> On 24-Jan-2024, at 8:59 AM, Numan Siddique <num...@ovn.org> wrote:
> 
> On Tue, Jan 23, 2024 at 8:02 PM Naveen Yerramneni
> <naveen.yerramn...@nutanix.com> wrote:
>> 
>> 
>> 
>>> On 16-Jan-2024, at 2:30 AM, Numan Siddique <num...@ovn.org> wrote:
>>> 
>>> On Tue, Dec 12, 2023 at 1:05 PM Naveen Yerramneni
>>> <naveen.yerramn...@nutanix.com> wrote:
>>>> 
>>>>   This patch contains changes to enable DHCP Relay Agent support for 
>>>> overlay subnets.
>>>> 
>>>>   USE CASE:
>>>>   ----------
>>>>     - Enable IP address assignment for overlay subnets from the 
>>>> centralized DHCP server present in the underlay network.
>>>> 
>>>>   PREREQUISITES
>>>>   --------------
>>>>     - Logical Router Port IP should be assigned (statically) from the same 
>>>> overlay subnet which is managed by DHCP server.
>>>>     - LRP IP is used for GIADRR field when relaying the DHCP packets and 
>>>> also same IP needs to be configured as default gateway for the overlay 
>>>> subnet.
>>>>     - Overlay subnets managed by external DHCP server are expected to be 
>>>> directly reachable from the underlay network.
>>>> 
>>>>   EXPECTED PACKET FLOW:
>>>>   ----------------------
>>>>   Following is the expected packet flow inorder to support DHCP rleay 
>>>> functionality in OVN.
>>>>     1. DHCP client originates DHCP discovery (broadcast).
>>>>     2. DHCP relay (running on the OVN) receives the broadcast and forwards 
>>>> the packet to the DHCP server by converting it to unicast. While 
>>>> forwarding the packet, it updates the GIADDR in DHCP header to its
>>>>        interface IP on which DHCP packet is received.
>>>>     3. DHCP server uses GIADDR field to decide the IP address pool from 
>>>> which IP has to be assigned and DHCP offer is sent to the same IP (GIADDR).
>>>>     4. DHCP relay agent forwards the offer to the client, it resets the 
>>>> GIADDR field when forwarding the offer to the client.
>>>>     5. DHCP client sends DHCP request (broadcast) packet.
>>>>     6. DHCP relay (running on the OVN) receives the broadcast and forwards 
>>>> the packet to the DHCP server by converting it to unicast. While 
>>>> forwarding the packet, it updates the GIADDR in DHCP header to its
>>>>        interface IP on which DHCP packet is received.
>>>>     7. DHCP Server sends the ACK packet.
>>>>     8. DHCP relay agent forwards the ACK packet to the client, it resets 
>>>> the GIADDR field when forwarding the ACK to the client.
>>>>     9. All the future renew/release packets are directly exchanged between 
>>>> DHCP client and DHCP server.
>>>> 
>>>>   OVN DHCP RELAY PACKET FLOW:
>>>>   ----------------------------
>>>>   To add DHCP Relay support on OVN, we need to replicate all the behavior 
>>>> described above using distributed logical switch and logical router.
>>>>   At, highlevel packet flow is distributed among Logical Switch and 
>>>> Logical Router on source node (where VM is deployed) and redirect 
>>>> chassis(RC) node.
>>>>     1. Request packet gets processed on the source node where VM is 
>>>> deployed and relays the packet to DHCP server.
>>>>     2. Response packet is first processed on RC node (which first recieves 
>>>> the packet from underlay network). RC node forwards the packet to the 
>>>> right node by filling in the dest MAC and IP.
>>>> 
>>>>   OVN Packet flow with DHCP relay is explained below.
>>>>     1. DHCP client (VM) sends the DHCP discover packet (broadcast).
>>>>     2. Logical switch converts the packet to L2 unicast by setting the 
>>>> destination MAC to LRP's MAC
>>>>     3. Logical Router receives the packet and redirects it to the OVN 
>>>> controller.
>>>>     4. OVN controller updates the required information(GIADDR) in the DHCP 
>>>> payload after doing the required checks. If any check fails, packet is 
>>>> dropped.
>>>>     5. Logical Router converts the packet to L3 unicast and forwards it to 
>>>> the server. This packets gets routed like any other packet (via RC node).
>>>>     6. Server replies with DHCP offer.
>>>>     7. RC node processes the DHCP offer and forwards it to the OVN 
>>>> controller.
>>>>     8. OVN controller does sanity checks and  updates the destination MAC 
>>>> (available in DHCP header), destination IP (available in DHCP header), 
>>>> resets GIADDR  and reinjects the packet to datapath.
>>>>        If any check fails, packet is dropped.
>>>>     9. Logical router updates the source IP and port and forwards the 
>>>> packet to logical switch.
>>>>     10. Logical switch delivers the packet to the DHCP client.
>>>>     11. Similar steps are performed for Request and Ack packets.
>>>>     12. All the future renew/release packets are directly exchanged 
>>>> between DHCP client and DHCP server
>>>> 
>>>>   NEW OVN ACTIONS
>>>>   ---------------
>>>> 
>>>>     1. dhcp_relay_req(<relay-ip>, <server-ip>)
>>>>         - This action executes on the source node on which the DHCP 
>>>> request originated.
>>>>         - This action relays the DHCP request coming from client to the 
>>>> server. Relay-ip is used to update GIADDR in the DHCP header.
>>>>     2. dhcp_relay_resp_fwd(<relay-ip>, <server-ip>)
>>>>         - This action executes on the first node (RC node) which processes 
>>>> the DHCP response from the server.
>>>>         - This action updates  the destination MAC and destination IP so 
>>>> that the response can be forwarded to the appropriate node from which 
>>>> request was originated.
>>>>         - Relay-ip, server-ip are used to validate GIADDR and SERVER ID in 
>>>> the DHCP payload.
>>>> 
>>>>   FLOWS
>>>>   -----
>>>>   Following are the flows required for one overlay subnet.
>>>> 
>>>>     1. table=27(ls_in_l2_lkup      ), priority=100  , match=(inport == 
>>>> <vm_port> && eth.src == <vm_mac> && ip4.src == 0.0.0.0 && ip4.dst == 
>>>> 255.255.255.255 && udp.src == 68 && udp.dst == 67), 
>>>> action=(eth.dst=<lrp_mac>;outport=<lrp-port>;next;/* DHCP_RELAY_REQ */)
>>>>     2. table=3 (lr_in_ip_input     ), priority=110  , match=(inport == 
>>>> <lrp_port> && ip4.src == 0.0.0.0 && ip4.dst == 255.255.255.255 && udp.src 
>>>> == 68 && udp.dst == 67), 
>>>> action=(dhcp_relay_req(<lrp_ip>,<dhcp_server_ip>);ip4.src=<lrp_ip>;ip4.dst=<dhcp_server_ip>;udp.src=67;next;
>>>>  /* DHCP_RELAY_REQ */)
>>>>     3. table=3 (lr_in_ip_input     ), priority=110  , match=(ip4.src == 
>>>> <dhcp_server_ip> && ip4.dst ==<lrp_ip> && udp.src == 67 && udp.dst == 67), 
>>>> action=(next;/* DHCP_RELAY_RESP */)
>>>>     4. table=17(lr_in_dhcp_relay_resp_fwd), priority=110  , match=(ip4.src 
>>>> == <dhcp_server_ip> && ip4.dst == <lrp_ip> && udp.src == 67 && udp.dst == 
>>>> 67), 
>>>> action=(dhcp_relay_resp_fwd(<lrp_ip>,<dhcp_server_ip>);ip4.src=<lrp_ip>;udp.dst=68;outport=<lrp_port>;output;
>>>>  /* DHCP_RELAY_RESP */)
>>>> 
>>>>   NEW PIPELINE STAGES
>>>>   -------------------
>>>>   Following stage is added for DHCP relay feature. Some of the flows are 
>>>> fitted into the existing pipeline tages.
>>>>     1. lr_in_dhcp_relay_resp_fwd
>>>>         - Forward teh DHCP response to the appropriate node
>>>> 
>>>>   NB SCHEMA CHANGES
>>>>   ----------------
>>>>     1. New DHCP_Relay table
>>>>         "DHCP_Relay": {
>>>>               "columns": {
>>>>           "name": {"type": "string"},
>>>>                   "servers": {"type": {"key": "string",
>>>>                                          "min": 0,
>>>>                                          "max": 1}},
>>>>                   "external_ids": {
>>>>                       "type": {"key": "string", "value": "string",
>>>>                               "min": 0, "max": "unlimited"}}},
>>>>               "isRoot": true},
>>>>     2. New column to Logical_Router_Port table
>>>>         "dhcp_relay": {"type": {"key": {"type": "uuid",
>>>>                               "refTable": "DHCP_Relay",
>>>>                               "refType": "weak"},
>>>>                               "min": 0,
>>>>                               "max": 1}},
>>>>     3. New column to Logical_Switch_table
>>>>         "dhcp_relay_port": {"type": {"key": {"type": "uuid",
>>>>                                       "refTable": "Logical_Router_Port",
>>>>                                       "refType": "weak"},
>>>>                                        "min": 0,
>>>>                                        "max": 1}}},
>>>> 
>>>>   Commands to enable the feature:
>>>>   ------------------------------
>>>>     - ovn-nbctl create DHCP_Relay servers=<ip>
>>>>     - ovn-nbctl set Logical_Router_port <lrp_uuid> 
>>>> dhcp_relay=<dhcp_relay_uuid>
>>>>     - ovn-nbctl set Logical_Switch <ls_uuid> dhcp_relay_port=<lrp_uuid>
>>>> 
>>>>   Example:
>>>>   -------
>>>>    ovn-nbctl ls-add sw1
>>>>    ovn-nbctl lsp-add sw1 sw1-port1
>>>>    ovn-nbctl lsp-set-addresses sw1-port1 <MAC> #Only MAC address has to be 
>>>> specified when logical ports are created.
>>>>    ovn-nbctl lr-add lr1
>>>>    ovn-nbctl lrp-add lr1 lr1-port1 <MAC> <GATEWAY_IP/Prefix> #GATEWAY IP 
>>>> is set in GIADDR field when relaying the DHCP requests to server.
>>>>    ovn-nbctl lsp-add sw1 lr1-attachment
>>>>    ovn-nbctl lsp-set-type lr1-attachment router
>>>>    ovn-nbctl lsp-set-addresses lr1-attachment <MAC>
>>>>    ovn-nbctl lsp-set-options lr1-attachment router-port=lr1-port1
>>>>    ovn-nbctl create DHCP_Relay servers=<DHCP_SERVER_IP>
>>>>    ovn-nbctl set Logical_Router_port <lrp_uuid> dhcp_relay=<relay_uuid>
>>>>    ovn-nbctl set Logical_Switch <ls_uuid> dhcp_relay_port=<lrp_uuid>
>>>> 
>>>>   Limitations:
>>>>   ------------
>>>>     - All OVN features that needs IP address to be configured on logical 
>>>> port (like proxy arp, etc) will not be supported for overlay subnets on 
>>>> which DHCP relay is enabled.
>>>> 
>>>>   References:
>>>>   ----------
>>>>     - rfc1541, rfc1542, rfc2131
>>>> 
>>>> Signed-off-by: Naveen Yerramneni <naveen.yerramn...@nutanix.com>
>>>> Co-authored-by: Huzaifa Calcuttawala <huzaif...@nutanix.com>
>>>> Signed-off-by: Huzaifa Calcuttawala <huzaif...@nutanix.com>
>>>> CC: Mary Manohar <mary.mano...@nutanix.com>
>>> 
>>> Hi Naveen,
>>> 
>>> Thanks for the patch.  Sorry for the delayed response.
>>> 
>>> I've a few comments.
>>> 
>>> 1.  Regarding the newly added Table - DHCP_Relay in NB DB and the
>>> newly added columns in Logical_Switch and
>>>   Logical_Router table.
>>> 
>>>   I don't think there is a need to add the new table DHCP_Relay
>>> since it only stores the dhcp relay agent server ip.
>>>   Also it could complicate the northd incremental processing.
