Multisite BGP - One site behind OpenVPN

[Michael McConnell]

Hello all,

I’ve been debating with myself the best way to handle this situation. I have a two site deployment with a /23 prefix available. I wish to assign 1 /24 to site one (Main), and 1 /24 to site two (Satellite) and then link them via OpenVPN. I am debating the pro’s and con’s of running bird at both sites with BGP or just doing a static route at site two behind the VPN.

BGP at Both Sites;
- Announce the /23 to the Internet at Main Site
- Announce one /24 and use locally at Main site
- Run a BGP session between Main and Satellite and announce the 2nd /24 at site two
I feel the main advantage here is that I can scale if more connectivity ever comes to the Satellite site.

BGP at single site with static route over VPN
- Announce the /23 to the Internet at Main Site
- Use VPN as default gateway for all satellite users

I feel like I must be missing something in both of these designs, can anyone see any issue with either of these setups and possibly suggest why one might be better over the other?

Thanks for your thoughts and time!
Mike