You can find a description of the Replication Agent configuration parameters that must be set to allow Replication Agent to connect to the primary Replication Server in Chapter 1 “Preparing for Installation” in the Replication Agent Installation Guide.
Replication Agent uses TCP/IP and the Sybase
JDBC driver (jConnect for JDBC, which is included in Replication
Agent installation) to communicate with other Sybase servers. The
Replication Agent does not rely on the Sybase interfaces file
for connectivity information.