everytime when i boot my system i have to config my IP address by this command ifconfig eth0 ip address up..
but after some time it does not show me ip address by this command ifconfig..
so anybody tell me how to short out this problem.

Do you have dhclient or dhcpc process running? Check with 'pgrep dhc' . I guess it resets IP address.

I don't see which distro you have. For some, distro's you can put your ifconfig commands in a standard network startup script so that it runs when you boot. On others, you can use a GUI network devices configuration program that either produces a similar script, or creates a configuration file in /etc/sysconfig/network/.
Do you mean that after using ifconfig to set an IP address, when you check what you IP address is using ifconfig, that you don't have an IP address?

Could you try a different unused IP address? I am wondering if another host may have used that IP address.

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how ifconfig command is put in standered network startup?? i tried to config it through GUI also but after activationg my network configuration after 2 min it deactivate..
after using ifconfig to set an IP address when i check my ip address using ifconfig it does not show me IP address information ..
no other is using that ip address..

What does your NIC connect to? Are you running on a laptop on batteries?

Do you have a built in NIC interface of a PCMCIA card?

Which distro are you using? Is there anything mentioned in the logs, such as /var/log/messages?

I'm wondering if you may have a bad ethernet cable. It doesn't sound right that a standard NIC device will suddenly loose it's IP address.

I asked about a laptop, because some laptops will shutdown the NIC device as a power saving feature to save battery power. This may happen after being idle a short period of time.

Do you disable everything related with dynamic IP and DHCP?

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