Hello,
I labbed this and it seems to work. Watch out though, there are a few bugs related to advertise-maps. I used IOS 12.2(24) Enterprise Plus.
Here is what I configured (obviously you will use other address ranges):
Router R1 is in AS1, router R2 is in AS2, and router R3 is in AS3. R1 has a EBGP peer relationship with both AS2 and AS3 routers (which is equivalent to your scenario). R1 advertises the following address spaces:
192.168.10.0
192.168.11.0
192.168.12.0
192.168.13.0
192.168.14.0
192.168.15.0
192.168.16.0
192.168.17.0
Fom R2, R1 receives the prefix 2.2.2.2/32, and from R3 it receives prefix 3.3.3.3/32 (these prefixes will be used to set the advertise condition).
Both R2 and R3 receive all prefixes, but after configuring the adveryise-maps, they will only receive half of the prefixes, unless the prefix received from the other router is not in the routing table of R1.
Here is the configuration of R1:
R1#
Current configuration : 2289 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname R1
!
!
ip subnet-zero
!
frame-relay switching
!
!
!
interface Loopback1
ip address 192.168.10.1 255.255.255.0
!
interface Loopback2
ip address 192.168.11.1 255.255.255.0
!
interface Loopback3
ip address 192.168.12.1 255.255.255.0
!
interface Loopback4
ip address 192.168.13.1 255.255.255.0
!
interface Loopback5
ip address 192.168.14.1 255.255.255.0
!
interface Loopback6
ip address 192.168.15.1 255.255.255.0
!
interface Loopback7
ip address 192.168.16.1 255.255.255.0
!
interface Loopback8
ip address 192.168.17.1 255.255.255.0
!
interface Ethernet0
ip address 192.168.6.1 255.255.255.0
no ip route-cache
no ip mroute-cache
!
interface Serial0
ip address 192.168.3.2 255.255.255.0
encapsulation ppp
no ip route-cache
no ip mroute-cache
clockrate 64000
!
interface Serial1
ip address 192.168.1.2 255.255.255.252
encapsulation frame-relay
no ip route-cache
no ip mroute-cache
clockrate 64000
frame-relay map ip 192.168.1.1 102 broadcast
no frame-relay inverse-arp
frame-relay intf-type dce
!
router bgp 1
bgp log-neighbor-changes
network 192.168.10.0
network 192.168.11.0
network 192.168.12.0
network 192.168.13.0
network 192.168.14.0
network 192.168.15.0
network 192.168.16.0
network 192.168.17.0
neighbor 192.168.1.1 remote-as 2
neighbor 192.168.1.1 advertise-map ADVERTISE-AS3 non-exist-map NON-EXIST-AS3
neighbor 192.168.3.1 remote-as 3
neighbor 192.168.3.1 advertise-map ADVERTISE-AS2 non-exist-map NON-EXIST-AS2
!
ip classless
no ip http server
!
access-list 1 permit 192.168.10.0
access-list 1 permit 192.168.11.0
access-list 1 permit 192.168.12.0
access-list 1 permit 192.168.13.0
access-list 2 permit 192.168.14.0
access-list 2 permit 192.168.15.0
access-list 2 permit 192.168.16.0
access-list 2 permit 192.168.17.0
access-list 3 permit 2.2.2.2
access-list 4 permit 3.3.3.3
route-map NON-EXIST-AS2 permit 10
match ip address 3
!
route-map NON-EXIST-AS3 permit 10
match ip address 4
!
route-map ADVERTISE-AS2 permit 10
match ip address 1
!
route-map ADVERTISE-AS3 permit 10
match ip address 2
!
!
!
line con 0
line aux 0
transport input all
line vty 0 4
login
!
You can test this by shutting down or disconnecting either one of the routers that peer with R1. The routes from the one will be installed on the other.
Sort of a long post, let me know if this is not entirely clear...
Regards,
Georg
