Router problem?

[Ciscouser1]

I have a CCNA lab with two 2501 and one 2503 routers connected together through serial ports by V35 DCE/DTE 60pin cables. One of the 2501 router's serial 0 connected to 2503 serial 1, the connection didn't work, the line protocol keeps up and down every 2 seconds (Can see the message on the 2501 console). The 2503 to the second 2501 worked ok. The configuration is encapsulation HDLC, IP address 192.168.1.1/24 on 2501 and 192.168.1.2/24 on 2503. I tried both serial ports on the first 2501 router and it gave the same problem. Is it possibly hardware damage or something? Please help. Thanks.

[Georg Pauwen]

Hello,

make sure you have a clock configured on one of the interfaces, e.g.:

interface Serial0

clock rate 64000

HTH,

GP

[Kevin Dorrell]

The protocol going up and down is misleading. It always says the protocol goes up until it has detected that has actually failed, i.e. during protocol setup, it is reported as up.

It sound like a physical problem, so the IP address, encapsulation etc don't enter into it.

Which side is the DCE? Make sure the DCE side has the clock rate defined.

Kevin Dorrell

Luxembourg

[Ciscouser1]

The clock rate is defined on the 2503 side and it worked on the second 2501. I even tried to lower the clock rate to 9600 and it had the same problem. If I make the faulty 2501 s0 as DCE there will be only one console message said "line protocol down" and no changes.

[Kevin Dorrell]

As I understand it, your setup is like this. If it is, please could you confirm. If it is not, could you please make it like this and let us know what happens.

1. Both serial interfaces of the 2503 have a DCE cable connected.

2. Both serial interfaces of the 2503 have a clockrate defined.

3. Both 2501s have the DTE cable connected.

4. Neither 2501 has a clockrate defined.

If this is correct, and you still have the problem, then there must be a hardware fault. Could it be a cable problem? Try swapping the two cable pairs and see what happens.

Kevin Dorrell

Luxembourg

[abhijeet80]

Hi,

I suggest try doing this,

First make one router DCE, give clockrate, and the other router DTE

Second put encapsulation HDLC or PPP on both interfaces.

Try pinging.

If not then try any other cable, mostly in Labs there is faulty cable fault and rarely a bad interface.

Hope this helps