# Prefix allocation and registration

To simply forward IPv6 traffic on CRXN one only needs an IPv6 link-local address which is always guaranteed to be assigned (most of the time), however normally people join CRXN so that they can _also_ host services (and access others) on the inter-network. Therefore, one needs to allocate a prefix and register it to be able to make use of the network in such a manner.

## Generating a prefix (allocation)

On CRXN we use addresses within the `fd00::/8` space otherwise known as the ULA-space. We then require users to generate a random ULA which is a subnet within this space with a prefix size of `/48`.

Here is what a ULA would look like: `fd2d:194b:a02f::/48`

You can generate your ULA you would like to use for CRXN using a tool such as [Unique Local IPv6 Generator](https://www.unique-local-ipv6.com/) or if you are good at basic programming and mathematics you could write a C program to do it.

## Registering the prefix

Once you have your prefix generated you then are required to register the prefix. This entails adding your prefix to a database known as _EntityDB_ which holds all such entries. This is done in order to ensure there are no clashes with addresses and also doubles as a source of truth in terms of what networks _should_ be available on CRXN along with some information about available services.

To register your prefix on EntityDB please visit the repository [here](https://codeberg.org/CRXN/entitydb), fork the repository, then follow the [`README.md`](https://codeberg.org/CRXN/entitydb/src/branch/master/README.md) on how to format your entry, create a pull request and wait for approval from a network administrator. Only then will you be allowed to continue with this tutorial.