PPP connection not start

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Aug 29th, 2009
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I'm config two routers for ppp connection:

Router1 :

The configuration is attache.


Router 2 :

The configuration is attache.


These routers are connected to two PARADYNE 7975M/SDSL, one of them is NTU and another is LTU.

But the connection doesn't start.

What is wrong ?

I was search the status of serial ports and know the modems or the connector cable is wrong.

The cable that connect two M/SDSL modems is right.

How do I test the modems for error.

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paolo bevilacqua Sat, 08/29/2009 - 23:21
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Your circuit is down, probably the modems are indicating this too with some light.

Note, it advantageous to use HDLC for serial circuits with cisco routers.

gnmcmltct08 Mon, 08/31/2009 - 01:35
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Are you connecting the 2 Routers in Point-to-Point connnection through WIC(WAN Interface Card)?

In your Router configuration the IP routing part is missing...

Reza Rezazadeh Mon, 08/31/2009 - 21:47
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Yes ,I'm connecting two routers with WIC,

Where is missing in the routing part ?

Thnak you

Peter Paluch Tue, 09/01/2009 - 03:13
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Hello Reza,

As Paolo has pointed out (and also you have indicated it), you have a problem with your circuit. As the both serial interfaces indicate down/down status, it means that they do not indicate the presence of any device directly connected to the serial interface.

I have briefly skimmed the operations manual to the modem you are using at:


According to it, the default mode of the synchronous serial port on the modem is E530A, not V.35. Make sure that you are using the proper serial cable to interconnect your WIC card with the modem - a factory label on the cable should tell you its type. Very often, the V.35 or X.21 cable types are used, in which case you absolutely have to change the port setting on the modem. In either case, it must match with the cable type you are using.

You have also asked how to test the modems. According to the operation manual, you can assign both modems an IP address for management purposes and telnet from one modem to another. So I suggest you do just that - configure the modems with IP addresses and try to telnet from one modem to another - again, consult the operations manual for details.

Let us know your findings.

Best regards,



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