Yes, in IPv6 you can use other initial hextets besides “2001” for global addresses.

The “2001” range is very common because it is part of the address space allocated for most current IPv6 uses, but it is not the only range available for global unicast addresses.

Global Address Ranges in IPv6

1. Rank 2000::/3: This is the primary range used for global unicast addresses in IPv6. Within this range, “2001” is just one specific example. The full range is from 2000:: to 3FFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF. This includes a wide variety of sub-ranks assigned for different purposes and organizations.
2. Rank 2001::/16: Specifically, this is a frequently used block that was one of the first allocated for IPv6 and is widely recognized due to its allocation to Internet services and for the early deployment of IPv6.
3. Other blocks allocated for global use:
   • 2600 :: / 12: Another example of a block used for IPv6 address assignments to service providers and end users around the world.
   • 2a00::/12: Commonly used in Europe and assigned to multiple entities for use in a variety of Internet applications and services.
   • 2400 :: / 12: Used in the Asia-Pacific region.

How Global Addresses Are Assigned

Global IPv6 addresses are assigned by regional Internet registries (RIRs), such as ARIN, RIPE NCC, APNIC, among others. These registries assign address blocks to organizations and service providers based on geographic region and need.

Each registry has different blocks of addresses assigned by the IANA (Internet Assigned Numbers Authority) that are intended for distribution.

Importance of Planning

When planning your IPv6 deployment, it is important to consider how and where addresses will be used.

Specific address blocks must be obtained through the corresponding RIRs and must be used in accordance with established policies to ensure proper functioning and interoperability on the global Internet.

In short, there are many more ranges available for global IPv6 addresses than just “2001,” and their use depends on the allocation and policies of regional Internet registries.

The choice of which range to use can be influenced by factors such as availability, geographic region, and specific service provider or enterprise network requirements.