When I try to connect beaglbone black with laptop it connects ..but when I try to connect it with sd card having Ubuntu 12.04 lti precise version ..it doesn't connect ...any fix ??
Did you configure 12.04 to do that? The default image has a script
that does that.
Here is one example of many ways to achive that..
https://github.com/RobertCNelson/tools/blob/master/scripts/beaglebone-black-g-ether-load.sh
Regards,