300-515 · Question #132
Which requirement must be implemented when an organization implements BGP as its PE-CE routing protocol and the CE sites exist in the same autonomous system?
The correct answer is C. The PEs must be placed in a different autonomous system from the CEs. When using BGP between a CE and its PE, you almost always run eBGP, which requires the two peers to be in different AS numbers. Placing the PEs in the same AS as the CEs would force you into iBGP for the PE–CE link - an uncommon design that brings additional constraints (like…
Question
Which requirement must be implemented when an organization implements BGP as its PE-CE routing protocol and the CE sites exist in the same autonomous system?
Options
- AThe PE must send labels to the CE.
- BThe AS-Override feature must be configured.
- CThe PEs must be placed in a different autonomous system from the CEs.
- DThe next-hop-self command must be configured on the PE for each VPNv4 neighbor within the
How the community answered
(29 responses)- A14% (4)
- B3% (1)
- C79% (23)
- D3% (1)
Explanation
When using BGP between a CE and its PE, you almost always run eBGP, which requires the two peers to be in different AS numbers. Placing the PEs in the same AS as the CEs would force you into iBGP for the PE–CE link - an uncommon design that brings additional constraints (like full- mesh requirements) and is not supported for standard MPLS L3VPN PE–CE sessions.
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