serial and line protocol up and down constantly- 2811 pont to point to a 1700

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RTR 21 years ago

Hi guys Have a cisco 2811 with 2 serail point to point t1 one to ISP other one to remote location

the remote location has a 1700 router. the connectivity is very flaky it keeps going up and down every few days and comes up and then goes down.

2811 does NAT to get the remote location on internet.

I checked on 2811 and did a show interface serial0/1/0:0

I see that every 15 seconds this what is happening

serial is up line protocol is up

15 seconds later serial is down line protocol is down
15 seconds later serial is up line protocol is down
15 seconds later serial is up line protocol is up
15 seconds later serial is down line protocol is down This cycle keeps going on and on.

checked with the provider they are saying circuit is fine.

------------------------------------------------ here is a output of sh interface command

Serial0/1/0:0 is down, line protocol is down (both are going up and down) Hardware is GT96K Serial Description: ---> T1 to ASHBURN. PROVIDER: AT&T Internet address is 10.95.4.1/24 MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation HDLC, loopback not set Keepalive set (10 sec) Last input 00:00:07, output 00:00:06, 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 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 2773 packets input, 153976 bytes, 0 no buffer Received 614 broadcasts, 0 runts, 1 giants, 0 throttles 555832 input errors, 555832 CRC, 237655 frame, 132855 overrun, 0 ignored, 417642 abort 2816 packets output, 223809 bytes, 0 underruns 0 output errors, 0 collisions, 48 interface resets 0 output buffer failures, 0 output buffers swapped out 433 carrier transitions Timeslot(s) Used:1-24, SCC: 0, Transmitter delay is 0 flags

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Thanks

RTR

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Delija 21 years ago

Check clocking with your provider for remote location.

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<Anthrax> 21 years ago

Seems to me to that is a layer 1 issue. your interface is restarting because is lossing keepalives (after lossing 3 keepalives in a row the interface will restart itself). Have you noticed that the carrier transitions are to the roof? What Delija said may be true, check all parameters agains your telco, make sure you have same encapsulation on both sides, if still failing do a loop test (follow this document

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make sure that you perform it creating the cable and not using the loopback command) if the test goes sucessfull on both sides there's no doubt is your telco.

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RTR 21 years ago

Hi guys,

I have done a loopback test using the loopback cable, i even tested the cable that is going to the demarc on both locations. No errors pings 100% and no input errors and no crc , on 1 side i got 1 input error. Did the extended ping about 30- 50 time on both ends No errors at all.

You guys mention about clocking, on one side the clocking is set to internal as this has a built in CSU/DSU. (Cisco2811)

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

on the other side (cisco 1700) clocking is not set, I have run sh controller serila0 in order to see clocking.

I am talking to the provider but they are trying to figure out what could be the problem on their side. what do u guys think.

RTR

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joe 21 years ago

Verify with your loop provider that it is configured for clear-channel T1 and that framing and line code are set to ESF and B8ZS.

We've had problems where the telco accidently re-provisioned links into the wrong framing or line code.

Also, set both ends to take clocking from the network, otherwise you'll slowly accumulate framing errors.

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serial and line protocol up and down constantly- 2811 pont to point to a 1700

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