Master Computer Networking with 38 Essential Mind Maps

01 TCP/IP Network Protocol Stack

The TCP/IP stack consists of four layers: Application, Transport, Internet, and Link. Each layer provides specific services, e.g., HTTP at the Application layer, TCP/UDP at Transport, IP at Internet, and Ethernet at Link.

02 TCP/IP Protocol Layering

Layering separates concerns: the Application layer hosts protocols like HTTP, DNS; the Transport layer provides reliable (TCP) or best‑effort (UDP) delivery; the Internet layer handles routing via IP; the Link layer manages framing and media access.

03 Transmission Media Overview

Common media include twisted‑pair copper (UTP/STP), coaxial cable, fiber‑optic (single‑mode, multimode), and wireless (radio, microwave). Selection depends on bandwidth, distance, and cost.

04 Ethernet Frame Structure

An Ethernet II frame contains: preamble, destination MAC, source MAC, EtherType/Length, payload (46‑1500 bytes), and CRC. VLAN tagging inserts a 4‑byte 802.1Q header after the source MAC.

05 IP Addressing

IPv4 uses 32‑bit addresses expressed in dotted‑decimal notation (e.g., 192.168.1.1). Subnet masks define network and host portions. CIDR notation (e.g., /24) replaces classful masks. IPv6 expands to 128‑bit addresses written in hexadecimal groups.

06 ICMP Protocol

ICMP provides diagnostic and control messages for IP, such as Echo Request/Reply (ping), Destination Unreachable, Time Exceeded, and Redirect. It operates directly over IP (protocol number 1).

07 ARP Protocol

ARP resolves IPv4 addresses to MAC addresses on a local LAN. An ARP request is broadcast; the host owning the IP replies with its MAC. Gratuitous ARP can announce a host's address.

08 Link Aggregation

Link Aggregation (LACP, IEEE 802.3ad) combines multiple physical links into a single logical channel, increasing bandwidth and providing redundancy. Traffic is distributed using hash algorithms based on MAC/IP/port fields.

09 VLAN Principles and Configuration

VLANs (IEEE 802.1Q) segment a Layer‑2 domain into separate broadcast domains. Each VLAN is identified by a 12‑bit VLAN ID (1‑4094). Switch ports are configured as access (single VLAN) or trunk (multiple VLANs with tagging).

10 VLAN Routing

Inter‑VLAN routing is performed by a Layer‑3 device (router or Layer‑3 switch). Each VLAN is assigned a SVI (Switched Virtual Interface) with an IP address; routing protocols or static routes forward traffic between SVIs.

11 Wireless LAN (WLAN)

WLANs use IEEE 802.11 standards (a/b/g/n/ac/ax). Key concepts include SSID, BSSID, authentication (WPA2/WPA3), channel selection, and roaming. Access points bridge wireless frames to the wired LAN.

12 DHCP

Dynamic Host Configuration Protocol automatically assigns IPv4 addresses, subnet masks, gateways, and DNS servers. DHCP operates over UDP ports 67 (server) and 68 (client) using a four‑step DORA process (Discover, Offer, Request, Acknowledge).

13 FTP

File Transfer Protocol uses separate control (port 21) and data (port 20 or passive ports) connections. It supports active and passive modes, binary/ascii transfer types, and authentication via username/password.

14 Telnet

Telnet provides unencrypted, line‑oriented remote terminal access over TCP port 23. Because credentials travel in clear text, it is deprecated in favor of SSH.

15 Access Control Lists (ACL)

ACLs filter traffic based on Layer‑3/4 fields (source/destination IP, protocol, ports). Standard ACLs match only source IP; extended ACLs can match source/destination IP, protocol, and ports. ACLs are applied inbound or outbound on interfaces.

16 AAA (Authentication, Authorization, Accounting)

AAA frameworks (e.g., RADIUS, TACACS+) centralize user authentication, define permitted actions (authorization), and log usage (accounting). They are essential for secure network device management.

17 GRE Principles and Configuration

Generic Routing Encapsulation (GRE) tunnels encapsulate any Layer‑3 protocol within IP. Configuration involves defining a tunnel interface, specifying source/destination IPs, and optionally setting a key for security.

