WRAP allows the relaying to be transparent in the sense that each IRT is simply a sequence of IPv4 addresses designating relay agents and endpoints, an Internet Relay Path (IRP). The IRT can also be opaque so that a holder of the IRT cannot determine the relay path nor can it forge a valid IRT.
Using a transparent IRT, the RA is stateless in the sense that the relaying only relies on routing/directory state and configuration state; it does not require state to be created on name lookups. In this mode of operation, the relay node is statically configured with an IPv4 address for each of the other realms it connects to, so that an address uniquely identifies which direction to relay a packet (and a particular ``egress'' address in that realm.) Upon receipt of a WRAP packet, the relay agent replaces the IP destination with the first forward token component, uses the egress address as the new IP source, and places the old IP source as the last component in the reverse token. This is the simplest possible relaying action, requiring only 4 words in the packet headers to be modified.
To make the WRAP addressing opaque to an observer, the relay agent can choose to put a random value in the IRT and translate it to/from IPv4 addresses using the relay table described earlier. This opaque form prevents a upstream source from fabricating IRTs, forcing it to rely instead on the directory service to supply IRTs. In particular, an ISP can retain control of routing, preventing customers from using unauthorized routes. It also prevents a third-party observer from determining protected information from addresses in the packets.
An IRT must have the reversibility property, namely that the component-wise reversal of the received IRT provides an IRT that can be used to send a packet back to the source of the packet using the relay agent from which the original packet was received.
An IRT normally also has the concatenation property, i.e. if the IRT to a relay agent is X from a host H and Y is the IRT to a destination D relative to this relay agent, then XY is an IRT to destination D from host H. The directory indicates whether the returned IRT supports concatenation or not.