Setting Clock Rate On Cisco 2501 Serial Port

[azev]

I just recently bought 2 cisco 2501 for CCNA lab. Both router are connected with DTE/DCE cable. I am confused on how to set the clock rate, and the book that I have doesnt help much.
What is are the number in clock rate mean?? Is not the speed isnt it?? because there is bandwith speed??
In real life scenario with T-1 frame relay, How would you determind what clock rate to use??

Thanks

 

[Nutz]

Config T-->interface s0-->clock rate xxx

Do this only on the Serial port with the DCE end of the cable connected.

 

[L3Guy]

<< What is are the number in clock rate mean?? >>

Its the speed the internal clock generator clocks the DCE interface.


<< because there is bandwith speed?? >>

That is a setting that routing protocols use to set metrics and the router uses for utilization calculations. It has no direct connection to the clocking of the interface.


<< In real life scenario with T-1 frame relay, How would you determind what clock rate to use?? >>

In real life, the CSU/DSU provides the clock. In most cases, the Telco is providing clock, with both CSU/DSU using the Telco clock. In the hundreds of FR circuits I have been involved in, I have never seen the CPE need to provide clock. If the Telco isn't providing clocking, the Frame provider is.

Never use the internal clock, except for testing / lab use. The clock on the CSU/DSU is at least an order of magnitude "better" than a router clock. Even in scenarios where SNA devices are being attached, I recommend a "modem eliminator" to provide clocking, rather than have the router do it. While that may be a tad excessive, I think you start to get the picture.

Doug