>>> 
>>>   If for example we have below logical switches and router
>>> 
>>>   ovn-nbctl lr-add R1
>>>   ovn-nbctl ls-add sw0
>>>   ovn-nbctl ls-add sw1
>>>   ovn-nbctl ls-add sw-ext
>>>   ovn-nbctl lrp-add R1 rp-sw0 00:00:01:01:02:03 192.168.1.1/24
>>>   ovn-nbctl lrp-add R1 rp-sw1 00:00:03:01:02:03 192.168.2.1/24
>>>   ovn-nbctl lrp-add R1 rp-ext 00:00:02:01:02:03 172.16.1.254/24
>>> 
>>>   ovn-nbctl lsp-add sw0 sw0-rp -- set Logical_Switch_Port sw0-rp \
>>>   type=router options:router-port=rp-sw0 \
>>>   -- lsp-set-addresses sw0-rp router
>>> 
>>>   ovn-nbctl lsp-add sw1 sw1-rp -- set Logical_Switch_Port sw1-rp \
>>>   type=router options:router-port=rp-sw1 \
>>>   -- lsp-set-addresses sw1-rp router
>>> 
>>>   I'd suggest doing something like below to enable this feature.
>>> 
>>>   ovn-nbctl set Logical_Switch_Port sw0-rp options:dhcp_relay=true
>>>   ovn-nbctl set Logical_Switch_Port sw1-rp options:dhcp_relay=true
>>> 
>>>   (Make sure that only one logical switch port of type router can
>>> have this flag - dhcp_relay set
>>>    for a given logical switch and document this limitation.)
>> 
>> Ack. This suggestion looks good.
>> 
>>>   ovn-nbctl set Logical_Router_port rp-sw0 options:dhcp_relay_ip=172.16.1.1
>>>   ovn-nbctl set Logical_Router_port rp-sw1 options:dhcp_relay_ip=172.16.1.1
>>> 
>>>   Let me know if there are any limitations with this.
>> 
>> The reason why I added new table is , it would be useful in future if we add
>> additional options (like setting hop count in DHCP header, etc) to DHCP relay
>> functionality. What do you recommend if we have to add more options
>> In future ?
> 
> I see.  If there is a possibility of adding more options, then having
> a separate table makes sense.
> I'd suggest to add the options column to the DHCP_Relay table even if
> this patch presently is not using
> any.  This would help in upgrades.
> 
> But I don't think there is a need to add a new column in the logical
> switch port table to enable dhcp realy.
> 
> Thanks
> Numan

Sure, I will add options column to DHCP_Relay column.
I will use options:dhcp_relay for LSP instead of new column as you suggested.

Thanks,
Naveen


> 
>> 
>> 
>> 
>>> 2.  Regarding the newly added actions - dhcp_relay_req() and
>>> dhcp_relay_resp_fwd().
>>>    Both of these actions are encoded as OVS controller action with
>>> pause enabled.
>>>    Which means ovs-vswitchd has to freeze the flow translation and
>>> resume the flow translation
>>>    once the ovn-controller resumes it.  But the functions
>>> pinctrl_handle_dhcp_relay_req()
>>>    and pinctrl_handle_dhcp_relay_resp_fwd() do not resume the packet
>>> if the packet
>>>    has some errors.  This is wrong.  Otherwise vswitchd will never thaw the
>>>    frozen translation.
>>> 
>>>    You can see the existing OVN actions - put_dhcp_opts() and few others 
>>> which
>>>    use controller action with pause.  In such actions, the result of
>>> these actions
>>>    are stored in a register bit (i.e if put_dhcp_opts() was successful or 
>>> not)
>>>    and in the next stage we take a decision based on the result.
>>> 
>>>    For the action dhcp_relay_req(relay_ip, server_ip),  I don't
>>> think you should use the pause flag.
>>>    Also in this action the argument server_ip is never used in the
>>> function pinctrl_handle_dhcp_relay_req()
>>>    other than to just log.
>>> 
>>>    I'd suggest you do something like this:
>>> 
>>>   table=3 (lr_in_ip_input     ), priority=110  , match=(inport ==
>>> "lrp1" && ip4.src == 0.0.0.0 && ip4.dst == 255.255.255.255 && udp.src
>>> == 68 && udp.dst == 67),
>>>   action=(dhcp_relay_req { ip4.src = 192.168.1.1; ip4.dst =
>>> 172.16.1.1; udp.src = 67; dhcp_header.giaddr = <relay_ip>;
>>> next(pipeline=ingress,table=S_ROUTER_IN_UNSNAT);  /* DHCP_RELAY_REQ */
>>> }
>>> 
>>>   dhcp_relay_req action would get translated into a controller
>>> action with pause=false and all the inner actions of this are encoded
>>> as
>>>   normal actions and stored in the userdata of controller action.
>>> Please see icmp4_error {} as an example.
>>>   Add a new OVN field 'dhcp_header.giaddr' which gets translated as
>>> controller action with pause flag set.
>>>   Please see the existing OVN field - icmp4.frag_mtu as an example
>>> and see this commit for reference [1]
>>>   When encoding this new OVN field, store the relay_ip in the
>>> userdata buffer and in pinctrl.c
>>>   get the relay_ip value and store it in the dhcp header field.
>>> 
>>> 
>>>   For the action dhcp_relay_resp_fwd,  I'd suggest something like below:
>>> 
>>>     table=17 (lr_in_dhcp_relay_resp_chk), priority=110  ,
>>> match=(ip4.src == 172.16.1.1 && ip4.dst == 192.168.1.1 && udp.src ==
>>> 67 && udp.dst == 67),
>>>     action=(reg0[0] = dhcp_relay_resp_chk(dhcp_header.giaddr ==
>>> <relay_ip>); next;)
>>>     table=17 (lr_in_dhcp_relay_resp), priority=110  , match=(ip4.src
>>> == 172.16.1.1 && ip4.dst == 192.168.1.1 && udp.src == 67 && udp.dst ==
>>> 67 && reg0[0] == 1),
>>>     action=(ip4.src = 192.168.1.1; udp.dst = 68; outport = "lrp1";
>>> output; /* DHCP_RELAY_RESP */)
>>> 
>>>      I used reg0[0] as an example.  You may need to check the free
>>> register bit and use it.
>>> 
>>>     You need to encode dhcp_relay_resp_chk as controller action with
>>> pause=true, and store the relay_ip in the userdata buffer.
>>>     And in pinctrl.c  check that  'dhcp_header.giaddr == relay_ip'
>>> or not.  If so, set the result register bit to 1, else to 0.
>>> 
>>>  Let me know if you've any questions.
>>> 
>> 
>> Ack. Thanks for the suggestions and detailed explanation.
>> Before implementation I had referred to icmp4_error and native dhcp_server 
>> flows
>> but I had slight misunderstanding about pause flag.
>> 
>> 
>>> 3.  The newly added functions in pinctrl.c have a lot of repetitive
>>> code and it is very much similar to existing
>>> pinctrl_handle_put_dhcp_opts()
>>>   Please see if the duplicate code can be avoided.
>> 
>> Ack.
>> 
>> 
>> 
>>> [1] - 
>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_ovn-2Dorg_ovn_commit_3d9fec3fd5992e1201b4d4fdf43f1f397e8d5ea1&d=DwIFaQ&c=s883GpUCOChKOHiocYtGcg&r=2PQjSDR7A28z1kXE1ptSm6X36oL_nCq1XxeEt7FkLmA&m=jUP6tr4FN6iSRj6v8rdyetsvEpT13QUHVMbw__3u6Sm7qAhyuu9tBdezdVmkqt0p&s=xAleLPNTzueIGuScqWZRp7ppL2D7bbjqLZc6q4xk3Rg&e=
>>> 
>>> Thanks
>>> Numan
>>> 
>>>> ---
>>>> controller/pinctrl.c  | 441 ++++++++++++++++++++++++++++++++++++++++++
>>>> include/ovn/actions.h |  26 +++
>>>> lib/actions.c         | 117 +++++++++++
>>>> lib/ovn-l7.h          |   1 +
>>>> northd/northd.c       | 177 ++++++++++++++++-
>>>> ovn-nb.ovsschema      |  25 ++-
>>>> ovn-nb.xml            |  28 +++
>>>> tests/atlocal.in      |   3 +
>>>> tests/ovn-northd.at   |  41 +++-
>>>> tests/ovn.at          |  12 +-
>>>> tests/system-ovn.at   | 150 ++++++++++++++
>>>> utilities/ovn-trace.c |  28 +++
>>>> 12 files changed, 1032 insertions(+), 17 deletions(-)
>>>> 
>>>> diff --git a/controller/pinctrl.c b/controller/pinctrl.c
>>>> index 5a35d56f6..45240f01d 100644
>>>> --- a/controller/pinctrl.c
>>>> +++ b/controller/pinctrl.c
>>>> @@ -1897,6 +1897,437 @@ is_dhcp_flags_broadcast(ovs_be16 flags)
>>>>    return flags & htons(DHCP_BROADCAST_FLAG);
>>>> }
>>>> 
>>>> +static const char *dhcp_msg_str[] = {
>>>> +[0] = "INVALID",
>>>> +[DHCP_MSG_DISCOVER] = "DISCOVER",
>>>> +[DHCP_MSG_OFFER] = "OFFER",
>>>> +[DHCP_MSG_REQUEST] = "REQUEST",
>>>> +[OVN_DHCP_MSG_DECLINE] = "DECLINE",
>>>> +[DHCP_MSG_ACK] = "ACK",
>>>> +[DHCP_MSG_NAK] = "NAK",
>>>> +[OVN_DHCP_MSG_RELEASE] = "RELEASE",
>>>> +[OVN_DHCP_MSG_INFORM] = "INFORM"
>>>> +};
>>>> +
>>>> +static bool
>>>> +dhcp_relay_is_msg_type_supported(uint8_t msg_type)
>>>> +{
>>>> +    return (msg_type >= DHCP_MSG_DISCOVER && msg_type <= 
>>>> OVN_DHCP_MSG_RELEASE);
>>>> +}
>>>> +
>>>> +static const char *dhcp_msg_str_get(uint8_t msg_type)
>>>> +{
>>>> +    if (!dhcp_relay_is_msg_type_supported(msg_type)) {
>>>> +        return "INVALID";
>>>> +    }
>>>> +    return dhcp_msg_str[msg_type];
>>>> +}
>>>> +
>>>> +/* Called with in the pinctrl_handler thread context. */
>>>> +static void
>>>> +pinctrl_handle_dhcp_relay_req(
>>>> +    struct rconn *swconn,
>>>> +    struct dp_packet *pkt_in, struct ofputil_packet_in *pin,
>>>> +    struct ofpbuf *userdata,
>>>> +    struct ofpbuf *continuation)
>>>> +{
>>>> +    enum ofp_version version = rconn_get_version(swconn);
>>>> +    enum ofputil_protocol proto = 
>>>> ofputil_protocol_from_ofp_version(version);
>>>> +    struct dp_packet *pkt_out_ptr = NULL;
>>>> +
>>>> +    /* Parse relay IP and server IP. */
>>>> +    ovs_be32 *relay_ip = ofpbuf_try_pull(userdata, sizeof *relay_ip);
>>>> +    ovs_be32 *server_ip = ofpbuf_try_pull(userdata, sizeof *server_ip);
>>>> +    if (!relay_ip || !server_ip) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: relay ip or server ip "
>>>> +                  "not present in the userdata");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    /* Validate the DHCP request packet.
>>>> +     * Format of the DHCP packet is
>>>> +     * 
>>>> ------------------------------------------------------------------------
>>>> +     *| UDP HEADER  | DHCP HEADER  | 4 Byte DHCP Cookie | DHCP 
>>>> OPTIONS(var len)|
>>>> +     * 
>>>> ------------------------------------------------------------------------
>>>> +     */
>>>> +
>>>> +    size_t in_l4_size = dp_packet_l4_size(pkt_in);
>>>> +    const char *end = (char *) dp_packet_l4(pkt_in) + in_l4_size;
>>>> +    const char *in_dhcp_ptr = dp_packet_get_udp_payload(pkt_in);
>>>> +    if (!in_dhcp_ptr) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: invalid or incomplete "
>>>> +                  "DHCP packet received");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    const struct dhcp_header *in_dhcp_data
>>>> +        = (const struct dhcp_header *) in_dhcp_ptr;
>>>> +    in_dhcp_ptr += sizeof *in_dhcp_data;
>>>> +    if (in_dhcp_ptr > end) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: invalid or incomplete "
>>>> +                "DHCP packet received, bad data length");
>>>> +        return;
>>>> +    }
>>>> +    if (in_dhcp_data->op != DHCP_OP_REQUEST) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: invalid opcode in the "
>>>> +                "DHCP packet: %d", in_dhcp_data->op);
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    /* DHCP options follow the DHCP header. The first 4 bytes of the DHCP
>>>> +     * options is the DHCP magic cookie followed by the actual DHCP 
>>>> options.
