350-029 · Question #138
In Any Transport over MPLS (AtoM) Control word is an optional 4-byte field used in the pseudowire packet. The control word carries generic and Layer 2 payload-specific information to emulate L2…
The correct answer is C. Inserted between the MPLS label stack and the Layer 2 payload. In the Layer 2 circuit IETF drafts, the control word is optional for most Layer 2 protocols, except Frame Relay and ATM AAL5 where it is required, The control word is 32-bit that is inserted between the VC label and the transported layer 2 frame in case of AToM, it's used to…
Question
In Any Transport over MPLS (AtoM) Control word is an optional 4-byte field used in the pseudowire packet. The control word carries generic and Layer 2 payload-specific information to emulate L2 packets correctly. In pseudowire packet, where is this Control Word inserted ?
Options
- AInserted between the MPLS label stack and the Layer 3 payload
- BInserted between the MPLS label stack and the Layer 3 Header
- CInserted between the MPLS label stack and the Layer 2 payload
- DInserted between the MPLS label stack and the Layer 2 header
How the community answered
(34 responses)- A3% (1)
- B6% (2)
- C82% (28)
- D9% (3)
Explanation
In the Layer 2 circuit IETF drafts, the control word is optional for most Layer 2 protocols, except Frame Relay and ATM AAL5 where it is required, The control word is 32-bit that is inserted between the VC label and the transported layer 2 frame in case of AToM, it's used to carries extra information such as protocol control information and sequence number, this information is needed to correctly and efficiently carry the layer 2 protocol across the MPLS network.
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