Wide-Area Relay Addressing Protocol


WRAP, Wide-area Relay Addressing Protocol, is a shim protocol that uses a variable-length header between the IP and the transport layer, providing NAT with extensible addressing.

WRAP relays packets by using Internet Relay Tokens (IRTs), mapped from domain names by the Directory Relay Protocol (DRP). The IRT, an inter-realm address, can take several forms. The simplest of these is the Internet Relay Path (IRP). It consists of a list of intra-realm (IPv4) addresses. Each intra-realm address specifies a Relay Agent (RA) that can forward packets from one address realm to another, where the next address in the list will be valid.

WRAP is an explicit relaying protocol. Unlike Loose Source Routing, WRAP updates the source address at each intermediate destination (Relay Agent) and does not use an IP option. Unlike IP encapsulation protocols, WRAP does not discard intermediate destination information.

WRAP supports the EXPRESS single-source model of multicast. WRAP can also be used for Virtual Private Networks (VPN) and support policy-based routing.

WRAP Specification