Comprehensive and Detailed In-Depth Explanation:
1. Understanding the MPLS Data Flow in the Figure
* PC1 (1.1.1.1) sends a ping to PC2 (3.3.3.3).
* The MPLS domain includes R1, R2, and R3.
* R1 pushes an MPLS label onto the packet (Label: 300).
* Packets from PC1 to PC2 are label-switched (MPLS forwarding).
* Packets from PC2 to PC1 do not carry an MPLS label (IP forwarding).
2. Evaluating Each Answer Option
* Option A: "If the device is R3, R3 forwards the packet from PC1 to PC2 over an IP route."
* Incorrect.
* The packet carries an MPLS label (Label 300) when entering the MPLS domain.
* This means that R3 forwards the packet using MPLS, not a standard IP route.
* If R3 were using an IP route, there would be no MPLS label in the packet.
* Option B: "Packets from PC1 to PC2 are forwarded based on MPLS labels in the MPLS domain.
"
* Correct.
* The packet capture shows an MPLS label (Label 300), proving that PC1's traffic is being forwarded using MPLS switching inside the MPLS domain.
* This confirms that MPLS is being used for forwarding in one direction (PC1 # PC2).
* Option C: "Packets from PC2 to PC1 are forwarded based on the IP packet header in the MPLS domain."
* Correct in concept but incorrect in context.
* The packet capture shows that the return traffic (PC2 # PC1) does not have an MPLS label.
* However, the phrase "in the MPLS domain" makes this statement misleading, as R3 is forwarding based on pure IP routing, not MPLS forwarding.
* Option D: "PC1 pings PC2."
* Correct.
* The packet capture clearly shows ICMP Echo Request (ping) from PC1 (1.1.1.1) to PC2 (3.3.3.3) and an ICMP Echo Reply from PC2.
* This confirms that PC1 is pinging PC2 successfully.
Final answer:
# B and D are correct.
HCIP-Datacom-Advanced Routing & Switching Technology References:
* MPLS Label Forwarding and Static LSPs
* MPLS vs. IP Routing in Different Traffic Flows
* Packet Header Analysis in MPLS Networks