2.2 Data, Control, and Management Plane Technologies 400-007 Practice Questions (Page 3)

Questions 11–15

1. 11expert · hard

   A service provider is designing a new MPLS core to carry both Layer 3 VPN and Layer 2 VPN services. The design team is evaluating whether to run BGP route reflectors in the core or to use a full mesh of iBGP sessions between all PE routers. The network will grow from 20 PEs to 200 PEs over three years. The operations team has limited experience with BGP route reflection and prefers a design that minimizes the number of control-plane sessions to manage. However, the design must also ensure that the control plane remains stable and does not introduce a single point of failure for VPN route distribution. Which design approach best meets these requirements?

   • ADeploy a single BGP route reflector in the core and have all PEs peer with it, because this minimizes the number of sessions to the absolute minimum and is the simplest design for the operations team.
   • BDeploy a full mesh of iBGP sessions between all PE routers, accepting the O(n²) session growth, because it eliminates any single point of failure and requires no new technology for the operations team.
   • CDeploy a pair of redundant BGP route reflectors in the core, with each PE establishing a session to both reflectors, and configure the reflectors as a cluster to avoid loop issues.
   • DUse BGP confederations to break the AS into sub-ASes, with full iBGP mesh inside each sub-AS and a few inter-sub-AS sessions, because this provides the best balance of scalability and operational familiarity.
   Reveal Solution Discussion Select an answer first
2. 12foundation · easy

   What is a typical impact of a control plane failure on the data plane in a network device?

   • AThe data plane immediately stops forwarding all traffic.
   • BThe data plane may continue forwarding traffic using existing forwarding table entries, but may not adapt to network changes.
   • CThe data plane automatically re-routes traffic based on its own calculations.
   • DThe data plane starts using management plane protocols to recover.
   Reveal Solution Discussion Select an answer first
4. 13foundation · easy

   In operational design, which approach is used to improve control plane scalability by reducing the number of routing peers and the amount of routing information exchanged?

   • AEnabling QoS queuing on all interfaces
   • BRoute summarization and route reflectors
   • CIncreasing the MTU on all interfaces
   • DUsing SNMP to poll devices more frequently
   Reveal Solution Discussion Select an answer first
5. 14application · medium

   A multinational corporation is deploying a new SD-WAN fabric. The network operations team needs to centrally manage and monitor the health of all edge devices and ensure that configuration changes are rolled out consistently. The design must also provide a secure out-of-band channel for the control plane to establish tunnels, even if the underlay network is partially congested. Which set of technologies should the design incorporate to meet these management and control-plane requirements?

   • AUse a centralized SD-WAN controller for configuration management and monitoring, and use DTLS to secure the control plane's communication with the edge devices.
   • BUse NETCONF/YANG for configuration management and rely on the underlay's IGP (e.g., OSPF) to carry the SD-WAN control plane traffic.
   • CUse SNMP for device monitoring and NetFlow for traffic analysis, and rely on the in-band data plane for all control traffic.
   • DUse CLI-based configuration management via SSH to each edge device, and use IPsec for all data and control plane traffic.
   Reveal Solution Discussion Select an answer first
6. 15foundation · easy

   In operational design, which practice is used to improve data plane resilience by providing redundant forwarding paths that can be used if a primary path fails?

   • ADisabling routing protocol authentication
   • BIncreasing the SNMP polling interval
   • CImplementing ECMP (Equal-Cost Multipath) or link redundancy
   • DUsing a single high-capacity link instead of multiple links
   Reveal Solution Discussion Select an answer first