diff --git a/Makefile b/Makefile
index 1f52d9c..67b89f3 100755
--- a/Makefile
+++ b/Makefile
@@ -47,7 +47,7 @@
 ROBOT_SANITY_TT_SINGLE_PON_FILE    ?= $(ROOT_DIR)/tests/data/bbsim-kind-tt.yaml
 ROBOT_DMI_SINGLE_BBSIM_FILE     ?= $(ROOT_DIR)/tests/data/dmi-components-bbsim.yaml
 ROBOT_DMI_SINGLE_ADTRAN_FILE     ?= $(ROOT_DIR)/tests/data/dmi-components-adtran.yaml
-ROBOT_ONOS_APP_UPGRADE_FILE     ?= $(ROOT_DIR)/tests/data/onos-app-upgrade.yaml
+ROBOT_SW_UPGRADE_FILE     ?= $(ROOT_DIR)/tests/data/software-upgrade.yaml
 
 # for backwards compatibility
 sanity-kind: sanity-single-kind
@@ -320,16 +320,23 @@
 # <app-name>,<version>,<oar-url>*<app-name>,<version>,<oar-url>*
 onos-app-upgrade-test: ROBOT_MISC_ARGS +=  -e notready -i functional
 onos-app-upgrade-test: ROBOT_FILE := ONOS_AppsUpgrade.robot
-onos-app-upgrade-test: ROBOT_CONFIG_FILE := $(ROBOT_ONOS_APP_UPGRADE_FILE)
+onos-app-upgrade-test: ROBOT_CONFIG_FILE := $(ROBOT_SW_UPGRADE_FILE)
 onos-app-upgrade-test: software-upgrade-test
 
 # Voltha Components to test for Software Upgrade need to be passed in the 'voltha_comps_under_test' variable in format:
 # <comp-label>,<comp-container>,<comp-image>*<comp-label>,<comp-container>,<comp-image>*
 voltha-comp-upgrade-test: ROBOT_MISC_ARGS +=  -e notready -i functional
 voltha-comp-upgrade-test: ROBOT_FILE := Voltha_ComponentsUpgrade.robot
-voltha-comp-upgrade-test: ROBOT_CONFIG_FILE := $(ROBOT_ONOS_APP_UPGRADE_FILE)
+voltha-comp-upgrade-test: ROBOT_CONFIG_FILE := $(ROBOT_SW_UPGRADE_FILE)
 voltha-comp-upgrade-test: software-upgrade-test
 
+# Requirement: Pass ONU image details in following parameters
+# onu_image_name, onu_image_url, onu_image_version, onu_image_crc, onu_image_local_dir
+onu-upgrade-test: ROBOT_MISC_ARGS +=  -e notready -i functional
+onu-upgrade-test: ROBOT_FILE := ONU_Upgrade.robot
+onu-upgrade-test: ROBOT_CONFIG_FILE := $(ROBOT_SW_UPGRADE_FILE)
+onu-upgrade-test: software-upgrade-test
+
 software-upgrade-test: vst_venv
 	source ./$</bin/activate ; set -u ;\
 	cd tests/software-upgrades ;\
diff --git a/libraries/voltctl.robot b/libraries/voltctl.robot
index e799e6c..a2b7d8f 100755
--- a/libraries/voltctl.robot
+++ b/libraries/voltctl.robot
@@ -795,3 +795,41 @@
     ${targetFlows}=    Set Variable If  $provisioned=='true'    ${afterFlows}   ${beforeFlows}
     Log     ${targetFlows}
     Wait Until Keyword Succeeds     10m     5s  Count OpenOLT Device Flows     ${targetFlows}
+
+Download ONU Device Image
+    [Documentation]    Downloads the given ONU software image
+    [Arguments]    ${id}    ${image}    ${url}    ${ver}    ${crc}    ${local_dir}
+    ${rc}=    Run and Return Rc
+    ...    voltctl -c ${VOLTCTL_CONFIG} device image download ${id} ${image} ${url} ${ver} ${crc} ${local_dir}
+    Should Be Equal As Integers    ${rc}    0
+
+Activate ONU Device Image
+    [Documentation]    Activatess the given ONU software image
+    [Arguments]    ${id}    ${image}    ${ver}    ${crc}    ${local_dir}
+    ${rc}=    Run and Return Rc
+    ...    voltctl -c ${VOLTCTL_CONFIG} device image activate ${id} ${image} ${ver} ${crc} ${local_dir}
+    Should Be Equal As Integers    ${rc}    0
+
+Verify ONU Device Image
+    [Documentation]    Verfies the ONU device image state
+    [Arguments]    ${dev_id}    ${download_state}    ${image_state}    ${expected_reason}
+    ${rc}    ${output}=    Run and Return Rc and Output