>>>> +     */
>>>> +    ovs_be32 magic_cookie = htonl(DHCP_MAGIC_COOKIE);
>>>> +    if (in_dhcp_ptr + sizeof magic_cookie > end ||
>>>> +        get_unaligned_be32((const void *) in_dhcp_ptr) != magic_cookie) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: magic cookie not present "
>>>> +                "in the packet");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (in_dhcp_data->giaddr) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: giaddr is already set");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (in_dhcp_data->htype != 0x1) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: packet is recieved with "
>>>> +                "unsupported hardware type");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    ovs_be32 *server_id_ptr = NULL;
>>>> +    const uint8_t *in_dhcp_msg_type = NULL;
>>>> +
>>>> +    in_dhcp_ptr += sizeof magic_cookie;
>>>> +    ovs_be32 request_ip = in_dhcp_data->ciaddr;
>>>> +    while (in_dhcp_ptr < end) {
>>>> +        const struct dhcp_opt_header *in_dhcp_opt =
>>>> +            (const struct dhcp_opt_header *) in_dhcp_ptr;
>>>> +        if (in_dhcp_opt->code == DHCP_OPT_END) {
>>>> +            break;
>>>> +        }
>>>> +        if (in_dhcp_opt->code == DHCP_OPT_PAD) {
>>>> +            in_dhcp_ptr += 1;
>>>> +            continue;
>>>> +        }
>>>> +        in_dhcp_ptr += sizeof *in_dhcp_opt;
>>>> +        if (in_dhcp_ptr > end) {
>>>> +            break;
>>>> +        }
>>>> +        in_dhcp_ptr += in_dhcp_opt->len;
>>>> +        if (in_dhcp_ptr > end) {
>>>> +            break;
>>>> +        }
>>>> +
>>>> +        switch (in_dhcp_opt->code) {
>>>> +        case DHCP_OPT_MSG_TYPE:
>>>> +            if (in_dhcp_opt->len == 1) {
>>>> +                in_dhcp_msg_type = DHCP_OPT_PAYLOAD(in_dhcp_opt);
>>>> +            }
>>>> +            break;
>>>> +        case DHCP_OPT_REQ_IP:
>>>> +            if (in_dhcp_opt->len == 4) {
>>>> +                request_ip = 
>>>> get_unaligned_be32(DHCP_OPT_PAYLOAD(in_dhcp_opt));
>>>> +            }
>>>> +            break;
>>>> +        /* Server Identifier */
>>>> +        case OVN_DHCP_OPT_CODE_SERVER_ID:
>>>> +            if (in_dhcp_opt->len == 4) {
>>>> +                server_id_ptr = DHCP_OPT_PAYLOAD(in_dhcp_opt);
>>>> +            }
>>>> +            break;
>>>> +        default:
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    /* Check whether the DHCP Message Type (opt 53) is present or not */
>>>> +    if (!in_dhcp_msg_type) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_REQ: missing message type");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    /* Relay the DHCP request packet */
>>>> +    uint16_t new_l4_size = in_l4_size;
>>>> +    size_t new_packet_size = pkt_in->l4_ofs + new_l4_size;
>>>> +
>>>> +    struct dp_packet pkt_out;
>>>> +    dp_packet_init(&pkt_out, new_packet_size);
>>>> +    dp_packet_clear(&pkt_out);
>>>> +    dp_packet_prealloc_tailroom(&pkt_out, new_packet_size);
>>>> +    pkt_out_ptr = &pkt_out;
>>>> +
>>>> +    /* Copy the L2 and L3 headers from the pkt_in as they would remain 
>>>> same*/
>>>> +    dp_packet_put(
>>>> +        &pkt_out, dp_packet_pull(pkt_in, pkt_in->l4_ofs), pkt_in->l4_ofs);
>>>> +
>>>> +    pkt_out.l2_5_ofs = pkt_in->l2_5_ofs;
>>>> +    pkt_out.l2_pad_size = pkt_in->l2_pad_size;
>>>> +    pkt_out.l3_ofs = pkt_in->l3_ofs;
>>>> +    pkt_out.l4_ofs = pkt_in->l4_ofs;
>>>> +
>>>> +    struct ip_header *out_ip = dp_packet_l3(&pkt_out);
>>>> +
>>>> +    struct udp_header *udp = dp_packet_put(
>>>> +        &pkt_out, dp_packet_pull(pkt_in, UDP_HEADER_LEN), UDP_HEADER_LEN);
>>>> +
>>>> +    struct dhcp_header *dhcp_data = dp_packet_put(&pkt_out,
>>>> +        dp_packet_pull(pkt_in, new_l4_size - UDP_HEADER_LEN),
>>>> +        new_l4_size - UDP_HEADER_LEN);
>>>> +    dhcp_data->giaddr = *relay_ip;
>>>> +    if (udp->udp_csum) {
>>>> +        udp->udp_csum = recalc_csum32(udp->udp_csum,
>>>> +            0, dhcp_data->giaddr);
>>>> +    }
>>>> +    pin->packet = dp_packet_data(&pkt_out);
>>>> +    pin->packet_len = dp_packet_size(&pkt_out);
>>>> +
>>>> +    /* Log the DHCP message. */
>>>> +    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(20, 40);
>>>> +    const struct eth_header *l2 = dp_packet_eth(&pkt_out);
>>>> +    VLOG_INFO_RL(&rl, "DHCP_RELAY_REQ:: MSG_TYPE:%s MAC:"ETH_ADDR_FMT
>>>> +                " XID:%u"
>>>> +                " REQ_IP:"IP_FMT
>>>> +                " GIADDR:"IP_FMT
>>>> +                " SERVER_ADDR:"IP_FMT,
>>>> +                dhcp_msg_str_get(*in_dhcp_msg_type),
>>>> +                ETH_ADDR_BYTES_ARGS(dhcp_data->chaddr), 
>>>> ntohl(dhcp_data->xid),
>>>> +                IP_ARGS(request_ip), IP_ARGS(dhcp_data->giaddr),
>>>> +                IP_ARGS(*server_ip));
>>>> +    queue_msg(swconn, ofputil_encode_resume(pin, continuation, proto));
>>>> +    if (pkt_out_ptr) {
>>>> +        dp_packet_uninit(pkt_out_ptr);
>>>> +    }
>>>> +}
>>>> +
>>>> +/* Called with in the pinctrl_handler thread context. */
>>>> +static void
>>>> +pinctrl_handle_dhcp_relay_resp_fwd(
>>>> +    struct rconn *swconn,
>>>> +    struct dp_packet *pkt_in, struct ofputil_packet_in *pin,
>>>> +    struct ofpbuf *userdata,
>>>> +    struct ofpbuf *continuation)
>>>> +{
>>>> +    enum ofp_version version = rconn_get_version(swconn);
>>>> +    enum ofputil_protocol proto = 
>>>> ofputil_protocol_from_ofp_version(version);
>>>> +    struct dp_packet *pkt_out_ptr = NULL;
>>>> +
>>>> +    /* Parse relay IP and server IP. */
>>>> +    ovs_be32 *relay_ip = ofpbuf_try_pull(userdata, sizeof *relay_ip);
>>>> +    ovs_be32 *server_ip = ofpbuf_try_pull(userdata, sizeof *server_ip);
>>>> +    if (!relay_ip || !server_ip) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP: relay ip or server ip "
>>>> +                "not present in the userdata");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    /* Validate the DHCP request packet.
>>>> +     * Format of the DHCP packet is
>>>> +     * 
>>>> ------------------------------------------------------------------------
>>>> +     *| UDP HEADER  | DHCP HEADER  | 4 Byte DHCP Cookie | DHCP 
>>>> OPTIONS(var len)|
>>>> +     * 
>>>> ------------------------------------------------------------------------
>>>> +     */
>>>> +
>>>> +    size_t in_l4_size = dp_packet_l4_size(pkt_in);
>>>> +    const char *end = (char *) dp_packet_l4(pkt_in) + in_l4_size;
>>>> +    const char *in_dhcp_ptr = dp_packet_get_udp_payload(pkt_in);
>>>> +    if (!in_dhcp_ptr) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP_FWD: invalid or incomplete "
>>>> +                "packet received");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    const struct dhcp_header *in_dhcp_data
>>>> +        = (const struct dhcp_header *) in_dhcp_ptr;
>>>> +    in_dhcp_ptr += sizeof *in_dhcp_data;
>>>> +    if (in_dhcp_ptr > end) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP_FWD: invalid or incomplete "
>>>> +                    "packet received, bad data length");
>>>> +        return;
>>>> +    }
>>>> +    if (in_dhcp_data->op != DHCP_OP_REPLY) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP_FWD: invalid opcode "
>>>> +                "in the packet: %d", in_dhcp_data->op);
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    /* DHCP options follow the DHCP header. The first 4 bytes of the DHCP
>>>> +     * options is the DHCP magic cookie followed by the actual DHCP 
>>>> options.
>>>> +     */
>>>> +    ovs_be32 magic_cookie = htonl(DHCP_MAGIC_COOKIE);
>>>> +    if (in_dhcp_ptr + sizeof magic_cookie > end ||
>>>> +        get_unaligned_be32((const void *) in_dhcp_ptr) != magic_cookie) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP_FWD: magic cookie not present "
>>>> +                "in the packet");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (!in_dhcp_data->giaddr) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP_FWD: giaddr is "
>>>> +                    "not set in request");
>>>> +        return;
>>>> +    }
>>>> +    ovs_be32 giaddr = in_dhcp_data->giaddr;
>>>> +
>>>> +    ovs_be32 *server_id_ptr = NULL;
>>>> +    ovs_be32 lease_time = 0;
>>>> +    const uint8_t *in_dhcp_msg_type = NULL;
>>>> +
>>>> +    in_dhcp_ptr += sizeof magic_cookie;
>>>> +    while (in_dhcp_ptr < end) {
>>>> +        const struct dhcp_opt_header *in_dhcp_opt =
>>>> +            (const struct dhcp_opt_header *) in_dhcp_ptr;
>>>> +        if (in_dhcp_opt->code == DHCP_OPT_END) {
>>>> +            break;
>>>> +        }
>>>> +        if (in_dhcp_opt->code == DHCP_OPT_PAD) {
>>>> +            in_dhcp_ptr += 1;
>>>> +            continue;
>>>> +        }
>>>> +        in_dhcp_ptr += sizeof *in_dhcp_opt;
>>>> +        if (in_dhcp_ptr > end) {
>>>> +            break;
>>>> +        }
>>>> +        in_dhcp_ptr += in_dhcp_opt->len;
>>>> +        if (in_dhcp_ptr > end) {
>>>> +            break;
>>>> +        }
>>>> +
>>>> +        switch (in_dhcp_opt->code) {
>>>> +        case DHCP_OPT_MSG_TYPE:
>>>> +            if (in_dhcp_opt->len == 1) {
>>>> +                in_dhcp_msg_type = DHCP_OPT_PAYLOAD(in_dhcp_opt);
>>>> +            }
>>>> +            break;
>>>> +        /* Server Identifier */
>>>> +        case OVN_DHCP_OPT_CODE_SERVER_ID:
>>>> +            if (in_dhcp_opt->len == 4) {
>>>> +                server_id_ptr = DHCP_OPT_PAYLOAD(in_dhcp_opt);
>>>> +            }
>>>> +            break;
>>>> +        case OVN_DHCP_OPT_CODE_LEASE_TIME:
>>>> +            if (in_dhcp_opt->len == 4) {
>>>> +                lease_time = 
>>>> get_unaligned_be32(DHCP_OPT_PAYLOAD(in_dhcp_opt));
>>>> +            }
>>>> +            break;
>>>> +        default:
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    /* Check whether the DHCP Message Type (opt 53) is present or not */
>>>> +    if (!in_dhcp_msg_type) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP: missing message type");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (!server_id_ptr) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP: missing server identifier");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (*server_id_ptr != *server_ip) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP: server identifier mismatch");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (giaddr != *relay_ip) {
>>>> +        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
>>>> +        VLOG_WARN_RL(&rl, "DHCP_RELAY_RESP: giaddr mismatch");
>>>> +        return;
>>>> +    }
>>>> +
>>>> +
>>>> +    /* Update destination MAC & IP so that the packet is forward to the
>>>> +     * right destination node.
