Internet router stops working, then boot and it get back working

Unanswered Question
Feb 13th, 2008
User Badges:
  • Bronze, 100 points or more


I have a router connected to an ISP over a serial interface using HDLC protocol.

Every day the traffic stop going to ISP then i reboot the router and the traffic work again.

I have tried to clear arp cache but it did not get back, only if i reboot it works, I have tried 3 different 1800 routes with 3 diferent IOSs.

All of the routers shows the same problem.


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Richard Burts Wed, 02/13/2008 - 08:35
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN


ARP is used by Ethernet (and FastEthernet, etc) interfaces. For your serial connection there is no ARP since it uses HDLC and HDLC has no ARP function.

The symptom of the router running for a while, then stopping forwarding traffic, and working again after a reboot sounds a bit like there was a memory leak. But if you have tried 3 different versions of IOS it seems a bit unlikely that the 3 different versions would all have the memory leak.

At the time when the router stops forwarding traffic can you log in to the router? Are there any messages in the log which might help explain why it stopped forwarding traffic? Can you do a show interface when the router is not forwarding and post the output? This might help us to figure what the problem is.



jim_berlow Wed, 02/13/2008 - 09:18
User Badges:
  • Bronze, 100 points or more

As Rick pointed out - this really sounds like a memory issue. Are you logging messages to a syslog server? I would recommend doing that right away. And if I was in your position, I would open a TAC case on this.

guibarati Wed, 02/13/2008 - 11:47
User Badges:
  • Bronze, 100 points or more

I said it wrong, it's not a serial interface, it's a ethernet link.

However i had no logg, I enabled it and will see if there is anything helpfull when it stops.

Rick Morris Wed, 02/13/2008 - 12:18
User Badges:
  • Silver, 250 points or more

If you are able to log in when the router stops routing

do a couple of commands:

sh ip int brief

sh proc

sh mem

sh ver

There are a few things that we could see what the problem might be and rule out some other possibilities too.


This Discussion