[c-nsp] BGP advertisements more specific than IGP

[James Urwiller]

I have a BGP multi-homed invironment that I am having problems balancing inbound traffic, besides prepends which don't seem to be helping anymore, I have heard that announcing my networks more specifically could also influence inbound traffic.  My question is, for example… If I have a /23 that I am using as a /23 in OSPF, can I announce that in BGP more specifically (2, /24's)  without having to them break it up internally as well?  What I foresee happening is this..

Example:
BGP:
Network 192.168.0.0/24
Network 192.168.1.0/24

OSPF:
Network 192.168.0.0/23

I would think in this scenario, the IP addresses 192.168.1.0 and 192.168.0.255 would not have a route in BGP, even though they are valid addresses for use when used as a /23.  Since I would be multi-homed, I would still advertise the network as the aggregate /23 on the circuit I don't want to take as much traffic, so would those IP addresses in this scenario still work, but only through the circuit I advertise as the aggregate??

James Urwiller
Network Operations Manager
CCNA 11567125
American Broadband
402-426-6257 - Office
402-278-1875 - Cell
402-426-6273 - Fax
jurwiller at americanbb.com<mailto:jurwiller at americanbb.com>