Category: Networking

IP Addressing & Subnetting — Complete Guide
IP addressing is the foundation of all networking. Every device on a network must have a unique IP address, and subnetting determines how networks are divided, how many hosts they support, and how routing behaves.

This guide covers IPv4, IPv6, subnet masks, CIDR notation, calculating network ranges, and converting between number systems — all using the formulas already shown in your Number Systems page .

IPv4 Addressing Basics

An IPv4 address is 32 bits, producing:

$2^{32} = 4, 294, 967, 296 total addresses$

IPv4 is written in dotted‑decimal format:
```
192.168.1.10
```
Each octet is 8 bits.

Subnet Masks & CIDR Notation

A subnet mask defines how many bits belong to:
- Network portion
- Host portion
Example:
```
255.255.255.0 = /24
```
Meaning:
- 24 network bits
- 8 host bits
Calculating Assignable Hosts

$Assignable Hosts = 2^{h} - 2$

Where:
- $h$ = number of host bits
- Subtract 2 for network and broadcast addresses
Example: /24
- Host bits = 8
- Assignable = $2^{8} - 2 = 254$
Calculating Number of Subnets

Formula:

$Subnets = 2^{s}$

Where:
- $s$ = number of borrowed bits (bits added to the default mask)
Example: Borrow 3 bits → $2^{3} = 8$ subnets.

Interesting Octet & Block Size

Formula:

$Block Size = 256 - Interesting Octet$

The interesting octet is the octet where the subnet mask stops being 255.

Example:
```
Mask: 255.255.255.192
Interesting Octet = 192
Block Size = 256 - 192 = 64
```
Subnets:
```
0–63
64–127
128–191
192–255
```
Calculating Network & Broadcast Addresses

Given an IP and mask:

Step 1 — Find block size

Use the formula above.

Step 2 — Determine which block the IP falls into

Example:
```
IP: 192.168.1.130
Mask: /26 (block size 64)
```
Blocks:
- 0–63
- 64–127
- 128–191 ← IP falls here
- 192–255
Step 3 — Network & Broadcast
```
Network:   192.168.1.128
Broadcast: 192.168.1.191
```
Step 4 — Usable Range
```
192.168.1.129 – 192.168.1.190
```
Binary, Hex, and Octal Conversions

Your Number Systems page already includes the conversion examples:

Decimal → Hexadecimal

Example from your draft: 2748 → ABC (A=10, B=11, C=12)

Decimal → Binary

Repeated division by 2 (your draft shows the full breakdown)

Binary → Hex

Group bits into 4s.

Binary → Octal

Group bits into 3s.

These conversions are essential for understanding subnetting at the bit level.

IPv6 Addressing Basics

Your draft includes the total IPv6 address space:

$2^{128} = 3.4 \times 10^{38}$

IPv6 uses:
- 128‑bit addresses
- Hexadecimal notation
- No broadcast addresses
- Vastly simplified subnetting
Example:
```
2001:db8:abcd:0012::/64
```
CIDR Summary Table

CIDR Hosts Block Size Notes
/24 254 1 Common LAN
/25 126 128 Split /24 in half
/26 62 64 Cameras, IoT
/27 30 32 Small networks
/30 2 4 Point‑to‑point links
May 13, 2026

CIDR	Hosts	Block Size	Notes
/24	254	1	Common LAN
/25	126	128	Split /24 in half
/26	62	64	Cameras, IoT
/27	30	32	Small networks
/30	2	4	Point‑to‑point links

Wi-Fi Standards

A complete reference for Wi‑Fi standards, frequencies, channels, security, antennas, and troubleshooting.

Wireless networking is built on the IEEE 802.11 family of standards. Each generation improves speed, efficiency, and spectrum usage. This toolkit provides a technician‑grade reference for Wi‑Fi technologies, frequency bands, channel planning, security, and performance optimization.

Wi‑Fi is defined by the IEEE 802.11 family of wireless networking standards. Each generation improves speed, range, efficiency, and spectrum usage. This guide summarizes every major Wi‑Fi standard from 802.11a to Wi‑Fi 7 and provides a technician‑grade reference for Wi‑Fi technologies, frequency bands, channel planning, security, and performance optimization.

