IPv6 Chart Sheet

Complete IPv6 subnet reference with prefix lengths and address calculations

Prefix Length Subnet Mask (Hex) Network Bits Host Bits Total Addresses Number of /64 Networks Common Usage
/128ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff128010Host address
/127ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffe127120Point-to-point links
/126ffff:ffff:ffff:ffff:ffff:ffff:ffff:fffc126240Point-to-point links
/125ffff:ffff:ffff:ffff:ffff:ffff:ffff:fff8125380Very small subnets
/124ffff:ffff:ffff:ffff:ffff:ffff:ffff:fff01244160Very small subnets
/120ffff:ffff:ffff:ffff:ffff:ffff:ffff:ff0012082560Small subnets
/112ffff:ffff:ffff:ffff:ffff:ffff:ffff:00001121665,5360Small networks
/96ffff:ffff:ffff:ffff:ffff:ffff:0000:000096324,294,967,2960Large subnets
/64ffff:ffff:ffff:ffff:0000:0000:0000:0000646418,446,744,073,709,551,6161Standard subnet
/56ffff:ffff:ffff:ff00:0000:0000:0000:000056724.7 × 10²¹256Site allocation
/48ffff:ffff:ffff:0000:0000:0000:0000:000048801.2 × 10²⁴65,536Organization
/40ffff:ffff:ff00:0000:0000:0000:0000:000040883.1 × 10²⁶16,777,216Large organization
/32ffff:ffff:0000:0000:0000:0000:0000:000032967.9 × 10²⁸4,294,967,296ISP allocation
/24ffff:ff00:0000:0000:0000:0000:0000:0000241042.0 × 10³¹1.1 × 10¹²Regional registry
/16ffff:0000:0000:0000:0000:0000:0000:0000161125.2 × 10³³2.8 × 10¹⁴Global registry
/12fff0:0000:0000:0000:0000:0000:0000:0000121168.3 × 10³⁴4.5 × 10¹⁵Special allocation
/8ff00:0000:0000:0000:0000:0000:0000:000081201.3 × 10³⁶7.2 × 10¹⁶Address type
/4f000:0000:0000:0000:0000:0000:0000:000041242.1 × 10³⁷1.2 × 10¹⁸Address class
/3e000:0000:0000:0000:0000:0000:0000:000031254.2 × 10³⁷2.3 × 10¹⁸Global unicast
/00000:0000:0000:0000:0000:0000:0000:000001283.4 × 10³⁸1.8 × 10¹⁹Entire IPv6 space

IPv6 Address Types & Special Use Ranges

IPv6 address categories and their specific usage

Unicast Addresses

Address Type Prefix/Range Allocation Scope RFC Description
Global Unicast 2000::/3 2000:: - 3fff:: Global RFC 4291 Internet routable addresses
Link-Local fe80::/10 fe80:: - febf:: Link RFC 4291 Not routable beyond local link
Unique Local (ULA) fc00::/7 fc00:: - fdff:: Local RFC 4193 Private addresses for local use
Loopback ::1/128 ::1 Node RFC 4291 Localhost address
Unspecified ::/128 :: Node RFC 4291 All zeros address
IPv4-mapped ::ffff:0:0/96 ::ffff:0.0.0.0 - ::ffff:255.255.255.255 Global RFC 4291 IPv4 addresses mapped to IPv6
IPv4-compatible ::/96 ::0.0.0.0 - ::255.255.255.255 Global RFC 4291 Deprecated IPv4 compatibility

Multicast Addresses

Address Type Prefix Scope Flag Description Examples
Multicast Address Format: ff0X::/16
Interface-local ff01::/16 1 0 Single interface only ff01::1 (All Nodes)
Link-local ff02::/16 2 0 Single link/subnet ff02::1 (All Nodes), ff02::2 (All Routers)
Site-local ff05::/16 5 0 Single site/organization ff05::2 (All Routers)
Organization-local ff08::/16 8 0 Single organization ff08::fb (mDNSv6)
Global ff0e::/16 E 0 Global Internet ff0e::1 (NTP)
Solicited-node ff02::1:ff00:0/104 2 0 Neighbor Discovery ff02::1:ffxx:xxxx

Special Use & Reserved Addresses

Address Range Prefix Purpose RFC Status Description
0000::/8 ::/8 Special Use RFC 4291 Reserved Contains loopback and unspecified
0100::/8 0100::/8 Reserved RFC 4291 Reserved Reserved by IETF
0200::/7 0200::/7 Reserved RFC 4291 Reserved Reserved by IETF
0400::/6 0400::/6 Reserved RFC 4291 Reserved Reserved by IETF
0800::/5 0800::/5 Reserved RFC 4291 Reserved Reserved by IETF
1000::/4 1000::/4 Reserved RFC 4291 Reserved Reserved by IETF
4000::/3 4000::/3 Reserved RFC 4291 Reserved Reserved by IETF
6000::/3 6000::/3 Reserved RFC 4291 Reserved Reserved by IETF
8000::/3 8000::/3 Reserved RFC 4291 Reserved Reserved by IETF
a000::/3 a000::/3 Reserved RFC 4291 Reserved Reserved by IETF
c000::/3 c000::/3 Reserved RFC 4291 Reserved Reserved by IETF
e000::/4 e000::/4 Reserved RFC 4291 Reserved Reserved by IETF
f000::/5 f000::/5 Reserved RFC 4291 Reserved Reserved by IETF
f800::/6 f800::/6 Reserved RFC 4291 Reserved Reserved by IETF
fc00::/7 fc00::/7 Unique Local RFC 4193 Active Unique Local Unicast
fe00::/9 fe00::/9 Reserved RFC 4291 Reserved Reserved by IETF
fe80::/10 fe80::/10 Link-Local RFC 4291 Active Link-Local Unicast
fec0::/10 fec0::/10 Site-Local RFC 3879 Deprecated Deprecated Site-Local
ff00::/8 ff00::/8 Multicast RFC 4291 Active Multicast Addresses

IPv4 vs IPv6 Comparison

Key differences between IPv4 and IPv6 protocols

Feature IPv4 IPv6 Improvement
Address Length 32 bits 128 bits 4x larger address space
Address Space ~4.3 billion addresses ~3.4 × 10³⁸ addresses Virtually unlimited addresses
Address Format Dotted decimal (192.168.1.1) Hexadecimal (2001:db8::1) More compact representation
Header Size 20-60 bytes (variable) 40 bytes (fixed) Simplified, fixed-size header
Fragmentation Routers and hosts Source hosts only Reduced router processing
Checksum Header checksum No header checksum Faster processing
Security Optional IPSec Built-in IPSec support Enhanced security
Configuration Manual or DHCP Auto-configuration + DHCPv6 Simplified setup
Broadcast Broadcast supported No broadcast (multicast only) More efficient communication
Private Addresses RFC 1918 ranges Unique Local (ULA) fc00::/7 Better private addressing
NAT Requirement Essential due to address shortage Not needed (end-to-end connectivity) True end-to-end communication
QoS Support Type of Service field Traffic Class + Flow Label Better quality of service