Complete Guide to Computer Networking

graph TB
    A[Computer A] --- S[Switch]
    B[Computer B] --- S
    C[Computer C] --- S
    S --- R[Router]
    R --- I[Internet]

sequenceDiagram
    participant S as Sender
    participant M as Medium
    participant R as Receiver

    S->>M: Data Packet
    M->>R: Data Packet
    R->>M: Acknowledgment
    M->>S: Acknowledgment

graph LR
    subgraph "PAN (Personal)"
        P1[Phone]
        P2[Laptop]
        P3[Headphones]
    end

    subgraph "LAN (Local)"
        L1[Office PC]
        L2[Printer]
        L3[Server]
    end

    subgraph "WAN (Wide)"
        W1[Branch Office A]
        W2[Branch Office B]
        W3[Headquarters]
    end

    PAN --- LAN
    LAN --- WAN

graph TB
    subgraph "OSI Model"
        L7[Layer 7: ApplicationHTTP, FTP, SMTP]
        L6[Layer 6: PresentationSSL, JPEG, MPEG]
        L5[Layer 5: SessionNetBIOS, RPC]
        L4[Layer 4: TransportTCP, UDP]
        L3[Layer 3: NetworkIP, ICMP, OSPF]
        L2[Layer 2: Data LinkEthernet, PPP]
        L1[Layer 1: PhysicalCables, Radio Waves]
    end

graph TB
    subgraph "TCP/IP Model"
        T4[Application LayerHTTP, FTP, DNS, DHCP]
        T3[Transport LayerTCP, UDP]
        T2[Internet LayerIP, ICMP, ARP]
        T1[Network Interface LayerEthernet, Wi-Fi]
    end

graph LR
    subgraph "OSI Model"
        O7[Application]
        O6[Presentation]
        O5[Session]
        O4[Transport]
        O3[Network]
        O2[Data Link]
        O1[Physical]
    end

    subgraph "TCP/IP Model"
        T4[Application]
        T3[Transport]
        T2[Internet]
        T1[Network Interface]
    end

    O7 -.-> T4
    O6 -.-> T4
    O5 -.-> T4
    O4 -.-> T3
    O3 -.-> T2
    O2 -.-> T1
    O1 -.-> T1

graph LR
    subgraph "UTP Categories"
        Cat5[Cat 5100 Mbps100m]
        Cat5e[Cat 5e1 Gbps100m]
        Cat6[Cat 61 Gbps100m]
        Cat6a[Cat 6a10 Gbps100m]
    end

graph LR
    subgraph "Fiber Types"
        SM[Single ModeLong DistanceHigh Bandwidth]
        MM[Multi ModeShort DistanceLower Cost]
    end

    SM --- C[Core: 9 μm]
    MM --- C2[Core: 50-62.5 μm]

graph TB
    subgraph "Digital Encoding"
        D1[NRZ - Non-Return to Zero]
        D2[Manchester]
        D3[Differential Manchester]
    end

    subgraph "Analog Encoding"
        A1[ASK - Amplitude Shift Keying]
        A2[FSK - Frequency Shift Keying]
        A3[PSK - Phase Shift Keying]
        A4[QAM - Quadrature Amplitude Modulation]
    end

graph LR
    A[Preamble] --> B[Destination MAC]
    B --> C[Source MAC]
    C --> D[Type/Length]
    D --> E[Data]
    E --> F[FCS]

graph LR
    subgraph "Ethernet Frame"
        P[Preamble8 bytes]
        DA[Dest Address6 bytes]
        SA[Source Address6 bytes]
        TL[Type/Length2 bytes]
        Data[Data46-1500 bytes]
        FCS[FCS4 bytes]
    end

graph TB
    D[Data: 1011010] --> P[Even Parity: 10110100Odd Parity: 10110101]

sequenceDiagram
    participant S as Sender
    participant R as Receiver

    S->>R: Frame 1
    R->>S: ACK 1
    S->>R: Frame 2
    R->>S: ACK 2

sequenceDiagram
    participant S as Sender
    participant R as Receiver

    S->>R: Frame 1
    S->>R: Frame 2
    S->>R: Frame 3
    R->>S: ACK 1
    S->>R: Frame 4
    R->>S: ACK 2
    R->>S: ACK 3

graph TB
    subgraph "IPv4 Header (20 bytes minimum)"
        V[Version4 bits]
        HL[Header Length4 bits]
        TOS[Type of Service8 bits]
        TL[Total Length16 bits]
        ID[Identification16 bits]
        FLAGS[Flags3 bits]
        FO[Fragment Offset13 bits]
        TTL[Time to Live8 bits]
        PROTO[Protocol8 bits]
        CHECKSUM[Header Checksum16 bits]
        SRC[Source IP Address32 bits]
        DEST[Destination IP Address32 bits]
    end

graph TB
    subgraph "IPv4 Address Classes"
        A[Class A: 1.0.0.0 to 126.255.255.255Network: /8, Hosts: 16,777,214]
        B[Class B: 128.0.0.0 to 191.255.255.255Network: /16, Hosts: 65,534]
        C[Class C: 192.0.0.0 to 223.255.255.255Network: /24, Hosts: 254]
        D[Class D: 224.0.0.0 to 239.255.255.255Multicast Addresses]
        E[Class E: 240.0.0.0 to 255.255.255.255Reserved for Research]
    end

graph LR
    subgraph "Private IP Ranges"
        P1[Class A: 10.0.0.0/810.0.0.0 - 10.255.255.255]
        P2[Class B: 172.16.0.0/12172.16.0.0 - 172.31.255.255]
        P3[Class C: 192.168.0.0/16192.168.0.0 - 192.168.255.255]
    end

graph TB
    subgraph "IPv6 Address Types"
        U[UnicastOne-to-one]
        M[MulticastOne-to-many]
        A[AnycastOne-to-nearest]
    end

graph TB
    A[Router A] --- B[Router B]
    B --- C[Router C]
    C --- D[Router D]
    A --- D

