Clock rate on 3640

Unanswered Question
Oct 11th, 2005
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Hi all,

I have a 3640 cisco router with IOS Enterprise w/ SNASW.

The serial 0/0 interface has the clock rate command by default. When i 'm trying to remove this command by:

#no clock rate

i got the following error:

FECPM PM doesn't support clock rate 0

When i connect a DTE cable, it is the same thing even if i entered encap x25 dte.

any ideas?



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stschmidt Tue, 10/11/2005 - 11:45
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"FECPM PM doesn't support clock rate 0"

Please attach a DTE cable and do a shut/no shut on the interface and this will remove the clockrate.

Here's a basic summary of the possible cause:

Cisco DB-60 serial interfaces can be used for many different types of cables, so when one is

connected, the router goes through a routine to determine what kind of cable it is. DTE cables have

certain pins "jumpered" together, so the serial interface can detect that it is a DTE cable; DCE

cables do not have this. As a result, if you've never plugged a DTE cable into the interface (or any

cable for that matter), the router assumes that the interface is to be used as a DCE device, for

which the clockrate command is mandatory and cannot be removed. A quick fix: plug a DTE cable into

the interface, do a "shut" then "no shut" on the interface, wait for few seconds for the serial

interface's controller to figure out that it's a DTE cable, and the clockrate command should

disappear from your configuration. To verify, type "show controller serial 0" to check what it

thinks the cable type is (V.35 DCE, RS-232 DTE, etc). Once this information has been updated in the

controller, you should be good to go!

Did you do a "shut/no shut" when you connected the DTE cable?


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