An engineer is troubleshooting AToM on an IOS XE router and receives an error when creating the xconnect. Which command does he need to complete to create the xconnect in AToM?

Question

Options

• Aencapsulation mpls
• Bencapsulation 12tpv3
• Cprotocol 12tpv3
• Dprotocol none

• A
  91% (30)
• B
  3% (1)
• C
  6% (2)

Explanation

Encapsulation mpls is required on the pseudowire interface before IOS XE will accept the xconnect command for AToM, because AToM literally stands for Any Transport over MPLS - the data plane relies on MPLS label switching, so the interface must declare MPLS as its encapsulation first or the router rejects the xconnect with an error.

Why the distractors are wrong:

• B & C (l2tpv3): L2TPv3 is an entirely different tunneling technology (IP-based, not MPLS-based); using it here would configure an L2TPv3 pseudowire, not an AToM circuit.
• D (protocol none): This disables LDP signaling for static pseudowires, which is a valid option after the xconnect is created, but it does not satisfy the prerequisite that triggers the error in the first place.

Memory tip: The acronym does the work - AToM = Any Transport over MPLS, so the missing piece is always MPLS encapsulation. If the router complains about the xconnect, ask "did I tell it to use MPLS yet?"

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