Serial Connection between Routers

I am trying to set up a CCIE pratice lab. Due to short of routers, I have to use a few Cisco c3250 mobile routers that I have. My cisco c3250 routers has two DB-9 serial ports with male connectors. I am trying to connect the serial port of the c3250 router to the serial port of my frame-relay switch (Cisco c2811 router with HWIC) with a CAB-SS-232FC cable (DB25F to Smart) + a Straight Serial cable (DB25M to DB9F). I got a link. The frame-relay switch shows as DCE V.24 and c3250 shows as DTE V.24. However, the LMI does not work with keepalive on. The DTE side keeps sending the keepalive message with "youseen=0". The DCE side shows "DCE LMI timeout". The interfaces on the both ends show "UP", but the line protocol is down. If I disable the keepalive, the interfaces show "UP, UP". However, I could not pass any traffic. Do any of you know what problem that I have and how should I resolve it?

Thank you in advance!


  • on your "frame-relay switch" try to emulate dce interface by means of interface-level frame-relay intf-type dce command.

  • Yes, the command was/is there. I have also tried with default encapsulation HDLC. The problem is same. I suspect that may be a cable issue (Cable length should not be a problem.). However, I could not test out easily with Smart connector.

    Thank you very much!



  • I have tried a few more things and found out more confusion. The DCE side of CAB-SS-232FC cable is at DB25 Famale side. The smart connector connected to my frame-relay switch is supposed to be DTE. The DB 9 F side connected to my Cisco c3250 mobile router (after DB25 F to DB9 F conversion) is supposed to be DCE. However, the "show controller" at frame-relay switch always shows "DCE", at Cisco c3250 always shows "DTE". If I have the command "frame-relay intf-type dce" at frame-relay switch, "show interface" will show as "DCE", otherwise "DTE" even the "show controller" shows "DCE". At both situations, the interfaces at both ends are "UP, Down". I wonder what cause the controller on the frame-relay switch to see it as DCE while it is connected to a DTE end of the cable. Did the DB25 to DB 9 conversion changed the cable direction?



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