+    ...    voltctl -c ${VOLTCTL_CONFIG} device image list ${dev_id} -o json
+    Should Be Equal As Integers    ${rc}    0
+    ${jsondata}=    To Json    ${output}
+    Log    ${jsondata}
+    ${length}=    Get Length    ${jsondata}
+    ${matched}=    Set Variable    False
+    FOR    ${INDEX}    IN RANGE    0    ${length}
+        ${value}=    Get From List    ${jsondata}    ${INDEX}
+        ${id}=    Get From Dictionary    ${value}    id
+        ${downloadstate}=    Get From Dictionary    ${value}    downloadState
+        ${imagestate}=    Get From Dictionary    ${value}    imageState
+        ${reason}=    Get From Dictionary    ${value}    reason
+        ${matched}=    Set Variable If    '${id}' == '${dev_id}'    True    False
+        Exit For Loop If    ${matched}
+    END
+    Should Be True    ${matched}    No ONU Device Image for Id: ${dev_id}
+    Should Be Equal    '${downloadstate}'    '${download_state}'    ONU Device ${id} Image downloadState does not match
+    Should Be Equal    '${imagestate}'    '${image_state}'    ONU Device ${id} Image imageState does not match
+    Should Be Equal    '${reason}'    '${expected_reason}'    ONU Device ${id} Image reason does not match
diff --git a/tests/data/onos-app-upgrade.yaml b/tests/data/software-upgrade.yaml
similarity index 100%
rename from tests/data/onos-app-upgrade.yaml
rename to tests/data/software-upgrade.yaml
diff --git a/tests/software-upgrades/ONU_Upgrade.robot b/tests/software-upgrades/ONU_Upgrade.robot
new file mode 100755
index 0000000..57a9450
--- /dev/null
+++ b/tests/software-upgrades/ONU_Upgrade.robot
@@ -0,0 +1,123 @@
+# Copyright 2021 - present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# FIXME Can we use the same test against BBSim and Hardware?
+
+*** Settings ***
+Documentation     Tests ONU Software Upgrade
+Suite Setup       Setup Suite
+Test Setup        Setup
+Test Teardown     Teardown
+Suite Teardown    Teardown Suite
+Library           Collections
+Library           String
+Library           OperatingSystem
+Library           XML
+Library           RequestsLibrary
+Library           ../../libraries/DependencyLibrary.py
+Resource          ../../libraries/onos.robot
+Resource          ../../libraries/voltctl.robot
+Resource          ../../libraries/voltha.robot
+Resource          ../../libraries/utils.robot
+Resource          ../../libraries/k8s.robot
+Resource          ../../variables/variables.robot
+
+*** Variables ***
+${POD_NAME}       flex-ocp-cord
+${KUBERNETES_CONF}    ${KUBERNETES_CONFIGS_DIR}/${POD_NAME}.conf
+${KUBERNETES_CONFIGS_DIR}    ~/pod-configs/kubernetes-configs
+#${KUBERNETES_CONFIGS_DIR}    ${KUBERNETES_CONFIGS_DIR}/${POD_NAME}.conf
+${KUBERNETES_YAML}    ${KUBERNETES_CONFIGS_DIR}/${POD_NAME}.yml
+${HELM_CHARTS_DIR}    ~/helm-charts
+${VOLTHA_POD_NUM}    8
+${NAMESPACE}      voltha
+# For below variable value, using deployment name as using grep for
+# parsing radius pod name, we can also use full radius pod name
+${RESTART_POD_NAME}    radius
+${timeout}        60s
+${of_id}          0
+${logical_id}     0
+${has_dataplane}    True
+${teardown_device}    False
+${scripts}        ../../scripts
+
+# Per-test logging on failure is turned off by default; set this variable to enable
+${container_log_dir}    ${None}
+
+${suppressaddsubscriber}    True
+
+# ONU Image to test for Upgrade needs to be passed in the following format:
