wan serial interface troubleshooting

[stylishazaz1]

hello everybody.i have a question if somebody knows kindly answer me.

i have connected 2 back to back router and the follwoing message appears.

serial0 is up,line protocol is down

somebody told me that this problem can occur because of the follwing 3 reasons

1.keepalive  

2.clockrate 

3.ecapsulation mismatch

 can any body explain me what keep alive is?????????????????????????????????????????????????

[Collin Clark]

IMO keepalive is incorrect. Typically it's the DTE/DCE [clockrate] setting. Check this link for a configuration example.

http://www.cisco.com/c/en/us/support/docs/wan/high-level-data-link-control-hdlc/7927-hdlc-back.html

Hope it helps.

[Aman Soi]

Hi,

you need to configure clockrate command on DCE serial port[port on which DCE cable is connected].

You can also check the signals like DTR, RTS, CTS, DCD,DSR on DTE and DCE ports

http://www.omnisecu.com/cisco-certified-network-associate-ccna/how-to-configure-router-serial-interfaces.php

you can run show controllers serial 0/0 to check if port is DCE or DTE after connecting the serial cable.

regds,

aman

[rvasquezmc]

If you are just practicing you are the one who has to set the clockrate , you will do something like:

interface serial 0/0.

clockrate 128000.

And by the default the encapsulation on cisco routers is HDLC but if you bought the routers with a previous configuration one of them could have PPP on it.

Check that out with the show interfaces "serial X" or the show running config ..