Exactprep 400-007 Questions

In a full-mesh iBGP design, every router must establish and maintain a BGP session with every other router. As the number of routers increases, the number of BGP sessions and the amount of BGP processing increases exponentially. This leads to high CPU utilization, especially in devices with limited processing capabilities, such as distribution routers.

Themost cost-effectiveandscalablesolution in this scenario is toimplement route reflectors (RRs)on the two core routers. Route reflectors significantly reduce the number of iBGP peerings required, eliminating the full mesh requirement by allowing the distribution routers (RR clients) to establish a single iBGP session with the route reflector. The route reflector handles route advertisement to other RR clients, thereby reducing overhead on the distribution routers.

This solution adheres to CCDE v3.1 design principles for:

Optimizing control plane scalability

Reducing unnecessary CPU load from control protocols

Ensuring a maintainable and scalable enterprise BGP deployment

Why the other options are incorrect:

BandD(Increasing memory): Addresses only hardware capacity without solving the root cause (BGP scaling issue).

C(Using eBGP): Misaligned with enterprise internal network design; eBGP adds complexity in route policy and administrative boundaries.

E(Increasing bandwidth): Bandwidth does not alleviate CPU overhead caused by BGP processing.

Implementing route reflectors aligns with both scalability and cost-efficiency goals as prescribed in the CCDE v3.1 methodology.

B (Minimize operational costs): A common business goal to reduce long-term operating expenses.

E (Reduce complexity): Simplifying designs reduces operational overhead, risk, and failure domains.

Why other options are incorrect:

A: Resiliency is a design goal, but not a business objective itself.

C: Endpoint posture is a technical security feature.

D: Faster obsolescence contradicts business optimization.

In data center migration scenarios, when legacy and VXLAN EVPN networks are connected for host mobility, a critical step is to ensure a seamless Layer 3 gateway handoff. This is typically achieved using VRRP (or HSRP) where both the old and new gateways share the same virtual IP.

The final step involves:

Increasing the VRRP priority on the new VXLAN-enabled infrastructure to make it the active default gateway.

Ensuring that hosts retain their original default gateway (no reconfiguration required).

Only after the new gateway is active, the legacy SVIs can be gracefully shut down.

This method ensures no packet loss or disruption to host connectivity during or after migration.

It aligns with CCDE v3.1 under the “Network Architecture Principles” domain, particularly for data center transformation, operational consistency, and seamless L2–L3 handoff design patterns.

Strictly Centralized Control Plane: Single point of failure and difficult to horizontally scale, most often used in experimental SDN controllers.

Semi or Logically Centralized Control Plane: Possible convergence difficulties, N instances to configure and manage, easy to horizontally scale, just deploy.

Fully Distributed Control Plane: Resilient to many failure points but still susceptible to issues around synchronization of state, canonical approach, one instance of control plane per device (logical or real).