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annedevries1978
Beginner

Cisco 888 and 878 router unreachable

Hi,

I am having a strange problem with two routers showing the same behaviour. The problem is that that the routers are not reachable form the corporate LAN after some time. Pinging the routers IP is not working anymore. When the network cable is unplugged and plugged in again the routers are responding again. The same applies when I connect my Laptop to the router. The interface is responsive right after I connect the cable. Also other devices on the network can ping the router. But after a few hours or sometimes 1,5 day the router is unreachable form the corporate network.

The problem first started a few weeks ago. The configuration did not change. The router 878 was not responsing and after changing all the cables and conncting it to another swith the problem remained. So I suspected a hardware failure and bought a replacement 888. After configuring the 888 it showed the same behaviour as the 878 router. The DSL connection is working all the time. I can even set up a vpn connection to the router and start a telnet session. than I can ping the internap IP of the router but pinging another device is not working.

What I noticed after the command sh int vlan1 is that the last input counter keeps increasing.

Any ideas whats coausing this or how to debug?

1 REPLY 1
Daniele Giordano
Rising star

It can be a Layer 2 loop in your LAN. Do you have enabled spanning-tree?

Use "sh spanning-tree" and check if there are blocking ports:

VLAN1 is executing the ieee compatible Spanning Tree protocol

  Bridge Identifier has priority 32768, address 30e4.dbab.ace0

  Configured hello time 2, max age 20, forward delay 15

  Current root has priority 32768, address 0025.6427.1cef

  Root port is 1 (FastEthernet0), cost of root path is 23

  Topology change flag not set, detected flag not set

  Number of topology changes 4 last change occurred 3d03h ago

          from FastEthernet2

  Times:  hold 1, topology change 35, notification 2

          hello 2, max age 20, forward delay 15

  Timers: hello 0, topology change 0, notification 0, aging 300

Port 1 (FastEthernet0) of VLAN1 is forwarding

   Port path cost 19, Port priority 128, Port Identifier 128.1.

   Designated root has priority 32768, address 0025.6427.1cef

   Designated bridge has priority 32768, address 0025.6427.20ac

   Designated port id is 128.23, designated path cost 4

   Timers: message age 2, forward delay 0, hold 0

   Number of transitions to forwarding state: 1

   BPDU: sent 4, received 137038

Port 3 (FastEthernet2) of VLAN1 is forwarding

   Port path cost 19, Port priority 128, Port Identifier 128.3.

   Designated root has priority 32768, address 0025.6427.1cef

   Designated bridge has priority 32768, address 30e4.dbab.ace0

   Designated port id is 128.3, designated path cost 23

   Timers: message age 0, forward delay 0, hold 0

   Number of transitions to forwarding state: 1

   BPDU: sent 137000, received 0

Regards.