>>>> +     */
>>>> +    uint16_t new_l4_size = in_l4_size;
>>>> +    size_t new_packet_size = pkt_in->l4_ofs + new_l4_size;
>>>> +
>>>> +    struct dp_packet pkt_out;
>>>> +    dp_packet_init(&pkt_out, new_packet_size);
>>>> +    dp_packet_clear(&pkt_out);
>>>> +    dp_packet_prealloc_tailroom(&pkt_out, new_packet_size);
>>>> +    pkt_out_ptr = &pkt_out;
>>>> +
>>>> +    /* Copy the L2 and L3 headers from the pkt_in as they would remain 
>>>> same*/
>>>> +    struct eth_header *eth = dp_packet_put(
>>>> +        &pkt_out, dp_packet_pull(pkt_in, pkt_in->l4_ofs), pkt_in->l4_ofs);
>>>> +
>>>> +    pkt_out.l2_5_ofs = pkt_in->l2_5_ofs;
>>>> +    pkt_out.l2_pad_size = pkt_in->l2_pad_size;
>>>> +    pkt_out.l3_ofs = pkt_in->l3_ofs;
>>>> +    pkt_out.l4_ofs = pkt_in->l4_ofs;
>>>> +
>>>> +    struct udp_header *udp = dp_packet_put(
>>>> +        &pkt_out, dp_packet_pull(pkt_in, UDP_HEADER_LEN), UDP_HEADER_LEN);
>>>> +
>>>> +    struct dhcp_header *dhcp_data = dp_packet_put(
>>>> +        &pkt_out, dp_packet_pull(pkt_in, new_l4_size - UDP_HEADER_LEN),
>>>> +        new_l4_size - UDP_HEADER_LEN);
>>>> +    memcpy(&eth->eth_dst, dhcp_data->chaddr, sizeof(eth->eth_dst));
>>>> +
>>>> +    /* Send a broadcast IP frame when BROADCAST flag is set. */
>>>> +    struct ip_header *out_ip = dp_packet_l3(&pkt_out);
>>>> +    ovs_be32 ip_dst;
>>>> +    ovs_be32 ip_dst_orig = get_16aligned_be32(&out_ip->ip_dst);
>>>> +    if (!is_dhcp_flags_broadcast(dhcp_data->flags)) {
>>>> +        ip_dst = dhcp_data->yiaddr;
>>>> +    } else {
>>>> +        ip_dst = htonl(0xffffffff);
>>>> +    }
>>>> +    put_16aligned_be32(&out_ip->ip_dst, ip_dst);
>>>> +    out_ip->ip_csum = recalc_csum32(out_ip->ip_csum,
>>>> +              ip_dst_orig, ip_dst);
>>>> +    if (udp->udp_csum) {
>>>> +        udp->udp_csum = recalc_csum32(udp->udp_csum,
>>>> +            ip_dst_orig, ip_dst);
>>>> +    }
>>>> +    /* Reset giaddr */
>>>> +    dhcp_data->giaddr = htonl(0x0);
>>>> +    if (udp->udp_csum) {
>>>> +        udp->udp_csum = recalc_csum32(udp->udp_csum,
>>>> +            giaddr, 0);
>>>> +    }
>>>> +    pin->packet = dp_packet_data(&pkt_out);
>>>> +    pin->packet_len = dp_packet_size(&pkt_out);
>>>> +
>>>> +    /* Log the DHCP message. */
>>>> +    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(20, 40);
>>>> +    const struct eth_header *l2 = dp_packet_eth(&pkt_out);
>>>> +    VLOG_INFO_RL(&rl, "DHCP_RELAY_RESP_FWD:: MSG_TYPE:%s MAC:"ETH_ADDR_FMT
>>>> +             " XID:%u"
>>>> +             " YIADDR:"IP_FMT
>>>> +             " GIADDR:"IP_FMT
>>>> +             " SERVER_ADDR:"IP_FMT,
>>>> +             dhcp_msg_str_get(*in_dhcp_msg_type),
>>>> +             ETH_ADDR_BYTES_ARGS(dhcp_data->chaddr), 
>>>> ntohl(dhcp_data->xid),
>>>> +             IP_ARGS(dhcp_data->yiaddr),
>>>> +             IP_ARGS(giaddr), IP_ARGS(*server_id_ptr));
>>>> +    queue_msg(swconn, ofputil_encode_resume(pin, continuation, proto));
>>>> +    if (pkt_out_ptr) {
>>>> +        dp_packet_uninit(pkt_out_ptr);
>>>> +    }
>>>> +}
>>>> +
>>>> /* Called with in the pinctrl_handler thread context. */
>>>> static void
>>>> pinctrl_handle_put_dhcp_opts(
>>>> @@ -3203,6 +3634,16 @@ process_packet_in(struct rconn *swconn, const 
>>>> struct ofp_header *msg)
>>>>        ovs_mutex_unlock(&pinctrl_mutex);
>>>>        break;
>>>> 
>>>> +    case ACTION_OPCODE_DHCP_RELAY_REQ:
>>>> +        pinctrl_handle_dhcp_relay_req(swconn, &packet, &pin,
>>>> +                                     &userdata, &continuation);
>>>> +        break;
>>>> +
>>>> +    case ACTION_OPCODE_DHCP_RELAY_RESP_FWD:
>>>> +        pinctrl_handle_dhcp_relay_resp_fwd(swconn, &packet, &pin,
>>>> +                                     &userdata, &continuation);
>>>> +        break;
>>>> +
>>>>    case ACTION_OPCODE_PUT_DHCP_OPTS:
>>>>        pinctrl_handle_put_dhcp_opts(swconn, &packet, &pin, &headers,
>>>>                                     &userdata, &continuation);
>>>> diff --git a/include/ovn/actions.h b/include/ovn/actions.h
>>>> index 49cfe0624..47d41b90f 100644
>>>> --- a/include/ovn/actions.h
>>>> +++ b/include/ovn/actions.h
>>>> @@ -95,6 +95,8 @@ struct collector_set_ids;
>>>>    OVNACT(LOOKUP_ND_IP,      ovnact_lookup_mac_bind_ip) \
>>>>    OVNACT(PUT_DHCPV4_OPTS,   ovnact_put_opts)        \
>>>>    OVNACT(PUT_DHCPV6_OPTS,   ovnact_put_opts)        \
>>>> +    OVNACT(DHCPV4_RELAY_REQ,  ovnact_dhcp_relay)      \
>>>> +    OVNACT(DHCPV4_RELAY_RESP_FWD, ovnact_dhcp_relay)      \
>>>>    OVNACT(SET_QUEUE,         ovnact_set_queue)       \
>>>>    OVNACT(DNS_LOOKUP,        ovnact_result)          \
>>>>    OVNACT(LOG,               ovnact_log)             \
>>>> @@ -387,6 +389,14 @@ struct ovnact_put_opts {
>>>>    size_t n_options;
>>>> };
>>>> 
>>>> +/* OVNACT_DHCP_RELAY. */
>>>> +struct ovnact_dhcp_relay {
>>>> +    struct ovnact ovnact;
>>>> +    int family;
>>>> +    ovs_be32 relay_ipv4;
>>>> +    ovs_be32 server_ipv4;
>>>> +};
>>>> +
>>>> /* Valid arguments to SET_QUEUE action.
>>>> *
>>>> * QDISC_MIN_QUEUE_ID is the default queue, so user-defined queues should
>>>> @@ -750,6 +760,22 @@ enum action_opcode {
>>>> 
>>>>    /* multicast group split buffer action. */
>>>>    ACTION_OPCODE_MG_SPLIT_BUF,
>>>> +
>>>> +    /* "dhcp_relay_req(relay_ip, server_ip)".
>>>> +     *
>>>> +     * Arguments follow the action_header, in this format:
>>>> +     *   - The 32-bit DHCP relay IP.
>>>> +     *   - The 32-bit DHCP server IP.
>>>> +     */
>>>> +    ACTION_OPCODE_DHCP_RELAY_REQ,
>>>> +
>>>> +    /* "dhcp_relay_resp_fwd(relay_ip, server_ip)".
>>>> +     *
>>>> +     * Arguments follow the action_header, in this format:
>>>> +     *   - The 32-bit DHCP relay IP.
>>>> +     *   - The 32-bit DHCP server IP.