    A -.-> RT1[Routing Table AB: 1 hopC: 2 hops via BD: 1 hop]

graph TB
    subgraph "Link State Process"
        S1[1. Discover neighbors]
        S2[2. Measure link costs]
        S3[3. Build link state packet]
        S4[4. Flood LSP to all routers]
        S5[5. Build network topology]
        S6[6. Calculate shortest paths]
    end

    S1 --> S2 --> S3 --> S4 --> S5 --> S6

graph TB
    subgraph "TCP Header"
        SP[Source Port16 bits]
        DP[Destination Port16 bits]
        SN[Sequence Number32 bits]
        AN[Acknowledgment Number32 bits]
        HL[Header Length4 bits]
        FLAGS[Control Flags9 bits]
        WS[Window Size16 bits]
        CS[Checksum16 bits]
        UP[Urgent Pointer16 bits]
    end

sequenceDiagram
    participant C as Client
    participant S as Server

    Note over C,S: Connection Establishment
    C->>S: SYN (seq=x)
    S->>C: SYN-ACK (seq=y, ack=x+1)
    C->>S: ACK (seq=x+1, ack=y+1)

    Note over C,S: Data Transfer
    C->>S: Data
    S->>C: ACK

    Note over C,S: Connection Termination
    C->>S: FIN
    S->>C: ACK
    S->>C: FIN
    C->>S: ACK

graph LR
    subgraph "UDP Header (8 bytes)"
        SP[Source Port16 bits]
        DP[Destination Port16 bits]
        L[Length16 bits]
        CS[Checksum16 bits]
    end

graph TB
    subgraph "TCP Applications"
        T1[Web Browsing - HTTP/HTTPS]
        T2[Email - SMTP/POP3/IMAP]
        T3[File Transfer - FTP]
        T4[Remote Access - SSH/Telnet]
    end

    subgraph "UDP Applications"
        U1[DNS Queries]
        U2[Video Streaming]
        U3[Online Gaming]
        U4[DHCP]
        U5[SNMP]
    end

graph TB
    subgraph "Common Well-Known Ports"
        P21[FTP: 21]
        P22[SSH: 22]
        P23[Telnet: 23]
        P25[SMTP: 25]
        P53[DNS: 53]
        P80[HTTP: 80]
        P110[POP3: 110]
        P443[HTTPS: 443]
    end

sequenceDiagram
    participant A as Application A
    participant B as Application B

    Note over A,B: Session Establishment
    A->>B: Session Request
    B->>A: Session Accept

    Note over A,B: Data Exchange
    A->>B: Data Transfer
    B->>A: Data Transfer

    Note over A,B: Session Termination
    A->>B: Session Close
    B->>A: Session Close ACK

graph LR
    subgraph "Presentation Layer Functions"
        E[EncryptionSSL/TLS, PGP]
        C[CompressionZIP, GZIP, JPEG]
        T[TranslationASCII, EBCDIC, Unicode]
    end

sequenceDiagram
    participant C as Client (Browser)
    participant S as Server

    C->>S: GET /index.html HTTP/1.1
    S->>C: HTTP/1.1 200 OK + HTML content
    C->>S: GET /style.css HTTP/1.1
    S->>C: HTTP/1.1 200 OK + CSS content

graph TB
    Client[Client] --> Resolver[DNS Resolver]
    Resolver --> Root[Root DNS Server]
    Root --> TLD["TLD DNS Server (.com)"]
    TLD --> Auth[Authoritative DNS Server]
    Auth --> TLD
    TLD --> Root
    Root --> Resolver
    Resolver --> Client

sequenceDiagram
    participant C as Client
    participant S as DHCP Server

    C->>S: DHCP Discover (Broadcast)
    S->>C: DHCP Offer
    C->>S: DHCP Request
    S->>C: DHCP ACK

    Note over C,S: Client now has IP configuration

graph LR
    subgraph "Email System"
        Sender[Email Client] --> SMTP[SMTP Server]
        SMTP --> Internet[Internet]
        Internet --> SMTP2[Recipient SMTP Server]
        SMTP2 --> Mailbox[Mailbox]
        Mailbox --> POP3[POP3/IMAP Server]
        POP3 --> Receiver[Email Client]
    end

graph LR
    A[Computer A] --- Bus[Main Bus Cable]
    B[Computer B] --- Bus
    C[Computer C] --- Bus
    D[Computer D] --- Bus
    T1[Terminator] --- Bus
    Bus --- T2[Terminator]

graph TB
    Hub[Hub/Switch] --- A[Computer A]
    Hub --- B[Computer B]
    Hub --- C[Computer C]
    Hub --- D[Computer D]
    Hub --- E[Computer E]

graph TB
    A[Computer A] --- B[Computer B]
    B --- C[Computer C]
    C --- D[Computer D]
    D --- E[Computer E]
    E --- A

graph TB
    A[Node A] --- B[Node B]
    A --- C[Node C]
    A --- D[Node D]
    B --- C
    B --- D
    C --- D

graph TB
    Root[Root Hub] --- A[Hub A]
    Root --- B[Hub B]
    A --- A1[Computer A1]
    A --- A2[Computer A2]
    B --- B1[Computer B1]
    B --- B2[Computer B2]
    B --- C[Hub C]
    C --- C1[Computer C1]
    C --- C2[Computer C2]

graph TB
    subgraph "Star-Bus Hybrid"
        Hub1[Hub 1] --- PC1[PC 1]
        Hub1 --- PC2[PC 2]
        Hub2[Hub 2] --- PC3[PC 3]
        Hub2 --- PC4[PC 4]
        Hub1 --- Backbone[Backbone Bus]
        Hub2 --- Backbone
        Hub3[Hub 3] --- Backbone
        Hub3 --- PC5[PC 5]
        Hub3 --- PC6[PC 6]
    end

graph LR
    A[Device A] --- R[Repeater] --- B[Device B]

    subgraph "Signal Regeneration"
        Weak[Weak Signal] --> Strong[Strong Signal]
    end

graph TB
    Hub[HubCollision Domain] --- A[PC A]
    Hub --- B[PC B]
    Hub --- C[PC C]
    Hub --- D[PC D]

