[VOL-2182] Test Failure Scenario: DHCP fails when ONU is not authenticated/subscriber is not added

Change-Id: Ic0ed7aa3f8c0c181662214e55f128a3942227103
diff --git a/libraries/utils.robot b/libraries/utils.robot
index 62c8569..cc7e1df 100644
--- a/libraries/utils.robot
+++ b/libraries/utils.robot
@@ -116,3 +116,13 @@
     Run Keyword If    '${auth_pass}' == 'False'    Sleep    20s
     Run Keyword If    '${auth_pass}' == 'False'    Check Remote File Contents    False    /tmp/wpa.log    
     ...    authentication completed successfully    ${ip}    ${user}    ${pass}    ${container_type}    ${container_name}
+
+Send Dhclient Request To Release Assigned IP
+    [Arguments]    ${iface}    ${ip}    ${user}    ${path_dhcpleasefile}    ${pass}=${None}    ${container_type}=${None}
+    ...    ${container_name}=${None}
+    [Documentation]    Executes a dhclient with option to release ip against a particular interface on the RG (src)
+    ${result}=    Login And Run Command On Remote System    dhclient -nw -r ${iface} && rm ${path_dhcpleasefile}/dhclient.*    ${ip}    ${user}
+    ...    ${pass}    ${container_type}    ${container_name}
+    Log    ${result}
+    #Should Contain    ${result}    DHCPRELEASE
+    [Return]    ${result}