300-515 · Question #50
Which Layer 2 VPN technology is implemented over an IP core network without the need for MPLS?
The correct answer is D. L2TPv3. L2TPv3 tunnels Layer 2 frames (Ethernet, Frame Relay, ATM, HDLC) directly over an IP backbone using IP protocol 115 - no MPLS label switching required, making it the only option here that operates purely over IP. Why the distractors are wrong: A. VPLS - Virtual Private LAN…
Question
Which Layer 2 VPN technology is implemented over an IP core network without the need for MPLS?
Options
- AVPLS
- BVPWS
- CAToM
- DL2TPv3
How the community answered
(57 responses)- A2% (1)
- B2% (1)
- C5% (3)
- D91% (52)
Explanation
L2TPv3 tunnels Layer 2 frames (Ethernet, Frame Relay, ATM, HDLC) directly over an IP backbone using IP protocol 115 - no MPLS label switching required, making it the only option here that operates purely over IP.
Why the distractors are wrong:
- A. VPLS - Virtual Private LAN Service is a multipoint L2 VPN, but its standard implementation relies on MPLS label-switched paths (LSPs) and LDP/RSVP signaling.
- B. VPWS - Virtual Private Wire Service provides point-to-point L2 circuits but is also an MPLS-based technology (a subset of pseudowire services over MPLS).
- C. AToM - "Any Transport over MPLS" - the name gives it away; AToM explicitly requires an MPLS core to carry L2 frames via pseudowires.
Memory tip: When you see "MPLS" embedded in or synonymous with the technology name (AToM = Any Transport over MPLS; VPLS/VPWS ride MPLS pseudowires), eliminate it. L2TPv3 is the odd one out - it's a Cisco/IETF protocol that predates widespread MPLS adoption and was specifically designed to extend L2 services over plain IP infrastructure.
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