Wi‑Fi Standards Overview (802.11a → Wi‑Fi 7)

Specification	Standard
Specification	802.11a	802.11b	802.11g	802.11n (Wi‑Fi 4)	802.11ac (Wi‑Fi 5)	802.11ax (Wi‑Fi 6)	802.11be (Wi‑Fi 7)
Frequency	5.75 GHz (U-NII)	2.4 GHz (ISM)	2.4 GHz (ISM)	2.4 GHz (ISM) or 5 GHz (U-NII)	5 GHz (optionally 2.4 GHz for compatibility)	2.4, 5, 6 GHz (Wi‑Fi 6E adds 6 GHz)	2.4/5/6 GHz
Maximum speed	54 Mbps	11 Mbps	54 Mbps	150, 300, or 600 Mbps (MIMO)	693 Mbps, 1.6 Gbps, 3.5 Gbps, 6.9 Gbps	up to 9.6 Gbps	up to 46.1 Gbps
Maximum range	150 Ft.	300 Ft.	300 Ft.	1200 Ft.
Modulation type					MU‑MIMO, 256‑QAM	OFDMA (massive efficiency boost), 1024‑QAM, Target Wake Time (TWT)
Channels (non-overlapped)	23 total, 12 non‑overlapping	11 total, 3 non‑overlapping	11 total, 3 non‑overlapping	5 GHz → 23 total (12 or 6 non‑overlapping), 2.4 GHz → 11 total (3 or 1 non‑overlapping)
Channel widths					80/160 MHz		320 MHz
Backwards-compatibility	N/A	No	802.11b	802.11a/b/g (depends on frequencies supported)
Notes	First 5 GHz Wi‑Fi standard; less interference but shorter range.	Cheap, long‑range, but slow and interference‑prone.		Introduced MIMO, channel bonding (40 MHz), and dual‑band Wi‑Fi.	Major speed boost; dominant standard for years.	Designed for dense environments (apartments, stadiums).	Extremely high throughput; next‑generation wireless.

Wi‑Fi Standards

	Frequency	Max Speed	Max Range	Channels (non-overlapping)	Backwards-compatibility
802.11a	5.725 GHz – 5.850 (U-NII)	54 Mbps	150 Ft.	23 (12)	N/A
802.11b	2.4 GHz (ISM)	11 Mbps	300 Ft.	11 (3)	No
802.11g	2.4 GHz (ISM)	54 Mbps	300 Ft.	11 (3)	With 802.11b
802.11n	2.4 GHz (ISM) or 5 GHz (U-NII)	150, 300, or 600 Mbps	1200 Ft.	5.75 GHz–23 (12 or 6) 2.4 GHz–11 (3 or 1)	With 802.11a/b/g, depending on frequencies supported
802.11ac (Wi-Fi 5)	2.4, 5	693 Mbps, 1.6 Gbps, 3.5 Gbps, 6.9 Gbps			802.11a/b/g/n
802.11ax (Wi-Fi 6)	2.4, 5, 6	1.15, 2.3, 4.8, 9.6 Gbps
802.11be (Wi-Fi 7)	2.4, 5, 6	11.5, 23, 35, 46.1 Gbps

Standard	Wi‑Fi Name	Frequency	Max Speed	Channel Widths	Key Features
802.11a (1999)	—	5 GHz	54 Mbps	20 MHz	OFDM, low interference
802.11b (1999)	—	2.4 GHz	11 Mbps	20 MHz	DSSS, long range
802.11g (2003)	—	2.4 GHz	54 Mbps	20 MHz	OFDM, backward‑compatible
802.11n (2009)	Wi‑Fi 4	2.4/5 GHz	150–600 Mbps	20/40 MHz	MIMO, channel bonding
802.11ac (2013)	Wi‑Fi 5	5 GHz	693 Mbps–6.9 Gbps	20/40/80/160 MHz	MU‑MIMO, 256‑QAM
802.11ax (2019–2021)	Wi‑Fi 6/6E	2.4/5/6 GHz	Up to 9.6 Gbps	20–160 MHz	OFDMA, 1024‑QAM, TWT
802.11be (2024+)	Wi‑Fi 7	2.4/5/6 GHz	Up to 46.1 Gbps	20–320 MHz	MLO, 4096‑QAM

