Windows 7 / Networking

Understanding Interface Identifiers

For all the types of unicast IPv6 addresses described in the preceding sections, the last 64 bits of the address represent the interface ID and are used to specify a unique interface on a local link or subnet. In previous versions of Windows, the interface ID is uniquely determined as follows:

  • For link-local addresses, such as a network adapter on an Ethernet segment, the interface ID is derived from either the unique 48-bit media access control (MAC)-layer address of the interface or the unique Extended Unique Identifier (EUI)-64 address of the interface as defined by the Institute of Electrical and Electronics Engineers (IEEE).
  • For global address prefixes, an EIU-64-based interface ID creates a public IPv6 address.
  • For global address prefixes, a temporary random interface ID creates a temporary address. This approach is described in RFC 3041; you can use it to help provide anonymity for client-based usage of the IPv6 Internet.

In Windows 7, however, the interface ID by default is randomly generated for all types of unicast IPv6 addresses assigned to LAN interfaces.

Note Windows 7 randomly generates the interface ID by default. You can also disable this behavior by typing netsh interface ipv6 set global randomizedidentifiers=disabled at a command prompt.

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In this tutorial:

  1. Deploying IPv6
  2. Understanding IPv6
  3. Understanding IPv6 Terminology
  4. Understanding IPv6 Addressing
  5. Understanding IPv6 Prefixes
  6. Understanding IPv6 Address Types
  7. Understanding Unicast Addresses
  8. Identifying IPv6 Address Types
  9. Understanding Interface Identifiers
  10. Comparing IPv6 with IPv4
  11. Understanding IPv6 Routing
  12. How IPv6 Routing Works
  13. IPv6 Route Determination Process
  14. IPv6 Routing Table Structure
  15. Understanding ICMPv6 Messages
  16. Understanding Neighbor Discovery
  17. Understanding Address Autoconfiguration
  18. Understanding Name Resolution
  19. Understanding Name Queries
  20. Understanding Name Registration
  21. PTR Records and IPv6
  22. IPv6 Enhancements in Windows 7
  23. Summary of IPv6 Enhancements in Windows 7
  24. Configuring and Troubleshooting IPv6 in Windows 7
  25. Configuring IPv6 in Windows 7 Using the User Interface
  26. Configuring IPv6 in Windows 7 Using Netsh
  27. Other IPv6 Configuration Tasks
  28. Enabling or Disabling IPv6
  29. Disabling Random Interface IDs
  30. Resetting IPv6 Configuration
  31. Displaying Teredo Client Status
  32. Troubleshooting IPv6 Connectivity
  33. Planning for IPv6 Migration
  34. Blocking Teredo
  35. Understanding ISATAP
  36. Migrating an Intranet to IPv6
  37. Step 1: Upgrading Your Applications and Services
  38. Step 2: Preparing Your DNS Infrastructure
  39. Step 3: Upgrading Your Hosts
  40. Step 4: Migrating from IPv4-only to ISATAP
  41. Step 5: Upgrading Your Routing Infrastructure
  42. Step 6: Upgrading Your DHCP Infrastructure
  43. Step 7: Migrating from ISATAP to Native IPv6
  44. The Advantages of IPv6
  45. Address Resolution in IPv6