CCIE Network Design FAQ: Applying the Principles of Network Design

CCIE Network Design FAQ: Applying the Principles of Network Design

Q1. What does hierarchy provide in a well-designed network?

Answer: The foundation, or the skeleton on which everything else hangs.
ccie-network-design-faq-applying-principles-network-design
Figure: Traffic and Routes in a WellDesigned Network

Q2. What is the primary tool used to bound the area affected by network changes?

Answer: Summarization.

Q3. How can it be determined which links can be removed from a full mesh core network to decrease the number of links?
Answer: By looking at the normal traffic patterns and determining which points the majority of the traffic will flow between.

Q4. What provides ways around failure points in the network?

Answer: Redundancy.

Q5. What two things are most desirable in a routing protocol?

Answer: Low overhead and fast convergence.

Q6. What can a routing protocol do to decrease its burden to hosts that are not running routing on a network?

Answer: Use multicast or unicast routing updates, reduce the frequency of updates, and reduce the number of packets required to transmit the required information.

Q7. List the addressing problems that are caused by having multiple links to external networks.

Answer:
  • Addressing conflicts with partners
  • Injecting multiple routes from external networks into your network

Q8. Given the network in Figure 4-10, how many routes do you think a core router will have in its table if no summarization is done?

Answer: 48 dial-ins, 95 remote sites, 8 links between the access and distribution layers, 6 common services networks, 9 HQ VLANs, 2 default routes, 3 routes to partner networks, 10 links from the core to other parts of the network, and 7 core network links. The total would be at least 179, not counting redundancy.

Q9. Given the network in Figure 4-10, how many routes do you think a core router will have in its table if all possible summarization is done?

Answer: 9 summaries from routers outside the core, 10 links from the core to other parts of the network, and 7 core network links. The total would be around 26.

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