Wi‑Fi Standards

Wi‑Fi Frequency Bands

2.4 GHz

Longest range
Lowest throughput
Most interference (Bluetooth, microwaves, IoT)
Only 3 non‑overlapping channels (1, 6, 11)

5 GHz

Medium range
High throughput
Many channels (DFS and non‑DFS)
Supports 20/40/80/160 MHz

6 GHz (Wi‑Fi 6E / Wi‑Fi 7)

Shortest range
Extremely high throughput
Clean spectrum
Up to 59 channels depending on region
Supports 160/320 MHz channels

Channel Widths & Channel Planning

Channel Widths

20 MHz — stable, best for crowded areas
40 MHz — faster, but more interference
80 MHz — high throughput (Wi‑Fi 5+)
160 MHz — very high throughput (Wi‑Fi 6/7)
320 MHz — Wi‑Fi 7 only

Channel Planning Tips

Use 1/6/11 on 2.4 GHz
Avoid DFS channels if you want maximum compatibility
Use 80 MHz only when the spectrum is clean
Use 6 GHz for high‑density, high‑speed environments

Wi‑Fi Security Standards

Standard	Status	Notes
WEP	Obsolete	Broken encryption
WPA	Legacy	TKIP, insecure
WPA2	Current	AES‑CCMP, widely used
WPA3	Modern	SAE handshake, stronger protection

Recommended: Use WPA3‑Personal or WPA2/WPA3 mixed mode for compatibility.

Antennas, MIMO, MU‑MIMO, OFDMA, Beamforming

MIMO (Multiple‑Input Multiple‑Output)

Multiple antennas increase throughput
Introduced in 802.11n

MU‑MIMO (Multi‑User MIMO)

Router can talk to multiple clients simultaneously
Introduced in 802.11ac

OFDMA (Orthogonal Frequency Division Multiple Access)

Splits channels into subcarriers
Great for dense environments
Introduced in 802.11ax

Beamforming

Directs signal toward the client
Improves range and stability

Wi‑Fi Device Types

Router — gateway + Wi‑Fi + switch
Access Point (AP) — dedicated wireless endpoint
Mesh System — multi‑node coverage
Range Extender — repeats signal (not recommended)
Wireless Bridge — connects wired devices to Wi‑Fi
Client Adapter — USB/PCIe Wi‑Fi card

Wireless Site Survey Basics

Key Metrics

RSSI (signal strength)
SNR (signal‑to‑noise ratio)
Channel overlap
Interference sources

Placement Rules

Place APs high and central
Avoid metal, concrete, and appliances
Use wired backhaul for mesh systems

Troubleshooting Quick Reference

Check signal strength
Switch to 5 GHz or 6 GHz
Change channels
Update firmware
Reposition AP
Reduce channel width
Check for interference
Restart DHCP or router

May 12, 2026

Ethernet Standards (IEEE 802.3)

Ethernet is the dominant LAN technology used worldwide. The IEEE 802.3 standard defines how Ethernet operates at the physical and data link layers, including signaling, cabling, speeds, and maximum distances. This guide summarizes the most common Ethernet standards from 10 Mbps to 100 Gbps.

