What I need to simulate a PSTN

Answered Question
May 23rd, 2012

Hi All,

Working towards me CCIE Voice Lab exam.....

I have 3745 Router with:

1 x NM-HDV

3 x PVDM-12

1 x VWIC-1MFT-E1 Module.

1 x 7960 Phone

I have placed a Loopback cable in the single E1 socket, but I get "RX <- BAD FRAME" received when debug isdn q921 is turned on. So this will not help me simulate a PSTN for me to see Q931 traffic.

Would a single VWIC-2MFT-E1 card be enough to simulate a ISDN q931 and q921 message if I loop the ports together with a E1 crossover and set one as USER and the other NETWORK?

I am trying to go for least cost solution with what I already have?

Thanks,

Ed

I have this problem too.
0 votes
Correct Answer by Ayodeji oladipo... about 1 year 11 months ago

You need two different routers. You are connecting them back to back. You cant do this on the same router.

You need 1 router acting as PSTN

you need another router acting as the User side

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Average Rating: 4.9 (5 ratings)
Chris Deren Wed, 05/23/2012 - 08:58

No, you will need 2 ports and connect them via cross-over T1 cable as well as setup one side as ISDN protocol-emulate network.

HTH,

Chris

Ayodeji oladipo... Wed, 05/23/2012 - 09:35

Hi, here are the configuration you need. As chris said you need a cross over E1 cable to connect the two routers back to back.

The pinout for a corss over e1/t1 is as follows:

1 <-> 4

2 <-> 5

4 <-> 1

5 <-> 2

Router 1 (PSTN SIDE)

controller E1 0/2/0

clock source internal (Because its PSTN side, it is the clock provider)

pri-group timeslots 1-31

description E1 Link to Labrouter 2

interface Serial0/2/0:15
no ip address
encapsulation hdlc
isdn switch-type primary-net5
isdn timer T310 120000
isdn protocol-emulate network (****Simulating PSTN SIDE)
isdn incoming-voice voice
no cdp enable

Router 2 (user side)

controller E1 0/1/1

pri-group timeslots 1-31

description E1 Link to Lab PSTN

interface Serial0/1/1:15

no ip address

encapsulation hdlc

isdn switch-type primary-net5

isdn incoming-voice voice

no cdp

Edip.Gumuskaya_2 Thu, 05/24/2012 - 01:51

Thanks guys,

Can I confirm that this can be done on the same route with 1 x 2 port VWIC card?

I understand that I will see both the inbound and outbound q931 messages on the same router.

Thanks,

Correct Answer
Ayodeji oladipo... Thu, 05/24/2012 - 02:11

You need two different routers. You are connecting them back to back. You cant do this on the same router.

You need 1 router acting as PSTN

you need another router acting as the User side

Pls rate useful posts

Chris Deren Thu, 05/24/2012 - 05:52

I suppose teaching people how to fish does not go far these days and step by step instructions are much more appreciated :-(

Chris

Ayodeji oladipo... Thu, 05/24/2012 - 06:21

Chris,

+5 for your inputs. I am actually confused as to how to help people on this forum. Should they be fed completely or should you lead them on the proactive approach. I mean sometimes you post a link to a document and people wont even bother reading it, so I share your thoughts...

Chris Deren Thu, 05/24/2012 - 04:15

Surely you can do this on the same router, for studying it will do the job.

Sent from Cisco Technical Support iPhone App

Ayodeji oladipo... Thu, 05/24/2012 - 04:19

Edip,

Chris is right, you can do it on the same router..I got things mixed up. But you need two different ports configured as I explained int he config section

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Posted May 23, 2012 at 8:42 AM
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