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Clocking

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hcclSmokey

Technical User
May 9, 2003
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Hi

I have a home lab and having a few difficulties with establishing connectivity from more than one serial interface using PPP. I can connect several 250x routers using serial 0 on each router to a 2523 which provides the clocking (this works fine I can ping the other interface). When I try to use serial 1 on the 250x routers to connect to another serial port on one of the 250x routers the line protocol always stays down. Is it the case that these routers cannot be a DTE and a DCE at the same time ? Or is DCE/DTE specific to the interface ?

Any advice would be appreciated.

Smokey
 
DCE/DTE is equipment specific - the pin assignments on the gear will actually be different. Think about it like Ethernet. You can plug a switch into a desktop with straight through cable, because one is DTE and one is DCE. But to plug a switch into another switch, or a router into another router you need a cross over cable.

You can probably solve your issue with a "Null Modem" cable.
 
I'm using a DTE/DCE DB60 crossover cables. My question is whether you can have one interface configured as DTE and another as DCE on the same device. So far I am I only seem to be able to have both as DTE or both as DCE. I cannot have one DTE and one DCE at the same time ?

Cheers
Smokey
 
If you have a router with multiple serial interfaces, they can individually be configured as DCE or DTE

Check that your DCE/DTE crossover cable is connected to the appropriate DCE/DTE interface on the router
 

You should be able to have DTE and DCE on the same router on different physical interfaces (not sub interfaces). Clock rate information is seperate on each physical interface.



 
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