Analysis

Table 1 lists some of the common SNALINK LU6.2 data loss problems.

Table 1. Common SNALINK LU6.2 data loss problems
If this is displayed. . . Then this might have occurred . . . Resolution
Data packets are lost between the TCP/IP and the SNALINK LU6.2 address space (either end). This problem can be due to one of the following situations:
  1. The DLC link between the TCP/IP address space and the SNALINK LU6.2 address space might not be active.
  2. The SNALINK LU6.2 address space might be discarding packets.
  1. See DLC connection problems to diagnose the DLC link problem.
  2. When a condition occurs in the SNALINK LU6.2 address space that causes data to be lost, “discarding datagram” messages are written to the data set specified by the SYSPRINT DD statement in the SNALINK LU6.2 cataloged procedure.

    See Finding error message documentation for details on finding the documentation for these messages. Text in the message documentation specifies the action required to fix the problem.
Data packets are actually not lost but the protocol (PING) times out. The SNALINK LU6.2 device might be establishing the LU type 6.2 connection to transfer the data packets. The delay in establishing the connection might be causing the protocol to time out. If the DATA parameter is specified on the DEST statement for the connection in the SNALINK LU6.2 configuration data set, the connection is not established until data is to be transferred over the connection. In this case, after the first data transfer, further data packets are transferred successfully.

If the TIMEOUT parameter is specified on the LINK statement for the connection in the SNALINK LU6.2 configuration data set, the connection can be timing out too often, causing the connection to be reestablished for each data transfer. In this case, the protocol timeout value or the connection timeout value should be increased.
Data packets are lost between the SNALINK LU6.2 devices. The network is failing. Check for VTAM® error messages on the MVS™ system console. See VTAM buffer traces for more details about using VTAM traces to diagnose the SNA network.
Parent topic: Data loss problems