18 IPSec VPN Principles and Configuration

IPSec provides confidentiality, integrity, and authentication for IP traffic. It uses two modes: Transport (protects payload) and Tunnel (protects entire packet). Key components are IKE for SA negotiation, ESP/AH for protection, and security policies.

19 Routing Basics

Routing moves packets between networks based on destination IP. Core concepts include routing tables, next‑hop determination, static vs dynamic routing, and default routes.

20 Static Routing Basics

Static routes are manually entered with destination network, mask, and next‑hop IP. They are simple, predictable, and useful for stub networks or backup paths.

21 VRP Basics

VRP (Versatile Routing Platform) is Huawei’s network‑OS. It supports routing protocols (OSPF, BGP), VLANs, ACLs, and device management via CLI similar to Cisco IOS.

22 Command Line Basics

Fundamental CLI commands include display (show configuration), system-view (enter configuration mode), interface (select interface), and quit (exit). Use ? for context‑sensitive help.

23 File System Basics

VRP file system commands: dir (list files), cd (change directory), copy (copy files), delete (remove files). Configuration files are stored as .cfg and can be backed up via TFTP.

24 IPv6 Basics Introduction

IPv6 expands the address space to 128 bits, represented as eight 16‑bit hexadecimal groups. Features include simplified header, built‑in security (IPsec), and autoconfiguration via SLAAC and DHCPv6.

25 IPv6 Routing Basics

IPv6 routing uses the same principles as IPv4 but with larger addresses. Common protocols include OSPFv3 and BGP4+. Link‑local addresses (fe80::/10) are used for neighbor discovery.

26 DHCPv6

DHCPv6 provides stateful address assignment and other configuration parameters (DNS, domain). It operates over UDP ports 546 (client) and 547 (server). Prefix Delegation enables routers to assign subnets to downstream devices.

27 HDLC & PPP Principles and Applications

HDLC is a synchronous, bit‑oriented framing protocol used on point‑to‑point links. PPP (Point‑to‑Point Protocol) builds on HDLC, adding LCP for link configuration, NCP for network‑layer protocol negotiation, and optional authentication (PAP/CHAP).

28 Frame Relay Principles and Configuration

Frame Relay is a packet‑switched WAN technology using DLCIs (Data Link Connection Identifiers) to identify virtual circuits. It provides low‑overhead, variable‑length frames and relies on LMI for status monitoring.

29 PPPoE

PPP over Ethernet encapsulates PPP frames inside Ethernet. It is widely used for DSL broadband. The discovery stage uses PADI/PADO/PADR/PADS packets; the session stage establishes a PPP link with LCP, authentication, and IPCP.

30 NAT (Network Address Translation)

NAT translates private IP addresses to a public address. Types include static NAT, dynamic NAT, and PAT (Port Address Translation, also called NAT overload). NAT modifies source IP/port in outbound packets and restores them on return.

31 Switch Network Basics

Layer‑2 switches forward frames based on MAC address tables. They support features such as port security, spanning‑tree, and VLAN tagging. Switches reduce broadcast domains when combined with VLANs.

32 STP (Spanning Tree Protocol)

STP (IEEE 802.1D) prevents loops in Layer‑2 networks by creating a tree topology. It elects a root bridge, calculates path costs, and blocks redundant ports. BPDU packets carry the topology information.

33 RSTP Principles and Configuration

Rapid STP (IEEE 802.1w) improves convergence time by using proposal/agreement handshakes and port roles (alternate, backup). Configuration typically involves enabling stp mode rstp on Huawei devices.

34 OSPF (Link State Routing Protocol)

OSPF divides the network into areas, with Area 0 as the backbone. Routers exchange LSAs to build a link‑state database, then run Dijkstra’s algorithm to compute shortest‑path trees. Supports authentication and stub areas.

35 VRP System Management

System management tasks include backup/restore of configuration, firmware upgrades via upgrade command, license activation, and monitoring via display version and display cpu.

36 GRE Principles and Configuration (Repeated)

See section 17 for details.

37 IPSec VPN Principles and Configuration (Repeated)

See section 18 for details.