Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

Unable to set clock rate on S0...

Hi all, ok I've got a 3 2500 series routers attempting to setup sim WAN links over frame-relay. take a looka t this:

Serial0 is up, line protocol is down

Hardware is HD64570

Internet address is

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation FRAME-RELAY, loopback not set

Keepalive set (10 sec)

LMI enq sent 0, LMI stat recvd 0, LMI upd recvd 0

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0, DCE LMI down

LMI DLCI 1023 LMI type is CISCO frame relay DCE

Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0

Last input never, output never, output hang never

Last clearing of "show interface" counters 00:48:57

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/0/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort


Ok now you can see that this intf is a DCE,now watch this:

2503-hub#config t

Enter configuration commands, one per line. End with CNTL/Z.

2503-hub(config)#int s0

2503-hub(config-if)#clock rate 125000

%Error: This command applies only to DCE interfaces


So why can I not set the clock rate on this intf is it's a DCE? Any help would be vastly appreciated..


Cisco Employee

Re: Unable to set clock rate on S0...

Setting the DCE at the FrameRelay level is not sufficient.

The only way to set the clock rate is to connect the router using a DCE cable. I suspect your serial port is not connected to a DCE cable. To find out, do a "show contr serial" command for the specific serial port as follow:

Router#sh contr serial 0

HD unit 0, idb = 0x1FFA74, driver structure at 0x207598

buffer size 1524 HD unit 1, V.35 DTE cable <+++++++

cpb = 0xE5, eda = 0xA83C, cda = 0xA850

This will tell you whether the serial interface is connected with the proper cable.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600

Re: Unable to set clock rate on S0...

I assume you have a FR switch (another cisco router configured as one). Since your end is giving error message that clock rate is applicable only on DCE interfaces, the cable end on the hub side is DTE. So the other end of the cable should be DCE (which is the FR switch). You can go into this router's serial interface connecting to the hub router and specify the clock rate 125000 there instead of recabling.

Otherwise you can recable by swapping the cable ends of the existing connection between hub router and FR switch.


New Member

Re: Unable to set clock rate on S0...

OMG man, I cannot believe it was that...Yeah see the 2503 was teh frame switching router with a 2501 off each serial. So yes, I had the cable reversed..I moved the DCE end back to the 2503 and VOILA! both links came up and now Im discovering routes viz eigrp...

Thanks a million!!!

CreatePlease to create content