Exam 350-501 topic 1 question 184 discussion

I guess is D, look... In e-learning Cisco (section 9.11), we have: Redistribution of core IGP into aggregation IGPs and vice-versa is in principle not performed as it would defeat the purpose of the UMPLS scaling benefits. The only exception is the redistribution of the RR (ABR) loopbacks from core IGP into aggregation IGPs because the loopback prefix of the RRs must be known in the aggregation IGP also, so that BGP on the PE router can peer with the loopback of the RR. Other prefixes are never redistributed between the core and aggregation layers. Route Reflectors are configured with the next-hop-self all feature to allow for RRs to change next hop to their own loopback IP even for the reflected prefixes. LDP operates normally inside the IGP islands, however ***BGP labeled unicast layer*** is responsible for the inter network segment label exchange.

D is correct.

I think its D: https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/multiprotocol-label-switching-mpls/119191-config-unified-mpls-00.html#anc4

D seems correct https://www.noction.com/blog/bgp-labeled-unicast-bgp-lu

I think it's supposed to be A n Figure 3 you can see that there are three segments with Label Discovery Protocol Labeled Switches Path (LDP LSP) and the access network does not have LDP enabled. The objective is to join them together so that there is a single MPLS path (Internal BGP (iBGP) hierarchal LSP) between Pre-Aggregation (Pre-Agg) Nodes. As the network is a single BGP Autonomous System (AS), all sessions are iBGP sessions. Each segment runs its own IGP (OSPF, IS-IS,or EIGRP) and LDP LSP paths within the IGP domain. Within Cisco Unified MPLS, the routers (ABRs) that join the segments must be BGP inline route-reflectors with the Next-Hop-Self and RFC 3107 in order to carry a IPv4 + Label configured on the sessions. These BGP speakers are within the Cisco Unified MPLS Architecture referenced to as ABRs. https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/118846-config-mpls-00.html

D is supposed to be the correct answer as in these kinds of scenarios, we don't need to do any redistributions and everything's handled by BGP plus label

Yep, I go along with D also, as needs to be bgp lu, C is not correct as we don’t want to preserve the next hop, we would need to change bgp ibgp next hop.