BGP conditional adv??

Hi experts,

I have some difficulties to catch this scenario with BGP conditional adv:

R1-----------R2
|
|
R3

R1 has lo0 1.1.1.1/8, R2 has Lo0 2.2.2.2/8 and R3 has also Lo0
3.3.3.3/8. All RTs are in same AS and all of them advertise their
loopbacks.
Task is next:
- if both nets 1.0.0.0 and 2.0.0.0 are up, R1 should advertise them both
- if 1.0.0.0/8 is DOWN, R1 should not advertise 2.0.0.0/8 to R3
- if 2.0.0.0/8 is DOWN, R1 should only advertise net 1.0.0.0/8 to R3

Solution on R1:
acl 1 permit 1.0.0.0 0.255.255.255
acl 2 permit 2.0.0.0 0.255.255.255

route-map ADV per 10
   match ip add 2
route-map EXIST per 10
  match ip add 1

router bgp 100
   neighbor R3 adv-map ADV exist-map EXIST

So, from my point of view this task should do next:
- if 1.0.0.0/8 is UP (2.0.0.0/8 can also be UP) advertise 2.0.0.0/8 to
R3 (task asks you to NOT advertise)
- if 1.0.0.0/8 is DOWN (2.0.0.0/8 can also be DOWN), do not advertise anything

This solution is correct, but I don't get the logic?

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Received on Wed Feb 24 2010 - 19:18:43 ART