400-007 Exam Dumps - Cisco Certified Design Expert (CCDE v3.1)

A (EoMPLS): Ethernet over MPLS can operate at Layer 2, and MACsec can encrypt traffic before entering the MPLS core.

E (KVPLS): Supports MACsec encryption for Layer 2 DCI services over VPLS solutions.

Why other options are incorrect:

B: MPLS L3 VPN operates at Layer 3, not suitable for MACsec (L2 encryption).

C: DMVPN uses IPsec, not MACsec.

D: GET VPN uses IPsec for L3 traffic encryption.

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The priority queue (strict priority queue) is intended for real-time, delay-sensitive traffic like voice and certain video, which have:

D. Intolerance to jitter: Real-time traffic requires consistent latency.

E. TCP-based application: Many real-time video streams and some financial trading apps use TCP but still require minimal jitter and latency.

CCDE v3.1 emphasizes that strict priority queue should only be used for traffic highly sensitive to delay and jitter to avoid starving other queues.

Why other options are incorrect:

A: HTTP-like small transactions are delay-tolerant.

B: WRED (Weighted Random Early Detection) is used for congestion avoidance, not prioritization.

C: Priority queue is specifically for traffic intolerant to loss and jitter.

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The performance degradation is caused by output queue drops on the 1 Gbps server port. Increasing the queue size allows more data to be buffered during transient congestion periods, preventing packet loss and retransmissions which significantly degrade iSCSI performance.

iSCSI is sensitive to packet loss due to its reliance on TCP.

Increasing the queue depth is a simple, cost-effective method to absorb bursts.

Changing to CIFS (A) is irrelevant since CIFS would suffer similar TCP congestion.

WRED (C) intentionally drops packets during congestion, which is undesirable here.

Enabling TCP Nagle (D) would likely introduce latency and reduce throughput for large data transfers.

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Comprehensive and Detailed Explanation:

To reduce oscillation and improve resiliency:

D: Increasing unequal-cost multipath (UCMP) paths allows the routing protocol to load-share over more than one path, preventing traffic congestion from oscillating between nodes.

E: Dual links to each site improve bandwidth and failover options, reducing reliance on overloaded peers.

Other options:

A: Increasing redundant paths may worsen convergence complexity and doesn ' t solve oscillation.

B: Removing inter-spoke links reduces redundancy.

C: Increasing convergence timers delays recovery and stability.

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Comprehensive and Detailed Explanation From Exact Extract of Design Expert (CCDE)

Controller-based networks centralize control logic, abstracting hardware complexity and providing consistency. This results in:

C. Abstraction: Devices are treated as policy endpoints rather than configuration silos, simplifying network operations and scalability.

E. Consistent Configuration: Policies and configurations are pushed uniformly across all devices from the controller, reducing human error and improving compliance.

These features align with CCDE v3.1 recommendations for modern, policy-driven, and scalable architectures that are easier to manage and automate.

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