350-501 · Question #260
The network-engineering team of a service provider is integrating several recently acquired networks into a more scalable common Unified MPLS architecture. The new network architecture will support…
The correct answer is A. Configure BGP-LU between ABR routers of each IGP domain to carry MPLS label information in. 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…
Question
The network-engineering team of a service provider is integrating several recently acquired networks into a more scalable common Unified MPLS architecture. The new network architecture will support end-to-end VPNv4 and VPNv6 services with these requirements:
- The IGP of the core layer is IS-IS In Area 0.
- The IGP of the aggregation layers is OSPF in Area 0.
- The LDP protocol Is used to distribute label bindings within each IGP
domain. Which task must the network engineer perform when implementing this new architecture?
Options
- AConfigure BGP-LU between ABR routers of each IGP domain to carry MPLS label information in
- BConfigure a BGP session between the ABR routers of each IGP domain to exchange VPNv4 or
- CConfigure the ABR in each IGP domain to preserve next-hop information on all VPNv4 and VPNv6
- DConfigure mutual redistribution of each IGP domain's loopback prefix to provide end-to-end LDP
How the community answered
(62 responses)- A74% (46)
- B3% (2)
- C16% (10)
- D6% (4)
Explanation
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 config-mpls-00.html
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