+${onu_image_name}    ${EMPTY}
+# Example value: twsh.img
+${onu_image_url}    ${EMPTY}
+# Example value: http://bbsim0:50074/images/software-image.img
+${onu_image_version}    ${EMPTY}
+# Example value: v1.0.0
+${onu_image_crc}    ${EMPTY}
+# Example value: 0
+${onu_image_local_dir}    ${EMPTY}
+# Example value: /tmp
+
+*** Test Cases ***
+Test ONU Upgrade
+    [Documentation]    Validates the ONU Upgrade doesn't affect the system functionality
+    ...    Performs the sanity and verifies all the ONUs are authenticated/DHCP/pingable
+    ...    Requirement: Pass image details in following parameters in the robot command
+    ...    onu_image_name, onu_image_url, onu_image_version, onu_image_crc, onu_image_local_dir
+    ...    Check [VOL-3903] for more details
+    [Tags]    functional   ONUUpgrade
+    [Setup]    Start Logging    ONUUpgrade
+    [Teardown]    Run Keywords    Collect Logs
+    ...           AND             Stop Logging    ONUUpgrade
+    ...           AND             Delete All Devices and Verify
+    # Add OLT device
+    Setup
+    # Performing Sanity Test to make sure subscribers are all DHCP and pingable
+    Run Keyword If    ${has_dataplane}    Clean Up Linux
+    Wait Until Keyword Succeeds    ${timeout}    2s    Perform Sanity Test
+    FOR    ${I}    IN RANGE    0    ${num_all_onus}
+        ${src}=    Set Variable    ${hosts.src[${I}]}
+        ${dst}=    Set Variable    ${hosts.dst[${I}]}
+        ${onu_device_id}=    Get Device ID From SN    ${src['onu']}
+        Download ONU Device Image    ${onu_device_id}    ${onu_image_name}    ${onu_image_url}    ${onu_image_version}
+        ...    ${onu_image_crc}    ${onu_image_local_dir}
+        # This additional pause to let image download finish on the OLT adapter
+        # as the DOWNLOADED_SUCCEEDED below only indicates that the command is accepted.
+        Run Keyword If    ${has_dataplane}    Sleep    12s
+        ...    ELSE    Sleep    2s
+        Wait Until Keyword Succeeds    ${timeout}    2s    Verify ONU Device Image    ${onu_device_id}
+        ...    DOWNLOAD_SUCCEEDED    IMAGE_UNKNOWN    NO_ERROR
+        Activate ONU Device Image    ${onu_device_id}    ${onu_image_name}    ${onu_image_version}
+        ...    ${onu_image_crc}    ${onu_image_local_dir}
+        # This additional pause to let image download and finish activate on the ONU (BBSim)
+        # as the IMAGE_ACTIVE below is only an indication that the image is accepted for the download to the ONU (BBSim).
+        Run Keyword If    ${has_dataplane}    Sleep    600s
+        ...    ELSE    Sleep    180s
+        Wait Until Keyword Succeeds    ${timeout}    2s    Verify ONU Device Image    ${onu_device_id}
+        ...    DOWNLOAD_SUCCEEDED    IMAGE_ACTIVE    NO_ERROR
+        Wait Until Keyword Succeeds    ${timeout}    5s    Perform Sanity Test     ${suppressaddsubscriber}
+    END
+    # Additional Verification
+    Wait Until Keyword Succeeds    ${timeout}    2s    Delete All Devices and Verify
+    Setup
+    Run Keyword If    ${has_dataplane}    Clean Up Linux
+    Wait Until Keyword Succeeds    ${timeout}    2s    Perform Sanity Test
+
+*** Keywords ***
+Setup Suite
+    [Documentation]    Set up the test suite
+    Common Test Suite Setup
+
+Teardown Suite
+    [Documentation]    Tear down steps for the suite
+    Run Keyword If    ${has_dataplane}    Clean Up Linux