We have a customer who is using our MPLS cloud for data transfer and has a backup via internet. The PE to CE is BGP and backup is using OSPF as routing protocol. Whenever the access circuit goes down at one of the site (Say Site A), the backup kicks in and site is able to access the servers at HO via OSPF. However the other sites loose the reachability to this site (Site A) and we need to manually advertize the subnets of the Site A in BGP at HO so that other sites can reach the Site A. Now we want to make this automated to avoid manual intervention and operations to be smoother.
Can anyone suggest the mechanism? Can we use BGP conditional advertisement feature i.e advertize-map and non-exist-map? If yes then how to itilize this feature?