[ovs-dev] [External] : [PATCH ovn v2] ovn-northd.c: Add proxy ARP support to OVN

Brendan Doyle brendan.doyle at oracle.com
Tue Jun 15 11:50:00 UTC 2021



On 14/06/2021 21:17, Numan Siddique wrote:
> On Mon, Jun 14, 2021 at 5:19 AM Brendan Doyle <brendan.doyle at oracle.com> wrote:
>> Hi,
>>
>> Just wondering how to move this along. It's been in the queue a while now.
>> The product I'm working on requires this feature and If I can't get it
>> upstream
>> I'll need to look at other options.
> Hi Brendan,
>
> Sorry for the late reply.  For some reason the patch doesn't apply to me.
Sorry I'm not sure what you mean, the patch did not apply, it works when 
I apply
to my repo?
> Please see below for a few comments.
>
>
>>
>> Thanks
>>
>> Brendan
>>
>> On 04/06/2021 15:51, Brendan Doyle wrote:
>>>  From 07ecd5d00f82658e094132102575d8d576161a6b Mon Sep 17 00:00:00 2001
>>> From: Brendan Doyle <brendan.doyle at oracle.com>
>>> Date: Fri, 28 May 2021 10:01:17 -0700
>>> Subject: [PATCH ovn] ovn-northd.c: Add proxy ARP support to OVN
>>>
>>> This patch provides the ability to configure proxy ARP IPs on a Logical
>>> Switch Router port. The IPs are added as Options for router ports. This
>>> provides a useful feature where traffic for a service must be sent to an
>>> address in a logical network address space, but the service is provided
>>> in a different network. For example an NFS service is provide to Logical
>>> networks at an address in their Logical network space, but the NFS
>>> server resides in a physical network. A Logical switch Router port can
>>> be configured to respond to ARP requests sent to the service "Logical
>>> address", the Logical Router/Gateway can then be configured to forward
>>> the traffic to the underlay/physical network.
>>>
>>> Signed-off-by: Brendan Doyle <brendan.doyle at oracle.com>
>>> ---
>>>   northd/ovn-northd.c |  44 ++++++++++++++++++++++
>>>   ovn-nb.xml          |   9 +++++
>>>   tests/ovn.at        | 103
>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>>>   3 files changed, 156 insertions(+)
>>>
>>> diff --git a/northd/ovn-northd.c b/northd/ovn-northd.c
>>> index 0e5092a..9b686d9 100644
>>> --- a/northd/ovn-northd.c
>>> +++ b/northd/ovn-northd.c
>>> @@ -6943,6 +6943,7 @@ build_lswitch_arp_nd_responder_known_ips(struct
>>> ovn_port *op,
>>>                                            struct ds *match)
>>>   {
>>>       if (op->nbsp) {
>>> +        const char *arp_proxy;
>>>           if (!strcmp(op->nbsp->type, "virtual")) {
>>>               /* Handle
>>>                *  - GARPs for virtual ip which belongs to a logical port
>>> @@ -7096,6 +7097,49 @@ build_lswitch_arp_nd_responder_known_ips(struct
>>> ovn_port *op,
>>>                   }
>>>               }
>>>           }
>>> +
>>> +        /*
>>> +         * Add responses for ARP proxies.
>>> +         */
>>> +        arp_proxy = smap_get(&op->nbsp->options,"arp_proxy");
> In my opinion instead of defining these proxy IPs in the logical
> switch port options,
> it is better to define them in the router port as generally a router
> would handle proxy arps (correct me if I'm wrong here).
>
> I'd suggest to add a new column "proxy_ips" (or something more appropriate)
> in the Logical_Router_Port and this column would point to an address set.
>
> CMS can define the list of IPs in the address set.  ovn-northd can add
> a logical flow like
>
> match = "inport == <router_port> && arp.tpa == $proxy_ip, action = {....}
> This would result in just one logical flow.
>
> CMS would do something like
>
> addr_set_uuid=$(ovn-nbctl create address_set name=proxy_arps
> addresses="10.0.0.4, 10.0.0.5")
> ovn-nbctl set logical_router_port <router_port> proxy_ip=$addr_set_uuid
>
> What do you think ?

In both cases only one OVS flows is created (after I made the changes) 
suggested by Dan.
I can see the point with respect to proxy ARP and routers, in physical 
equipment proxy ARP is done
by routers.  But I think doing the proxy ARP on the LRP of the LS is 
consistent with the use of
the "options : nat-addresses" entry in the Logical_Switch_Port TABLE . 
The patch makes it clear
that this feature is associated with a router, It is after all in the 
"Options  for router ports". I think
it is also more efficient in that we'd respond to the ARP request 
earlier in the datapath flows.

The suggestion you make is a lot more involved, touching much more code 
and changes the DB
schema, so I'm hesitant to go down that path.

Brendan.