    Note[All ports share bandwidthCollisions can occur]

graph LR
    subgraph "LAN Segment 1"
        A[PC A] --- B[PC B]
    end

    subgraph "LAN Segment 2"
        C[PC C] --- D[PC D]
    end

    Bridge[Bridge] --- A
    Bridge --- C

graph TB
    Switch[SwitchMAC Address Table] --- A[PC AMAC: AA:AA:AA:AA:AA:AA]
    Switch --- B[PC BMAC: BB:BB:BB:BB:BB:BB]
    Switch --- C[PC CMAC: CC:CC:CC:CC:CC:CC]
    Switch --- D[PC DMAC: DD:DD:DD:DD:DD:DD]

    subgraph "MAC Address Table"
        Entry1[Port 1: AA:AA:AA:AA:AA:AA]
        Entry2[Port 2: BB:BB:BB:BB:BB:BB]
        Entry3[Port 3: CC:CC:CC:CC:CC:CC]
        Entry4[Port 4: DD:DD:DD:DD:DD:DD]
    end

graph TB
    subgraph "Network 192.168.1.0/24"
        A[PC A192.168.1.10] --- Switch1[Switch]
        B[PC B192.168.1.20] --- Switch1
    end

    subgraph "Network 192.168.2.0/24"
        C[PC C192.168.2.10] --- Switch2[Switch]
        D[PC D192.168.2.20] --- Switch2
    end

    Router[Router192.168.1.1192.168.2.1] --- Switch1
    Router --- Switch2
    Router --- Internet[Internet]

graph LR
    Internal[Internal Network] --- Firewall[FirewallSecurity Rules]
    Firewall --- Internet[Internet]

    subgraph "Firewall Rules"
        Rule1[Allow HTTP port 80]
        Rule2[Allow HTTPS port 443]
        Rule3[Deny Telnet port 23]
        Rule4[Allow SSH port 22 from admin]
    end

graph TB
    Client[Client Requests] --> LB[Load Balancer]
    LB --> Server1[Web Server 1]
    LB --> Server2[Web Server 2]
    LB --> Server3[Web Server 3]

    subgraph "Load Balancing Algorithms"
        RR[Round Robin]
        LC[Least Connections]
        WRR[Weighted Round Robin]
        LR[Least Response Time]
    end

graph LR
    subgraph "IPv4 Address: 192.168.1.100"
        Octet1[19211000000]
        Octet2[16810101000]
        Octet3[100000001]
        Octet4[10001100100]
    end

graph TB
    subgraph "IP Address: 192.168.1.100"
        Network[Network Portion192.168.1]
        Host[Host Portion100]
    end

    subgraph "Subnet Mask: 255.255.255.0"
        NetMask[Network Bits11111111.11111111.11111111]
        HostMask[Host Bits00000000]
    end

    Network -.-> NetMask
    Host -.-> HostMask

graph TB
    subgraph "Common CIDR Notations"
        C8["/8 = 255.0.0.016,777,214 hosts"]
        C16["/16 = 255.255.0.065,534 hosts"]
        C24["/24 = 255.255.255.0254 hosts"]
        C30["/30 = 255.255.255.2522 hosts"]
    end

graph TB
    Original[Original Network192.168.1.0/24254 hosts] 

    Original --> Sub1[Subnet 1192.168.1.0/2662 hostsRange: .1 to .62]
    Original --> Sub2[Subnet 2192.168.1.64/2662 hostsRange: .65 to .126]
    Original --> Sub3[Subnet 3192.168.1.128/2662 hostsRange: .129 to .190]
    Original --> Sub4[Subnet 4192.168.1.192/2662 hostsRange: .193 to .254]

graph TB
    Main[Network: 192.168.0.0/221022 hosts total]

    Main --> Large[Large Subnet192.168.0.0/24254 hosts for servers]
    Main --> Medium1[Medium Subnet 1192.168.1.0/25126 hosts for dept A]
    Main --> Medium2[Medium Subnet 2192.168.1.128/25126 hosts for dept B]
    Main --> Small1[Small Subnet 1192.168.2.0/2730 hosts for printers]
    Main --> Small2[Small Subnet 2192.168.2.32/2814 hosts for management]
    Main --> PTP[Point-to-Point192.168.2.48/302 hosts for WAN link]

graph TB
    subgraph "Special IPv4 Addresses"
        Private[Private Addresses10.0.0.0/8172.16.0.0/12192.168.0.0/16]

        Loopback[Loopback127.0.0.0/8127.0.0.1 = localhost]

        APIPA[APIPA169.254.0.0/16Automatic Private IP]

        Multicast[Multicast224.0.0.0/4Group communication]

        Broadcast[Broadcast255.255.255.255Limited broadcast]

        Network[Network AddressFirst address in subnetAll host bits = 0]

        BroadcastSub[Subnet BroadcastLast address in subnetAll host bits = 1]
    end

graph TB
    Routing[Routing Algorithms] --> Static[Static Routing]
    Routing --> Dynamic[Dynamic Routing]

    Static --> Manual[Manually ConfiguredNo automatic updates]

    Dynamic --> DistVec[Distance VectorRIP, EIGRP]
    Dynamic --> LinkState[Link StateOSPF, ISIS]
    Dynamic --> PathVec[Path VectorBGP]

graph TB
    subgraph "Autonomous System 1"
        R1[Router 1] --- R2[Router 2]
        R2 --- R3[Router 3]
    end

    subgraph "Autonomous System 2"
        R4[Router 4] --- R5[Router 5]
        R5 --- R6[Router 6]
    end

    R3 -.->|"BGP (EGP)"| R4

    IGP1["IGP: OSPF, RIP, EIGRPWithin AS"]
    EGP1["EGP: BGPBetween AS"]

graph TB
    A[Router A] --- B[Router B]
    B --- C[Router C]
    C --- D[Router D]
    A --- E[Router E]
    E --- D

    subgraph "RIP Routing Table (Router A)"
        Net1[Network B: 1 hop via B]
        Net2[Network C: 2 hops via B]
        Net3[Network D: 3 hops via B or 2 via E]
        Net4[Network E: 1 hop via E]
    end

sequenceDiagram
    participant A as Router A
    participant B as Router B
    participant C as Router C

