I have a MPLS WAN with Verizon that connects my 6 locations. My routers are running BGP. I'm far from an expert so be kind.
Verizon added fiber connections at 3 of my locations. These fiber circuits will replace my copper lines I have now. So I received new BGP IP info from Verizon and I connected up the cables to a different interface on the router. So the current WAN cables are still connected.
So I shutdown the current interface and I'm assuming the new BGP routes will take affect but they don't. The info below is from router 1.
router bgp 65001
timers bgp 10 30
neighbor 152.176.XXX.XXX remote-as 65000 (current BGP)
neighbor 199.220.XXX.XXX remote-as 65000 (new BGP)