Last time we built a network with two adjacent BGP routers. Now let’s see what happens when we add a core router between them:

There are at least four ways to get connectivity between PE2 and EXT routers. The lab exercise doesn’t allow you to use route redistribution or aggregation/default route. You could use MPLS (or SRv6) if you wish, or give up and do what’s usually done in large networks running BGP.