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New Member

Serial2/1 is up, line protocol is down

Hi All,

I am connecting two sites with Dialup Modems (Paradyne 3810).

Configuration of the two sites are following;

SITE A:

#interface serial0/0

#ip address 172.28.xx.xx 255.255.255.252

#no shutdown

Got the following error on A site

______________________________________

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

Hardware is GT96K Serial

Internet address is 172.28.xx.xx/30

MTU 1500 bytes, BW 1544 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 00:00:16, 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 0/4/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1158 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

473 packets output, 15896 bytes, 0 underruns

0 output errors, 0 collisions, 198 interface resets

0 output buffer failures, 0 output buffers swapped out

10 carrier transitions

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

______________________________________

SITE B:

#interface serial2/1

#ip address 172.28.xx.xx 255.255.255.252

#no shutdown

On Site B, i get the error Serial 2/1 is up, line protocol is down.

________________________________________

Serial2/1 is up, line protocol is down

Hardware is M4T

Internet address is 172.28.xx.xx/30

MTU 1500 bytes, BW 2048 Kbit, DLY 20000 usec,

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

Encapsulation HDLC, crc 16, loopback not set

Keepalive set (10 sec)

Last input never, output 05:58:57, output hang never

Last clearing of "show interface" counters 10w4d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1660

Queueing strategy: weighted fair

Output queue: 16/1000/64/1660 (size/max total/threshold/drops)

Conversations 1/4/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 1536 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

59 packets output, 4927 bytes, 0 underruns

0 output errors, 0 collisions, 29 interface resets

0 output buffer failures, 0 output buffers swapped out

44 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up

________________________________________

When i "shut" and "no shut" the interface, the SERAIL 2/1 IS UP FOR ABOUT 10 SECONDS AND AGAIN DOWN.

Kindly suggest where could be the problem; circuit or cable (connected to serial) or protocol.

Please also mention how to resolve it by some additional configuration if required.

5 REPLIES
Hall of Fame Super Silver

Re: Serial2/1 is up, line protocol is down

Abdul

It is quite probable that the immediate cause of the problem is that the interface is configured with protocol HDLC and that the HDLC keepalives are not getting through. It is not so clear what is preventing the HDLC keepalives but I suspect that it is something with the Paradyne 3810 modem. The serial interface is not configured with anything about dialup, so am I correct to assume that all of the dial up parameters are configured on the Paradyne 3810? Can you check on the Paradyne 3810 and see whether there is some problem with it? Is it attempting to dial? Is the dial connection being completed?

HTH

Rick

Re: Serial2/1 is up, line protocol is down

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

Are the calls being completed/negotiated correctly?

Hall of Fame Super Gold

Re: Serial2/1 is up, line protocol is down

Dialup modem with synch interfaces?

That is usually a recipe for failure.

Get ADSL on the sites, and do VPN. Or GSM dta service. Or get ISDN. Anything less isn't even worth the effort these days.

New Member

Re: Serial2/1 is up, line protocol is down

Try to Shut down the interface from one side and then DIAL - UP - connect the modems and then NO shut to check .

for further trouble shooting try to reduce the MTU size .

Further more - If you can find any thing in the log after 10 sec when the link goes down - it might be helpful.

New Member

Re: Serial2/1 is up, line protocol is down

Nauman,

It is taking the Default MTU now. and i tried to shut and no shut the interface 4,5 times but it use to get up for some time and than again down.

Kindly tell me some troubleshooting (debugging) commands sequence. I'll log the session and will paste it here for further support if required.

___________________________________

Rick,

Kindly note that the Modems are configured with default parameters. I just configured the Phone numbers which needed to be dialed.

So please tell me(the specific commands) if any thing needed to be added at the modems or router interfaces.

Waiting for reply....

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