Master Computer Networking: From Basic Concepts to Advanced Protocols Explained

Chapter 1 Overview

Basic Concepts

Link: physical connections such as copper, fiber, satellite.

Node: computers, hubs, switches, routers.

Protocol: rules for message format, semantics, timing.

Service: layer-to-layer services.

Entity: any hardware or software that can send/receive.

Peer Entity: two entities at the same layer communicating.

Layer PDU: data unit exchanged between peer layers.

Communication Models

C/S model: client‑server.

B/S model: browser‑server.

P2P model: peer‑to‑peer.

Network Types

LAN, WAN, MAN, PAN definitions.

Network Performance Parameters

Rate (bits/s).

Bandwidth (maximum data rate).

Throughput (actual data rate).

Delay (time from source to destination).

Round‑trip time.

Channel utilization.

Chapter 2 Internet Composition

Edge part consists of end systems (hosts, mobile devices, supercomputers). Core part consists of interconnected routers performing routing and forwarding.

Chapter 3 Switching Techniques

Circuit Switching : dedicated resources, three phases (setup, communication, release).

Packet Switching : messages are divided into packets, each packet carries a header and is routed independently.

Datagram Switching : each packet is stored and forwarded hop‑by‑hop.

Virtual‑Circuit Switching : logical path established before data transfer; packets carry a VC identifier.

Chapter 4 TCP/IP Architecture

TCP/IP consists of four layers: link, internet, transport, application. Data encapsulation adds headers at each layer.

Chapter 5 Transport Layer

Provides end‑to‑end reliable communication.

UDP

Supports unicast, multicast, broadcast.

Connectionless, unreliable.

Any transmission rate.

TCP

Connection‑oriented, reliable, ordered.

Flow control, congestion control.

TCP Header Fields : source port, destination port, sequence number, acknowledgment number, window size, data offset, checksum, flags (URG, ACK, PSH, RST, SYN, FIN).

TCP Reliability : timeout retransmission, sliding window, cumulative ACK, piggyback ACK.

TCP Congestion Control : slow start, congestion avoidance, ssthresh, fast retransmit.

TCP Connection Establishment : three‑way handshake (SYN, SYN‑ACK, ACK).

TCP Connection Termination : four‑way handshake (FIN, ACK, FIN, ACK).

Chapter 6 Application Layer

DNS

Maps domain names to IP addresses. Hierarchical structure with root, top‑level, authoritative, and local name servers. Supports iterative and recursive queries; caches results.

FTP

File Transfer Protocol uses TCP. Control connection on port 21, data connection on port 20. Supports anonymous access via command line, web browser, or FTP client.

HTTP

Hypertext Transfer Protocol enables web communication. URL format: protocol://host:port/path. Supports persistent connections, pipelining, cookies, and three types of web documents (static, dynamic, active).

Email

Components: client, server, protocols (SMTP on TCP 25, POP3/IMAP for retrieval). MIME extends format for multimedia. Web‑based email uses HTTP.

DHCP

Dynamic Host Configuration Protocol assigns IP address, subnet mask, default gateway, DNS server. Process: DISCOVER, OFFER, REQUEST, ACK. Lease renewal at 50% and 87.5% of lease time. Supports relay agents.

P2P File Distribution

Uses tit‑for‑tat strategy: each peer selects top‑4 fastest neighbors, re‑evaluates every 10 s, and randomly selects one additional neighbor every 30 s.

Chapter 7 Network Security

Common attacks: eavesdropping, data modification, malware, DoS.

Cryptography

Symmetric: same key for encryption/decryption.

Asymmetric: public key for encryption, private key for decryption.

Digital Signatures : provide authentication, integrity, non‑repudiation.

Key Distribution : KDC (Kerberos) and CA (PKI) models.

Chapter 8 Wireless LAN

Infrastructure WLAN uses Access Points (AP); Ad‑hoc WLAN is peer‑to‑peer without AP. Wireless sensor networks are low‑power, low‑bandwidth.

CSMA/CA : carrier sense, defer interval (DIFS), random backoff, short interframe space (SIFS), ACK.

802.11 Frame Format : supports up to four address fields.

Chapter 9 Other Topics

Address lengths: MAC 48 bits, IPv4 32 bits, IPv6 128 bits, port 16 bits.

Header sizes: Ethernet 18 bytes, IPv4 20‑60 bytes, IPv6 40 bytes.

Checksum methods: CRC for frames, IPv4 header checksum, TCP/UDP pseudo‑header checksum.

Routing protocols: RIP (distance‑vector), OSPF (link‑state), BGP (path‑vector), MPLS (label switching).

Data exchange methods: circuit switching, message switching, packet switching.

TCP vs UDP comparison.

IPv4 vs IPv6 differences.

P2P vs C/S models.

Search engine types: full‑text vs directory.

CSMA/CD vs CSMA/CA.

Common network attacks: worms, trojans, logic bombs, backdoors, rogue software, eavesdropping, DoS.

Chapter 10 Commands

ipconfig : /all, /displaydns, /flushdns, /release, /renew.

ping : -n count, -l size, -t continuous.

tracert : trace route to destination.

arp : -a show, -d delete, -s add static entry.

Chapter 11 Terminology

ISP, IXP, Hub, LAN, MAN, WAN, WLAN, VLAN, P2P, C/S, CSMA/CD, CSMA/CA, LiFi, WiFi, ADSL, HFC, FTTH/FTTB/FTTC, URL, VPN, IPSec, NAT, ICMP, IGMP, MSS, BGP, AS, HTTPS, MPLS, AP, SSID, AdHoc, Blockchain.