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Trouble with serial interface or line?

I inherited management of a Cisco 3640 and I only have a basic knowledge of Cisco. We currently have a new customer with a leased line setup but the interface on our 3640 at the Telco office says "Line Protocol Down". The Telco has checked the line but says everything is fine. We have several other sites that work just fine. They all run out of the same cable on the back of the E1 channelized card. I have looked at the configuration but everything seems correct and very straightforward. The only thing I could think to try is do a "shut" on the interface and then a "no shut". After doing this, the "sh int s2/0:8" command actually shows the "line protocol is up", but it only lasts maybe 15 seconds. Then it goes to "line protocol is down" again. I will do a "show int" on a good site and this problem site to see if anyone has ideas for me.

Serial2/0:8 is up, line protocol is down Hardware is DSX1 Description: "Non-Working Site" Internet address is 204.142.197.201/30 MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation HDLC, loopback not set Keepalive set (10 sec) Last input never, output 00:00:05, 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 96 kilobits/sec 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute 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 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 14421 packets output, 349138 bytes, 0 underruns 0 output errors, 0 collisions, 4811 interface resets 0 output buffer failures, 0 output buffers swapped out 1 carrier transitions Timeslot(s) Used:30-31, Transmitter delay is 0 flags

Serial2/0:7 is up, line protocol is up Hardware is DSX1 Description: "Working Site" Internet address is 204.142.197.197/30 MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec, reliability 255/255, txload 21/255, rxload 93/255 Encapsulation HDLC, loopback not set Keepalive set (10 sec) Last input 00:00:01, output 00:00:00, output hang never Last clearing of "show interface" counters never Input queue: 0/75/2/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/27/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 96 kilobits/sec 5 minute input rate 47000 bits/sec, 9 packets/sec 5 minute output rate 11000 bits/sec, 8 packets/sec 404054 packets input, 115782707 bytes, 0 no buffer Received 16864 broadcasts, 0 runts, 0 giants, 0 throttles 2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored, 1 abort 389221 packets output, 170896813 bytes, 0 underruns 0 output errors, 0 collisions, 2 interface resets 0 output buffer failures, 0 output buffers swapped out 1 carrier transitions Timeslot(s) Used:19-20, Transmitter delay is 0 flags

This is the relevant area of the configuration.

--------------- controller E1 2/0 framing NO-CRC4 channel-group 1 timeslots 1-4 channel-group 2 timeslots 5-6 channel-group 3 timeslots 9-12 channel-group 4 timeslots 13-16 channel-group 5 timeslots 7-8 channel-group 6 timeslots 17-18 channel-group 7 timeslots 19-20 channel-group 8 timeslots 30-31

interface Serial2/0:7 description "Working Site" ip address 204.142.197.197 255.255.255.252 ! interface Serial2/0:8 description "Non-Working Site" ip address 204.142.197.201 255.255.255.252

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Thanks a lot for any suggestions.

Reply to
Thread7
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just a thought:

is the remote router cisco or from a different vendor? if the latter applies, you might want to opt for ppp encapsulation - hdlc is cisco proprietary.

cheers,

sven

snipped-for-privacy@hotmail.com wrote:

Reply to
Sven Juergensen

The remote router is just a Cisco 2501. I keep thinking it is some problem at the main router 3640 end though. To narrow down the problem I telnetted into the remote Cisco 2501 at the working site and rebooted it. Then on the 3640 I constantly checked the sh int s2/0:7 for two minutes while the remote 2501 was rebooting. It said "Line protocol is up" the whole time.

Therefore, even if the remote router is turned off, it seems like it does not affect the serial interface at the main 3640 router. So for my non-working site, it seems like it should not be a problem at the remote 2501.

Reply to
Thread7

I should also say that the 2501 at the customer site says both the serial interface and line protocol are up.

Reply to
Thread7

Have you done any testing with the telco?

Reply to
jem12475

Yes, and the Telco says everything is fine from his end. He has been out to the site and can send data across the line.

Reply to
Thread7

Right: The line is assumed up when it comes up, but after 3 missed keepalives (30 seconds) the line is marked as "protocol down" meaning it cannot pass traffic.

[...]

Packets are sent, nothing received back. Telco issue, most likely they have logically crossed timeslots.

Serial 2/0:8 is channel group 8 (timeslots 30-31, 2x64k channels, 128k total). Have the telco report to you where they think the timeslots are mapped on the other side.

This is not rocket science. Te telco is at fault if it suddenly stopped working.

If the remote side is saying serial interface and line protocol are up for more than the first thirty seconds, it is connected SOMEWHERE, but not to the timeslots and circuit you are expecting. They need to tell you where they have mapped the 128k virtual circuit.

Remember rule #1 of telcos. They lie.

Reply to
Phillip Remaker

Maybe you have clocking problem please check it and set a new clocking rate. Then you should see your error lists . look you have many error resets on your interface this says that your link is not suitable for service. you could check your line by Multimeter for test that is it stable ? and is your link has a fix resistance or not. if you checked them and your problem wasn't solved notify me again.

Reply to
m.zebardast

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