Comprehensive Guide to IP Addressing and IPv6 in TCP/IP Networks

1. Key Terminology

• Bit: Binary digit (0 or 1)
• Byte: 8 bits
• Octet: 8-bit value (0 to 255)
• IP Address: Logical identifier of a device
• Network Address: Refers to the entire subnet
• Broadcast Address: Sends to all hosts in subnet

2. IPv4 Structure

IPv4 addresses are 32-bit and can be written in decimal, binary, or hexadecimal form.

Decimal: 172.16.30.56  
Binary: 10101100.00010000.00011110.00111000  
Hex: AC.10.1E.38

This hierarchical format enables routing efficiency and address management.

3. IPv4 Address Classes

Class	Range	Format	Hosts/Subnet
A	0–127	network.host.host.host	16,777,214
B	128–191	network.network.host.host	65,534
C	192–223	network.network.network.host	254
D	224–239	Multicast	Group only
E	240–255	Reserved	Experimental

4. Reserved and Private IPs

• 0.0.0.0 → Default route
• 127.0.0.1 → Loopback
• 255.255.255.255 → Universal broadcast
• Private IP Ranges (RFC 1918):
• Class A: 10.0.0.0/8
• Class B: 172.16.0.0/12
• Class C: 192.168.0.0/16

5. IPv4 Address Types

• Unicast: One-to-one communication
• Broadcast: Sent to all devices
• Multicast: Sent to a group (Class D)
• Virtual IP: Logical IP not bound to physical NIC

6. Automatic Private IP Addressing (APIPA)

If DHCP is unavailable, devices auto-assign IP in this range:

169.254.0.1 to 169.254.255.254  
Subnet Mask: 255.255.0.0

Used for limited local communication only.

7. Introduction to IPv6

• 128-bit address space
• 3.4 × 10³⁸ unique addresses
• No broadcast; relies on multicast
• Built-in IPSec and mobile compatibility

8. IPv6 Address Format

Full: 2001:0db8:3c4d:0012:0000:0000:1234:56ab  
Simplified: 2001:db8:3c4d:12:0:0:1234:56ab  
With "::" → 2001:db8:3c4d:12::1234:56ab

Note: "::" can only appear once in an address.

9. IPv6 Address Types

• Global Unicast: 2000::/3
• Link-Local: FE80::/10
• Unique Local: FC00::/7
• Multicast: FF00::/8
• Anycast: One-to-nearest

10. Special IPv6 Addresses

• :: → Equivalent to 0.0.0.0
• ::1 → Loopback address
• 2001:db8::/32 → Reserved for documentation
• 2002::/16 → Used in 6to4 tunneling

11. IPv6 Auto Configuration (SLAAC)

- Router sends prefix  
- Device uses MAC to create Interface ID  
- MAC: 00:60:d6:73:19:87  
- Interface ID → 02:60:d6:FF:FE:73:19:87

Bit 7 (U/L) is flipped to indicate local vs global scope.

12. DHCPv6

Similar to IPv4 DHCP but optimized for 128-bit addressing. Provides DNS, domain, and detailed control.

13. Migrating to IPv6

• Dual Stack: Run IPv4 and IPv6 together
• Tunneling: Methods include 6to4 and Teredo

14. Conclusion

IP addressing underpins reliable, scalable network architecture. Mastering IPv4 and IPv6 ensures robust deployment and exam readiness, especially for Network+ certification.