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Serial link problem

Unanswered Question
Oct 29th, 2006
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Dear Friends,


I have a numbers of serial links. I am using 3700,2600 and 1941 series router.Recently I am experienced a trouble in my 3700 and 1941 series router. Problem is as belows:


The seral link goes off . It shows that the serial is up but the line protocol is down.The e1 controller is alwas up.For testing link, I set the local loopback and found that teh link is still down. After some time , the link gets up autometically. Please see the sh interface result before and after loop back. Please help as soon as possible and feel free to querey.


Yours,


bikash


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


Serial0/2:0 is up, line protocol is down

Hardware is GT96K Serial

Description: XXXX LINK

Internet address is 172.16.254.50/30

MTU 1500 bytes, BW 1984 Kbit, DLY 20000 usec,

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

Encapsulation PPP, LCP Listen

Closed: CDPCP, PPPMUXCP, IPCP, loopback not set

Last input 00:00:08, output 00:00:06, output hang never

Last clearing of "show interface" counters 7w6d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 51

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

1075084 packets input, 330059814 bytes, 0 no buffer

Received 0 broadcasts, 228 runts, 0 giants, 0 throttles

739213 input errors, 739207 CRC, 149247 frame, 33546 overrun, 0 ignored, 16

3867 abort

4738928 packets output, 219644729 bytes, 0 underruns

0 output errors, 0 collisions, 7454 interface resets

0 output buffer failures, 0 output buffers swapped out

4351 carrier transitions

Timeslot(s) Used:1-31, SCC: 2, Transmitter delay is 0 flags


AAAAAA#conf t

Enter configuration commands, one per line. End with CNTL/Z.

AAAAAA(config)#inter Serial0/2:0

AAAAAA(config-if)#loop

AAAAAA(config-if)#loopback ?

<cr>


AAAAAA(config-if)#loopback

AAAAAA(config-if)#do sh inter Serial0/2:0

Serial0/2:0 is up, line protocol is down

Hardware is GT96K Serial

Description: XXXX LINK

Internet address is 172.16.254.50/30

MTU 1500 bytes, BW 1984 Kbit, DLY 20000 usec,

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

Encapsulation PPP, LCP Listen

Closed: CDPCP, PPPMUXCP, IPCP, loopback set

Last input 00:00:19, output 00:00:11, output hang never

Last clearing of "show interface" counters 7w6d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 51

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

1075095 packets input, 330059968 bytes, 0 no buffer

Received 0 broadcasts, 228 runts, 0 giants, 0 throttles

739221 input errors, 739215 CRC, 149248 frame, 33546 overrun, 0 ignored, 16

3868 abort

4738956 packets output, 219645113 bytes, 0 underruns

0 output errors, 0 collisions, 7458 interface resets

0 output buffer failures, 0 output buffers swapped out

4351 carrier transitions

Timeslot(s) Used:1-31, SCC: 2, Transmitter delay is 0 flags


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network.king Mon, 10/30/2006 - 02:40
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Hi,


Pls check with the telco regarding the framing and line code options configured at his end . Try once to reset the card at his end .


Pls provide the controller configs to check further.


regards

vanesh k

bikash_bd Mon, 10/30/2006 - 03:06
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Hi,


Both routers are under control of myself. Framing and linke code is same to each other.Pls professy.


Bikash

bikash_bd Mon, 10/30/2006 - 19:18
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Hi,


Here is the status of controllar .


rtr4huaweipacific2#sh contr e1 0/2

E1 0/2 is up.

Applique type is Channelized E1 - balanced

Description: BOGRA LINK

Far End Block Errors Detected

No alarms detected.

alarm-trigger is not set

Version info Firmware: 20030516, FPGA: 15

Framing is CRC4, Line Code is HDB3, Clock Source is Line.

VWIC relays are closed

Link noise monitor disabled

Data in current interval (351 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

Data in Interval 1:

0 Line Code Violations, 1 Path Code Violations

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

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

Data in Interval 2:

0 Line Code Violations, 2 Path Code Violations

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

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

Data in Interval 3:

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 Interval 4:

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 Interval 5:

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 Interval 6:

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 Interval 7:

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 Interval 8:

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 Interval 9:

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 Interval 10:

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 Interval 11:

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 Interval 12:

--More--

Adam Frederick Mon, 10/30/2006 - 19:29
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You have a terribly high number of carrier transitions and CRC errors. Have you had telco test this circuit? 99% of the time I have seen a high number of carrier transitions there has been a problem with telco.


Post just a "show controller e1" so we can get a summarized view of your controller activity.


