Exam 350-501 topic 1 question 320 discussion

The answer must be B for the following reasons : A and C : mpls ldp autoconfig CAN'T be configured under the interface. It Has to be configured under the router ospf sub config mode D - □ D can't be because mpls ldp autoconfig requires mpls ip to be enabled on an interface first. Which is not the case here. As written in this guide https://www.cisco.com/c/en/us/td/docs/ios/12_2sb/12_2sba/feature/guide/sbadpaut.html --> "if LDP is disabled globally, the mpls ldp autoconfig command fails and generates a console message explaining that LDP must be enabled globally by means of the global mpls ip command first."

Router 1: bash Copy code Router1(config)# interface fa0/0 Router1(config-if)# mpls ip Router1(config-if)# mpls ldp autoconfig Router1(config)# router ospf 1 Router1(config-router)# mpls ldp autoconfig area 0 Router 2: bash Copy code Router2(config)# interface fa0/0 Router2(config-if)# mpls ip Router2(config-if)# mpls ldp autoconfig Router2(config)# router ospf 1 Router2(config-router)# mpls ldp autoconfig area 0

B is excluded because mpls ldp discovery transport-address is a global command A and C are excluded because mpls ldp autoconfig is a router context command.

I choose B due to interface and configuration consistency. I tested both of them in my lab and they both work.

A and C are wrong since "mpls ldp autoconfig" is invalid under the interface. Both B and D will build the ldp neighborship. To pick as the minimum config (must), the correct answer is "D"

I think that is B, I just want to make a quick note that on older IOS versions you will need to run the mpls ip command globally, this configures hop-by-hop globally but does not enable MPLS on the interface. In newer IOS versions it is enabled by default. you can configure LDP to use a physical interface as the transport address. Remember this is not the same as the router ID. This is the address used to create the TCP session. mpls ldp discovery transport-address interface

I think the command "mpls Ip" should be configure under global config instead of under interface config https://www.cisco.com/c/en/us/td/docs/ios/12_2sb/12_2sba/feature/guide/sbadpaut.html#wp1027195