[c-nsp] BGP conditional advertisemet - NON-EXIST route map's access-list problem

[Burak Dikici]

  I am getting full internet route from ISP-1 and getting just a default
route from ISP-2. ( Both ISP connection is terminated on the one central
site router.) What i am trying to do , to make an ISP-2 connection is
completly backup for inbound traffic. To achieve that ,i am trying to use
BGP conditional advertisemet configuration. I have got a problem with
NON-EXIST route map's access-list. In the NON-EXIST router map i am using
the commands which is written below ;


ip as-path access-list 1 permit ^200 !!! (ISP-1 AS number) !!!

access-list 65 permit any !!! (permit any packet from ISP-2) !!!

route-map NON-EXIST permit 10 !!! (this matches any route from AS200) !!!
match ip address 65
match as-path 1


router bgp 10 !!! (My AS number) !!!
neighbor X.Y.Z.W (ISP-2 ip address) advertise-map ADVERTISE non-exist-map
NON-EXIST !!! (What is says. This router will only advertise "networks
defined in the route-map named ADVERTISE" if and only if "routes that are
defined in the route-map named NON-EXISTS" do not appear in the BGP routing
table.) !!!


with this configuration when the ISP-1 connection is up , my router still
adversite my subnet to the ISP-2. What should i write in the access-list 65
to not advertise my subnet to the ISP-2 until the failure of ISP-1
connection ? ( As i said , i am getting the full internet table from ISP-1.)


Kind Regards...

Burak Dikici