Classification	Standard	Bandwidth/Speed	Medium	Maximum cable length
Thicknet	10BASE5	10 Mbps	Coaxial	500 meters
Thinnet	10BASE2	10 Mbps	Coaxial	185 meters
Standard Ethernet	10BASE-T	10 Mbps (half duplex)	Twisted pair (Cat3, 4, or 5)	100 meters
	10BASE-T	20 Mbps (full duplex)	Twisted pair (Cat3, 4, or 5)	100 meters
	10BaseFL	10 Mbps (multimode cable)	Fiber optic	1,000 to 2,000 meters
Fast Ethernet	100BaseTX	100 Mbps (half duplex)	Twisted pair (Cat5 or higher) Uses 2 pairs of wires	100 meters
		200 Mbps (full duplex)
		155 Mbps (Asynchronous Transfer Mode; ATM)
	100BaseFX	100 Mbps (multimode cable)	Fiber optic	412 meters (half-duplex)
	100BaseFX	100 Mbps (multimode cable)	Fiber optic	2 kilometers (full duplex)
Gigabit Ethernet	1000BaseT	1,000 Mbps (half duplex) 2,000 Mbps (full duplex)	Twisted pair (Cat5e, Cat6 or higher)	100 meters
	1000BaseCX (short copper)		Special copper (150 ohm)	25 meters, used within wiring closets
	1000BaseSX (short)		Fiber optic	220 to 550 meters depending on cable quality
	1000BaseLX (long)		Multi-mode optical fiber	550 meters
	1000BaseLX (long)		Single-mode optical fiber	10 kilometers
10 Gigabit Ethernet	10GBASE-T	10 Gbps (full duplex only)	Twisted pair (Cat 6a, or higher)	100 meters
	10GBaseSR		Multi-mode optical fiber	26–400 m
	10GBaseSW		Multi-mode optical fiber	300 meters
	10GBaseLR		Single-mode optical fiber	10–25 km
	10GBaseLW			10 kilometers
	10GBaseER			40 kilometers
	10GBaseEW			40 kilometers
40 Gigabit Ethernet	40GBASE-T	40 Gbps	Twisted pair (Cat 8)	30 to 36 meters
100 Gigabit Ethernet	100GBASE-SR10	100 Gbps	Multi-mode optical fiber	125 m
	100GBASE-LR4		Single-mode optical fiber (SMF)	10 km
	100GBASE-ER4		Single-mode optical fiber (SMF)	40 km

Ethernet Standards IEEE 802.3 Table

non‑IEEE Ethernet Standards

Classification	Standard	Bandwidth/Speed	Medium	Maximum cable length	Notes
Fast Ethernet	100BASE‑SX	100 Mbps	MMF	300 m	Vendor‑driven extension)
Gigabit Ethernet	1000BASE‑LH	1 Gbps (half-duplex), 2 Gbps (full-duplex)	SMF	10 km	1000BASE‑LH is not an IEEE standard. It is a Cisco/industry term for “long haul” optics, typically 20–70 km depending on optics.
Gigabit Ethernet	1000BASE‑ZX	1 Gbps (half-duplex), 2 Gbps (full-duplex)	SMF	70 km	Vendor‑driven extension)
10 Gigabit Ethernet	10GBASE‑EW	10 Gbps (full-duplex only)	SMF	40 kilometers	WAN PHY variants (SONET/SDH framing)
	10GBASE‑LW		SMF	10 kilometers
	10GBASE‑SW		MMF	300 meters

non‑IEEE Ethernet Standards Table

Frequently Asked Questions

What does “BASE” mean in Ethernet names?

“BASE” means baseband signaling, where the entire bandwidth is used for Ethernet only.

Why do some standards (like ZX or LH) not appear in IEEE tables?

Because they are vendor‑defined, not official IEEE 802.3 standards.

What does the letter after “BASE” mean?

It indicates the medium:

T = Copper twisted pair
T = Twisted pair
SX = Short‑range fiber
LX = Long‑range fiber
SR/LR/ER = Short/Long/Extended fiber

What does the number before “BASE” mean?

It indicates the speed:

100G = 100 Gbps
10 = 10 Mbps
100 = 100 Mbps
1000 = 1 Gbps
10G = 10 Gbps
40G = 40 Gbps

What is the maximum distance for twisted‑pair Ethernet?

Almost all twisted‑pair standards (10BASE‑T, 100BASE‑TX, 1000BASE‑T, 10GBASE‑T) are limited to 100 meters.