>>>> +     */
>>>> +    ACTION_OPCODE_DHCP_RELAY_RESP_FWD,
>>>> };
>>>> 
>>>> /* Header. */
>>>> diff --git a/lib/actions.c b/lib/actions.c
>>>> index a73fe1a1e..69df428c6 100644
>>>> --- a/lib/actions.c
>>>> +++ b/lib/actions.c
>>>> @@ -2629,6 +2629,118 @@ ovnact_controller_event_free(struct 
>>>> ovnact_controller_event *event)
>>>>    free_gen_options(event->options, event->n_options);
>>>> }
>>>> 
>>>> +static void
>>>> +format_DHCPV4_RELAY_REQ(const struct ovnact_dhcp_relay *dhcp_relay,
>>>> +                struct ds *s)
>>>> +{
>>>> +    ds_put_format(s, "dhcp_relay_req("IP_FMT","IP_FMT");",
>>>> +                  IP_ARGS(dhcp_relay->relay_ipv4),
>>>> +                  IP_ARGS(dhcp_relay->server_ipv4));
>>>> +}
>>>> +
>>>> +static void
>>>> +parse_dhcp_relay_req(struct action_context *ctx,
>>>> +               struct ovnact_dhcp_relay *dhcp_relay)
>>>> +{
>>>> +    /* Skip dhcp_relay_req( */
>>>> +    lexer_force_match(ctx->lexer, LEX_T_LPAREN);
>>>> +
>>>> +    /* Parse relay ip and server ip. */
>>>> +    if (ctx->lexer->token.format == LEX_F_IPV4) {
>>>> +        dhcp_relay->family = AF_INET;
>>>> +        dhcp_relay->relay_ipv4 = ctx->lexer->token.value.ipv4;
>>>> +        lexer_get(ctx->lexer);
>>>> +        lexer_match(ctx->lexer, LEX_T_COMMA);
>>>> +        if (ctx->lexer->token.format == LEX_F_IPV4) {
>>>> +            dhcp_relay->family = AF_INET;
>>>> +            dhcp_relay->server_ipv4 = ctx->lexer->token.value.ipv4;
>>>> +            lexer_get(ctx->lexer);
>>>> +        } else {
>>>> +            lexer_syntax_error(ctx->lexer, "expecting IPv4 dhcp server 
>>>> ip");
>>>> +            return;
>>>> +        }
>>>> +    } else {
>>>> +          lexer_syntax_error(ctx->lexer, "expecting IPv4 dhcp relay "
>>>> +                          "and server ips");
>>>> +          return;
>>>> +    }
>>>> +    lexer_force_match(ctx->lexer, LEX_T_RPAREN);
>>>> +}
>>>> +
>>>> +static void
>>>> +encode_DHCPV4_RELAY_REQ(const struct ovnact_dhcp_relay *dhcp_relay,
>>>> +                    const struct ovnact_encode_params *ep,
>>>> +                    struct ofpbuf *ofpacts)
>>>> +{
>>>> +    size_t oc_offset = 
>>>> encode_start_controller_op(ACTION_OPCODE_DHCP_RELAY_REQ,
>>>> +                                                  true, ep->ctrl_meter_id,
>>>> +                                                  ofpacts);
>>>> +    ofpbuf_put(ofpacts, &dhcp_relay->relay_ipv4,
>>>> +            sizeof(dhcp_relay->relay_ipv4));
>>>> +    ofpbuf_put(ofpacts, &dhcp_relay->server_ipv4,
>>>> +            sizeof(dhcp_relay->server_ipv4));
>>>> +    encode_finish_controller_op(oc_offset, ofpacts);
>>>> +}
>>>> +
>>>> +static void
>>>> +format_DHCPV4_RELAY_RESP_FWD(const struct ovnact_dhcp_relay *dhcp_relay,
>>>> +                    struct ds *s)
>>>> +{
>>>> +    ds_put_format(s, "dhcp_relay_resp("IP_FMT","IP_FMT");",
>>>> +                  IP_ARGS(dhcp_relay->relay_ipv4),
>>>> +                  IP_ARGS(dhcp_relay->server_ipv4));
>>>> +}
>>>> +
>>>> +static void
>>>> +parse_dhcp_relay_resp_fwd(struct action_context *ctx,
>>>> +               struct ovnact_dhcp_relay *dhcp_relay)
>>>> +{
>>>> +    /* Skip dhcp_relay_resp( */
>>>> +    lexer_force_match(ctx->lexer, LEX_T_LPAREN);
>>>> +
>>>> +    /* Parse relay ip and server ip. */
>>>> +    if (ctx->lexer->token.format == LEX_F_IPV4) {
>>>> +        dhcp_relay->family = AF_INET;
>>>> +        dhcp_relay->relay_ipv4 = ctx->lexer->token.value.ipv4;
>>>> +        lexer_get(ctx->lexer);
>>>> +        lexer_match(ctx->lexer, LEX_T_COMMA);
>>>> +        if (ctx->lexer->token.format == LEX_F_IPV4) {
>>>> +            dhcp_relay->family = AF_INET;
>>>> +            dhcp_relay->server_ipv4 = ctx->lexer->token.value.ipv4;
>>>> +            lexer_get(ctx->lexer);
>>>> +        } else {
>>>> +            lexer_syntax_error(ctx->lexer, "expecting IPv4 dhcp server 
>>>> ip");
>>>> +            return;
>>>> +        }
>>>> +    } else {
>>>> +          lexer_syntax_error(ctx->lexer, "expecting IPv4 dhcp relay and "
>>>> +                          "server ips");
>>>> +          return;
>>>> +    }
>>>> +    lexer_force_match(ctx->lexer, LEX_T_RPAREN);
>>>> +}
>>>> +
>>>> +static void
>>>> +encode_DHCPV4_RELAY_RESP_FWD(const struct ovnact_dhcp_relay *dhcp_relay,
>>>> +                    const struct ovnact_encode_params *ep,
>>>> +                    struct ofpbuf *ofpacts)
>>>> +{
>>>> +    size_t oc_offset = encode_start_controller_op(
>>>> +                                ACTION_OPCODE_DHCP_RELAY_RESP_FWD,
>>>> +                                true, ep->ctrl_meter_id,
>>>> +                                ofpacts);
>>>> +    ofpbuf_put(ofpacts, &dhcp_relay->relay_ipv4,
>>>> +                  sizeof(dhcp_relay->relay_ipv4));
>>>> +    ofpbuf_put(ofpacts, &dhcp_relay->server_ipv4,
>>>> +                  sizeof(dhcp_relay->server_ipv4));
>>>> +    encode_finish_controller_op(oc_offset, ofpacts);
>>>> +}
>>>> +
>>>> +static void ovnact_dhcp_relay_free(
>>>> +          struct ovnact_dhcp_relay *dhcp_relay OVS_UNUSED)
>>>> +{
>>>> +}
>>>> +
>>>> static void
>>>> parse_put_opts(struct action_context *ctx, const struct expr_field *dst,
>>>>               struct ovnact_put_opts *po, const struct hmap *gen_opts,
>>>> @@ -5451,6 +5563,11 @@ parse_action(struct action_context *ctx)
>>>>        parse_sample(ctx);
>>>>    } else if (lexer_match_id(ctx->lexer, "mac_cache_use")) {
>>>>        ovnact_put_MAC_CACHE_USE(ctx->ovnacts);
>>>> +    } else if (lexer_match_id(ctx->lexer, "dhcp_relay_req")) {
>>>> +        parse_dhcp_relay_req(ctx, 
>>>> ovnact_put_DHCPV4_RELAY_REQ(ctx->ovnacts));
>>>> +    } else if (lexer_match_id(ctx->lexer, "dhcp_relay_resp_fwd")) {
>>>> +        parse_dhcp_relay_resp_fwd(ctx,
>>>> +              ovnact_put_DHCPV4_RELAY_RESP_FWD(ctx->ovnacts));
>>>>    } else {
>>>>        lexer_syntax_error(ctx->lexer, "expecting action");
>>>>    }
>>>> diff --git a/lib/ovn-l7.h b/lib/ovn-l7.h
>>>> index ad514a922..e08581123 100644
>>>> --- a/lib/ovn-l7.h
>>>> +++ b/lib/ovn-l7.h
>>>> @@ -69,6 +69,7 @@ struct gen_opts_map {
>>>> */
>>>> #define OVN_DHCP_OPT_CODE_NETMASK      1
>>>> #define OVN_DHCP_OPT_CODE_LEASE_TIME   51
>>>> +#define OVN_DHCP_OPT_CODE_SERVER_ID    54
>>>> #define OVN_DHCP_OPT_CODE_T1           58
>>>> #define OVN_DHCP_OPT_CODE_T2           59
>>>> 
>>>> diff --git a/northd/northd.c b/northd/northd.c
>>>> index 07dffb15a..7ac831fae 100644
>>>> --- a/northd/northd.c
>>>> +++ b/northd/northd.c
>>>> @@ -181,11 +181,13 @@ enum ovn_stage {
>>>>    PIPELINE_STAGE(ROUTER, IN,  IP_ROUTING_ECMP, 14, 
>>>> "lr_in_ip_routing_ecmp") \
>>>>    PIPELINE_STAGE(ROUTER, IN,  POLICY,          15, "lr_in_policy")        
>>>>   \
>>>>    PIPELINE_STAGE(ROUTER, IN,  POLICY_ECMP,     16, "lr_in_policy_ecmp")   
>>>>   \
>>>> -    PIPELINE_STAGE(ROUTER, IN,  ARP_RESOLVE,     17, "lr_in_arp_resolve") 
>>>>     \
>>>> -    PIPELINE_STAGE(ROUTER, IN,  CHK_PKT_LEN,     18, "lr_in_chk_pkt_len") 
>>>>     \
>>>> -    PIPELINE_STAGE(ROUTER, IN,  LARGER_PKTS,     19, "lr_in_larger_pkts") 
>>>>     \
>>>> -    PIPELINE_STAGE(ROUTER, IN,  GW_REDIRECT,     20, "lr_in_gw_redirect") 
>>>>     \
>>>> -    PIPELINE_STAGE(ROUTER, IN,  ARP_REQUEST,     21, "lr_in_arp_request") 
>>>>     \
>>>> +    PIPELINE_STAGE(ROUTER, IN,  DHCP_RELAY_RESP_FWD, 17,                  
>>>>     \
>>>> +                  "lr_in_dhcp_relay_resp_fwd")                            
>>>>     \
>>>> +    PIPELINE_STAGE(ROUTER, IN,  ARP_RESOLVE,     18, "lr_in_arp_resolve") 
>>>>     \
>>>> +    PIPELINE_STAGE(ROUTER, IN,  CHK_PKT_LEN,     19, "lr_in_chk_pkt_len") 
>>>>     \
>>>> +    PIPELINE_STAGE(ROUTER, IN,  LARGER_PKTS,     20, "lr_in_larger_pkts") 
>>>>     \
>>>> +    PIPELINE_STAGE(ROUTER, IN,  GW_REDIRECT,     21, "lr_in_gw_redirect") 
>>>>     \
>>>> +    PIPELINE_STAGE(ROUTER, IN,  ARP_REQUEST,     22, "lr_in_arp_request") 
>>>>     \
>>>>                                                                      \
>>>>    /* Logical router egress stages. */                               \
>>>>    PIPELINE_STAGE(ROUTER, OUT, CHECK_DNAT_LOCAL,   0,                      
>>>>  \
>>>> @@ -9610,6 +9612,80 @@ build_dhcpv6_options_flows(struct ovn_port *op,
>>>>    ds_destroy(&match);
>>>> }
>>>> 
>>>> +static void
>>>> +build_lswitch_dhcp_relay_flows(struct ovn_port *op,
>>>> +                           const struct hmap *lr_ports,
>>>> +                           const struct hmap *lflows,
>>>> +                           const struct shash *meter_groups OVS_UNUSED)
>>>> +{
>>>> +    if (op->nbrp || !op->nbsp) {
>>>> +        return;
>>>> +    }
>>>> +    /* consider only ports attached to VMs */
>>>> +    if (strcmp(op->nbsp->type, "")) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (!op->od || !op->od->n_router_ports ||
>>>> +        !op->od->nbs || !op->od->nbs->dhcp_relay_port) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    struct ds match = DS_EMPTY_INITIALIZER;
>>>> +    struct ds action = DS_EMPTY_INITIALIZER;
>>>> +    struct nbrec_logical_router_port *lrp = op->od->nbs->dhcp_relay_port;
>>>> +    struct ovn_port *rp = ovn_port_find(lr_ports, lrp->name);
>>>> +
>>>> +    if (!rp || !rp->nbrp || !rp->nbrp->dhcp_relay) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    struct ovn_port *sp = NULL;
>>>> +    struct nbrec_dhcp_relay *dhcp_relay = rp->nbrp->dhcp_relay;
>>>> +
>>>> +    for (int i = 0; i < op->od->n_router_ports; i++) {
>>>> +        struct ovn_port *sp_tmp = op->od->router_ports[i];
>>>> +        if (sp_tmp->peer == rp) {
>>>> +            sp = sp_tmp;
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +    if (!sp) {
>>>> +      return;
>>>> +    }
>>>> +
>>>> +    char *server_ip_str = NULL;
>>>> +    uint16_t port;
>>>> +    int addr_family;
>>>> +    struct in6_addr server_ip;
>>>> +
>>>> +    if (!ip_address_and_port_from_lb_key(dhcp_relay->servers, 
>>>> &server_ip_str,
>>>> +                                         &server_ip, &port, 
>>>> &addr_family)) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (server_ip_str == NULL) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    ds_put_format(
>>>> +        &match, "inport == %s && eth.src == %s && "
>>>> +        "ip4.src == 0.0.0.0 && ip4.dst == 255.255.255.255 && "
>>>> +        "udp.src == 68 && udp.dst == 67",
>>>> +        op->json_key, op->lsp_addrs[0].ea_s);
>>>> +    ds_put_format(&action,
>>>> +                  "eth.dst=%s;outport=%s;next;/* DHCP_RELAY_REQ */",
>>>> +                  rp->lrp_networks.ea_s,sp->json_key);
