# Destination Address Handling

## Packet Destination Address Handling

Every ILPv4 `Prepare` packet has a destination address that indicates where a packet should ultimately be delivered. These addresses MUST always conform to [IL-RFC-15](https://github.com/interledger/rfcs/blob/master/0015-ilp-addresses) and may begin with one of several valid address-prefixes. 

Each of these prefixes has special meaning, and is handled by the Connector in slightly different ways, as described in the following chart.

|            Address Prefix            |       System Applicability      |                                                                                                        Purpose                                                                                                        |                                                                                                 Connector Handling                                                                                                | Accepts External Packets |    Forwards Out of Connector   |
| :----------------------------------: | :-----------------------------: | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | :----------------------: | :----------------------------: |
|                 `g.`                 |     Global Allocation Scheme    |                                                         ILP addresses that are intended to send and receive money from any other address in the global scheme.                                                        |                                                                               Forwarded to a plugin by the Packet-switching fabric.                                                                               |            Yes           |               Yes              |
|              `private.`              |        Private allocation       |                                                For ILP addresses that only have meaning in a private subnet or intranet. Analogous to the 192.168.0.0/16 range in IPv4.                                               |                                                                               Forwarded to a plugin by the Packet-switching fabric.                                                                               |            No            |               Yes              |
|              `example.`              |             Examples            |                                                  For "non-real" addresses that are used as examples or in documentation. Analogous to "555 phone numbers" in the USA.                                                 |                                                                                         Always rejected by the Connector.                                                                                         |            No            |               No               |
| `test.`, `test1.`, `test2.`,`test3.` | Interledger testnet and testing |                                           For addresses used on the public Interledger testnet and in local tests, such as unit or integration tests of compatible software.                                          |                                     Handled identically to a `g.` address if the Connector's Operating Address begins with `test`; Otherwise always rejected by the Connector.                                    |            Yes           |               Yes              |
|               `local.`               |         Connector-local         |                                          For addresses that are valid only in the a local-connector network, such among a cluster of connectors operated by the same entity.                                          |                                                                          Forwarded to a connected plugin by the Packet-switching fabric.                                                                          |            No            | Yes (only to another `local.`) |
|                `peer.`               |             Peering             | Addresses for exchange of packets only with a direct peer. Connectors MUST NOT forward packets with peer. addresses. Packets exchanged between peers to pass routing and config information will use peer. addresses. |                                                                                 Handled by the Connector as a message from a Peer.                                                                                |            Yes           |               No               |
|                `self.`               |          Local loopback         |               For addresses that are only valid on the local machine. For example, `self.ping`, `self.echo`, and other internal addresses that the Connector forwards traffic to for internal handling.               | External packets *can* make their way to `self.` handlers, but only indirectly. For example, Ping packets are addressed to this Connector's operator address, and are then forwarded to `self.ping` for handling. |            No            |               No               |