My network is losing the ip-address

Question

It happens often after a while und ubuntu 8.04 on my notebook in my wired LAN. After I couldn't find a reason in the logs I started a terminal and a ping. Reading my emails I recognized that the network is gone away and a look in my terminal-windows shows the follwing:

64 bytes from 192.168.134.1: icmp_seq=6036 ttl=64 time=1.61 ms
64 bytes from 192.168.134.1: icmp_seq=6037 ttl=64 time=0.222 ms
64 bytes from 192.168.134.1: icmp_seq=6038 ttl=64 time=0.406 ms
64 bytes from 192.168.134.1: icmp_seq=6039 ttl=64 time=0.226 ms
64 bytes from 192.168.134.1: icmp_seq=6040 ttl=64 time=0.216 ms
From 169.254.7.74 icmp_seq=6042 Destination Host Unreachable
From 169.254.7.74 icmp_seq=6043 Destination Host Unreachable
From 169.254.7.74 icmp_seq=6044 Destination Host Unreachable
From 169.254.7.74 icmp_seq=6046 Destination Host Unreachable
From 169.254.7.74 icmp_seq=6047 Destination Host Unreachable

Is there anybody who can give me a hint where to look to fix it?

Ah: Other PCs in my Network don't have this issue, the DHCP-Server is working fine.

Peace

Ice

Answer 1

When ping states 'Destination Host unreachable', that is a likely indication that the router could not forward the ICMP packet across to the specific host across the internet.

Simple steps to check:

• ifconfig eth0 - checks to see if the network device is up and running
• ping 127.0.0.1 - checks to see if the tcp/ip stack is functioning
• ping {your_routers_ip_address - checks to see if the nic can transmit data to your router's ip address (by default, 192.168.1.1) - if it doesn't at this stage, then your nic could be faulty. If it works, then the issue is with the router...

If the NIC appears to be faulty, check the log by issuing this on the command line

less /var/log/messages

  If this fails, you need to use this instead: 

sudo less /var/log/messages 

  then enter your password when prompted to do so.

and look for the specific keyword eth0 followed by the message on the same line - double check it. Maybe an update of the driver might be required or an incorrect configuration that causes your pc to drop connections.

If the issue is the router - there could be a fault on the line itself. As John mentioned - don't be surprised - even the simplest thing as a bad cable can mislead you. Swap the cable for a new one and repeat the steps above. If it still fails, the problem is on your computer's NIC.

Can you please confirm all of this first and let us know what driver you are using, make/manufacturer of the NIC, what kind of router etc..this will help us all in troubleshooting further.

Hope this helps, Best regards, Tom.

Answer 2

Start with some basic network connectivity checks. If it's a cabled network my first guess would be a bad cable. Try another. If it's wireless you may be losing the signal.