While your MPLS core is using Cisco Routers, the core of a company you have acquired is not. After extending your MPLS VPN networks by integrating the cores, you discover that the end-to-end LPS path between PE routers can’t be established. Which of the following may have caused this problem?

A.
The BGP protocol versions do not match

B.
You are using Cisco Proprietary TDP in your existing core

C.
MP-BGP is not supported between different vendors

D.
The MTUs do not match

E.
MPLS is not supported between different vendors