Book cover for Computer Networks A Systems Approach

Computer Networks A Systems Approach

Larry L. Peterson, Bruce S. Davie

ISBN #9781558608320

3rd Edition

406 Questions

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Homework Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

Internetworking is the crucial process of connecting isolated networks that use diverse technologies into a unified system. Despite the apparent similarity in network structures, a hierarchical organization is essential for efficient data routing and communication. Understanding these principles and employing the proper techniques ensures that disparate networks work together seamlessly to build robust, scalable systems.

Learning Objectives

1

Explain the concept of internetworking and its role in linking isolated networks.

2

Identify the underlying hierarchy in network structures and its significance in data routing.

3

Discuss the principles and strategies used to create robust internetwork systems.

4

Analyze how disparate networks can operate together seamlessly through effective internetworking.

Key Concepts

CONCEPT

DEFINITION

Internetworking

The process of connecting and linking different networks, often using varied technologies, to form a larger, cohesive network system.

Hierarchy in Networks

An organized structure within networks that prioritizes data routing and communication, ensuring efficient operational flow from one network to another.

Disparate Networks

Networks that operate on different technologies or protocols, which require specialized methods for integration and communication.

Example Problems

Example 1

What aspect of IP addresses makes it necessary to have one address per network interface, rather than just one per host? In light of your answer, why does IP tolerate point-to-point interfaces that have nonunique addresses or no addresses?

Example 2

Why does the Offset field in the IP header measure the offset in 8-byte units? (Hint: Recall that the Offset field is 13 bits long.)

Example 3

Some signalling errors can cause entire ranges of bits in a packet to be overwritten by all 0 s or all 1s. Suppose all the bits in the packet including the Internet checksum are overwritten. Could a packet with all 0s or all 1s be a legal IPv4 packet? Will the Internet checksum catch that error? Why or why not?

Example 4

Suppose a TCP message that contains 2048 bytes of data and 20 bytes of TCP header is passed to IP for delivery across two networks of the Internet (i.e., from the source host to a router to the destination host). The first network uses 14-byte headers and has an MTU of 1024 bytes; the second uses 8-byte headers with an MTU of 512 bytes. Each network's MTU gives the size of the largest IP datagram that can be carried in a link-layer frame. Give the sizes and offsets of the sequence of fragments delivered to the network layer at the destination host. Assume all IP headers are 20 bytes.

Example 5

Path MTU is the smallest MTU of any link on the current path (route) between two hosts. Assume we could discover the path MTU of the path used in the previous exercise, and that we use this value as the MTU for all the path segments. Give the sizes and offsets of the sequence of fragments delivered to the network layer at the destination host.
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Step-by-Step Explanations

QUESTION

How can two isolated networks using different technologies be connected for efficient data communication?

STEP-BY-STEP ANSWER:

Step 1: Identify and analyze the technologies and protocols used in each isolated network.
Step 2: Determine the compatibility issues and requirements for bridging these technologies.
Step 3: Employ internetworking devices such as routers or gateways that can translate between different protocols.
Step 4: Establish a hierarchical structure that prioritizes data routing, ensuring that network traffic follows the most efficient paths.
Step 5: Test the connection for data flow, integrity, and robustness, making adjustments as necessary.
Final Answer: By using appropriate internetworking devices and establishing a hierarchical routing structure, two disparate networks can be connected to operate seamlessly together.

Internetworking

QUESTION

Why is a hierarchical structure important in internetworking?

STEP-BY-STEP ANSWER:

Step 1: Understand that a hierarchical structure organizes the network into layers for clearer management.
Step 2: Recognize that each layer in the hierarchy is responsible for specific tasks, such as routing, switching, or access control.
Step 3: See that data is directed efficiently through predefined paths, reducing bottlenecks and improving performance.
Step 4: Acknowledge that without hierarchy, data routing would be random, leading to inefficiencies and potential communication failures.
Final Answer: A hierarchical structure ensures that data is routed through efficient, organized paths, thereby optimizing network performance in internetworking.

Network Hierarchy

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Common Mistakes

  • Assuming that all networks are compatible without considering the differences in underlying technologies.
  • Overlooking the importance of a hierarchical structure in managing data flow and routing.
  • Confusing internetworking with standard networking, when internetworking specifically addresses the challenges of connecting diverse systems.