This chapter covers the following subjects:
WAN Design Methodologies: This section discusses the processes of identifying business and technology strategies, assessing the existing network, and creating a design that is scalable, flexible, and resilient.
Design for High Availability: This section covers removing the single points of failure from a network design by using software features or hardware-based resiliency.
Internet Connectivity: This section discusses public network access and securely connecting business locations.
Backup Connectivity: This section discusses providing an alternative WAN path between locations when primary paths are unavailable.
QoS Strategies: This section discusses design models for providing QoS service differentiation.
Designing End-to-End QoS Policies: This section discusses options for QoS mechanisms such as queuing, policing, and traffic shaping.
This chapter covers WAN design and QoS. Expect plenty of questions on the ENSLD 300-420 exam about the selection and use of WAN designs in enterprise networks. A CCNP enterprise designer must understand WAN availability and the QoS models that are available to protect traffic flows in the network. This chapter starts with WAN methodologies and then covers WAN availability with deployment models using MPLS, hybrid, and Internet designs. This chapter also explores backup connectivity and failover designs. Finally, it covers QoS strategies and designing end-to-end QoS policies.
“Do I Know This Already?” Quiz
The “Do I Know This Already?” quiz helps you identify your strengths and deficiencies in this chapter’s topics. This quiz, derived from the major sections in the “Foundation Topics” portion of the chapter, helps you determine how to spend your limited study time. Table 9-1 outlines the major topics discussed in this chapter and the “Do I Know This Already?” quiz questions that correspond to those topics. You can find the answers in Appendix A, “Answers to the ‘Do I Know This Already?’ Quiz Questions and Q&A Questions.”
Table 9-1 “Do I Know This Already?” Foundation Topics Section-to-Question Mapping
Foundation Topics Section |
Questions Covered in This Section |
|---|---|
WAN Design Methodologies |
1–2 |
Design for High Availability |
3 |
Internet Connectivity |
4–5 |
Backup Connectivity |
6 |
QoS Strategies |
7–8 |
Designing End-to-End QoS Policies |
9–10 |
1. Which of the following is a measure of data transferred from one host to another in a given amount of time?
Reliability
Response time
Throughput
Jitter
2. Which of the following is a description of the key design principle scalability?
Modularity with additional devices, services, and technologies
Redundancy through hardware, software, and connectivity
Ease of managing and maintaining the infrastructure
Providing enough capacity and bandwidth for applications
3. What percentage of availability allows for four hours of downtime in a year?
99.5%
99.99%
99.999%
99.95%
4. What Internet connectivity option provides the highest level of resiliency for services?
Single-router dual-homed
Single-router single-homed
Dual-router dual-homed
Shared DMZ
5. Which of the following eliminates single points of failures with the router and the circuit?
Dual-router dual-homed
Single-router dual-homed
Shared DMZ
Single-router single-homed
6. What backup option allows for both a backup link and load-sharing capabilities using the available bandwidth?
Dial backup
Secondary WAN link
IPsec tunnel
GRE tunnel
7. Which of the following adds a strict priority queue to modular class-based QoS?
FIFO
CBWFQ
WFQ
LLQ
8. Which of the following is a mechanism to handle traffic overflow using a queuing algorithm with QoS?
Congestion management
Traffic shaping and policing
Classification
Link efficiency
9. Which QoS model uses Resource Reservation Protocol (RSVP) to explicitly request QoS for the application along the end-to-end path through devices in the network?
DiffServ
IntServ
CBWFQ
BE
10. What technique does traffic shaping use to release the packets into the output queue at a preconfigured rate?
Token bucket
Leaky bucket
Tagging
Interleaving