Connect DTE to DCE and Frame Relay

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Jan 18th, 2009
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Hello ,

1- I'm connect a Cisco 2600 Router through serial port to a PARADYNE 7975 M/SDSL .

My problem is when run "sho int" , status of the serial interface is down,down , whereas DTE LED from 7975M/SDSL is on.

I'm connected S0/1 to DCE. The output is attached.

2- When I connect COM port of 7975M/SDSL to COM1 of my PC for use HyperTerminal to configure it , the pc goes hang up.

How can I config 7975M/SDSL ?

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Giuseppe Larosa Sun, 01/18/2009 - 23:49
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Hello Reza,

>> 0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=down RTS=down CTS=up

I'm afraid the cable setup is not fine : the cable may be not complete:

the routers senses the DCE: DCD, DSR and CTS comes from DCE side but the leads on the DTE side are down.

you can use for further troubleshooting

sh controller interface ser0/1

see what type of cable is sensed and the rx clock.


see the following guide

you need to use the following cable

EIA-530A-to-V.35 Cable Interface

pag.112 of the above link and you need a cisco DTE cable to V.35 DTE and to connect the two V.35 connectors between them.

Hope to help


Reza Rezazadeh Mon, 01/19/2009 - 00:03
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Hello Giuseppe ,

I'm connecting S0/1 to DCE not S0/0. Please look at S0/1 status. Nothing is connect to S0/0, but I don't know what about in result.

I use a same cable. EIA-530A-to-V.35.

Information that you requested are attached.

Reza Rezazadeh Mon, 01/19/2009 - 01:05
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Hello ,

1- Is this correct that connect Router 2621 to 7975M/SDSL and the same at remote site to implement Frame Relay ?

2- I used another router 2610XM and connect to another 7975M/SDSL , but the same result .

Thanks your help

Giuseppe Larosa Mon, 01/19/2009 - 07:48
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Hello Reza,

the setup with a router, V.35 interface configured with FR encapsulation, 7975M/SDSL is shown in the guide in the link of my first post.

I suggest you to give it a look I suspect you need to perform some basic setup actions so look at the configuration chapter.

Notice that you can connect via console to the device to configure it

if you want to connect them in back to back for example one of the two must provide clock to the other on the SDSL link

Hope to help



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