Protocol is a segment of the host description string. This segment defines the protocol that can be used to connect to the host described in the string. For example, when specifying AF_PROTOCOL_UDP in a host description, the described host can be accessed using UDP.
The following table lists the possible types and their meaning.
|AF_PROTOCOL_UDP||UDP is used as transport protocol.|
|AF_PROTOCOL_TCP||TCP is used as transport protocol.|
|AF_PROTOCOL_TLS||Specifies a TLS connection to a server, e.g., a TLS connection to a SIP proxy.|