An engineer is troubleshooting an EoMPLS circuit on a Cisco IOS XR router interface that removes a VLAN from the distribution layer. Which configuration should the engineer apply in order to…

Question

Options

• Ainterface GigabitEthernet 0/10.l2transport
• Binterface GigabitEthernet 0/10.10
• Cinterface GigabitEthernet 0/10.10 l2transport
• Dinterface GigabitEthernet 0/10.10 l2transport

• B
  2% (1)
• C
  94% (50)
• D
  4% (2)

Explanation

Option C is correct because IOS XR requires the l2transport keyword appended after the subinterface number in the interface command to enable Layer 2 transport mode, which is necessary for EoMPLS pseudowire signaling - the subinterface (.10) maps to the VLAN being stripped at the PE router edge before the traffic is encapsulated into an MPLS pseudowire.

Why the distractors are wrong:

• A is syntactically invalid - it uses .l2transport as the subinterface identifier itself, rather than as a trailing keyword after a numeric subinterface (.10).
• B creates a standard Layer 3 subinterface with no L2 transport capability; it cannot participate in EoMPLS because it lacks the l2transport keyword entirely.
• D appears identical to C in this question, which is likely a formatting error in the exam - watch for subtle differences (extra spaces, missing numbers) in real exam versions.

Memory tip: Think of the IOS XR formula as Number then Mode - you must declare the subinterface number first (.10), then declare its mode (l2transport). If either piece is missing or swapped, the interface won't function as an EoMPLS endpoint.

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