Unit_3

School of Engineering and Electronics

  • Faculty of Engineering at University of Leeds

  • Course Code: ELEC5471M

  • Course Title: Data Communications and Network Security

  • Focus on the Network Layer and IP

Learning Objectives

  • Gain knowledge of data communications and wireless sensor networks.

  • Explore possible applications of data communications.

  • Topics to be covered:

    • ISO/OSI 7-layer protocol architecture.

    • The Internet and TCP/IP architecture.

    • Examination of the transport layer, specifically TCP and UDP.

    • Discuss methods for security across networks.

    • Functions of the Network Layer and the role of IP.

    • Techniques for sharing a common transmission medium (MAC).

Contribution Requirements

  • Lecture Attendance: Basic provision of material will be presented.

  • Private Study: Essential to reinforce lecture content.

  • Reading Material: Engage with all advised texts and suggested additional texts.

  • Preparation: Prepare and review lecture content.

Module Assessment

  • Assessment checks achievement of learning objectives.

  • Grades reflect the extent of knowledge exceeded beyond objectives.

  • Exam Questions:

    • Layered Protocol Architectures (ISO and TCP/IP).

    • Transport Layer, TCP & UDP operation (including congestion control).

    • Network layer issues (addressing and routing).

    • Link layer issues (e.g., MAC).

    • Security aspects project.

Course Delivery

  • Instructor: Prof. A. H. Kemp

  • Potential support from field experts.

  • Assessment consists of one 3-hour exam.

Recommended Texts

  • Computer Networking by Kurose and Ross, ISBN: 0201976994

  • Protocols and Architectures for Wireless Sensor Networks by Holger, K. and Willig, A. ISBN: 978-0-470-02432-5

  • Computer Networks by Tanenbaum, ISBN: 0133499456

  • Multimedia Communications by Halsall, ISBN: 0201398184

  • For general reading: Data & Computer Communications by Stallings, ISBN: 0135712742

Network Layer and Internet Protocol

  • Key Topics:

    • Addressing: IPv4 and IPv6.

    • Routing: link-state, distance vector, Internet, Routers.

IP Addressing and Structure

  • Each host, gateway, and router has a unique IP address.

  • IPv4 uses a 32-bit address space and various addressing schemes.

  • IPv6 provides a different addressing solution, with a proposed 128-bit address space.

Address Breakdown

  • Net-ID and Host-ID components derived from the address.

  • IPv4 Addressing: 32-bit addresses, commonly seen in dotted decimal notation.

  • Example: 128.3.2.3 where netid is 128.3 and hostid is 2.3.

Class-Based Addressing Schemes

  • Classes: A, B, C, D, E.

    • Class A: 7-bit Net-ID, 24-bit Host-ID.

    • Class B: 14-bit Net-ID, 16-bit Host-ID.

    • Class C: 21-bit Net-ID, 8-bit Host-ID.

    • Class D: Reserved for multicast.

    • Class E: Experimental, reserved for future use.

Subnetting

  • Reduced number of Net-IDs by using subnets for efficient routing.

  • Host-ID consists of subnetid and local hostid.

  • Example: A class B IP address 150.10.0.0 is divided to allow 100 subnets.

Classless Addressing and CIDR

  • Definition of network part can now vary in bits.

  • Format: w.x.y.z/n indicating bits in network part.

  • Example: To accommodate 1000 hosts, w.x.y.z/22 available, suggesting bits shared by netid and hostid.

Network Address Translation (NAT)

  • Temporary solution for IPv4 shortages.

  • Private addresses not directed on the Internet and monitored through NAT routers using TCP port addresses.

IPv6 Features

  • Long-term solution involves 128-bit addressing.

  • Features include:

    • Increased address space (2^128 addresses),

    • Hierarchical addressing,

    • Simplified headers,

    • Enhanced security,

    • Autoconfiguration capabilities,

    • Quality of Service (QoS) guarantees,

    • Mobile computing support.

Interoperability Between IPv4 and IPv6

  • Challenges exist due to widespread IPv4 deployment.

  • Strategies to facilitate communication between the two protocol versions include:

    • IPv4 and IPv6 hosts communicating with a single server.

    • Tunneling and dual stack methods to transition smoothly between protocols.

    • Use of network address and protocol translators for inter-system communication.

Routing in the Network Layer

  • Definition: Selecting paths for data transit in a network.

    • Occurs at Network Layer (Layer 3 in OSI model).

    • Routers forward data packets through a routing process.

Routing Algorithms

  • Link-State and Distance-Vector algorithms for determining data paths.

  • Dijkstra's algorithm used for finding least-cost paths.

  • Bellman-Ford equation utilized in Distance-Vector algorithms for routing efficiency.

Conclusion: Key Network Layer Functions

  • The main functions of the network layer include routing, maintaining QoS, and ensuring efficient communication across networks.