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Looped Interface Issue- please help!!!

echo-224.0.0.5
Level 1
Level 1

Hi,

I have a lab environment with 3 routers back to back but one which should be taking the clock (DTE) is up/looped. I have no loop back interfaces on this router and can't understand why this router is reporting back as looped. Can anyone help?  I have provided the sh ver info along with interface statuses concerned.

Thanks.

R3-Paris(config-if)#do sh ver

Cisco IOS Software, C2600 Software (C2600-ADVSECURITYK9-M), Version 12.4(15)T8, RELEASE SOFTWARE (fc3)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2008 by Cisco Systems, Inc.

Compiled Mon 01-Dec-08 14:23 by prod_rel_team

ROM: System Bootstrap, Version 12.2(8r) [cmong 8r], RELEASE SOFTWARE (fc1)

R3-Paris uptime is 1 hour, 11 minutes

System returned to ROM by power-on

System image file is "flash:c2600-advsecurityk9-mz.124-15.T8.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

Cisco 2610XM (MPC860P) processor (revision 3.1) with 127422K/3650K bytes of memory.

Processor board ID FOC08360GQ3

M860 processor: part number 5, mask 2

1 FastEthernet interface

1 Serial interface

8 Low-speed serial(sync/async) interfaces

32K bytes of NVRAM.

32768K bytes of processor board System flash (Read/Write)

Configuration register is 0x2102

R3-Paris#sh int s1/0

Serial1/0 is up, line protocol is up (looped)

  Hardware is CD2430 in sync mode

  Description: Link to R1-NY

  Internet address is 192.168.3.2/30

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

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

  Encapsulation HDLC, loopback not set

  Keepalive set (10 sec)

  Last input 00:00:03, output 00:00:03, 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  0/1/32 (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

     1150 packets input, 75700 bytes, 0 no buffer

     Received 405 broadcasts, 0 runts, 0 giants, 0 throttles

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

     1152 packets output, 75788 bytes, 0 underruns

     0 output errors, 0 collisions, 1 interface resets

     3 unknown protocol drops

     3 unknown protocol drops

     0 output buffer failures, 0 output buffers swapped out

     0 carrier transitions

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

R3-Paris#sh int s1/1

Serial1/1 is up, line protocol is up (looped)

  Hardware is CD2430 in sync mode

  Description: Link to R2-chicago

  Internet address is 192.168.2.2/30

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

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

  Encapsulation HDLC, loopback not set

  Keepalive set (10 sec)

  Last input 00:00:06, output 00:00:06, output hang 00:47:37

  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  0/2/32 (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

     335 packets input, 23290 bytes, 0 no buffer

     Received 335 broadcasts, 0 runts, 0 giants, 0 throttles

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

     398 packets output, 25107 bytes, 0 underruns

     0 output errors, 0 collisions, 64 interface resets

     1 unknown protocol drops

     1 unknown protocol drops

     0 output buffer failures, 0 output buffers swapped out

     0 carrier transitions

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

R3-Paris#

2 Replies 2

stevjarbeck
Level 1
Level 1

Make sure encapsulation and clock speeds match on both ends.

The clocks have been checked again to ensure R3 is DTE. Please see below the controller details and the encapsulation types on each. I tried another serial interface which worked quite alright I now suspect if it's the NM-8A/S card that's problematic. If you can think of anything else please let me.

R3-Paris#sh controller s1/0 | i DTE

idb 0x83BB12AC, buffer size 1524, V.35 DTE cable

R3-Paris#sh int s1/0 | i Encap

  Encapsulation HDLC, loopback not set

R3-Paris#sh controller s1/1 | i DTE

idb 0x83BB5F14, buffer size 1524, V.35 DTE cable

R3-Paris#

R3-Paris#sh int s1/1 | i Encap

  Encapsulation HDLC, loopback not set

R3-Paris#

R2-chicago#sh controllers s1/1 | i DCE
idb 0x83B69254, buffer size 1524, V.35 DCE cable, clockrate 56000
R2-chicago#
R2-chicago#sh int s1/1 | i Encap
  Encapsulation HDLC, loopback not set
R2-chicago#
R1-NY#sh int s1/1 | i Encap
  Encapsulation HDLC, loopback not set
R1-NY#sh controller s1/1 | i DCE
idb 0x83AEC4D4, buffer size 1524, V.35 DCE cable, clockrate 56000

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