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Community Member

point to point T1 will not come up.

We are upgrading from a 256k frame relay connection to a point to point T1. Router "A" is a 3620, Router "B" is is a 3660. Both are using T1-WIC-1-DSU cards. The original (frame relay) configurations are as follows:

Router A

interface Serial0/0

bandwidth 256

ip address 172.16.1.66 255.255.255.252

ip broadcast-address 172.16.1.67

ip directed-broadcast

encapsulation frame-relay

no fair-queue

service-module t1 timeslots 1-4

cdp enable

Router B

interface Serial1/0

bandwidth 256

ip address 172.16.1.65 255.255.255.252

ip broadcast-address 172.16.1.67

ip directed-broadcast

encapsulation frame-relay

service-module t1 timeslots 1-4

cdp enable

For the T1 upgrade, I removed all frame relay specific configuration from the interfaces and added the following to both routers:

service-module t1 clock source line

service-module t1 timeslots 1-24 speed 64

service-module t1 framing esf

service-module t1 linecode b8zs

encapsulation ppp

I have alarm lights at both ends on the telcos equipment which does not go away regardless of whatever tweaking I try. A 'show service-module' issued on the routers shows the following:

Router A:

CO-ISDN#sh service-module

Module type is T1/fractional

Hardware revision is 0.96, Software revision is 0.2,

Image checksum is 0xED22BEC5, Protocol revision is 0.1

Transmitter is sending remote alarm.

Receiver has loss of signal, loss of frame,

Framing is ESF, Line Code is B8ZS, Current clock source is line,

Fraction has 24 timeslots (64 Kbits/sec each), Net bandwidth is 1536 Kbits/sec.

Last module self-test (done at startup): Passed

Last clearing of alarm counters 6d00h

loss of signal : 5, current duration 01:04:40

loss of frame : 6, current duration 01:04:40

AIS alarm : 0,

Remote alarm : 0,

Module access errors : 0,

Total Data (last 96 15 minute intervals):

255 Line Code Violations, 255 Path Code Violations

0 Slip Secs, 3795 Fr Loss Secs, 5 Line Err Secs, 2 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 3795 Unavail Secs

Data in current interval (79 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 79 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 79 Unavail Secs

Router B

Module type is T1/fractional

Hardware revision is 0.96, Software revision is 0.2,

Image checksum is 0xED22BEC5, Protocol revision is 0.1

Transmitter is sending remote alarm.

Receiver has loss of frame, AIS alarm,

Framing is ESF, Line Code is B8ZS, Current clock source is line,

Fraction has 24 timeslots (64 Kbits/sec each), Net bandwidth is 1536 Kbits/sec.

Last module self-test (done at startup): Passed

Last clearing of alarm counters 00:04:20

loss of signal : 0,

loss of frame : 1, current duration 00:04:11

AIS alarm : 1, current duration 00:04:11

Remote alarm : 0,

Module access errors : 0,

Total Data (last 0 15 minute intervals):

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

Data in current interval (261 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 261 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 261 Unavail Secs

I cleared the counters and put a loopback plug into each DSU, and the errors didn't come back. I will admit that I'm just using a straight through RJ-45 patch cord from the smart jack to the WIC instead of a 1,2,4,5 T1 patch. Also at the Router A end, the dmarc is extended about 100' from the smart jack and is only on CAT 3 cable. I am pulling a new wire in the morning, but it *is* the same line that the frame worked fine on for over two years. The telco (naturally) assures me that their equipment tests fine (What else would they say?). My question then is basically.....What have missed, or what should I try, so that I can positively rule this a telco issue?

Thank-you

7 REPLIES
Bronze

Re: point to point T1 will not come up.

Matthew,

Try putting loops toward the routers from the demarcs at each end and see if the alarms clear. If they do not, you have an internal cabling problem. Next, put loops towards the far end at each demarc, and see if, in either case, the alarms at the remote end clear. This will test the carrier's portion of the T1.

If your tests still indicate a carrier problem, point out to the telco that the loss-of-signal alarm means that the router is seeing NOTHING from the T1 line. Both routers, in response to the alarms they are receiving, are sending remote alarms. If the line was even half-way working, one end should see the remote alarm generated by the other.

HTH

Mark

Community Member

Re: point to point T1 will not come up.

Is this just a matter of issuing 'loopback local' checking the errors, then 'loopback remote' and checking the errors? Or is there something more to it?

Thanks

Bronze

Re: point to point T1 will not come up.

Is the telco providing clocking on the circuit? If not, I think you'll need a 'service-module t1 clock source internal' on one of the routers.

Community Member

Re: point to point T1 will not come up.

Thanks, I tried that. :)

I also tried inverting the data code, chaning the framing, changing the linecode, and everything else I could think of configuration related. I even changed the IP addresses to unnumbered just in case for some truly bizzare reason it didn't want to play nicely with the addresses assigned to the interface. Nothing helps-- the only thing that changes is that I lose the DS1 light on the telco's card when I alter the original configuration.

VIP Purple

Re: point to point T1 will not come up.

Hello,

I had a similar problem once: not sure if you tried this yet, but you could change the encapsulation from PPP to HDLC and then back, that worked for me (I guess the line had te renegotiate all the PPP parameters).

Regards,

Georg

Community Member

Re: point to point T1 will not come up.

Try rolling the pairs in the cable(or jack).

This happens to me occasionally where the telco has the pairs rolled so that if you insert the cable into your router you get no carrier, nothing. But if you put a loopback plug into the jack and have the carrier test it comes back clean.

ChrisV

Community Member

Re: point to point T1 will not come up.

It works now.

It was a combination of two things:

1) Pulling a new wire for the extended dmarc got the "loss of signal" errors to go away so I could see alarms on the line.

2) changing the encapsulation to hdlc and back to ppp finally ended up doing the trick!

Thanks to all

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