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Problem interface LAN (status UP, Prorotocol Down)

Hi everybody,

I have a problem with my interface 4 of my cisco 800 router. the status is Up but the protocol is down.

the interface is not administratively down, and the cable is ok. Also, When i connect the same cable to the FE3, i get both status and protocol Up.

i have rebooted the device without success.

Can someone let me know what can cause this issue ? how to detect that is a hardware problem in FE4 ?

Thanks and regards.

Kimberly Adams


Can you please post up the configuration of the router and what this interface is being used for, ie...inside or outside or what?

This will help with a diag of this issue.



Thanks and Cheers! Kimberly Please remember to rate helpful posts.

I agree with Kimberly that seeing the configuration may be helpful. I would also ask that you post the output of show interface.  This would help us to see some things such as whether keepalives are configured.





Thanks you for your reply.

The show int output is :


Router#sh int fa04
FastEthernet4 is up, line protocol is down
  Hardware is PQII_PRO_UEC, address is 0026.99c1.f998 (bia 0026.99c1.f998)
  Description: *** interface LAN- LAN1 ***
  Internet address is
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, Auto Speed, 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 19:30:40, 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
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog
     0 input packets with dribble condition detected
     35 packets output, 2160 bytes, 0 underruns
     0 output errors, 0 collisions, 5 interface resets
     0 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out


the config is the fe4 is :


interface FastEthernet4
description *** interface LAN- LAN1 ***
ip address
ip access-group 180 in
no ip redirects
ip tcp adjust-mss 1380
ip ospf authentication-key 7 XXXXX
duplex full
speed auto
vrrp 91 ip
vrrp 91 authentication XXXXXXX
crypto ipsec client ezvpn IPSEC inside


Thanks again and regards.

What does access-list 180 do?  Is the same one applied to fa03 when you moved the cable to that interface?  What is the configuration of fa03 when it worked?

All these questions are just trying to get to the bottom of this issue for you.



Thanks and Cheers! Kimberly Please remember to rate helpful posts.

The access list is to secure outgoing trafic. Under FE3, i don't have any command.

Normaly, access-list cannot shutdown or desative interface but permit or deny trafic.

Thanks for your reply.

   Trying changing the interface duplex to auto and see what happens .  I don't know much about these but if its like  their other gear and it uses mdix it will only work as auto/auto for speed and duplex if you are using the incorrect cable and it has to correct the pairs . If not maybe a hardware issue.

Frequent Contributor

the meaning of protocol down is that the router does not receive keepalive. By default, ethernet interfaces on cisco routers send out keepalive in every 10 seconds. It can be seen on the show interface:

Router#sh int fa04


Keepalive set (10 sec)

When the device connecting to fa04, it should send the keepalive back to fa04.

If you want, you can configure "no keepalive". However, it may mask a cabling issue. I suggest that you configure no keepalive first. Then, find out if you have any connectivity problem between the router and the device on fa4

The no keeplive command didn't resolve the issue.   the router has been remplaced and it works using the same config, port interface.

Thanks for your help.


What device do you have plugged into that port?

Hello Abdazdoud ,


Instead of asking each question , You can make picture of your connectivity with the necessary details to answer for your question can be uploaded. It will increase the chances of getting answers in short time.



Thanghadurai S