Q34MPLS and Segment Routing
The network-engineering team at a service provider is integrating several newly acquired networks into a more scalable, common Unified MPLS architecture. The new network architecture will provide end-to-end VPNv4 and VPNv6 services with these requirements: - The core layer uses IS-IS in Area 0 as its IGP. - The aggregation layers use OSPF in Area 0 as their IGP. - LDP distributes label bindings within each IGP domain. Which task must the network engineer complete when implementing this new architecture?
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Discussion · 8
9
I guess it's 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 also be known in the aggregation IGP, 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 set with the next-hop-self all feature to let RRs change next hop to their own loopback IP even for the reflected prefixes. LDP works normally inside the IGP islands, however ***BGP labeled unicast layer*** is in charge of the inter network segment label exchange.
3
also see: https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/118846-config-mpls-00.html
3
Yep, I also agree with D, since it needs to be bgp lu, C is not right because we do not want to keep the next hop, we would need to change bgp ibgp next hop.
D 2
Selected Answer: D
I think it's 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 2
Selected Answer: D
D is right.
1
D is meant to be the correct answer, since in these kinds of scenarios, we don't need to do any redistribution and everything is handled by BGP plus label
1
I think it should be A
n Figure 3 you can see there are three segments with Label Discovery Protocol Labeled Switches Path (LDP LSP) and the access network does not have LDP enabled. The goal is to connect them together so there is one single MPLS path (Internal BGP (iBGP) hierarchal LSP) between Pre-Aggregation (Pre-Agg) Nodes. Since the network is one BGP Autonomous System (AS), all sessions are iBGP sessions. Each segment runs its own IGP (OSPF, IS-IS,or EIGRP) and LDP LSP paths inside the IGP domain. Within Cisco Unified MPLS, the routers (ABRs) that connect 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 in the Cisco Unified MPLS Architecture are referred to as ABRs.
https://www.cisco.com/c/en/us/support/docs/multiprotocol-label-switching-mpls/mpls/118846-config-mpls-00.html
1
D looks correct
https://www.noction.com/blog/bgp-labeled-unicast-bgp-lu