CISSP Question #1410: Real Exam Question with Answer & Explanation

Question

Which Wide Area Network (WAN) technology requires the first router in the path to determine the full path the packet will travel, removing the need for other routers in the path to make independent determinations?

Options

• AMultiprotocol Label Switching (MPLS)
• BSynchronous Optical Networking (SONET)
• CSession Initiation Protocol (SIP)
• DFiber Channel Over Ethernet (FCoE)

Explanation

Multiprotocol Label Switching (MPLS) is a WAN technology that requires the first router in the path to determine the full path the packet will travel, removing the need for other routers in the path to make independent determinations. MPLS works by adding a label to each packet at the ingress router, which indicates the forwarding equivalence class (FEC) of the packet. The FEC is a group of packets that share the same destination and quality of service (QoS) requirements. The label is then used by the intermediate routers to forward the packet along a predetermined label-switched path (LSP), without inspecting the packet header or performing routing lookups. The label is removed at the egress router, and the packet is delivered to the destination. MPLS can improve the performance, scalability, and efficiency of WAN networks, as well as support multiple protocols and services.

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