>>>> +    ovn_lflow_add_with_hint__(lflows, op->od,
>>>> +                              S_SWITCH_IN_L2_LKUP, 100,
>>>> +                              ds_cstr(&match),
>>>> +                              ds_cstr(&action),
>>>> +                              op->key,
>>>> +                              NULL,
>>>> +                              &lrp->header_);
>>>> +    free(server_ip_str);
>>>> +}
>>>> +
>>>> static void
>>>> build_drop_arp_nd_flows_for_unbound_router_ports(struct ovn_port *op,
>>>>                                                 const struct ovn_port 
>>>> *port,
>>>> @@ -10181,6 +10257,13 @@ build_lswitch_dhcp_options_and_response(struct 
>>>> ovn_port *op,
>>>>        return;
>>>>    }
>>>> 
>>>> +    if (op->od && op->od->nbs
>>>> +        && op->od->nbs->dhcp_relay_port) {
>>>> +        /* Don't add the DHCP server flows if DHCP Relay is enabled on the
>>>> +         * logical switch. */
>>>> +        return;
>>>> +    }
>>>> +
>>>>    bool is_external = lsp_is_external(op->nbsp);
>>>>    if (is_external && (!op->od->n_localnet_ports ||
>>>>                        !op->nbsp->ha_chassis_group)) {
>>>> @@ -14458,6 +14541,86 @@ build_dhcpv6_reply_flows_for_lrouter_port(
>>>>    }
>>>> }
>>>> 
>>>> +static void
>>>> +build_dhcp_relay_flows_for_lrouter_port(
>>>> +        struct ovn_port *op, struct hmap *lflows,
>>>> +        struct ds *match)
>>>> +{
>>>> +    if (!op->nbrp || !op->nbrp->dhcp_relay) {
>>>> +        return;
>>>> +    }
>>>> +    struct nbrec_dhcp_relay *dhcp_relay = op->nbrp->dhcp_relay;
>>>> +    if (!dhcp_relay->servers) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    int addr_family;
>>>> +    /* currently not supporting custom port */
>>>> +    uint16_t port;
>>>> +    char *server_ip_str = NULL;
>>>> +    struct in6_addr server_ip;
>>>> +
>>>> +    if (!ip_address_and_port_from_lb_key(dhcp_relay->servers, 
>>>> &server_ip_str,
>>>> +                                         &server_ip, &port, 
>>>> &addr_family)) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (server_ip_str == NULL) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    struct ds dhcp_action = DS_EMPTY_INITIALIZER;
>>>> +    ds_clear(match);
>>>> +    ds_put_format(
>>>> +        match, "inport == %s && "
>>>> +        "ip4.src == 0.0.0.0 && ip4.dst == 255.255.255.255 && "
>>>> +        "udp.src == 68 && udp.dst == 67",
>>>> +        op->json_key);
>>>> +    ds_put_format(&dhcp_action,
>>>> +                "dhcp_relay_req(%s,%s);"
>>>> +                "ip4.src=%s;ip4.dst=%s;udp.src=67;next; /* DHCP_RELAY_REQ 
>>>> */",
>>>> +                op->lrp_networks.ipv4_addrs[0].addr_s, server_ip_str,
>>>> +                op->lrp_networks.ipv4_addrs[0].addr_s, server_ip_str);
>>>> +
>>>> +    ovn_lflow_add_with_hint(lflows, op->od, S_ROUTER_IN_IP_INPUT, 110,
>>>> +                            ds_cstr(match), ds_cstr(&dhcp_action),
>>>> +                            &op->nbrp->header_);
>>>> +
>>>> +    ds_clear(match);
>>>> +    ds_clear(&dhcp_action);
>>>> +
>>>> +    ds_put_format(
>>>> +        match, "ip4.src == %s && ip4.dst == %s && "
>>>> +        "udp.src == 67 && udp.dst == 67",
>>>> +        server_ip_str, op->lrp_networks.ipv4_addrs[0].addr_s);
>>>> +    ds_put_format(&dhcp_action, "next;/* DHCP_RELAY_RESP */");
>>>> +    ovn_lflow_add_with_hint(lflows, op->od, S_ROUTER_IN_IP_INPUT, 110,
>>>> +                            ds_cstr(match), ds_cstr(&dhcp_action),
>>>> +                            &op->nbrp->header_);
>>>> +
>>>> +    ds_clear(match);
>>>> +    ds_clear(&dhcp_action);
>>>> +
>>>> +    ds_put_format(
>>>> +        match, "ip4.src == %s && ip4.dst == %s && "
>>>> +        "udp.src == 67 && udp.dst == 67",
>>>> +        server_ip_str, op->lrp_networks.ipv4_addrs[0].addr_s);
>>>> +    ds_put_format(&dhcp_action,
>>>> +          "dhcp_relay_resp_fwd(%s,%s);ip4.src=%s;udp.dst=68;"
>>>> +          "outport=%s;output; /* DHCP_RELAY_RESP */",
>>>> +          op->lrp_networks.ipv4_addrs[0].addr_s, server_ip_str,
>>>> +          op->lrp_networks.ipv4_addrs[0].addr_s, op->json_key);
>>>> +    ovn_lflow_add_with_hint(lflows, op->od, 
>>>> S_ROUTER_IN_DHCP_RELAY_RESP_FWD,
>>>> +                            110,
>>>> +                            ds_cstr(match), ds_cstr(&dhcp_action),
>>>> +                            &op->nbrp->header_);
>>>> +
>>>> +    ds_clear(match);
>>>> +    ds_clear(&dhcp_action);
>>>> +
>>>> +    free(server_ip_str);
>>>> +}
>>>> +
>>>> static void
>>>> build_ipv6_input_flows_for_lrouter_port(
>>>>        struct ovn_port *op, struct hmap *lflows,
>>>> @@ -15673,6 +15836,8 @@ build_lrouter_nat_defrag_and_lb(struct 
>>>> ovn_datapath *od, struct hmap *lflows,
>>>>    ovn_lflow_add(lflows, od, S_ROUTER_OUT_POST_SNAT, 0, "1", "next;");
>>>>    ovn_lflow_add(lflows, od, S_ROUTER_OUT_EGR_LOOP, 0, "1", "next;");
>>>>    ovn_lflow_add(lflows, od, S_ROUTER_IN_ECMP_STATEFUL, 0, "1", "next;");
>>>> +    ovn_lflow_add(lflows, od, S_ROUTER_IN_DHCP_RELAY_RESP_FWD, 0, "1",
>>>> +                  "next;");
>>>> 
>>>>    const char *ct_flag_reg = features->ct_no_masked_label
>>>>                              ? "ct_mark"
>>>> @@ -16154,6 +16319,7 @@ build_lswitch_and_lrouter_iterate_by_lsp(struct 
>>>> ovn_port *op,
>>>>    build_lswitch_dhcp_options_and_response(op, lflows, meter_groups);
>>>>    build_lswitch_external_port(op, lflows);
>>>>    build_lswitch_ip_unicast_lookup(op, lflows, actions, match);
>>>> +    build_lswitch_dhcp_relay_flows(op, lr_ports, lflows, meter_groups);
>>>> 
>>>>    /* Build Logical Router Flows. */
>>>>    build_ip_routing_flows_for_router_type_lsp(op, lr_ports, lflows);
>>>> @@ -16183,6 +16349,7 @@ build_lswitch_and_lrouter_iterate_by_lrp(struct 
>>>> ovn_port *op,
>>>>    build_egress_delivery_flows_for_lrouter_port(op, lsi->lflows, 
>>>> &lsi->match,
>>>>                                                 &lsi->actions);
>>>>    build_dhcpv6_reply_flows_for_lrouter_port(op, lsi->lflows, &lsi->match);
>>>> +    build_dhcp_relay_flows_for_lrouter_port(op, lsi->lflows, &lsi->match);
>>>>    build_ipv6_input_flows_for_lrouter_port(op, lsi->lflows,
>>>>                                            &lsi->match, &lsi->actions,
>>>>                                            lsi->meter_groups);
>>>> diff --git a/ovn-nb.ovsschema b/ovn-nb.ovsschema
>>>> index b2e0993e0..6863d52cd 100644
>>>> --- a/ovn-nb.ovsschema
>>>> +++ b/ovn-nb.ovsschema
>>>> @@ -1,7 +1,7 @@
>>>> {
>>>>    "name": "OVN_Northbound",
>>>> -    "version": "7.2.0",
>>>> -    "cksum": "1069338687 34162",
>>>> +    "version": "7.3.0",
>>>> +    "cksum": "2325497400 35185",
>>>>    "tables": {
>>>>        "NB_Global": {
>>>>            "columns": {
>>>> @@ -89,7 +89,12 @@
>>>>                    "type": {"key": {"type": "uuid",
>>>>                                     "refTable": "Forwarding_Group",
>>>>                                     "refType": "strong"},
>>>> -                                     "min": 0, "max": "unlimited"}}},
>>>> +                                     "min": 0, "max": "unlimited"}},
>>>> +                "dhcp_relay_port": {"type": {"key": {"type": "uuid",
>>>> +                                            "refTable": 
>>>> "Logical_Router_Port",
>>>> +                                            "refType": "weak"},
>>>> +                                            "min": 0,
>>>> +                                            "max": 1}}},
>>>>            "isRoot": true},
>>>>        "Logical_Switch_Port": {
>>>>            "columns": {
>>>> @@ -436,6 +441,11 @@
>>>>                "ipv6_prefix": {"type": {"key": "string",
>>>>                                      "min": 0,
>>>>                                      "max": "unlimited"}},
>>>> +                "dhcp_relay": {"type": {"key": {"type": "uuid",
>>>> +                                            "refTable": "DHCP_Relay",
>>>> +                                            "refType": "weak"},
>>>> +                                            "min": 0,
>>>> +                                            "max": 1}},
>>>>                "external_ids": {
>>>>                    "type": {"key": "string", "value": "string",
>>>>                             "min": 0, "max": "unlimited"}},
>>>> @@ -529,6 +539,15 @@
>>>>                    "type": {"key": "string", "value": "string",
>>>>                             "min": 0, "max": "unlimited"}}},
>>>>            "isRoot": true},
>>>> +        "DHCP_Relay": {
>>>> +            "columns": {
>>>> +                "servers": {"type": {"key": "string",
>>>> +                                       "min": 0,
>>>> +                                       "max": 1}},
>>>> +                "external_ids": {
>>>> +                    "type": {"key": "string", "value": "string",
>>>> +                             "min": 0, "max": "unlimited"}}},
>>>> +            "isRoot": true},
>>>>        "Connection": {
>>>>            "columns": {
>>>>                "target": {"type": "string"},
>>>> diff --git a/ovn-nb.xml b/ovn-nb.xml
>>>> index fcb1c6ecc..dc20892e1 100644
>>>> --- a/ovn-nb.xml
>>>> +++ b/ovn-nb.xml
>>>> @@ -608,6 +608,11 @@
>>>>      Please see the <ref table="DNS"/> table.
>>>>    </column>
>>>> 
>>>> +    <column name="dhcp_relay_port">
>>>> +      This column defines the <ref table="Logical_Router_Port"/> on which
>>>> +      DHCP relay is enabled.
>>>> +    </column>
>>>> +
>>>>    <column name="forwarding_groups">
>>>>      Groups a set of logical port endpoints for traffic going out of the
>>>>      logical switch.
>>>> @@ -2980,6 +2985,11 @@ or
>>>>      port has all ingress and egress traffic dropped.
>>>>    </column>
>>>> 
>>>> +    <column name="dhcp_relay">
>>>> +      This column is used to enabled DHCP Relay. Please refer
>>>> +      to <ref table="DHCP_Relay"/> table.
>>>> +    </column>
>>>> +
>>>>    <group title="Distributed Gateway Ports">
>>>>      <p>
>>>>        Gateways, as documented under <code>Gateways</code> in the OVN
>>>> @@ -4286,6 +4296,24 @@ or
>>>>    </group>
>>>>  </table>
>>>> 
>>>> +  <table name="DHCP_Relay" title="DHCP Relay">
>>>> +    <p>
>>>> +      OVN implements native DHCPv4 relay support which caters to the 
>>>> common
>>>> +      use case of relaying the DHCP requests to external DHCP server.
>>>> +    </p>
>>>> +
>>>> +    <column name="servers">
>>>> +      <p>
>>>> +        The DHCPv4 server IP address.
>>>> +      </p>
>>>> +    </column>
>>>> +    <group title="Common Columns">
>>>> +      <column name="external_ids">
>>>> +        See <em>External IDs</em> at the beginning of this document.
