From: simon hart (simon@harttel.com)
Date: Thu Oct 13 2005 - 07:40:22 GMT-3
Jian,
The commands are quite different
The conditional advertisement will advertise a route when certain conditions
are met. These conditions are set by the advertise-map and the
non-exist-map, both are created via route-maps.
If the condition in the non-exist-map is not met then the prefix in the
advertise map is sent. So if I have the following
route-map advertise permit 10
match ip address prefix-list 10
route-map noexist permit 10
match ip address prefix-list 20
ip prefix-list 10 permit 129.1.1.0/24
ip prefix-list 20 permit 192.168.1.0/24
Neighbor 10.10.10.1 advertise-map advertise non-exist-map noexist
In this situation if 192.168.1.0 is in the bgp table, then 129.1.1.0 does
not get advertised to this peer. If 192.168.1.0 is not in the bgp table
then 129.1.1.0 will be advertised to the peer.
Now the bgp inject is used to inject more specific prefixes into an
advertisement. Say for argument I am recieving the prefix 10.0.0.0, however
I wish to advertise 10.10.10.0/24, I need to 'inject' this into the bgp
table. So without using the inject map, the router will advertise the
10.0.0.0 prefix to all peers and with it, it will advertise the more
specific prefix 10.10.10.0/24 to peers.
This will only happen whiles 10.0.0.0 is in the BGP routing table and that
the source of the advertising router matches the match ip route-source
within the exist-map of this command.
HTH
Simon
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Jian
Gu
Sent: 13 October 2005 07:46
To: Cisco certification
Subject: BGP conditioanl inject and conditional advertisement
Hi, Could someone please explain to me what exactly the difference is
between bgp conditional inject and bgp conditional advertisement?
conditional inject: bgp inject-map <map_name> exist-map <map_name>
and conditional advertisement: neighbor <map_name> advertise-map <map_name>
non-exist-map|exit-map <map_name>
Besides that conditional inject does not have "non-exist-map" option, both
seem to achieve the same goal, also why one is configured under "router bgp"
while the other is configured under "neighbor" ?
Thanks,
Jian
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