simulate a network failure

Hi Folks,

I have an ESXi 5.1 enviornment with two uplinks (vmnic0 and vmnic1), both configured to vDistributed Switch. I am running some tests to validate the network and want to simulate one of the network failure, rather than pulling out the cable. 

This should be possible thru esxcli but not sure about the steps. Can someone help me know the steps?

Thanks.