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New Member

Drop & Insert Question

Greetings All,

Here's a description of a problem I'm trying to work through:

- Currently, we have a point-to-point T1 connecting a branch office back to the main office.

- This T1 is currently terminated on both ends by an Adtran TA-600R Gen 3.

- Channels 1-16 carry data, 17-24, voice

- The voice channels are listed in the Adtran's "DS0 Maps" as being connected to "DSX-1", which is an outgoing port to a PBX. On the outgoing side, they're still on channels 17-24.

- Although there's no way to see/set this in the Adtran, I know these ports to be E&M, Wink-Start signaling. (Phone guy confirmed this, and added that they use channel 24 for data)

- PTP Data T1 encapsulation is PPP.

WHAT I WANT TO DO:

- I have two Cisco 2811 units with VWICs I want to replace the Adtrans with.

WHAT WORKS, WHAT DOESN'T:

I was lead to believe that I could accomplish this functionality with "Drop and Insert". Here's how I tried it:

- I connected the incoming T1 to T1 0/0/0 on the 2811 (Remember, an Adtran is still on the other end at the remote office)

- I configured a channel group, with timeslots 1-16

- I configured a tdm group, with timeslots 17-24, type e&m

- I configured a tdm group with timeslots 17-24, type e&m, on T1 0/0/1

- I connected T1 0/0/1 to the PBX

- I did the D&I on the two tdm groups

- I set the serial port created by the channel-group command to encapsulation ppp, set up ip & routing, and the data portion worked great.

- The D&I only showed status "ADMIN UP" and didn't work.

WHAT I'M GUESSING THE PROBLEM IS:

- I need to "pass-through" a "raw" DS0.

- I could remove the tdm group, and create ds0-groups on those channels, of type e&m-wink

- There appears to be no way to do a D&I on a ds0-group. - and therein lies the problem, as far as I can tell!

So, what I'm asking is:

Can D&I do this?

If not, how would I accomplish this? Is there an external CSU/DSU that can do this? The end result of this is that I need to use PPP MultiLink on a pair of T1s for data, channels 1-16 of the first and all of the second T1.

Any ideas or suggestions would be greatly appreciated.

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Drop & Insert Question

I think it might be your cable -

T1 0/0/1 is down.

Applique type is Channelized T1

Cablelength is long gain36 0db

Transmitter is sending remote alarm.

Receiver has loss of signal. <-------- means there is no physical connection !

Try a t1 cross over cable from this port to the PBX. Pinouts are like this -

1 ---- 4

2 ---- 5

4 ---- 1

5 ---- 2

If this does pass 'data' on the timeslot (which corresponds to the D channel) then it sounds like PRI, so you should take off the E&M keyword on the TDM group commands.

10 REPLIES
Hall of Fame Super Gold

Re: Drop & Insert Question

Hi,

your first configuration approach is correct.

First question, which T1 HW do you have ?

"show diag" to confirm. And which exact IOS ?

Can you send show controllers T1 when you try to go in service ?

Technically speaking, what type of CAS signaling is on the D&I timeslots, doesn't matter. This is why the adtran is not telling you what it is, because it doesn't know and does not need too. The router on the other hand, wants this information, for some reason that isn't really easy to explain.

Then, the creating ds0 group doesn't work, as you have also seen, because ds0-group are always terminated in the router, and cannot be D&I'ed.

With ds0-group, you could do voip and probably it would work great, except that perhaps is not what you want to do.

New Member

Re: Drop & Insert Question

Thanks for answering!

The T1 hardware is a VWIC-2MFT-T1-DI.

IOS is: Cisco IOS Software, 2800 Software (C2800NM-IPBASE-M), Version 12.4(3g), RELEASE SOFTWARE (fc2)

I don't have that router connected at present, but tonight I can hook it back up and get you a "show controllers t1" output. Basically, though, I've done this and T1 0/0/0 shows as up and everything works, T1 0/0/1 shows as down with remote sending alarm.

I'll post that output this afternoon.

Does everything else look "right" to you?

-John

Hall of Fame Super Gold

Re: Drop & Insert Question

Ok, show alarm means, the PBX doesn't have your signal. Check cabling especially in the direction router -> PBX. Set clock internal under controller T1 0/0/1, and correct linecode and framing.