    Note over A,C: RIP Updates every 30 seconds
    A->>B: Routing Update
    B->>C: Routing Update
    C->>B: Routing Update
    B->>A: Routing Update

graph TB
    subgraph "Area 0 (Backbone)"
        ABR1[ABR 1] --- ABR2[ABR 2]
        ABR2 --- ABR3[ABR 3]
        ABR3 --- ABR1
    end

    subgraph "Area 1"
        R1[Router 1] --- R2[Router 2]
        R1 --- ABR1
    end

    subgraph "Area 2"
        R3[Router 3] --- R4[Router 4]
        R3 --- ABR2
    end

    subgraph "Area 3"
        R5[Router 5] --- R6[Router 6]
        R5 --- ABR3
    end

graph TB
    subgraph "OSPF LSA Types"
        LSA1[Type 1: Router LSARouter's links within area]
        LSA2[Type 2: Network LSANetwork links in area]
        LSA3[Type 3: Summary LSANetworks from other areas]
        LSA4[Type 4: ASBR Summary LSAPath to ASBR]
        LSA5[Type 5: External LSAExternal routes]
    end

graph LR
    subgraph "EIGRP Metric Components"
        BW[BandwidthK1 = 1]
        Delay[DelayK3 = 1]
        Reliability[ReliabilityK5 = 0]
        Load[LoadK4 = 0]
        MTU["MTUNot used in calculation"]
    end

    Formula["Metric = 256 * (K1*BW + K2*BW/256-Load + K3*Delay)"]

graph TB
    subgraph "BGP Peering"
        AS1[AS 65001] -->|eBGP| AS2[AS 65002]
        AS2 -->|eBGP| AS3[AS 65003]
        AS1 -->|eBGP| AS3
    end

    subgraph "AS 65001 Internal"
        R1[Router 1] -->|iBGP| R2[Router 2]
        R1 -->|iBGP| R3[Router 3]
        R2 -->|iBGP| R3
    end

graph TB
    Start["BGP Path Selection"] --> Weight["1). Highest Weight"]
    Weight --> LocalPref["2). Highest Local Preference"]
    LocalPref --> Originate["3). Locally Originated"]
    Originate --> ASPath["4). Shortest AS Path"]
    ASPath --> Origin["5). Lowest Origin Code"]
    Origin --> MED["6). Lowest MED"]
    MED --> External["7). External over Internal"]
    External --> IGP["8). Lowest IGP Metric"]
    IGP --> RouterID["9). Lowest Router ID"]

graph TB
    subgraph "Network Security Threats"
        Passive[Passive Attacks- Eavesdropping- Traffic Analysis]
        Active[Active Attacks- Modification- Denial of Service- Replay Attacks]
        Internal[Internal Threats- Malicious Insiders- Accidental Exposure]
        External[External Threats- Hackers- Malware- Social Engineering]
    end

graph TB
    subgraph "CIA Triad"
        Confidentiality[ConfidentialityData privacy and secrecy]
        Integrity[IntegrityData accuracy and completeness]
        Availability[AvailabilitySystem accessibility when needed]
    end

    Confidentiality --- Integrity
    Integrity --- Availability
    Availability --- Confidentiality

graph LR
    Internet[InternetUntrusted] --- Firewall[FirewallSecurity Policy]
    Firewall --- Internal[Internal NetworkTrusted]

    subgraph "Firewall Types"
        Packet[Packet Filter]
        Stateful[Stateful Inspection]
        Application[Application Layer]
        Next[Next Generation]
    end

graph TB
    Network[Network Traffic] --> IDS[IDS Sensor]
    IDS --> Analysis[Traffic Analysis]
    Analysis --> Alert[Generate Alerts]
    Alert --> Admin[Security Administrator]

    subgraph "IDS Types"
        NIDS[Network-based IDS]
        HIDS[Host-based IDS]
    end

graph LR
    External[External Network] --> IPS[IPSInline Device]
    IPS --> Internal[Internal Network]
    IPS --> Drop[Drop Malicious Traffic]
    IPS --> Alert[Generate Alerts]

graph LR
    Plain[Plaintext] --> Encrypt[EncryptionSame Key]
    Encrypt --> Cipher[Ciphertext]
    Cipher --> Decrypt[DecryptionSame Key]
    Decrypt --> Plain2[Plaintext]

    Key[Shared Secret Key] -.-> Encrypt
    Key -.-> Decrypt

graph LR
    Plain[Plaintext] --> Encrypt[EncryptionPublic Key]
    Encrypt --> Cipher[Ciphertext]
    Cipher --> Decrypt[DecryptionPrivate Key]
    Decrypt --> Plain2[Plaintext]

    PublicKey[Public Key] -.-> Encrypt
    PrivateKey[Private Key] -.-> Decrypt

sequenceDiagram
    participant A as Alice
    participant B as Bob

    A->>A: Create hash of message
    A->>A: Encrypt hash with private key (signature)
    A->>B: Send message + signature
    B->>B: Decrypt signature with Alice's public key
    B->>B: Create hash of received message
    B->>B: Compare hashes

    Note over B: If hashes match, signature is valid

graph LR
    subgraph Site_A["Site A"]
        LAN1["Local Network 192.168.1.0/24"]
        Router1[VPN Router A]
    end

    subgraph Internet["Public Internet"]
        Tunnel["Encrypted Tunnel"]
    end

    subgraph Site_B["Site B"]
        Router2[VPN Router B]
        LAN2["Local Network 192.168.2.0/24"]
    end

    LAN1 --- Router1
    Router1 -.->|Encrypted| Tunnel
    Tunnel -.->|Encrypted| Router2
    Router2 --- LAN2

graph LR
    Remote[Remote UserVPN Client] -.->|Encrypted Tunnel| Internet[Internet]
    Internet -.->|Encrypted Tunnel| VPN[VPN Server]
    VPN --- Corporate[Corporate Network]

graph TB
    subgraph "Wi-Fi Security Evolution"
        WEP[WEPWired Equivalent PrivacyWeak - Deprecated]
        WPA[WPAWi-Fi Protected AccessBetter than WEP]
        WPA2[WPA2AES EncryptionCurrent Standard]
        WPA3[WPA3Enhanced SecurityLatest Standard]
    end