Thanks

bikash_bd Mon, 10/30/2006 - 20:11
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Dear friend,


Now this is happening in my 3745 routers. Interesting thing is that when I set loopback in serial interface softwarely, it shows that link protocol is down . I think It should shows serial is up,line protocol is up ( looped). But when I use physical loopback with i-connector , it shows everything is up.


Do I wrong?

bikash_bd Mon, 10/30/2006 - 20:30
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Dear friend,


Now this is happening in my 3745 routers. Interesting thing is that when I set loopback in serial interface softwarely, it shows that link protocol is down . I think It should shows serial is up,line protocol is up ( looped). But when I use physical loopback with i-connector , it shows everything is up.


Do I wrong?

cisconoval Mon, 10/30/2006 - 23:13
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Hi,

While search in Cisco I found the below. Hope it may help you.


Error : Serial x is down, line protocol is down (DTE mode)

Causes

======

* Typically indicates that the router is not sensing a CD signal (that is, CD is not active).


* Telephone company problem-Line is down or line is not connected to CSU/DSU


* Faulty or incorrect cabling


* Hardware failure (CSU/DSU)


Solution

=======

1 Check the LEDs on the CSU/DSU to see if CD is active, or insert a breakout box on the line to check for the CD signal.


2 Verify that you are using the proper cable and interface (see your hardware installation documentation).


3 Insert a breakout box and check all control leads.


4 Contact your leased-line or other carrier service to see if there is a problem.


5 Swap faulty parts.


6 If you suspect faulty router hardware, change the serial line to another port. If the connection comes up, the previously connected interface has a problem





Error : Serial x is up, line protocol is down (DTE mode)

Causes

======

* Local or remote router is misconfigured


* Keepalives are not being sent by remote router


* Leased-line or other carrier service problem-Noisy line, or misconfigured or failed switch


* Timing problem on cable (SCTE not set on CSU/DSU) Failed local or remote CSU/DSU


* Failed local or remote CSU/DSU


* Router hardware failure (local or remote)



Solution

==========

1 Put the modem, CSU, or DSU in local loopback mode and use the show interfaces serial command to see if the line protocol comes up.


2 If the line protocol comes up, a telephone company problem or a failed remote router is the likely problem.


3 If the problem appears to be on the remote end, repeat Step 1 on the remote modem, CSU, or DSU.


4 Verify all cabling. Make sure that the cable is attached to the correct interface, the correct CSU/DSU, and the correct telephone company network termination point. Use the show controllers EXEC command to determine which cable is attached to which interface.


5 Enable the debug serial interface EXEC command.


Caution: Because debugging output is assigned a high priority in the CPU process, it can render the system unusable. For this reason, use debug commands only to troubleshoot specific problems or during troubleshooting sessions with Cisco technical support staff. Moreover, it is best to use debug commands during periods of low network traffic and fewer users. Debugging during these periods decreases the likelihood that increased debug command processing overhead will affect system use.


6 If the line protocol does not come up in local loopback mode and if the output of the debug serial interface EXEC command shows that the keepalive counter is not incrementing, a router hardware problem is likely. Swap router interface hardware.


7 If the line protocol comes up and the keepalive counter increments, the problem is not in the local router. Troubleshoot the serial line as described in the sections "Troubleshooting Clocking Problems" and "CSU and DSU Loopback Tests," later in this chapter.


8 If you suspect faulty router hardware, change the serial line to an unused port. If the connection comes up, the previously connected interface has a problem




teetdogs420 Thu, 11/02/2006 - 09:11
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I had this same problem with a 3845 series router, for 2 weeks i suspected it was the telco they however told me it was my equipment well it turned out that the telco had a bad timing card at one of their POP My guess is that it would be you provider. one thing that you could try is put a crossover T1 cable between your suspected hardware and a known good router if it works fine its your telco

amit-singh Thu, 11/02/2006 - 09:30
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Hi Bikash,


First of all clear the counters on the interface and remove the software loop on the interfae.


When you have encapsulation PPP set on the interface it will never show the interface as looped. take the encapsulation PPP out of the interface and it will show your teh correct ststus.


Conf t

int s 0/2:0

no encapsulation PPP


If i were you I would have used hardware look instead of the software. First try giving the local loop from the CSU/DSU or the ISp modem towards your router interface. If that is OK then try to get the local loop from the ISP's NOC towards your router.


If that is Ok the next step is to take a remote loop from your ISP from the remote end towards your router interface and check for the status. If you get the loop then let be there for few minutes. Most of the time it is the problem with the ISP and your telco will be able to solve this.Just follow the above steps and you will be able to resolve the issue.


HTH, Please rate if it does.


-amit singh

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