Retransmission

Within its local networks, a routing daemon is the source (that is, the sending daemon) of all the forwarded messages that it rebroadcasts. That routing daemon handles retransmission requests (for example, if a listening application in the local network misses a packet).

Retransmission and rvrd illustrates this concept:

Procedure 

1.

An application in network A sends a message.

2.

Routing daemon A forwards the message to routing daemon B.

3.

Routing daemon B rebroadcasts the message on network B.

4.

A receiving application in network B misses a packet, and its rvd requests retransmission.

5.

If the packet is within the reliability window of routing daemon B, then it retransmits the packet.

Otherwise, it denies the retransmission request; it does not attempt to get a new copy of the message from routing daemon A.

Figure 72: Retransmission and rvrd