    WEP --> WPA --> WPA2 --> WPA3

sequenceDiagram
    participant Client
    participant AP as Access Point
    participant AS as Auth Server

    Client->>AP: Association Request
    AP->>Client: Association Response
    Client->>AP: EAPOL-Start
    AP->>AS: Access-Request (EAP)
    AS->>AP: Access-Challenge (EAP)
    AP->>Client: EAP-Request
    Client->>AP: EAP-Response (Credentials)
    AP->>AS: Access-Request (Credentials)
    AS->>AP: Access-Accept + Keys
    AP->>Client: EAP-Success + Keys

graph TB
    subgraph WiFi_Standards_Evolution["Wi-Fi Standards Evolution"]
        Legacy["802.11 (1997) - 2 Mbps, 2.4 GHz"]
        A["802.11a (1999) - 54 Mbps, 5 GHz"]
        B["802.11b (1999) - 11 Mbps, 2.4 GHz"]
        G["802.11g (2003) - 54 Mbps, 2.4 GHz"]
        N["802.11n (2009) - 600 Mbps, 2.4/5 GHz"]
        AC["802.11ac (2013) - 6.93 Gbps, 5 GHz"]
        AX["802.11ax / Wi-Fi 6 (2019) - 9.6 Gbps, 2.4/5/6 GHz"]
    end

    Legacy --> A
    Legacy --> B
    B --> G
    G --> N
    N --> AC
    AC --> AX

graph TB
    subgraph "Basic Service Set (BSS)"
        AP[Access PointBSSID: MAC Address]
        Client1[Laptop]
        Client2[Smartphone]
        Client3[Tablet]
    end

    Client1 --- AP
    Client2 --- AP
    Client3 --- AP
    AP --- Router[Wired Router]
    Router --- Internet[Internet]

graph TB
    subgraph "ESS - Same SSID"
        subgraph "BSS 1"
            AP1[Access Point 1Channel 1]
            C1[Clients]
        end

        subgraph "BSS 2"
            AP2[Access Point 2Channel 6]
            C2[Clients]
        end

        subgraph "BSS 3"
            AP3[Access Point 3Channel 11]
            C3[Clients]
        end
    end

    C1 --- AP1
    C2 --- AP2
    C3 --- AP3
    AP1 --- DS[Distribution System]
    AP2 --- DS
    AP3 --- DS

graph TB
    subgraph "Independent BSS"
        Device1[Device 1] --- Device2[Device 2]
        Device2 --- Device3[Device 3]
        Device3 --- Device4[Device 4]
        Device4 --- Device1
    end

    Note[No Access PointPeer-to-peer communication]

graph LR
    subgraph "2.4 GHz Channels (US)"
        C1[Ch 12412 MHz]
        C2[Ch 22417 MHz]
        C3[Ch 32422 MHz]
        C4[Ch 42427 MHz]
        C5[Ch 52432 MHz]
        C6[Ch 62437 MHz]
        C7[Ch 72442 MHz]
        C8[Ch 82447 MHz]
        C9[Ch 92452 MHz]
        C10[Ch 102457 MHz]
        C11[Ch 112462 MHz]
    end

    NonOverlap[Non-overlapping: 1, 6, 11]

graph TB
    subgraph "5 GHz Bands"
        UNII1[UNII-15.150-5.250 GHzChannels 36-48]
        UNII2[UNII-25.250-5.350 GHzChannels 52-64DFS Required]
        UNII2E[UNII-2 Extended5.470-5.725 GHzChannels 100-144DFS Required]
        UNII3[UNII-35.725-5.825 GHzChannels 149-165]
    end

graph TB
    subgraph "Wireless Security Protocols"
        Open["OpenNo EncryptionNot Recommended"]
        WEP["WEPRC4 Encryption64/128-bit keysDeprecated"]
        WPA["WPATKIP EncryptionPre-shared keyLegacy"]
        WPA2["WPA2AES-CCMPPersonal/EnterpriseCurrent Standard"]
        WPA3["WPA3Enhanced SecuritySAE (Dragonfly)Latest Standard"]
    end

    Open --> WEP --> WPA --> WPA2 --> WPA3

sequenceDiagram
    participant C as Client (Supplicant)
    participant AP as Access Point (Authenticator)
    participant AS as Authentication Server (RADIUS)

    C->>AP: Association Request
    AP->>C: Association Response

    Note over C,AS: 802.1X Authentication
    C->>AP: EAPOL-Start
    AP->>AS: RADIUS Access-Request
    AS->>AP: RADIUS Access-Challenge
    AP->>C: EAP-Request Identity
    C->>AP: EAP-Response (Username)
    AP->>AS: RADIUS Access-Request

    Note over AS: Authenticate User
    AS->>AP: RADIUS Access-Accept + PMK
    AP->>C: EAP-Success

    Note over C,AP: 4-Way Handshake
    AP->>C: Message 1 (ANonce)
    C->>AP: Message 2 (SNonce, MIC)
    AP->>C: Message 3 (GTK, MIC)
    C->>AP: Message 4 (MIC)

    Note over C,AP: Data transmission with encryption keys

graph TB
    subgraph "Signal Problems"
        LowSignal[Low Signal Strength- Distance from AP- Physical obstacles- RF interference]

        Interference[RF Interference- Other Wi-Fi networks- Microwave ovens- Bluetooth devices- Baby monitors]

        Multipath[Multipath Fading- Signal reflections- Indoor environments- Moving objects]
    end

graph LR
    subgraph "Performance Factors"
        Channel[Channel CongestionMultiple APs same channel]
        Bandwidth[Bandwidth LimitationShared medium]
        Protocol[Protocol OverheadCSMA/CA, ACK frames]
        Range[Distance vs SpeedFarther = Slower]
    end

graph TB
    Requirements["1). Gather Requirements- Coverage area- User density- Applications- Performance needs"]

    PreSurvey["2). Pre-deployment Survey- RF environment- Interference sources- Physical layout- AP placement planning"]

    Deploy["3). Deployment- Install APs- Configure settings- Test connectivity"]

    PostSurvey["4). Post-deployment Survey- Validate coverage- Measure performance- Optimize configuration"]