>>>> +      </column>
>>>> +    </group>
>>>> +  </table>
>>>> +
>>>>  <table name="Connection" title="OVSDB client connections.">
>>>>    <p>
>>>>      Configuration for a database connection to an Open vSwitch database
>>>> diff --git a/tests/atlocal.in b/tests/atlocal.in
>>>> index 63d891b89..32d1c374e 100644
>>>> --- a/tests/atlocal.in
>>>> +++ b/tests/atlocal.in
>>>> @@ -187,6 +187,9 @@ fi
>>>> # Set HAVE_DHCPD
>>>> find_command dhcpd
>>>> 
>>>> +# Set HAVE_DHCLIENT
>>>> +find_command dhclient
>>>> +
>>>> # Set HAVE_BFDD_BEACON
>>>> find_command bfdd-beacon
>>>> 
>>>> diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
>>>> index 19e4f1263..4d8c9ff26 100644
>>>> --- a/tests/ovn-northd.at
>>>> +++ b/tests/ovn-northd.at
>>>> @@ -8786,9 +8786,9 @@ ovn-nbctl --wait=sb set logical_router_port R1-PUB 
>>>> options:redirect-type=bridged
>>>> ovn-sbctl dump-flows R1 > R1flows
>>>> AT_CAPTURE_FILE([R1flows])
>>>> 
>>>> -AT_CHECK([grep "lr_in_arp_resolve" R1flows | grep priority=90 | sort], 
>>>> [0], [dnl
>>>> -  table=17(lr_in_arp_resolve  ), priority=90   , match=(outport == 
>>>> "R1-PUB" && ip4.src == 10.0.0.3 && is_chassis_resident("S0-P0")), 
>>>> action=(get_arp(outport, reg0); next;)
>>>> -  table=17(lr_in_arp_resolve  ), priority=90   , match=(outport == 
>>>> "R1-PUB" && ip6.src == 1000::3 && is_chassis_resident("S0-P0")), 
>>>> action=(get_nd(outport, xxreg0); next;)
>>>> +AT_CHECK([grep "lr_in_arp_resolve" R1flows | grep priority=90 | sed 
>>>> 's/table=../table=??/' | sort], [0], [dnl
>>>> +  table=??(lr_in_arp_resolve  ), priority=90   , match=(outport == 
>>>> "R1-PUB" && ip4.src == 10.0.0.3 && is_chassis_resident("S0-P0")), 
>>>> action=(get_arp(outport, reg0); next;)
>>>> +  table=??(lr_in_arp_resolve  ), priority=90   , match=(outport == 
>>>> "R1-PUB" && ip6.src == 1000::3 && is_chassis_resident("S0-P0")), 
>>>> action=(get_nd(outport, xxreg0); next;)
>>>> ])
>>>> 
>>>> AT_CLEANUP
>>>> @@ -10966,3 +10966,38 @@ Status: active
>>>> 
>>>> AT_CLEANUP
>>>> ])
>>>> +
>>>> +OVN_FOR_EACH_NORTHD_NO_HV([
>>>> +AT_SETUP([check DHCP RELAY AGENT])
>>>> +ovn_start NORTHD_TYPE
>>>> +
>>>> +check ovn-nbctl ls-add ls0
>>>> +check ovn-nbctl lsp-add ls0 ls0-port1
>>>> +check ovn-nbctl lsp-set-addresses ls0-port1 02:00:00:00:00:10
>>>> +check ovn-nbctl lr-add lr0
>>>> +check ovn-nbctl lrp-add lr0 lrp1 02:00:00:00:00:01 192.168.1.1/24
>>>> +check ovn-nbctl lsp-add ls0 lrp1-attachment
>>>> +check ovn-nbctl lsp-set-type lrp1-attachment router
>>>> +check ovn-nbctl lsp-set-addresses lrp1-attachment 00:00:00:00:ff:02
>>>> +check ovn-nbctl lsp-set-options lrp1-attachment router-port=lrp1
>>>> +check ovn-nbctl lrp-add lr0 lrp-ext 02:00:00:00:00:02 192.168.2.1/24
>>>> +
>>>> +dhcp_relay=$(ovn-nbctl create DHCP_Relay servers=172.16.1.1)
>>>> +check ovn-nbctl set Logical_Router_port lrp1 dhcp_relay=$dhcp_relay
>>>> +rp_uuid=$(ovn-nbctl --bare --colum=_uuid list logical_router_port lrp1)
>>>> +check ovn-nbctl set Logical_Switch ls0 dhcp_relay_port=$rp_uuid
>>>> +
>>>> +check ovn-nbctl --wait=sb sync
>>>> +
>>>> +ovn-sbctl lflow-list > lflows
>>>> +AT_CAPTURE_FILE([lflows])
>>>> +
>>>> +AT_CHECK([grep -e "DHCP_RELAY_" lflows | sed 's/table=../table=??/'], 
>>>> [0], [dnl
>>>> +  table=??(lr_in_ip_input     ), priority=110  , match=(inport == "lrp1" 
>>>> && ip4.src == 0.0.0.0 && ip4.dst == 255.255.255.255 && udp.src == 68 && 
>>>> udp.dst == 67), 
>>>> action=(dhcp_relay_req(192.168.1.1,172.16.1.1);ip4.src=192.168.1.1;ip4.dst=172.16.1.1;udp.src=67;next;
>>>>  /* DHCP_RELAY_REQ */)
>>>> +  table=??(lr_in_ip_input     ), priority=110  , match=(ip4.src == 
>>>> 172.16.1.1 && ip4.dst == 192.168.1.1 && udp.src == 67 && udp.dst == 67), 
>>>> action=(next;/* DHCP_RELAY_RESP */)
>>>> +  table=??(lr_in_dhcp_relay_resp_fwd), priority=110  , match=(ip4.src == 
>>>> 172.16.1.1 && ip4.dst == 192.168.1.1 && udp.src == 67 && udp.dst == 67), 
>>>> action=(dhcp_relay_resp_fwd(192.168.1.1,172.16.1.1);ip4.src=192.168.1.1;udp.dst=68;outport="lrp1";output;
>>>>  /* DHCP_RELAY_RESP */)
>>>> +  table=??(ls_in_l2_lkup      ), priority=100  , match=(inport == 
>>>> "ls0-port1" && eth.src == 02:00:00:00:00:10 && ip4.src == 0.0.0.0 && 
>>>> ip4.dst == 255.255.255.255 && udp.src == 68 && udp.dst == 67), 
>>>> action=(eth.dst=02:00:00:00:00:01;outport="lrp1-attachment";next;/* 
>>>> DHCP_RELAY_REQ */)
>>>> +])
>>>> +
>>>> +AT_CLEANUP
>>>> +])
>>>> diff --git a/tests/ovn.at b/tests/ovn.at
>>>> index e8c79512b..839c07ce2 100644
>>>> --- a/tests/ovn.at
>>>> +++ b/tests/ovn.at
>>>> @@ -21905,7 +21905,7 @@ eth_dst=00000000ff01
>>>> ip_src=$(ip_to_hex 10 0 0 10)
>>>> ip_dst=$(ip_to_hex 172 168 0 101)
>>>> send_icmp_packet 1 1 $eth_src $eth_dst $ip_src $ip_dst c4c9 
>>>> 0000000000000000000000
>>>> -AT_CHECK_UNQUOTED([as hv1 ovs-ofctl dump-flows br-int 
>>>> metadata=0x$lr0_dp_key | awk '/table=28, n_packets=1, n_bytes=45/{print 
>>>> $7" "$8}'],[0],[dnl
>>>> +AT_CHECK_UNQUOTED([as hv1 ovs-ofctl dump-flows br-int 
>>>> metadata=0x$lr0_dp_key | awk '/table=29, n_packets=1, n_bytes=45/{print 
>>>> $7" "$8}'],[0],[dnl
>>>> priority=80,ip,reg15=0x$lr0_public_dp_key,metadata=0x$lr0_dp_key,nw_src=10.0.0.10
>>>>  actions=drop
>>>> ])
>>>> 
>>>> @@ -28964,7 +28964,7 @@ AT_CHECK([
>>>>        grep "priority=100" | \
>>>>        grep -c 
>>>> "ct(commit,zone=NXM_NX_REG11\\[[0..15\\]],.*exec(move:NXM_OF_ETH_SRC\\[[\\]]->NXM_NX_CT_LABEL\\[[32..79\\]],load:0x[[0-9]]->NXM_NX_CT_MARK\\[[16..31\\]]))"
>>>> 
>>>> -        grep table=25 hv${hv}flows | \
>>>> +        grep table=26 hv${hv}flows | \
>>>>        grep "priority=200" | \
>>>>        grep -c 
>>>> "move:NXM_NX_CT_LABEL\\[[\\]]->NXM_NX_XXREG1\\[[\\]],move:NXM_NX_XXREG1\\[[32..79\\]]->NXM_OF_ETH_DST"
>>>>    done; :], [0], [dnl
>>>> @@ -29089,7 +29089,7 @@ AT_CHECK([
>>>>        grep "priority=100" | \
>>>>        grep -c 
>>>> "ct(commit,zone=NXM_NX_REG11\\[[0..15\\]],.*exec(move:NXM_OF_ETH_SRC\\[[\\]]->NXM_NX_CT_LABEL\\[[32..79\\]],load:0x[[0-9]]->NXM_NX_CT_MARK\\[[16..31\\]]))"
>>>> 
>>>> -        grep table=25 hv${hv}flows | \
>>>> +        grep table=26 hv${hv}flows | \
>>>>        grep "priority=200" | \
>>>>        grep -c 
>>>> "move:NXM_NX_CT_LABEL\\[[\\]]->NXM_NX_XXREG1\\[[\\]],move:NXM_NX_XXREG1\\[[32..79\\]]->NXM_OF_ETH_DST"
>>>>    done; :], [0], [dnl
>>>> @@ -29586,7 +29586,7 @@ if test X"$1" = X"DGP"; then
>>>> else
>>>>    prio=2
>>>> fi
>>>> -AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | grep -E "table=25, 
>>>> n_packets=1,.* 
>>>> priority=$prio,ip,$inport.*$outport.*metadata=0x${sw_key},nw_dst=10.0.1.1 
>>>> actions=drop" -c], [0], [dnl
>>>> +AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | grep -E "table=26, 
>>>> n_packets=1,.* 
>>>> priority=$prio,ip,$inport.*$outport.*metadata=0x${sw_key},nw_dst=10.0.1.1 
>>>> actions=drop" -c], [0], [dnl
>>>> 1
>>>> ])
>>>> 
>>>> @@ -29605,13 +29605,13 @@ AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | 
>>>> grep "actions=controller" | grep
>>>> 
>>>> if test X"$1" = X"DGP"; then
>>>>    # The packet dst should be resolved once for E/W centralized NAT 
>>>> purpose.
>>>> -    AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | grep -E "table=25, 
>>>> n_packets=1,.* priority=100,reg0=0xa000101,reg15=.*metadata=0x${sw_key} 
>>>> actions=mod_dl_dst:00:00:00:00:01:01,resubmit" -c], [0], [dnl
>>>> +    AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | grep -E "table=26, 
>>>> n_packets=1,.* priority=100,reg0=0xa000101,reg15=.*metadata=0x${sw_key} 
>>>> actions=mod_dl_dst:00:00:00:00:01:01,resubmit" -c], [0], [dnl
>>>> 1
>>>> ])
>>>> fi
>>>> 
>>>> # The packet should've been finally dropped in the lr_in_arp_resolve stage.
>>>> -AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | grep -E "table=25, 
>>>> n_packets=2,.* 
>>>> priority=$prio,ip,$inport.*$outport.*metadata=0x${sw_key},nw_dst=10.0.1.1 
>>>> actions=drop" -c], [0], [dnl
>>>> +AT_CHECK([as hv1 ovs-ofctl dump-flows br-int | grep -E "table=26, 
>>>> n_packets=2,.* 
>>>> priority=$prio,ip,$inport.*$outport.*metadata=0x${sw_key},nw_dst=10.0.1.1 
>>>> actions=drop" -c], [0], [dnl
>>>> 1
>>>> ])
>>>> OVN_CLEANUP([hv1])
>>>> diff --git a/tests/system-ovn.at b/tests/system-ovn.at
>>>> index 7b9daba0d..591933a95 100644
>>>> --- a/tests/system-ovn.at
>>>> +++ b/tests/system-ovn.at
>>>> @@ -12032,3 +12032,153 @@ as
>>>> OVS_TRAFFIC_VSWITCHD_STOP(["/failed to query port patch-.*/d
>>>> /connection dropped.*/d"])
>>>> AT_CLEANUP
>>>> +
>>>> +OVN_FOR_EACH_NORTHD([
>>>> +AT_SETUP([DHCP RELAY AGENT])
>>>> +AT_SKIP_IF([test $HAVE_DHCPD = no])
>>>> +AT_SKIP_IF([test $HAVE_DHCLIENT = no])
>>>> +AT_SKIP_IF([test $HAVE_TCPDUMP = no])
>>>> +ovn_start
>>>> +OVS_TRAFFIC_VSWITCHD_START()
>>>> +
>>>> +ADD_BR([br-int])
>>>> +ADD_BR([br-ext])
>>>> +
>>>> +ovs-ofctl add-flow br-ext action=normal
>>>> +# Set external-ids in br-int needed for ovn-controller
>>>> +ovs-vsctl \
>>>> +        -- set Open_vSwitch . external-ids:system-id=hv1 \
>>>> +        -- set Open_vSwitch . 
