Cisco:How to solve line protocol down problem for serial interface in packet tracer

I am using cisco 2811 router with 1 WIC-1T card for serial interface

Both router is connected by serial (DCE/DTE) interface and and ip is set as follows:
router 1:
router 1:

Problem: line protocol is showing down .
Example bellow :

R1#show ip interface brief 
Interface              IP-Address      OK? Method Status                Protocol
FastEthernet0/0        unassigned      YES manual administratively down down
FastEthernet0/1        unassigned      YES manual administratively down down
Serial0/3/0       YES manual up                    down
Vlan1                  unassigned      YES manual administratively down down

Reason :
one of the reason is on DCE , clock rate is set to : no clock , as bellow example

R1#show controllers serial 0/3/0
Interface Serial0/3/0
Hardware is PowerQUICC MPC860
DCE V.35, no clock
idb at 0x81081AC4, driver data structure at 0x81084AC0
SCC Registers:
General [GSMR]=0x2:0x00000000, Protocol-specific [PSMR]=0x8
Events [SCCE]=0x0000, Mask [SCCM]=0x0000, Status [SCCS]=0x00
Transmit on Demand [TODR]=0x0, Data Sync [DSR]=0x7E7E
Interrupt Registers:
Config [CICR]=0x00367F80, Pending [CIPR]=0x0000C000
Mask   [CIMR]=0x00200000, In-srv  [CISR]=0x00000000
Command register [CR]=0x580
Port A [PADIR]=0x1030, [PAPAR]=0xFFFF
       [PAODR]=0x0010, [PADAT]=0xCBFF
Port B [PBDIR]=0x09C0F, [PBPAR]=0x0800E
       [PBODR]=0x00000, [PBDAT]=0x3FFFD
Port C [PCDIR]=0x00C, [PCPAR]=0x200
       [PCSO]=0xC20,  [PCDAT]=0xDF2, [PCINT]=0x00F
Receive Ring
        rmd(68012830): status 9000 length 60C address 3B6DAC4
        rmd(68012838): status B000 length 60C address 3B6D444
Transmit Ring

add clock rate by hand

R1#configure t
R1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#interface se
R1(config)#interface serial 0/3/0
R1(config-if)#clock r
R1(config-if)#clock rate 1000000
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/3/0, changed state to up

9 Responses to “Cisco:How to solve line protocol down problem for serial interface in packet tracer”

  1. Ameya says:

    I got problem in cisco 2811.
    I got error like:
    “F0/1 is up but line protocol is down.
    What should I do?

  2. Fosiul says:

    ‘@Ameya ‘

    Hi ya..

    How this router is connected each other ?

    are you using straight cable or cross over cable ?

  3. jahan says:

    hi ameya

    you just need to change the connection link
    or set the clock rate for the serial port

    good luck

  4. Learning Objectives

    Configure Cisco router global configuration settings
    Configure Cisco router password access
    Configure Cisco router interfaces
    Save the router configuration file
    Configure a Cisco switch

    In this lab students will configure common settings on a Cisco Router and Cisco Switch.

    Given an IP address of, with 4 bits borrowed for subnets, fill in the following information in the table above in your notebook or on a separate sheet of paper. (Hint: fill in the subnet number, then the host address. Address information will be easy to compute with the subnet number filled in first)

    Maximum number of usable subnets (including the 0th subnet)?
    Number of usable hosts per subnet?


  5. Rob says:

    I fixed mine, which was a serial down, I just erased all start up config data and restarted the router and it work, so far anyway. XD

  6. afaq bhat says:

    i have getting problem in up the link of serial interface in packet tracer..

    Router(config-if)#interface Serial0/1/0
    Router(config-if)#ip address
    Router(config-if)#no shutdown

    %LINK-5-CHANGED: Interface Serial0/1/0, changed state to down

    please tell me how to up the serial interface link

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