Data Communication & Networks

Data Communication & Networks is a clear course in data communication and computer networking for students: 70 topics in 15 sections, from bits and signals to OSI, TCP/IP, IP subnetting and network security.
Every topic has an original drawing, worked examples with real numbers and practice questions. It all works offline.

What you will learn

• Networking Basics: what data communication is, types of networks (LAN, WAN and the Internet), network topologies, protocols and standards, bandwidth, throughput and delay
• Network Models: layers and encapsulation, the OSI reference model, the TCP/IP model, MAC addresses, IP addresses and ports
• Signals: analog and digital signals, sine waves, spectrum, bandwidth and Fourier, bit rate, decibels, transmission impairments, channel capacity with Nyquist and Shannon
• Digital Transmission: line coding, NRZ and RZ, Manchester and differential Manchester, bipolar and multilevel codes, block coding and scrambling, sampling, PCM and quantisation
• Modulation: ASK, FSK and PSK, QPSK and QAM with constellation diagrams, AM, FM and PM
• Multiplexing and Spreading: FDM, time-division multiplexing with T1 and E1, WDM and OFDM, spread spectrum
• Media and Switching: twisted-pair cable, coaxial cable, optical fibre, wireless transmission, circuit and packet switching
• Error Detection and Correction: Hamming distance, parity checks, cyclic redundancy check (CRC), the Internet checksum, Hamming code
• Data Link Control: framing, flow control and stop-and-wait, sliding window protocols (Go-Back-N and Selective Repeat), HDLC and PPP
• Media Access Control: ALOHA, CSMA/CD, CSMA/CA, controlled access and channelisation (TDMA, CDMA)
• Ethernet and Wi-Fi: Ethernet frames and MAC addresses, Ethernet standards and speeds, switches and VLANs, Wi-Fi (IEEE 802.11) up to Wi-Fi 7
• Network Layer: IPv4 addresses, subnetting, VLSM and route summarisation, the IPv4 packet and ICMP, ARP, DHCP and NAT, IPv6 basics, longest prefix match, routing algorithms and protocols
• Transport and Applications: ports and UDP, TCP connections, TCP flow and congestion control, DNS, HTTP and the web, email
• Network Security: security goals and threats, cryptography basics, TLS, VPNs and firewalls
• Quick Reference: a formula sheet with the main data communication formulas on one page

Features
• 70 topics in 15 sections, written for a first course in computer networks
• 70 original drawings: waveforms, line codes, constellations, OSI and TCP/IP layer diagrams, frame formats, timing diagrams and network graphs
• 72 worked examples, from Shannon capacity to CRC division and subnetting step by step
• 168 practice questions with tap-to-reveal answers
• Search all topics from the home screen
• Previous and Next buttons to work through a section in order
• Dark mode
• Works offline, no account needed
• Available in 8 languages: English, Español, Português, Français, Deutsch, العربية, हिन्दी and Bahasa Indonesia

Who it is for
• Students in a data communication and networking course in computer science, IT, electronics or telecommunication engineering
• Anyone learning computer networking from the ground up, from the OSI model to TCP/IP
• Students who want subnetting, CRC and channel capacity worked out step by step before an exam
• Teachers and tutors who want clear drawings of networking concepts

Data Communication & Networks is an independent study aid. Content is checked against IETF RFCs, IEEE 802 and ITU-T standards and MIT OpenCourseWare course notes. It is not affiliated with any textbook publisher, university or standards body.

Recent changes:
Stability improvements.