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400 CHAPTER 25: CONFIGURING DLSW
above example, c1 and c2 are the equipment of PU2.0 type, and c3 is the
equipment of PU2.1 type.
Diagnosis and
Troubleshooting of
DLSw Fault
The normal communication of DLSw requires the sound coordination between the
two SNA equipments and two routers operating DLSw, which participate in the
communication. Problem in the co-ordination between any of the two points is
likely to result in failure in connection.
Fault 1: TCP channel can not be created. The status shown is DISCONNECT
when using command display dlsw remote.
Creating TCP channel is the first step for the successful connection of DLSw. If TCP
connection can't be established, the problem lies between the two routers.
Generally, the problem is the configuration of IP address of the router. You can
check if the IP address of remote-peer is accessible by the ping command with the
source address. Also you can use display ip routing-table command to see if there
is any route to the network segment. TCP connection can be created once both
parties have established correct routes.
Fault 2: circuit can not be created correctly. To display dlsw circuits, the
virtual circuit can't attain CONNECTED state.
There are many causes that circuit can't be created. First of all, please make sure
that TCP connection to the opposite end is successfully established. If TCP
connection can be established successfully, while circuit can' t be created, this is
generally caused by the problem in the coordination of the router and SNA
equipment, mainly the problem of SDLC configuration.
Firstly, open the debugging switch of SDLC to observe if the SDLC interface can
receive and send messages successfully. You can use display interface command to
observe the condition of receiving and sending messages on the interface. If the
messages can't be received and sent correctly, it is generally because something is
wrong with the encoding mode of the interface, baud rate or clock configuration.
Generally, this can be solved by modifying the interface configuration parameter
of the router or adjusting the configuration parameter of SDLC equipment.
If the messages can be received and sent correctly, please check if the
configuration PU type is correct. You can use sdlc xid command to configure XID,
changing the setup of PU type.
If the messages can be received and sent correctly, you can check with display dlsw
circuits verbose command to see if the virtual circuit can enter into CIRCUIT_EST
status. If CIRCUIT_EST is not accessible all the time, it suggests that something is
wrong with the coordination between the MAC address and the partner
configured. Generally, this can be solved by modifying configuration parameters
such as sdlc partner.
If circuit can attain CIRCUIT_EST state, but can not attain CONNECTED state, it
suggests that the SDLC configuration of the router and the configuration of SNA
equipment are not matching. Check the configuration of SDLC equipment on
both ends and the configuration of the router to see if the configuration of the
XID of SNA equipment (PU2.1) and the configuration of XID of the router (PU2.0)
are correct. If nothing is wrong with the configuration, check the SDLC line on the