Each generic data link control (GDLC) provides problem determination data that can be used to isolate network problems. Four types of diagnostic information are provided:
Status information can be obtained for a service access point (SAP) or a link station (LS) using the DLC_QUERY_SAP and DLC_QUERY_LS ioctl subroutines to call the specific DLC kernel device manager in use.
The DLC_QUERY_SAP ioctl subroutine obtains individual device driver statistics from various devices:
The DLC_QUERY_LS ioctl subroutine obtains LS statistics from various DLCs. These statistics include data link protocol counters. Each counter is reset by the DLC during the DLC_START_LS ioctl subroutine and generally runs continuously until the LS is terminated and its storage is freed. If a counter reaches the maximum count, the count is frozen and no wraparound occurs.
The suggested counters provided by a DLC device manager are listed as follows. Some DLCs can modify this set of counters based on the specific protocols supported. For example, the number of rejects or receive-not-ready packets received might be meaningful.
Each DLC provides entries to the system error log whenever errors are encountered. To call the kernel error collector, use the errsave kernel service.
The error conditions are reported by the system-product error log using the error log daemon (errdemon).
The user can obtain formatted error-log data by issuing the errpt command. When used with the -N DLCName flag, the errpt command produces a summary report of all the error log entries for the resource name indicated by the DLCName parameter. Valid values for the DLCName parameter include:
The format of each required alert vector can be found in Appendix A of SNA Format and Protocol Reference Manual: Management Services (SC30-3346).
For more information on the error log facility, refer to "Error Logging Overview" in AIX Problem Solving Guide and Reference.
GDLC provides optional entries to a generic system trace channel as required by the system product Reliability/Availability/Serviceability (RAS). The default is trace-disabled, provides maximum performance, and reduces the number of system resources used. For information on additional trace facilities, see "DLC Local Area Network Monitor Trace" in AIX Version 4.3 System Management Guide: Communications and Networks.
The operating system supports up to seven generic trace channels in operation at the same time. Before starting an LS trace, a user must allocate a channel with the DLC_START_LS ioctl operation or the DLC_TRACE ioctl operation. Begin the trace sessions with the trcstart and trcon subroutines.
Trace activity in the LS must be stopped either by halting the LS or by issuing a DLC_TRACE ioctl operation to that station. Once the LS has stopped tracing, the channel is disabled with the trcoff subroutine and returned to the system with the trcstop subroutine.
The user can obtain formatted trace log data by issuing the trcrpt command with the appropriate file name, such as:
trcrpt /tmp/link1.log
This example produces a detailed report of all link trace entries in the /tmp/link1.log file, provided a prior trcstart subroutine specified the /tmp/link1.log file as the -o name for the trace log.
For each trace entry, GDLC generates the trcgenkt kernel service to the kernel generic trace.