Rendezvous is a service that is used for double NAT penetration technology. Most of SONM participants don't have public IPs. To make them interact in peer-to-peer manner SONM provides a technology to make direct connections for devices behind NATs.

In this technology only one service with public IP is used. This service coordinates Workers and Client nodes to create a direct connection. After the connection is established Rendezvous is not used for data transfers.

Relay is a service that is also used for double NAT penetration when Rendezvous cannot. There are some types of NATs that will not be passed through using Rendevous. In that case SONM Client and Worker nodes will automatically use Relay service. The service with a public IP will retransmit all data got from one node to another.