If you are using a gigabit switch i.e your LAPTOP/PC is connected to gigabit switch and USRP is connected to gigabit switch then there should not be any problem. If you don't fine an extra cable, you can test Ethernet cable by connecting a PC/router and pinging it. Please see following links for your question on netmanager and dhcp:
>>>> I have not changed the
fpga firmware. I used the build-gnuradio script to install gnuradio. I
am not finding another ethernet cable in the lab. I will check that and
let you know in some hours.
>>>>My ethernet card in laptop is rtl 8101e. I checked that it is
capable of only 100 Mbps. But here i am using a gigabit switch, so it
shouldn't be a problem right. How should i check if my ethernet port is
managed by >>>>netmanager with dhcp support? In my network connections it
says auto eth0 for ethernet