5. Troubleshooting Connectivity : How You Diagnose Connectivity Problems : Connection Errors
Share this page                  
Connection Errors
Connection errors can occur for a variety of reasons. For example, a failure in any of the internal connections described in How Connection Between the Application and DBMS Server Is Established results in a connection error.
How connection errors are reported depends on where the failure occurs. If failure occurs:
At the local instance, errors are reported directly to the user interface program or the application.
Between the local and remote instances, for example, when attempting to connect from the local Communications Server to the remote Communications Server, errors go to the local errlog.log file as well as to the application.
At the server installation, errors are reported to both the local and remote errlog.log file and to the application.
Local Connection Errors
Each Communications Server has a GCA and GCC listen address. The GCA listen address is the server’s connection to local processes and is known only to the local Name Server (iigcn). The GCC listen address is the server’s connection to the network and is known to all nodes in the network. These listen addresses are stored separately.
The GCA address is stored at runtime in an IICOMSVR file in the Name Server database. You can obtain this address using the iinamu utility. Do not attempt to view these files directly. For more information about iinamu, see the “Command Reference” chapter in the User Guide.
The GCC address is stored in the config.dat file when the installation is configured. To view or change the GCC address, use the Net Server Protocol Configuration screen in the Configuration-By-Forms (cbf) utility, or the Net Server Protocols page in Configuration Manager (vcbf).
When the Communications Server starts up, it must be able to obtain the use of the network (GCC) listen address. If the Communications Server cannot use this listen address because the operating system has allocated the address to another process, the Communications Server cannot listen on that protocol. This problem can occasionally arise if the installation is not started from the machine boot file.
How You Resolve Remote Connection Errors
When you cannot establish a remote connection, use this procedure to diagnose the problem:
1. Check the errlog.log for error messages.
2. If that does not identify the problem, follow the procedure for your protocol in the General Net Installation Check section of this chapter. This procedure tells you if your network and protocol are working properly and if the Name Server (iigcn) and Communications Server (iigcc) processes are working properly.
3. If the problem remains unidentified after you have looked at the error messages and performed the installation check, use the following procedure to verify that your netutil connection data entry contains the correct listen address.
a. From the local instance, check the connection data for the remote instance. Note the listen address specified in the netutil Connection Data table.
b. From the remote instance, check to see which GCC listen address the remote instance’s Communications Server is using. You can find this information in the Net Server Protocol Configuration screen in the Configuration-By-Forms (cbf) utility, or the Net Server Protocols page in Configuration Manager (vcbf).
c. If the listen address found Step a does not match the listen address found in Step b, correct the problem by re-registering the remote instance’s GCC listen address. Do this from the local instance, using netutil to edit the incorrect entry. For procedures for adding, deleting, and changing a vnode definition, see the chapter "Creating Server Connection Definitions."