Juniper Networks Certified Internet Specialist (JNCIS) Exam: MPLS Label Operations
Question
Your network is using the Junos default MPLS settings.
Which label operation is performed by penultimate router?
Answers
Explanations
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A. B. C. D.A
The pop operation removes a label from the beginning of the packet. Once the label is removed, the TTL is copied from the label into the IP packet header, and the underlying IP packet is forwarded as a native IP packet.
In MPLS (Multiprotocol Label Switching), labels are assigned to packets to identify the path they should take through the network. Each router in the path performs a label operation on the packet, adding, swapping, or removing the label as necessary.
The penultimate router is the router that is just before the last router in the path. It is responsible for removing the label assigned by the last router and forwarding the packet to its final destination.
The label operation performed by the penultimate router is "pop", which means it removes the label assigned by the last router before forwarding the packet to the final destination. This operation is also known as PHP (Penultimate Hop Popping).
The reason for performing a "pop" operation is to reduce the processing load on the final router in the path, which may have to process a large number of packets. By removing the label before the packet reaches the final router, the penultimate router can reduce the processing load on the final router and improve the overall performance of the network.
Therefore, the correct answer to the given question is (A) pop.
