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Internetworking with TCP/IP: Pearson New International Edition

Douglas E. Comer

Chapter 19

Network Virtualization: VPNs, NATs, And Overlays - all with Video Answers

Educators

Chapter Questions

Problem 1

Under what circumstances will a VPN transter substantially more packets than conventional IP when sending the same data across the Internet? (Hint: think about encapsulation.)

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Problem 2

Software implementations of NAT that are used to provide remote employees access to an organization's intranet often reduce the network MTU that is reported to local applications. Explain why.

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01:48

Problem 3

Look up the definition of cone as applied to NAT. When is a NAT system considered to be full cone?

Danielle Ashley
Danielle Ashley
Numerade Educator

Problem 4

NAT translates both source and destination IP addresses. Which addresses are translated on datagrams that arrive from the Internet?

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Problem 5

Consider an ICMP host unreachable message sent through two NAT boxes that interconnect three address domains. How many address translations will occur? How many translations of protocol port numbers will occur?

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02:44

Problem 6

Imagine that we decide to create a new Internet parallel to the existing Internet that allocates addresses from the same address space. Can NAT technology be used to connect the two arbitrarily large Intemets that use the same address space? If so, explain how. If not, explain why not.

Shelby Mohamed
Shelby Mohamed
Numerade Educator

Problem 7

Is NAT completely transparent to a host? To answer the question, try to find a sequence of packets that a host can transmit to determine whether it is located behind a NAT box.

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Problem 8

What are the advantages of combining NAT technology with VPN technology? The disadvantages?

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Problem 9

Configure NAT on a Linux system between a private address domain and the Internet. Which well-known services work correctly and which do not?

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01:35

Problem 10

Read about a variant of NAT called twice NAT that allows communication to be initiated from either side of the NAT box at any time. How does twice NAT ensure that translations are consistent? If two instances of twice NAT are used to interconnect three address domains, is the result completely transparent to all hosts?

James Kiss
James Kiss
Numerade Educator
00:58

Problem 11

Draw a diagram of the protocol layering used with an overlay network.

Shreya Jain
Shreya Jain
Numerade Educator

Problem 12

Overlay technology can be used with Layer 2 as well as Layer 3. Design a system that uses an overlay to form a large Ethernet VLAN that includes multiple sites.

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