Need help fixing old BGP setup
I have inherited a piecemeal network that has many things I haven't figured out yet. I'm no network engineer so I lean of the TAC for most complex changes.
I have an issue with our BGP changing routes today for some reason and I'm trying to figure out how I can fix it and prevent it from happening again.
At some point today our BGP on our edge router (CORE-RTR1) connected to our ISP changed it default route and Gateway of Last Resort from our ISP to another router (OLD-RTR1) on our network that USED TO have a redundant internet connection.
This cause a loop where the other two rouers were just sending traffic back and forth to one another. During this - I realized I need to reset/recalculate the routes. In a hurry - I rebooted CORE-RTR1. This fixed this routing issue but I'm pretty sure caused me to lose as information which would have let me see the reason for the route change.
My BGP routes are correct now but I want to prevent them from changing again.
The BGP section on the two routers is below. Please let me know what additional info would be helpful.