> # Establishing a TCP/IP Connection

> If you are experiencing problems when a TCP/IP connection is made to a SequeLink Server, follow these recommendations:

> - If the server host is specified by a symbolic host name instead of an IP formatted address, make sure that the host name can be mapped to an IP address. Error 2469 indicates that the specified server could not map the server host name to an IP address.

> Other TCP/IP applications, such as ping, telnet, ftp, or traceroute, should return similar errors.

> - Confirm that it is possible to make a TCP/IP connection with the specified server host using other TCP/IP applications, such as ping, telnet, ftp, or traceroute, if the requested service is available on that host. If other TCP/IP applications can connect to the server host, look for the following problems in SequeLink:
> - An invalid IP address has been specified.
> - An invalid host name has been specified, even if the host name is mapped to a valid IP address.
> - The server host may not be operational.
> - The server host could not be reached from the client machine because of a routing problem.
> - If a time limit is set on the connection, check whether a timeout occurred. Error 2320 is returned when TCP/IP cannot connect to the server host within the specified time. Increase the time interval and try again to connect.
> - If the port is specified by a name instead of a number, check whether the name can be mapped to a port number. Error 2470 is returned if the specified name cannot be mapped to a port number. Check the TCP/IP services configuration file.
> - Verify that a SequeLink service is listening on the server host at the specified port. Use the `netstat -a` command on the host to obtain a list of TCP ports that are in the listening state.
> - Check for congestion problems on the server. Error 2306 or Error 2308 is returned if TCP/IP can reach the server and a service is listening on the server host at the specified port, but too many TCP/IP connection attempts are being made simultaneously for the server to handle.