Layer 1 or Layer 8 problem?

[Patrick Evans]

So i am studying for my CCNA and i have a problem getting a serial link to work.  I have tried 2 cables and re-seating the serial module. Have i done something wrong or is it broken?  I have switched loopback on both side and the line protocol doesnt come back up on the DTE end.

Here is the DTE end:

ICND1-RTR2#sho int s1/0

Serial1/0 is up, line protocol is down

  Hardware is CD2430 in sync mode

  Internet address is 192.168.11.1/31

  MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,

     reliability 140/255, txload 1/255, rxload 1/255

  Encapsulation HDLC, loopback not set

  Keepalive set (10 sec)

  Last input never, output 00:00:01, 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: 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

     0 packets input, 0 bytes, 0 no buffer

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

     2007826 input errors, 0 CRC, 0 frame, 2007826 overrun, 0 ignored, 0 abort

     271 packets output, 10465 bytes, 270 underruns

     270 output errors, 0 collisions, 90 interface resets

     0 output buffer failures, 0 output buffers swapped out

     34 carrier tr

*Mar  1 00:43:31.873: Serial1/0: HDLC myseq 53, mineseen 0, yourseen 0, line down

*Mar  1 00:43:32.943: Serial1/0: attempting to restart

*Mar  1 00:43:32.943: Serial0, cd2430_sync_mode_init

*Mar  1 00:43:32.943: CIRRUS(0): Deasserting DTR

*Mar  1 00:43:32.943: CIRRUS(0): Deasserting RTS

*Mar  1 00:43:32.943: CIRRUS(0): Reset from 0x80392624

*Mar  1 00:43:32.947: CIRRUS(0): Asserting DTR

*Mar  1 00:43:32.947: CIRRUS(0): Asserting RTS ansitions

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

And here is the DCE end:

ICND1-RTR1#sho int s0/0

Serial0/0 is up, line protocol is down

  Hardware is PowerQUICC Serial

  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 00:20:49, output 00:00:08, 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: 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

     151 packets input, 11954 bytes, 0 no buffer

     Received 151 broadcasts, 0 runts, 0 giants, 0 throttles

     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

     302 packets output, 17528 bytes, 0 underruns

     0 output errors, 0 collisions, 53 interface resets

     0 output buffer failures, 0 output buffers swapped out

     185 carrier transitions

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

ICND1-RTR1#

*Mar  1 00:45:20.307: Serial0/0: HDLC myseq 64, mineseen 0, yourseen 0, line dow

Cheers Guys.

[paolo bevilacqua]

OSI layer 8 is "political", so I don't think it applies here.

[Alessio Andreoli]

Hi Patrick,
This is a layer 2 issue at the most. I would invert the cable ends to check if he DTE is connected on the right side and the encapsulation you need for. Is it a back to back link?

Alessio

Sent from Cisco Technical Support iPad App

Ps: do not consider the political layer for your studies. They are only 7 if you consider the ISO/OSI stack model.

[paul driver]

Hello

Is this a back to back connection? - if so

Disable keepsalives and provide clocking for the dce

Res
Paul

Sent from Cisco Technical Support iPad App

[Subeh Sharma]

Patrick,

Please paste the serial interface configuration here.

Thanks,

Subeh

[Patrick Evans]

Hi Everyone. 

It is a back to back link yes.  Below is the config for both Routers.

ICND1-RTR2#sho run int s1/0

Building configuration...

Current configuration : 101 bytes

!

interface Serial1/0

ip address 192.168.11.1 255.255.255.254

no fair-queue

clock rate 64000

end

ICND1-RTR1#sho run int s0/0

Building configuration...

Current configuration : 109 bytes

!

interface Serial0/0

no ip address

ip nat inside

ip virtual-reassembly

no keepalive

no fair-queue

end

Thanks Patrick

[Subeh Sharma]

Patrick,

1. Give clock rate command on RTR1 as it is the DCE

2. Configure an IP on RTR1 in the same subnet.

Thanks,

Subeh

[Patrick Evans]

Hi Subeh,

Thanks for getting back to me. 

One thing that I though I put in my original post but missed is :

*Mar  1 00:03:56.559: PowerQUICC(0/0): DCD is down.

*Mar  1 00:03:56.559: PowerQUICC(0/0): DCD is up.

*Mar  1 00:03:56.559: PowerQUICC(0/0): DCD is down.

I changed the WIC 1T module and that solved that.  After i got the line up.  You were completely correct, I had forgotten to address the other interface on RTR1.  I have done that now and i can ping acccross the link.

Thanks to everyone that responded. 

PS Alessio and Paulo, I come from an IT support background where layer 8 is generally used as "user" ?(in this case me)

[Subeh Sharma]

Glad to know the issue has been resolved, Patrick!

Regards,

Subeh