Hopefully once the controller is clear of alarms and slips, you should have that working.

Cisco Employee

Re: Drop & Insert Question

Drop and Insert should be easy to get running , the only gotcha with the connection to the PBX is you need to use the 'type e&m' option on the TDM group configuration to tell the router to pass the ABCD bits from one T1 to the other.

Refer here for a note on configuring Drop and Insert -

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_configuration_example09186a008010f05d.shtml

New Member

Re: Drop & Insert Question

OK, I tried that and it still doesn't work.

EDIT: Just to add to this, since the phone guy said "data is on channel 24" does this mean it's PRI and not CAS? If it's PRI, does that mean D&I won't work on it? (Thought I read that somewhere...)

Here's the config blurb:

controller T1 0/0/0

framing esf

linecode b8zs

channel-group 1 timeslots 1-16

tdm-group 2 timeslots 17-24 type e&m

!

controller T1 0/0/1

framing esf

clock source internal

linecode b8zs

tdm-group 1 timeslots 17-24 type e&m

!

connect t1-xconnect T1 0/0/0 2 T1 0/0/1 1

!

Here's the output of show controller t1:

T1 0/0/0 is up.

Applique type is Channelized T1

Cablelength is long gain36 0db

No alarms detected.

alarm-trigger is not set

Soaking time: 3, Clearance time: 10

AIS State:Clear LOS State:Clear LOF State:Clear

Version info Firmware: 20050620, FPGA: 16, spm_count = 0

Framing is ESF, Line Code is B8ZS, Clock Source is Line.

CRC Threshold is 320. Reported from firmware is 320.

Data in current interval (119 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

T1 0/0/1 is down.

Applique type is Channelized T1

Cablelength is long gain36 0db

Transmitter is sending remote alarm.

Receiver has loss of signal.

alarm-trigger is not set

Soaking time: 3, Clearance time: 10

AIS State:Clear LOS State:Clear LOF State:Clear

Version info Firmware: 20050620, FPGA: 16, spm_count = 0

Framing is ESF, Line Code is B8ZS, Clock Source is Internal.

CRC Threshold is 320. Reported from firmware is 320.

Data in current interval (138 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 138 Unavail Secs

Here's the output of show connect all;

ID Name Segment 1 Segment 2 State

========================================================================

12 t1-xconnect T1 0/0/0 02 -T1 0/0/1 01 ADMIN UP

Any ideas?

(I'm going to go try some cabling changes right now. Data is working fine.)

EDIT: It's not cabling. Tried two different cables.

Thanks!

-John

New Member

Re: Drop & Insert Question

Another Addendum - restarting the router changed the connection state to OPER DOWN.

-John

Cisco Employee

Re: Drop & Insert Question

I think it might be your cable -

T1 0/0/1 is down.

Applique type is Channelized T1

Cablelength is long gain36 0db

Transmitter is sending remote alarm.

Receiver has loss of signal. <-------- means there is no physical connection !

Try a t1 cross over cable from this port to the PBX. Pinouts are like this -

1 ---- 4

2 ---- 5

4 ---- 1

5 ---- 2

If this does pass 'data' on the timeslot (which corresponds to the D channel) then it sounds like PRI, so you should take off the E&M keyword on the TDM group commands.

New Member

Re: Drop & Insert Question

You, sir, are 100% correct!

Removed the E&M type, made a T1/X cable, plugged 'er in and we're rolling.

Many thanks to you and p.bevilaqua!

If you're ever in the Portsmouth, NH, area, shoot me an email and I'll by you guys a round. john hytronix (dot) com.

Thanks again!

-John

Cisco Employee

Re: Drop & Insert Question

Thanks for the offer! Might be difficult due to the tyranny of distance ... Paolo's in Italy and I am in Australia. Maybe you could buy more Cisco gear and push up the stock price :-)

Hall of Fame Super Gold

Re: Drop & Insert Question

Dropped cisco stock long ago :)

A simple thank you is enough and makes us happy.

Now next step, you run voip to recoup the full T1 for data! I know, users are vary of VoIP, but the good news is that when done properly, they can't even tell they are on it.

You only need a PVDM2-8 (-16 would be better) in the router and a config change.

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