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Understanding IPv6 Stateless Addressing

Apr 23, 2025

IPv6 Networking and Stateless Addressing

Overview

  • IPv6 incorporates techniques from IPv4, updated for modern networks.
  • Includes DHCP for IPv6, similar to IPv4, but with enhancements for redundancy and enterprise use.

IPv6 Address Assignment

  • Stateless Addressing:
    • IPv6 allows devices to self-assign IP addresses without DHCP servers.
    • Known as Stateless Address Autoconfiguration (SLAAC).
    • No need to track IP or MAC addresses.
    • No lease time, thus no need to release IP addresses.

Neighbor Discovery Protocol (NDP)

  • Replaces ARP in IPv6 networks.
  • Uses multicast instead of broadcast for efficient communication.

Functions of NDP

  • Router Discovery:

    • Devices use Router Solicitation to find local routers.
    • Routers can send unsolicited Router Advertisements to all devices.
    • Provides subnet, prefix, DNS server, and other IPv6 configuration.
  • Duplicate Address Detection (DAD):

    • Ensures no duplicate addresses exist on the network.

Stateless Address Autoconfiguration (SLAAC)

  1. Subnet Discovery:

    • Uses NDP to identify the local subnet through Router Solicitation.
    • Router responds with Router Advertisement including prefix info.
  2. Interface ID Creation:

    • Last 64 bits of the IPv6 address.
    • Often derived from a modified MAC address with inserted 'FFFE'.
    • Alternatives include using a randomly generated value.
  3. Address Verification:

    • Uses NDP's DAD to verify the uniqueness of the assigned address.

Conclusion

  • Devices gain a unique, routable IPv6 address without needing a DHCP server.
  • Efficient and automated address management process in IPv6 networks.