CIDR /103 IPv6 Reference

Understanding CIDR notation for IPv6 subnets

CIDR (Classless Inter-Domain Routing) notation is a compact method for specifying IP addresses and their routing suffix. This page provides detailed information about the /103 subnet.

IPv6 /103 Subnet Details

Small subnet or host-specific allocation

IPv6 uses a 128-bit address space, a massive increase from IPv4's 32 bits. This allows for approximately 340 undecillion (3.4 x 1038) unique addresses, effectively eliminating the address exhaustion concerns of IPv4.

IPv6 /103 Information

Prefix Length/103
Address Space225 addresses
Number of /64 NetworksN/A (smaller than /64)
Common UsageInterface subnet or special purpose

IPv6 addresses are represented as eight groups of four hexadecimal digits, separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). Leading zeros in each group can be omitted, and one sequence of consecutive all-zero groups can be replaced by a double colon (::), for instance 2001:db8::1.

Key Differences from IPv4 Subnetting

  • No Broadcast Addresses: IPv6 uses multicast for one-to-many communication instead of broadcast.
  • No Network/Broadcast Reserved Addresses: Unlike IPv4, the first and last addresses in an IPv6 subnet are typically usable host addresses. There's no concept of reserving addresses for network ID or broadcast.
  • Simplified Addressing: The fixed /64 boundary for host interfaces simplifies network design and enables SLAAC.
  • Header Simplicity: The IPv6 header is simpler than IPv4's, which can improve routing efficiency.

Other CIDR References

IPv4 CIDR

/0/1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/24/25/26/27/28/29/30/31/32