    Requirements --> PreSurvey --> Deploy --> PostSurvey

graph TB
    Problem["1). Identify the Problem- Gather information- Question users- Document symptoms"]

    Theory["2). Establish Theory- Probable cause- Consider multiple causes- Question the obvious"]

    Test["3). Test Theory- Determine next steps- If theory confirmed, implement solution- If not, establish new theory"]

    Plan["4). Establish Action Plan- Plan implementation- Identify potential effects- Get approval if needed"]

    Implement["5). Implement Solution- Execute the plan- Monitor results- Document changes"]

    Verify["6). Verify Functionality- Test full system- Confirm resolution- Implement preventive measures"]

    Document["7). Document Process- Record findings- Update procedures- Share knowledge"]

    Problem --> Theory --> Test --> Plan --> Implement --> Verify --> Document

graph TB
    Physical[Layer 1: Physical- Cable connections- Link lights- Power status]

    DataLink[Layer 2: Data Link- Switch port status- MAC address tables- VLAN configuration]

    Network[Layer 3: Network- IP configuration- Routing tables- Ping connectivity]

    Transport[Layer 4: Transport- Port connectivity- Telnet tests- Service status]

    Application[Layer 5-7: Upper Layers- Application logs- Service configuration- User authentication]

    Physical --> DataLink --> Network --> Transport --> Application

graph TB
    subgraph "Layer 1 Issues"
        Cable[Cable Problems- Damaged cables- Wrong cable type- Loose connections]

        Power[Power Issues- Device not powered- Power supply failure- PoE problems]

        Hardware[Hardware Failure- NIC problems- Port failures- Device malfunction]
    end

    subgraph "Layer 2 Issues"
        Switch[Switching Problems- Port disabled- VLAN misconfiguration- STP issues]

        Duplex[Duplex Mismatch- Half vs Full duplex- Speed mismatch- Auto-negotiation failure]
    end

    subgraph "Layer 3 Issues"
        IP[IP Configuration- Wrong IP address- Incorrect subnet mask- Missing default gateway]

        Routing[Routing Problems- Missing routes- Wrong next hop- Routing loops]

        DNS[DNS Issues- Wrong DNS server- DNS resolution failure- Cache problems]
    end

graph TB
    subgraph "Windows Network Commands"
        ipconfig[ipconfig /allIP configuration]
        ping[ping targetConnectivity test]
        tracert[tracert targetPath tracing]
        nslookup[nslookup domainDNS resolution]
        netstat[netstat -anNetwork connections]
        arp[arp -aARP table]
        route[route printRouting table]
    end

graph TB
    subgraph "Linux Network Commands"
        ifconfig[ifconfigInterface configuration]
        ping2[ping targetConnectivity test]
        traceroute[traceroute targetPath tracing]
        dig[dig domainDNS lookup]
        netstat2[netstat -tulnNetwork connections]
        ss[ss -tulnSocket statistics]
        ip[ip addr showIP configuration]
    end

sequenceDiagram
    participant User
    participant Local as Local Host
    participant Gateway as Default Gateway
    participant Remote as Remote Host
    participant DNS as DNS Server

    Note over User: Test local configuration
    User->>Local: ipconfig /all

    Note over User: Test loopback
    User->>Local: ping 127.0.0.1

    Note over User: Test local IP
    User->>Local: ping [own IP]

    Note over User: Test default gateway
    User->>Gateway: ping [gateway IP]

    Note over User: Test DNS server
    User->>DNS: ping [DNS IP]

    Note over User: Test remote host by IP
    User->>Remote: ping [remote IP]

    Note over User: Test DNS resolution
    User->>DNS: nslookup google.com

    Note over User: Test remote host by name
    User->>Remote: ping google.com

graph TB
    subgraph "Bandwidth Issues"
        Congestion[Network Congestion- Too much traffic- Insufficient bandwidth- Broadcast storms]

        QoS[QoS Problems- Missing QoS policies- Wrong priority settings- Bandwidth allocation]

        Duplex2[Duplex Issues- Half-duplex on full-duplex link- Collisions and retransmissions- Performance degradation]
    end

graph LR
    subgraph "Latency Causes"
        Distance[Physical DistanceSpeed of light delays]
        Processing[Processing DelayRouter/switch processing]
        Queuing[Queuing DelayBuffer congestion]
        Serialization[Serialization DelayTime to transmit bits]
    end

graph TB
    Manager[SNMP ManagerNetwork Management System]

    Manager --> Agent1[SNMP AgentRouter]
    Manager --> Agent2[SNMP AgentSwitch]
    Manager --> Agent3[SNMP AgentServer]

    subgraph "SNMP Operations"
        Get[GET - Retrieve data]
        Set[SET - Configure device]
        Trap[TRAP - Unsolicited alerts]
        Walk[WALK - Bulk retrieval]
    end

graph TB
    subgraph "Key Performance Indicators"
        Bandwidth[Bandwidth Utilization% of link capacity used]
        Latency2[Latency/RTTRound-trip time]
        PacketLoss[Packet Loss% of packets lost]
        Jitter[JitterVariation in latency]
        Throughput[ThroughputActual data transfer rate]
        Availability[AvailabilityUptime percentage]
    end

graph TB
    subgraph "Traditional Networking"
        T1[Switch 1Control + Data]
        T2[Switch 2Control + Data]
        T3[Switch 3Control + Data]
        T4[Router 1Control + Data]
    end

    subgraph "SDN Architecture"
        Controller[SDN ControllerCentralized Control Plane]

        subgraph "Data Plane"
            S1[OpenFlow Switch 1]
            S2[OpenFlow Switch 2]
            S3[OpenFlow Switch 3]
            R1[OpenFlow Router 1]
        end

        Controller -->|OpenFlow| S1
        Controller -->|OpenFlow| S2
        Controller -->|OpenFlow| S3
        Controller -->|OpenFlow| R1
    end

sequenceDiagram
    participant C as SDN Controller
    participant S as OpenFlow Switch

    Note over C,S: Initial Connection
    S->>C: Hello Message
    C->>S: Hello Message
    C->>S: Features Request
    S->>C: Features Reply

