Which statement about MPLS LDP router ID is true?
Click on the arrows to vote for the correct answer
A. B. C. D.B.
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_ldp/configuration/12-4m/mp-ldp-12-4m-book.pdfMPLS LDP (Multiprotocol Label Switching Label Distribution Protocol) is a protocol used to establish label-switched paths (LSPs) in an MPLS network. The MPLS LDP router ID is used as a unique identifier for the LDP-speaking routers in the network. The router ID is a 32-bit value that is used to identify the router in the network.
Now, let's go through each answer option to determine which one is true:
A. If not configured, the operational physical interface is chosen as the router ID even if a loopback is configured. This statement is false. By default, the router ID is chosen as the highest IP address on any loopback interface that is configured. If no loopback interface is configured, the router ID is chosen as the highest IP address on any operational physical interface. However, if a loopback interface is configured, it is preferred over any physical interface.
B. The loopback with the highest IP address is selected as the router ID. This statement is true. As mentioned earlier, if a loopback interface is configured, the router ID is chosen as the highest IP address on any loopback interface that is configured. If multiple loopback interfaces are configured, the router ID is chosen as the highest IP address among them.
C. The MPLS LDP router ID must match the IGP router ID. This statement is false. The MPLS LDP router ID does not have to match the IGP router ID. However, it is recommended that the router ID is chosen from a stable and unique source, such as a loopback interface, to avoid any inconsistencies in the network.
D. The force keyword changes the router ID to the specified address without causing any impact. This statement is false. The force keyword is used to manually configure the router ID to a specified address, but it may cause an impact on the network. If the specified address is already in use by another router in the network, it may cause routing inconsistencies and affect the overall network performance.
Therefore, the correct answer is B. The loopback with the highest IP address is selected as the MPLS LDP router ID.