May 12, 2026

OSI Model

Layer			Protocol data unit (PDU)	Function	Common Protocols
Host layers	7	Application	Data	High-level protocols such as for resource sharing or remote file access, e.g. HTTP.	DNS, HTTP, HTTPS, FTP, POP, IMAP, SMTP, SNMP
	6	Presentation		Translation of data between a networking service and an application; including character encoding, data compression and encryption/decryption	MIME, SSL/TLS, XDR
	5	Session		Managing communication sessions, i.e., continuous exchange of information in the form of multiple back-and-forth transmissions between two nodes	Named pipe, NetBIOS, SAP, PPTP, RTP, SOCKS, X.225, Domain Name Sytem, Remote Procedure Call, Network File System
	4	Transport	Segment, Datagram	Reliable transmission of data segments between points on a network, including segmentation, acknowledgement, and multiplexing	TCP, UDP, SCTP, DCCP, SPX
Media layers	3	Network	Packet	Structuring and managing a multi-node network, including addressing, routing and traffic control	IP (IPv4, IPv6), ICMP, IPsec, IGMP, IPX, IS-IS, AppleTalk, X.25, PLP, RIP
	2	Datalink	Frame	Transmission of data frames between two nodes connected by a physical layer	ATM, ARP, Synchronous Data Link Control, High-Level Data Link Control, CSLIP, Serial Line Interface Protocol, GFP, PLIP, IEEE 802.2, LLC, MAC, L2TP, IEEE 802.3, Frame Relay, ITU-T G.hn DLL, Point-to-Point Protocol, X.25 LAPB, Q.922 Link Access Procedure, STP
	1	Physical	Bit, Symbol	Transmission and reception of raw bit streams over a physical medium	RS-232, RS-449, ITU-T V-Series, I.430, I.431, PDH, SONET/SDH, PON, OTN, DSL, IEEE 802.3, IEEE 802.11, IEEE 802.15, IEEE 802.16, IEEE 1394, ITU-T G.hn PHY, USB, Bluetooth

OSI Model		Protocol data unit (PDU)	Protocols
Layer		Protocol data unit (PDU)	Protocols
Layer 4	Application		SMTP, FTP, HTTP, DNS, TFTP, RIP, SNMP
Layer 3	Transport	Segment, Datagram	TCP, UDP
Layer 2	Internet	Packet	ARP, RARP, IP, IGMP, ICMP
Layer 1	Link (Network Access/ Interface)	Frame	Ethernet, 802.11 Wireless LAN, FRAME RELAY, ATM

OSI Model		Protocol data unit (PDU)	Protocols
OSI Model		Protocol data unit (PDU)	Protocols
Layer 7	Application	Data	DNS, HTTP, HTTPS, FTP, POP, IMAP, SMTP, SNMP
Layer 6	Presentation	Data	MIME, SSL/TLS, XDR
Layer 5	Session	Data	Named pipe, NetBIOS, SAP, PPTP, RTP, SOCKS, X.225, Domain Name System, Remote Procedure Call, Network File System
Layer 4	Transport	Segment, Datagram	TCP, UDP, SCTP, DCCP, SPX
Layer 3	Network	Packet	IP (IPv4, IPv6), ICMP, IPsec, IGMP, IPX, IS-IS, AppleTalk, X.25, PLP, RIP
Layer 2	Data Link	Frame	ATM, ARP, Synchronous Data Link Control, High-Level Data Link Control, CSLIP, Serial Line Interface Protocol, GFP, PLIP, IEEE 802.2, LLC, MAC, L2TP, IEEE 802.3, Frame Relay, ITU-T G.hn DLL, Point-to-Point Protocol, X.25 LAPB, Q.922 Link Access Procedure, STP
Layer 1	Physical	Bit, Symbol	RS-232, RS-449, ITU-T V-Series, I.430, I.431, PDH, SONET/SDH, PON, OTN, DSL, IEEE 802.3, IEEE 802.11, IEEE 802.15, IEEE 802.16, IEEE 1394, ITU-T G.hn PHY, USB, Bluetooth

December 3, 2025

Category: Networking

IP Addressing & Subnetting — Complete Guide

IPv4 Addressing Basics

Subnet Masks & CIDR Notation

Calculating Assignable Hosts

Calculating Number of Subnets

Interesting Octet & Block Size

Calculating Network & Broadcast Addresses

Step 1 — Find block size

Step 2 — Determine which block the IP falls into

Step 3 — Network & Broadcast

Step 4 — Usable Range

Binary, Hex, and Octal Conversions

Decimal → Hexadecimal

Decimal → Binary

Binary → Hex

Binary → Octal

IPv6 Addressing Basics

CIDR Summary Table