    Note over C,S: Flow Table Management
    C->>S: Flow Mod (Add Entry)
    S->>C: Flow Removed
    C->>S: Stats Request
    S->>C: Stats Reply

    Note over C,S: Packet Processing
    S->>C: Packet In (Unknown flow)
    C->>S: Packet Out (Forward decision)

graph TB
    subgraph "Traditional Network Functions"
        Firewall1[Physical Firewall]
        Router1[Physical Router]
        LoadBalancer1[Physical Load Balancer]
        IDS1[Physical IDS]
    end

    subgraph "NFV Architecture"
        subgraph "NFVI (NFV Infrastructure)"
            Hardware[Commodity Hardware]
            Hypervisor[Virtualization Layer]
            VMs[Virtual Machines]
        end

        subgraph "VNFs (Virtual Network Functions)"
            vFirewall[Virtual Firewall]
            vRouter[Virtual Router]
            vLB[Virtual Load Balancer]
            vIDS[Virtual IDS]
        end

        MANO[NFV MANOManagement & Orchestration]
    end

    Hardware --> Hypervisor --> VMs
    VMs --> vFirewall
    VMs --> vRouter
    VMs --> vLB
    VMs --> vIDS
    MANO --> VMs

graph TB
    subgraph "Cloud Service Models"
        IaaS[Infrastructure as a Service- Virtual machines- Storage- Networking]

        PaaS[Platform as a Service- Application runtime- Development tools- Database services]

        SaaS[Software as a Service- Complete applications- Web-based access- No infrastructure management]
    end

    IaaS --> PaaS --> SaaS

graph TB
    subgraph "AWS VPC Example"
        VPC[Virtual Private Cloud10.0.0.0/16]

        subgraph "Availability Zone A"
            PublicA[Public Subnet10.0.1.0/24]
            PrivateA[Private Subnet10.0.2.0/24]
        end

        subgraph "Availability Zone B"
            PublicB[Public Subnet10.0.3.0/24]
            PrivateB[Private Subnet10.0.4.0/24]
        end

        IGW[Internet Gateway]
        NAT[NAT Gateway]

        VPC --> PublicA
        VPC --> PrivateA
        VPC --> PublicB
        VPC --> PrivateB

        PublicA --- IGW
        PublicB --- IGW
        PrivateA --- NAT
        PrivateB --- NAT
        NAT --- IGW
    end

graph TB
    subgraph "QoS Models"
        BestEffort[Best Effort- No guarantees- Default service- FIFO queuing]

        IntServ[Integrated Services- Per-flow reservations- RSVP protocol- Guaranteed service]

        DiffServ[Differentiated Services- Traffic classification- DSCP marking- PHB behaviors]
    end

graph LR
    subgraph "Traffic Types & Priorities"
        Voice[Voice Traffic- Highest priority- Low latency- Low jitter]

        Video[Video Traffic- High priority- Bandwidth intensive- Burst tolerant]

        Data[Data Traffic- Normal priority- Variable requirements- Delay tolerant]

        Bulk[Bulk Transfer- Low priority- High bandwidth- Delay insensitive]
    end

graph TB
    subgraph "QoS Implementation"
        Classification[1. ClassificationIdentify traffic types]
        Marking[2. MarkingTag packets with priority]
        Policing[3. PolicingRate limiting]
        Shaping[4. ShapingSmooth traffic flow]
        Queuing[5. QueuingBuffer management]
        Scheduling[6. SchedulingTransmit order]
    end

    Classification --> Marking --> Policing --> Shaping --> Queuing --> Scheduling

graph TB
    subgraph "IPv6 Address Structure"
        Global[Global Unicast2000::/3Routable on Internet]

        LinkLocal[Link-LocalFE80::/10Local network only]

        Unique[Unique LocalFC00::/7Private networks]

        Multicast[MulticastFF00::/8Group communication]

        Loopback[Loopback::1Local host]
    end

graph TB
    subgraph "IPv6 Transition Technologies"
        DualStack[Dual Stack- IPv4 and IPv6 simultaneously- Gradual migration- Both protocols active]

        Tunneling[Tunneling- IPv6 over IPv4- 6to4, Teredo- Encapsulation method]

        Translation[Translation- NAT64/DNS64- Protocol conversion- IPv6-only to IPv4]
    end

graph LR
    subgraph "Network Automation Tools"
        Ansible[Ansible- Agentless- YAML playbooks- Network modules]

        Python[Python- Netmiko library- NAPALM framework- Custom scripts]

        Terraform[Terraform- Infrastructure provisioning- Cloud resources- State management]

        NETCONF[NETCONF- Network configuration- XML-based- Standardized protocol]
    end

sequenceDiagram
    participant Script as Automation Script
    participant API as Network API
    participant Device as Network Device

    Script->>API: GET /interfaces
    API->>Device: Query interface status
    Device->>API: Interface data
    API->>Script: JSON response

    Script->>API: POST /config
    API->>Device: Apply configuration
    Device->>API: Success/Error
    API->>Script: Configuration result

graph TB
    subgraph "IoT Characteristics"
        Scale[Massive ScaleBillions of devices]

        Power[Power EfficiencyBattery-operated devices]

        Range[Variable RangeShort to long distance]

        Data[Low Data RatesSensor data transmission]

        Cost[Low CostAffordable deployment]

        Reliability[High ReliabilityMission-critical applications]
    end

graph TB
    subgraph "IoT Communication Protocols"
        subgraph "Application Layer"
            MQTT[MQTTMessage queuing]
            CoAP[CoAPConstrained application]
            HTTP2[HTTP/2Web communication]
        end

        subgraph "Transport Layer"
            TCP2[TCPReliable transport]
            UDP2[UDPLightweight transport]
        end

        subgraph "Network Layer"
            IPv62[IPv6Address space]
            6LoWPAN[6LoWPANIPv6 over low power]
        end

        subgraph "Physical/Data Link"
            WiFi[Wi-FiHigh bandwidth]
            Zigbee[ZigbeeMesh networking]
            LoRa[LoRaLong range, low power]
            NB[NB-IoTCellular IoT]
        end
    end

graph TB
    subgraph "Bandwidth Optimization Techniques"
        Compression[Data Compression- Reduce payload size- CPU vs bandwidth tradeoff- Protocol-specific]

