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Link fails to start - failed to open GDLC device

Technote (troubleshooting)


A link station fails to start. The sna.err log records the following GDLC error:
Failed to open GDLC device.


A link fails to start.

The sna.err log records a message similar to the following:

    2008-08-05 09:52:34 EDT 1536-24(1-10) E (testlab)
    Failed to open GDLC device.                                      
    Device name = /dev/dlctoken/tok0                                
    DLC         = TOK0                                              
    Return code = 2                                                  
    2008-08-05 09:52:34 EDT 512-77(3-10) P (testlab)
    DLC failed.                                                      
    DLC name           = TOK0                                        
    2008-08-05 09:55:24 EDT 1536-24(1-10) E (testlab)
    Failed to open GDLC device.
    Device name = /dev/dlc8023/ent55
    DLC         = ENT55
    Return code = 19
    2008-08-05 09:55:24 EDT 512-77(3-10) P (testlab)
    DLC failed.
    DLC name           = ENT55


The first error has return code errno 2, which is ENOENT or "no such file or directory". This indicates that the DLC device does not exist. Possible causes for this include:

  • The appropriate bos.dlc.* fileset is not installed.
  • The DLC device was never created.
  • The system was restored from a backup tape, which sometimes does not recreate the DLC devices.

The second error has return code errno 19, which is ENODEV or "no such device". This indicates that the specified adapter (in this case ent55) does not exist.
Possible causes for this include:
  • An incorrect adapter_number was specified in the CSAIX configuration.
  • The network adapter has been removed from AIX.

Resolving the problem

Following is a list of DLCs that SNA uses to communicate with the adapters. The DLCs are for general types of adapters, not for specific adapters. Also listed is the fileset name for each DLC type. Use the lslpp -L fileset_name command to determine if the fileset is installed.

bos.dlc.8023 Ethernet (802.3)
bos.dlc.ether Standard Ethernet
bos.dlc.fddi FDDI
bos.dlc.qllc X.25
bos.dlc.sdlc SDLC
Token Ring
Multi-Path Channel

These bos.dlc.* filesets are provided on the AIX installation media, and the sna.dlcmpc fileset is provided on the CS/AIX media. The sna.dlcchannel fileset is no longer provided, but was provided on the CS/AIX media with V5, V6.0, and V6.1. The bos.dlc.* filesets are not automatically installed in a standard installation of AIX.

The lsdev -Cc dlc command will show the status of the DLCs on the system. If the DLC is in the list, the relevant DLC fileset is installed. The DLC must be available for SNA to use it.

# lsdev -Cc dlc
dlctoken   Available  Token-Ring Data Link Control
dlcether   Available  Standard Ethernet Data Link Control
dlc8023    Available  IEEE Ethernet (802.3) Data Link Control
dlcchannel Available  Channel Data Link Control
dlcmpc     Available  MPC Data Link Control
dlcsdlc    Available  SDLC Data Link Control
dlcqllc    Available  X.25 QLLC Data Link Control
dlcfddi    Available  FDDI Data Link Control

If the required DLC is not present, but the appropriate fileset is installed, then use SMIT fastpath "commodev" to access the "Services" menu for the appropriate adapter type, choose the "Data Link Controls" menu, and "Add" a Data Link Control. The DLC device should become available. It is now ready for use by CS/AIX.

The lsdev -Cc adapter command will display a list that includes network adapters on the system. Check that the adapter listed in the error message is present and available in this list. Either correct AIX to ensure that the desired adapter exists, or correct CS/AIX configuration to use an existing adapter.

Cross reference information
Segment Product Component Platform Version Edition
Networking IBM Communications Server for Data Center Deployment All AIX

Product Alias/Synonym

sna communications server aix comserver comserver comserv csaix cs/aix aixsna

Document information

More support for: Communications Server for AIX

Software version: 5.0, 6.0, 6.1, 6.3, 6.3.1, 6.4,,,,,

Operating system(s): AIX

Reference #: 1315432

Modified date: 2008-09-02