400-007: Cisco Certified Design ExpertDemo

By Cisco · Question Mode

QuestionQ298

Network Design

Your company uses many different types of network transports and wants to improve network efficiency. Which solution can improve network efficiency across PPPoE, IPsec, and GRE networks?

  • A PMTUD
  • B Host Discovery Protocol
  • C OATM
  • D IRDP
Explanation

Path MTU Discovery (PMTUD) determines the smallest MTU along the path so endpoints and tunnels can use packet sizes that account for PPPoE, GRE, and IPsec encapsulation overhead. This avoids fragmentation, reassembly overhead, and unnecessarily small packets, improving efficiency. Cisco documents PMTUD as a way to dynamically adjust GRE tunnel MTU in GRE/IPsec deployments and identifies PPPoE header overhead.

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