        Caching[Caching- Local content storage- Reduce WAN traffic- Web and application caches]

        Deduplication[Data Deduplication- Eliminate redundant data- Block-level or file-level- Storage and bandwidth savings]

        LoadBalancing[Load Balancing- Distribute traffic- Multiple paths- Failover capability]
    end

graph LR
    subgraph "Latency Reduction Methods"
        CDN[Content Delivery Network- Edge caching- Geographic distribution- Reduced RTT]

        Acceleration[WAN Acceleration- TCP optimization- Protocol acceleration- Application awareness]

        EdgeComputing[Edge Computing- Process data locally- Reduced round trips- Real-time processing]

        FastPath[Fast Path Processing- Hardware acceleration- Bypass software stack- Specialized ASICs]
    end

graph TB
    subgraph "Network Telemetry"
        SNMP2[SNMPTraditional pollingLimited scalability]

        Streaming[Streaming Telemetry- Real-time data- Push model- High frequency]

        NetFlow[Flow-based Monitoring- Traffic analysis- Application visibility- Security insights]

        Synthetic[Synthetic Monitoring- Active probing- End-to-end testing- User experience]
    end

graph TB
    subgraph "AI/ML Applications"
        Prediction[Predictive Analytics- Capacity planning- Failure prediction- Performance trends]

        Anomaly[Anomaly Detection- Unusual traffic patterns- Security threats- Performance degradation]

        Optimization[Network Optimization- Routing decisions- Load balancing- Resource allocation]

        Automation[Intelligent Automation- Self-healing networks- Auto-configuration- Policy enforcement]
    end

graph TB
    Internet[Internet] --- Router[Router192.168.1.1]
    Router --- Switch[Switch]
    Switch --- PC1[PC-1 192.168.1.10]
    Switch --- PC2[PC-2 192.168.1.11]
    Switch --- Server[Server 192.168.1.100]
    Switch --- Printer[Network Printer 192.168.1.200]

graph TB
    subgraph "VLAN Configuration"
        Switch[Managed Switch]

        subgraph "VLAN 10 - Sales"
            PC1[PC 1]
            PC2[PC 2]
        end

        subgraph "VLAN 20 - Engineering"
            PC3[PC 3]
            PC4[PC 4]
        end

        subgraph "VLAN 30 - Management"
            Server[Server]
            Admin[Admin PC]
        end
    end

    Switch --- PC1
    Switch --- PC2
    Switch --- PC3
    Switch --- PC4
    Switch --- Server
    Switch --- Admin

graph TB
    subgraph "Wireless Deployment"
        Controller[Wireless Controller]

        subgraph "Building A"
            AP1[Access Point 1Channel 1]
            AP2[Access Point 2Channel 6]
        end

        subgraph "Building B"
            AP3[Access Point 3Channel 11]
            AP4[Access Point 4Channel 1]
        end

        subgraph "Wireless Clients"
            Laptop[Laptop]
            Phone[Smartphone]
            Tablet[Tablet]
        end
    end

    Controller --- AP1
    Controller --- AP2
    Controller --- AP3
    Controller --- AP4

    AP1 -.-> Laptop
    AP2 -.-> Phone
    AP3 -.-> Tablet

graph LR
    subgraph "CompTIA Network+ Topics"
        Fundamentals[Network Fundamentals23% of exam]
        Implementation[Network Implementation19% of exam]
        Operations[Network Operations16% of exam]
        Security[Network Security20% of exam]
        Troubleshooting[Network Troubleshooting22% of exam]
    end

graph TB
    subgraph "Cisco Certification Path"
        CCNA[CCNACisco Certified Network Associate]
        CCNP[CCNP EnterpriseCore + Concentration]
        CCIE[CCIE EnterpriseLab + Written]

        CCNA --> CCNP --> CCIE

        subgraph "CCNP Concentrations"
            ENARSI[ENARSIAdvanced Routing & Services]
            ENCOR[ENCORCore Technologies]
        end
    end

graph TB
    subgraph "5G Network Architecture"
        Core[5G Core NetworkService-based architecture]

        subgraph "Radio Access Network"
            gNB[gNodeB5G base station]
            mmWave[mmWaveHigh frequency]
            Massive[Massive MIMOMultiple antennas]
        end

        subgraph "Edge Computing"
            MEC[Multi-access Edge Computing]
            EdgeDC[Edge Data Centers]
        end

        subgraph "Use Cases"
            eMBB[Enhanced Mobile Broadband]
            URLLC[Ultra-Reliable Low Latency]
            mMTC[Massive Machine Type Communications]
        end
    end

    Core --- gNB
    gNB --- mmWave
    gNB --- Massive
    Core --- MEC
    MEC --- EdgeDC

graph LR
    subgraph "Quantum Network Concepts"
        Entanglement[Quantum EntanglementInstant correlationSecure communication]

        Teleportation[Quantum TeleportationState transferNo physical transmission]

        QKD[Quantum Key DistributionUnbreakable encryptionDetection of eavesdropping]

        QInternet[Quantum InternetGlobal quantum networkDistributed computing]
    end

graph TB
    subgraph "Intent-Based Network Architecture"
        Intent[Business IntentHigh-level policies]

        Translation[Intent TranslationPolicy to configuration]

        Activation[Network ActivationAutomated deployment]

        Assurance[Network AssuranceContinuous monitoringSelf-correction]
    end

    Intent --> Translation --> Activation --> Assurance
    Assurance --> Translation

graph TB
    Foundation[Build Strong Foundation- OSI Model- TCP/IP- Basic protocols] 

    Practical[Gain Practical Experience- Lab exercises- Home networks- Virtual environments]

    Certification[Pursue Certifications- CompTIA Network+- Vendor certifications- Specialized areas]

    Specialization[Develop Specializations- Security- Wireless- Cloud networking- Automation]

    StayCurrent[Stay Current- Industry trends- New technologies- Best practices]

    Foundation --> Practical --> Certification --> Specialization --> StayCurrent
    StayCurrent --> Foundation