>>>> external-ids:ovn-remote=unix:$ovs_base/ovn-sb/ovn-sb.sock \
>>>> +        -- set Open_vSwitch . external-ids:ovn-encap-type=geneve \
>>>> +        -- set Open_vSwitch . external-ids:ovn-encap-ip=169.0.0.1 \
>>>> +        -- set bridge br-int fail-mode=secure 
>>>> other-config:disable-in-band=true
>>>> +
>>>> +# Start ovn-controller
>>>> +start_daemon ovn-controller
>>>> +
>>>> +ADD_NAMESPACES(sw01)
>>>> +ADD_VETH(sw01, sw01, br-int, "0", "f0:00:00:01:02:03")
>>>> +ADD_NAMESPACES(sw11)
>>>> +ADD_VETH(sw11, sw11, br-int, "0", "f0:00:00:02:02:03")
>>>> +ADD_NAMESPACES(server)
>>>> +ADD_VETH(s1, server, br-ext, "172.16.1.1/24", "f0:00:00:01:02:05", \
>>>> +         "172.16.1.254")
>>>> +
>>>> +check ovn-nbctl lr-add R1
>>>> +
>>>> +check ovn-nbctl ls-add sw0
>>>> +check ovn-nbctl ls-add sw1
>>>> +check ovn-nbctl ls-add sw-ext
>>>> +
>>>> +check ovn-nbctl lrp-add R1 rp-sw0 00:00:01:01:02:03 192.168.1.1/24
>>>> +check ovn-nbctl lrp-add R1 rp-sw1 00:00:03:01:02:03 192.168.2.1/24
>>>> +check ovn-nbctl lrp-add R1 rp-ext 00:00:02:01:02:03 172.16.1.254/24
>>>> +
>>>> +dhcp_relay=$(ovn-nbctl create DHCP_Relay servers=172.16.1.1)
>>>> +check ovn-nbctl set Logical_Router_port rp-sw0 dhcp_relay=$dhcp_relay
>>>> +check ovn-nbctl set Logical_Router_port rp-sw1 dhcp_relay=$dhcp_relay
>>>> +check ovn-nbctl lrp-set-gateway-chassis rp-ext hv1
>>>> +
>>>> +check ovn-nbctl lsp-add sw0 sw0-rp -- set Logical_Switch_Port sw0-rp \
>>>> +    type=router options:router-port=rp-sw0 \
>>>> +    -- lsp-set-addresses sw0-rp router
>>>> +check ovn-nbctl lsp-add sw1 sw1-rp -- set Logical_Switch_Port sw1-rp \
>>>> +    type=router options:router-port=rp-sw1 \
>>>> +    -- lsp-set-addresses sw1-rp router
>>>> +
>>>> +rp_uuid=$(ovn-nbctl --bare --colum=_uuid list logical_router_port rp-sw0)
>>>> +check ovn-nbctl set Logical_Switch sw0 dhcp_relay_port=$rp_uuid
>>>> +rp_uuid=$(ovn-nbctl --bare --colum=_uuid list logical_router_port rp-sw1)
>>>> +check ovn-nbctl set Logical_Switch sw1 dhcp_relay_port=$rp_uuid
>>>> +
>>>> +check ovn-nbctl lsp-add sw-ext ext-rp -- set Logical_Switch_Port ext-rp \
>>>> +    type=router options:router-port=rp-ext \
>>>> +    -- lsp-set-addresses ext-rp router
>>>> +check ovn-nbctl lsp-add sw-ext lnet \
>>>> +        -- lsp-set-addresses lnet unknown \
>>>> +        -- lsp-set-type lnet localnet \
>>>> +        -- lsp-set-options lnet network_name=phynet
>>>> +
>>>> +check ovn-nbctl lsp-add sw0 sw01 \
>>>> +    -- lsp-set-addresses sw01 "f0:00:00:01:02:03"
>>>> +
>>>> +check ovn-nbctl lsp-add sw1 sw11 \
>>>> +    -- lsp-set-addresses sw11 "f0:00:00:02:02:03"
>>>> +
>>>> +AT_CHECK([ovs-vsctl set Open_vSwitch . 
>>>> external-ids:ovn-bridge-mappings=phynet:br-ext])
>>>> +
>>>> +OVN_POPULATE_ARP
>>>> +
>>>> +check ovn-nbctl --wait=hv sync
>>>> +
>>>> +DHCP_TEST_DIR="/tmp/dhcp-test"
>>>> +rm -rf $DHCP_TEST_DIR
>>>> +mkdir $DHCP_TEST_DIR
>>>> +cat > $DHCP_TEST_DIR/dhcpd.conf <<EOF
>>>> +subnet 172.16.1.0 netmask 255.255.255.0 {
>>>> +}
>>>> +subnet 192.168.1.0 netmask 255.255.255.0 {
>>>> +  range 192.168.1.10 192.168.1.10;
>>>> +  option routers 192.168.1.1;
>>>> +  option broadcast-address 192.168.1.255;
>>>> +  default-lease-time 60;
>>>> +  max-lease-time 120;
>>>> +}
>>>> +subnet 192.168.2.0 netmask 255.255.255.0 {
>>>> +  range 192.168.2.10 192.168.2.10;
>>>> +  option routers 192.168.2.1;
>>>> +  option broadcast-address 192.168.2.255;
>>>> +  default-lease-time 60;
>>>> +  max-lease-time 120;
>>>> +}
>>>> +EOF
>>>> +cat > $DHCP_TEST_DIR/dhclien.conf <<EOF
>>>> +timeout 2
>>>> +EOF
>>>> +
>>>> +touch $DHCP_TEST_DIR/dhcpd.leases
>>>> +chown root:dhcpd $DHCP_TEST_DIR $DHCP_TEST_DIR/dhcpd.leases
>>>> +chmod 775 $DHCP_TEST_DIR
>>>> +chmod 664 $DHCP_TEST_DIR/dhcpd.leases
>>>> +
>>>> +
>>>> +NETNS_DAEMONIZE([server], [dhcpd -4 -f -cf $DHCP_TEST_DIR/dhcpd.conf s1 > 
>>>> dhcpd.log 2>&1], [dhcpd.pid])
>>>> +
>>>> +NS_CHECK_EXEC([server], [tcpdump -l -nvv -i s1  udp > pkt.pcap 
>>>> 2>tcpdump_err &])
>>>> +OVS_WAIT_UNTIL([grep "listening" tcpdump_err])
>>>> +on_exit 'kill $(pidof tcpdump)'
>>>> +
>>>> +NS_CHECK_EXEC([sw01], [dhclient -1 -q -lf 
>>>> $DHCP_TEST_DIR/dhclient-sw01.lease -pf $DHCP_TEST_DIR/dhclient-sw01.pid 
>>>> -cf $DHCP_TEST_DIR/dhclien.conf sw01])
>>>> +NS_CHECK_EXEC([sw11], [dhclient -1 -q -lf 
>>>> $DHCP_TEST_DIR/dhclient-sw11.lease -pf $DHCP_TEST_DIR/dhclient-sw11.pid 
>>>> -cf $DHCP_TEST_DIR/dhclien.conf sw11])
>>>> +
>>>> +OVS_WAIT_UNTIL([
>>>> +    total_pkts=$(cat pkt.pcap | wc -l)
>>>> +    test ${total_pkts} -ge 8
>>>> +])
>>>> +
>>>> +on_exit 'kill `cat $DHCP_TEST_DIR/dhclient-sw01.pid` &&
>>>> +kill `cat $DHCP_TEST_DIR/dhclient-sw11.pid` && rm -rf $DHCP_TEST_DIR'
>>>> +
>>>> +NS_CHECK_EXEC([sw01], [ip addr show sw01 | grep -oP 
>>>> '(?<=inet\s)\d+(\.\d+){3}'], [0], [dnl
>>>> +192.168.1.10
>>>> +])
>>>> +NS_CHECK_EXEC([sw11], [ip addr show sw11 | grep -oP 
>>>> '(?<=inet\s)\d+(\.\d+){3}'], [0], [dnl
>>>> +192.168.2.10
>>>> +])
>>>> +OVS_APP_EXIT_AND_WAIT([ovn-controller])
>>>> +
>>>> +as ovn-sb
>>>> +OVS_APP_EXIT_AND_WAIT([ovsdb-server])
>>>> +
>>>> +as ovn-nb
>>>> +OVS_APP_EXIT_AND_WAIT([ovsdb-server])
>>>> +
>>>> +as northd
>>>> +OVS_APP_EXIT_AND_WAIT([NORTHD_TYPE])
>>>> +
>>>> +as
>>>> +OVS_TRAFFIC_VSWITCHD_STOP(["/.*error receiving.*/d
>>>> +/failed to query port patch-.*/d
>>>> +/.*terminating with signal 15.*/d"])
>>>> +AT_CLEANUP
>>>> +])
>>>> diff --git a/utilities/ovn-trace.c b/utilities/ovn-trace.c
>>>> index 0b86eae7b..ae9dd77de 100644
>>>> --- a/utilities/ovn-trace.c
>>>> +++ b/utilities/ovn-trace.c
>>>> @@ -2328,6 +2328,25 @@ execute_put_dhcp_opts(const struct ovnact_put_opts 
>>>> *pdo,
>>>>    execute_put_opts(pdo, name, uflow, super);
>>>> }
>>>> 
>>>> +static void
>>>> +execute_dhcpv4_relay_resp_fwd(const struct ovnact_dhcp_relay *dr,
>>>> +                                const char *name, struct flow *uflow,
>>>> +                                struct ovs_list *super)
>>>> +{
>>>> +    ovntrace_node_append(
>>>> +        super, OVNTRACE_NODE_ERROR,
>>>> +        "/* We assume that this packet is DHCPOFFER or DHCPACK and "
>>>> +            "DHCP broadcast flag is set. Dest IP is set to broadcast. "
>>>> +            "Dest MAC is set to broadcast but in real network this is 
>>>> unicast "
>>>> +            "which is extracted from DHCP header. */");
>>>> +
>>>> +    /* Assume DHCP broadcast flag is set */
>>>> +    uflow->nw_dst = 0xFFFFFFFF;
>>>> +    /* Dest MAC is set to broadcast but in real network this is unicast */
>>>> +    struct eth_addr bcast_mac = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
>>>> +    uflow->dl_dst = bcast_mac;
>>>> +}
>>>> +
>>>> static void
>>>> execute_put_nd_ra_opts(const struct ovnact_put_opts *pdo,
>>>>                       const char *name, struct flow *uflow,
>>>> @@ -3215,6 +3234,15 @@ trace_actions(const struct ovnact *ovnacts, size_t 
>>>> ovnacts_len,
>>>>                                  "put_dhcpv6_opts", uflow, super);
>>>>            break;
>>>> 
>>>> +        case OVNACT_DHCPV4_RELAY_REQ:
>>>> +            /* Nothing to do for tracing. */
>>>> +            break;
>>>> +
>>>> +        case OVNACT_DHCPV4_RELAY_RESP_FWD:
>>>> +            
>>>> execute_dhcpv4_relay_resp_fwd(ovnact_get_DHCPV4_RELAY_RESP_FWD(a),
>>>> +                                    "dhcp_relay_resp_fwd", uflow, super);
>>>> +            break;
>>>> +
>>>>        case OVNACT_PUT_ND_RA_OPTS:
>>>>            execute_put_nd_ra_opts(ovnact_get_PUT_DHCPV6_OPTS(a),
>>>>                                   "put_nd_ra_opts", uflow, super);
>>>> --
>>>> 2.36.6
>>>> 
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