06-02-2005 05:01 AM - edited 03-03-2019 09:43 AM
We have a point to point T1 from Verizon using a clock source on the one side (uses the standard command: service-module t1 clock source internal). Both routers are 1601R's and they are both running version 12.0(8). We have had these routers in place for almost four years without incident. Recently, the T1 has begun dropping on an intermittant basis. Verizon has tested several times without finding any errors. They believe it is our clock source. Unfortunately, I don't have a lot of experience with router configs and am at a loss as to how to proceed. Any assistance will be greatly appreciated.
Thanks!
PS.: Please advise as to any additional info needed.
06-02-2005 05:47 AM
Hi,
Ganerally, we use the clock source provided by telco on the line. I would suggest you to change the clock source to line instead of internal. command : Got to config mode
controller T1 6/0
framing ESF
channel-group 0 timeslots 1-31
service-module t1 clock source line
Please check the following link and it will come handy.
HTH,
-amit singh
06-02-2005 10:41 AM
Amit,
Thanks so much for the info. Unfortunately, I now have more info than I did when I originally wrote the message. My boss was dealing with the Verizon engineer. Evidently, he told us that there may or may not be clocking on the line. Does that sound reasonable and if so, where do we go from here?
Thanks again...
06-03-2005 06:24 AM
yes it does, Telco might decide not to sync it to their network..if telco uses "loop" timing at all DS1 interfaces .
Otherwise, they set each transmitter to master and use their clock distribution system as the external source to sync the transmit to the telco network.thus providing you clocking .
can you post your "show interface serial x output"
06-03-2005 08:17 AM
Olufemi,
Thank you! Here is my serial output from both ends of the T1.
CENTRAL LOCATION
Serial1 is up, line protocol is up
Hardware is HD64570
Internet address is 10.21.0.1/16
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 3/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:05, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 145
Queueing strategy: weighted fair
Output queue: 0/64/138 (size/threshold/drops)
Conversations 0/22 (active/max active)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 19000 bits/sec, 14 packets/sec
5 minute output rate 24000 bits/sec, 14 packets/sec
16408916 packets input, 2548491689 bytes, 0 no buffer
Received 177232 broadcasts, 0 runts, 0 giants
23340 input errors, 23340 CRC, 1100 frame, 0 overrun, 0 ignored, 381 abort
16521609 packets output, 3759067403 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 output buffer failures, 0 output buffers swapped out
2 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
REMOTE LOCATION
Serial1 is up, line protocol is up
Hardware is QUICC Serial (with FT1 CSU/DSU WIC)
Internet address is 10.121.0.2/16
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 660
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/26/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 25000 bits/sec, 5 packets/sec
5 minute output rate 3000 bits/sec, 4 packets/sec
177280328 packets input, 2918610694 bytes, 19 no buffer
Received 2816433 broadcasts, 0 runts, 15 giants, 19 throttles
51034689 input errors, 28392547 CRC, 13632440 frame, 0 overrun, 0 ignored,
9009697 abort
169434143 packets output, 964429514 bytes, 0 underruns
0 output errors, 0 collisions, 1989 interface resets
0 output buffer failures, 0 output buffers swapped out
533 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
06-04-2005 06:18 PM
it is really hard to point at a problem now. since the counters have never been cleared for both interfaces.
can you clear the counters to ensure you are getting current information.
06-06-2005 08:46 AM
99% of the time you are going to set both sides of your network to line timing which is the default. Do that first. Then if you are still getting input errors put a local loop at the telco at one side and then clear the counters, then look to see if you are getting input errors at such after five minutes. If you are then you know the problem is between your router and the telco. If you don't get errors then move the loop to the Distant end pointing back to you, clear the counters and see if get any errors. Continue this until you find out where you are getting problems.
06-07-2005 04:38 AM
No problem. I cleared them yesterday morning around 9:00 am Eastern Time. Here they are:
CENTRAL LOCATION
fp-hv#show int s1
Serial1 is up, line protocol is up
Hardware is QUICC Serial (with FT1 CSU/DSU WIC)
Internet address is 10.121.0.1/16
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 22:56:33
Input queue: 0/75/0 (size/max/drops); Total output drops: 3
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/25/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 2000 bits/sec, 2 packets/sec
5 minute output rate 1000 bits/sec, 2 packets/sec
634500 packets input, 184433794 bytes, 0 no buffer
Received 12155 broadcasts, 0 runts, 0 giants, 0 throttles
3738 input errors, 1946 CRC, 1543 frame, 0 overrun, 0 ignored, 249 abort
652038 packets output, 299404218 bytes, 0 underruns
0 output errors, 0 collisions, 105 interface resets
0 output buffer failures, 0 output buffers swapped out
20 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
REMOTE LOCATION
FANDANGO#show int s1
Serial1 is up, line protocol is up
Hardware is QUICC Serial (with FT1 CSU/DSU WIC)
Internet address is 10.121.0.2/16
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 22:58:57
Input queue: 1/75/0 (size/max/drops); Total output drops: 2
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/26/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 1000 bits/sec, 3 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
651835 packets input, 299089431 bytes, 0 no buffer
Received 12164 broadcasts, 0 runts, 0 giants, 0 throttles
1276902 input errors, 721196 CRC, 336932 frame, 0 overrun, 0 ignored, 21877
4 abort
634758 packets output, 184459782 bytes, 0 underruns
0 output errors, 0 collisions, 105 interface resets
0 output buffer failures, 0 output buffers swapped out
20 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
FANDANGO#
06-07-2005 05:34 AM
You have had 105 interface resets which is not good. Have you done the local loops yet to determine if you have a local problem?
06-07-2005 06:54 AM
No, unfortunately, I'm not well versed with your instructions. I know enough to create simple configs and run various commands. I have contacted Verizon, and they instructed me to contact them as soon as the circuit goes down again and they will check the stats on the cards.
I'm not sure what else to do at this point. We don't have anyone at the remote site to assist us.
06-10-2005 04:32 AM
Okay, Verizon has done all the local loop testing requested above. CSU to CSU tested clean. Where do I go from here? Thanks!
06-10-2005 06:03 AM
I had a similar problem with my point to point T1, I changed the clock source to every configuration, I pulled a new cable form the smart jack and all along the telco is telling me it's my problem. They tested it numerous times and it was always clean. After a month of continous calls to them they sent a local tech out to test the line, before he tested it he told me that my area's cables were in bad shape and he knew where the problem was. They rerouted my circuit thru another area and I havent had any problems since. My advice is: Stay On Them, they will always say it isnt there problem. If it turns out that it wasnt there problem then you can always say your sorry.
06-10-2005 07:26 AM
Thanks so much for the info. I was actually starting to think the same thing. I can't see why my routers would just start "acting up." I'll keep trying with Verizon to see what I can get them to do.
06-10-2005 06:32 AM
Actually what I meant by local loop is to have the CSU go into local loop mode and look at the router. The data stream will be sent out the router to the CSU/DSU through the loop and right back at the same router. If you do a show interface on the router, it will usually see that it is looped and up and up, from there clear the counters and see if you see any errors come in, if you do then you know you have a problem between the router and the CSU/DSU. If you don't look at the other router, it should see itself in a far end loop (if not, throw its DSU/CSU in a loop and test again) and you should be able to determine from those tests where you are getting errors at.
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