PE-CE Routing Protocols
Routing needs to occur between the PE and CE routers. The PE-CE routing protocols that Cisco IOS supports are static routing, RIPv2, Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (EIGRP), Intermediate System-to-Intermediate System (IS-IS), and eBGP.
Strictly speaking, the connected routes are not a routing protocol. However, to ensure connectivity, it is best practice to redistribute the connected routes on the PE router into BGP. That way, when the user launches a ping from a CE router to the remote CE router, the return packet is routed back. By default, if the user sends a ping and does not specify the source IP address, it takes as the source IP address the IP address ...