BGP configuration

does anyone have any information on how to set up the bgp.cnf to route across a VPN?
I cannot find any info in the documentation.

Hello!

You will probably need GRE over IPsec as the GRE will route at a layer 2.

Here is a specific document

http://ftp1.digi.com/support/documentation/qn_020_gre_over_ipsec_with_bgp.pdf