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New Member

P2p T1

I need a hand on getting a P2P T1 up and running. I have an up/down link. I am using static routes and have tried using bgp but nothing is bringing the link up.

Serial0/1/0 is up, line protocol is down

Hardware is GT96K with integrated T1 CSU/DSU

Description: P2P Connection to Recruiting Office

Internet address is

MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,

reliability 206/255, txload 1/255, rxload 1/255

Encapsulation HDLC, loopback not set

Keepalive set (10 sec)

Last input never, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/1/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1152 kilobits/sec

30 second input rate 0 bits/sec, 0 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

85 input errors, 85 CRC, 4 frame, 2 overrun, 0 ignored, 2 abort

86 packets output, 3267 bytes, 0 underruns

0 output errors, 0 collisions, 31 interface resets

0 output buffer failures, 0 output buffers swapped out

3 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up


interface Serial0/1/0

description P2P Connection to Recruiting Office

bandwidth 1536

ip address

load-interval 30


Hall of Fame Super Gold

Re: P2p T1

Hi, your circuit is faulty or something grossly mis configured somewhere. Check that you have as many input errors as packets.

Hope this helps, please rate post if it does!

Hall of Fame Super Silver

Re: P2p T1


If your serial interface is line up line protocol down then it does not have anything to do with what routing you are doing. Static routes or BGP or any other routing protocol has nothing to do with this.

In addition to the suggestion from Paolo I would suggest a couple of things. I frequently see this symptom when the line encapsulation is mismatched between the two ends. I see that your end is configured for HDLC. Please check the router on the other end and see if it is configured for HDLC or for something else. There might also be an issue with clocking on the line. How to check this depends on the model of router - it might be show controller T1 or it might be show service module.



New Member

Re: P2p T1

screen shot of my show service-module

c2821-600-ATT#sh service-module serial 0/1/0

Interface Serial0/1/0

Module type is T1/fractional

Hardware revision is 1.2, Software revision is 20070424,

Image checksum is 0x4144A7, Protocol revision is 0.1

Receiver has no alarms.

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 00:14:53

loss of signal : 0,

loss of frame : 3, last occurred 00:02:04

AIS alarm : 1, last occurred 00:02:04

Remote alarm : 1, last occurred 00:14:53

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 (893 seconds elapsed):

13104 Line Code Violations, 89 Path Code Violations

0 Slip Secs, 132 Fr Loss Secs, 5 Line Err Secs, 12 Degraded Mins

79 Errored Secs, 11 Bursty Err Secs, 6 Severely Err Secs, 128 Unavail Secs



Re: P2p T1

I see you are getting excessive line code violations with other errors. I would first check the configuration of the remote end to verify that you are both setup identical (24DS0's, ESF/B8ZS). Perform local loops from your Demarcation point in your Telco room to each end device. Verify that your loops are good. If OK, then I would turn the line out to the Phone Company to check.

Re: P2p T1


1.With the help of your first post I found that the Telco line having itself problem. Reliability is poor, as well as having Input Packet & CRC Error.

2.From your next post I found that they're also some error, i.e. AIS Loss, RA, Fr Loss Secs

3.Don't forget to check the both end encapsulation.

Suggesting go with the opinion with "pciaccio" also verify the Framing & Line Code at the both-end with your the help of your Telco.

Please rate if its work!!!


New Member

Re: P2p T1


Thanks for the input, I just found out that the service provider programmed the line wrong. They have it as a SF/AMI when it should be a ESF/B8ZS. Hopefully when they make the change the circuit will come right up.



Hall of Fame Super Silver

Re: P2p T1


Thanks for posting the update. Having the line provisioned incorrectly would explain the problem. I am optimistic that when they get the correct parameters set that the line will come up just fine.