Ethernet Network device not managed on Ubuntu 14.10

Today i installed ubuntu 14.10 in my machine but after installation the Device Manager says "device not managed".

i found wired network is not managed by NetworkManager. I enable wired network settings on NetworkManager by changing "managed=false" to "managed=true" in /etc/NetworkManager/NetworkManager.conf.

root@manivel:~# vim /etc/NetworkManager/NetworkManager.conf

[main]
plugins=ifupdown,keyfile,ofono
dns=dnsmasq

[ifupdown]
managed=true

after that i restarted the network manager service using below command

root@manivel:~# service network-manager restart

or

root@manivel:~# ifdown eth0

root@manivel:~# ifup eth0

finally i got Ethernet network connection.