Emulating T1's

Answered Question
Dec 2nd, 2008

I have 2 Cisco 3825 routers with VWIC 2MFT-T1 cards along with VWIC 1MFT-T1 in NM-HDV slots in a test lab.

Is there any way I can simulate/emulate a T1 environment between each router? I'm trying to learn how to setup DS-1 connections, bundle t1's etc.

I also have 2 Cisco 2503 with BRI ports if I can do anything with them...

Any suggestions?

Correct Answer by Giuseppe Larosa about 8 years 2 months ago

Hello Sparky,

you can test T1 as data links:

one side needs to provide the clock.

This configuration should be done under controller T1

clock source internal instead of clock source line

You need also to cross-connect the cabling so that TX on one side is connected to RX on the other side and viceversa.

For doing this you can :

- use external adapters called balun they are thought to convert from RJ48 to two coaxial cables: you use a straight lan cable from the port to first balun : you then need two coaxial cables and you cross-connect TX to RX (balun coaxial are labeled)

balun info I mean the one with two coaxial cables output

http://www.tekmos.co.uk/balun/tk703cba.shtml

- or you can build a special cross-over cable different from an ethernet cable that does the job (and it is good only for back-to-back connections)

see

http://www.juniper.net/techpubs/software/jseries/junos92/jseries-getting-started-2/e1-and-t1-rj-48-cable-pinouts.html

table 88 crossover RJ-48 cable

Note:

about BRIs : without a device acting as an ISDN switch they are useless you cannot connect them back to back

Hope to help

Giuseppe

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Correct Answer
Giuseppe Larosa Tue, 12/02/2008 - 21:58

Hello Sparky,

you can test T1 as data links:

one side needs to provide the clock.

This configuration should be done under controller T1

clock source internal instead of clock source line

You need also to cross-connect the cabling so that TX on one side is connected to RX on the other side and viceversa.

For doing this you can :

- use external adapters called balun they are thought to convert from RJ48 to two coaxial cables: you use a straight lan cable from the port to first balun : you then need two coaxial cables and you cross-connect TX to RX (balun coaxial are labeled)

balun info I mean the one with two coaxial cables output

http://www.tekmos.co.uk/balun/tk703cba.shtml

- or you can build a special cross-over cable different from an ethernet cable that does the job (and it is good only for back-to-back connections)

see

http://www.juniper.net/techpubs/software/jseries/junos92/jseries-getting-started-2/e1-and-t1-rj-48-cable-pinouts.html

table 88 crossover RJ-48 cable

Note:

about BRIs : without a device acting as an ISDN switch they are useless you cannot connect them back to back

Hope to help

Giuseppe

cisconoobie Wed, 12/03/2008 - 18:12

Quick question. When ISPs hand you off a T1, what kind of device/s do they use to provide customers with T1 access. Meaning whats on their backend that creates this T1 connection and is it configured differently?

May be dumb question but wondering how these things work.

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