filtering configuration#############

ip ipv6-prefix ASN-789-IPV6-IN index 10 permit 2XXX:2XXX:: 32

ip ipv6-prefix ASN-789-IPV6-OUT index 10 permit :: 0

route-policy ASN-789-IPv6-OUT permit node 20

 if-match ipv6 address prefix-list ASN-789-IPV6-OUT

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route-policy ASN-789-IPv6-IN permit node 20

 if-match ipv6 address prefix-list ASN-789-IPV6-IN

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