>
> Thanks
> Numan
>
>>> +        if (arp_proxy && op->peer) {
>>> +            char *ips, *ip, *rest;
>>> +            int i = 0;
>>> +
>>> +            ips = xstrdup(arp_proxy);
>>> +            rest = ips;
>>> +
>>> +            /*
>>> +             * Match rule on all proxy ARP IPs.
>>> +             */
>>> +            ds_clear(match);
>>> +            ds_put_cstr(match, "arp.op == 1 && (");
>>> +            while ((ip = strtok_r(rest,",", &rest))) {
>>> +                if (i++ > 0) {
>>> +                        ds_put_cstr(match, " || ");
>>> +                };
>>> +                ds_put_format(match, "arp.tpa == %s", ip);
>>> +            }
>>> +            ds_put_cstr(match, ")");
>>> +
>>> +            ds_clear(actions);
>>> +            ds_put_format(actions,
>>> +                "eth.dst = eth.src; "
>>> +                "eth.src = %s; "
>>> +                "arp.op = 2; /* ARP reply */ "
>>> +                "arp.tha = arp.sha; "
>>> +                "arp.sha = %s; "
>>> +                "arp.tpa <-> arp.spa; "
>>> +                "outport = inport; "
>>> +                "flags.loopback = 1; "
>>> +                "output;",
>>> +                op->peer->lrp_networks.ea_s,
>>> +                op->peer->lrp_networks.ea_s);
>>> +
>>> +            ovn_lflow_add_with_hint(lflows, op->od,
>>> S_SWITCH_IN_ARP_ND_RSP,
>>> +                50, ds_cstr(match), ds_cstr(actions),
>>> &op->nbsp->header_);
>>> +            free(ips);
>>> +        }
>>>       }
>>>   }
>>>
>>> diff --git a/ovn-nb.xml b/ovn-nb.xml
>>> index 02fd216..4b6c183 100644
>>> --- a/ovn-nb.xml
>>> +++ b/ovn-nb.xml
>>> @@ -848,6 +848,15 @@
>>>               </dd>
>>>             </dl>
>>>           </column>
>>> +
>>> +        <column name="options" key="arp_proxy">
>>> +          Optional. A comma separated list IPv4 addresses that this
>>> +          logical switch <code>router</code> port will reply to ARP
>>> requests.
>>> +          Example: <code>169.254.239.254,169.254.239.2</code>. The
>>> +          <ref column="options" key="router-port"/>'s logical router
>>> should
>>> +          have a route to forward packets sent to configured proxy
>>> ARP IPs to
>>> +          an appropriate destination.
>>> +        </column>
>>>         </group>
>>>
>>>         <group title="Options for localnet ports">
>>> diff --git a/tests/ovn.at b/tests/ovn.at
>>> index 2c3c36d..4befe4a 100644
>>> --- a/tests/ovn.at
>>> +++ b/tests/ovn.at
>>> @@ -26527,3 +26527,106 @@ AT_CHECK([test $(ovn-appctl -t
>>> ovn-controller coverage/read-counter lflow_run) =
>>>   OVN_CLEANUP([hv1])
>>>   AT_CLEANUP
>>>   ])
>>> +
>>> +OVN_FOR_EACH_NORTHD([
>>> +AT_SETUP([ovn -- proxy-arp: 1 HVs, 1 LSs, 1 lport/LS, 1 LR])
>>> +AT_KEYWORDS([proxy-arp])
>>> +ovn_start
>>> +
>>> +# Logical network:
>>> +# One LR - lr1 has switch ls1 (192.16.1.0/24) connected to it,
>>> +# and and one HV with IP 192.16.1.6.
>>> +
>>> +ovn-nbctl lr-add lr1
>>> +ovn-nbctl ls-add ls1
>>> +
>>> +# Connect ls1 to lr1
>>> +ovn-nbctl lrp-add lr1 ls1 00:00:00:01:02:f1 192.16.1.1/24
>>> +ovn-nbctl lsp-add ls1 rp-ls1 -- set Logical_Switch_Port rp-ls1 \
>>> +    type=router options:router-port=ls1 addresses=\"00:00:00:01:02:f1\"
>>> +
>>> +# Create logical port ls1-lp1 in ls1
>>> +ovn-nbctl lsp-add ls1 ls1-lp1 \
>>> +-- lsp-set-addresses ls1-lp1 "00:00:00:01:02:03 192.16.1.6"
>>> +
>>> +
>>> +# Create one hypervisor and create OVS ports corresponding to logical
>>> ports.
>>> +net_add n1
>>> +
>>> +sim_add pa-hv
>>> +as pa-hv
>>> +ovs-vsctl add-br br-phys
>>> +ovn_attach n1 br-phys 192.16.0.1
>>> +
>>> +# Note: tx/rx are with respect to the LS port, so
>>> +# tx on switch port is HV rx, etc.
>>> +ovs-vsctl -- add-port br-int vif1 -- \
>>> +    set interface vif1 external-ids:iface-id=ls1-lp1 \
>>> +    options:tx_pcap=pa-hv/vif1-tx.pcap \
>>> +    options:rxq_pcap=pa-hv/vif1-rx.pcap \
>>> +    ofport-request=1
>>> +
>>> +# And proxy ARP flows for 69.254.239.254 and 169.254.239.2
>>> +# and check that SB flows have been added.
>>> +ovn-nbctl --wait=hv add Logical_Switch_Port rp-ls1 \
>>> +options arp_proxy='"169.254.239.254,169.254.239.2"'
>>> +ovn-sbctl dump-flows > sbflows
>>> +AT_CAPTURE_FILE([sbflows])
>>> +
>>> +AT_CHECK([ovn-sbctl dump-flows | grep ls_in_arp_rsp | grep
>>> "169.254.239.2" | wc -l], [0], [dnl
>>> +1
>>> +])
>>> +
>>> +# Remove and check that the flows have been removed
>>> +ovn-nbctl --wait=hv remove Logical_Switch_Port rp-ls1 options
>>> arp_proxy='"169.254.239.254,169.254.239.2"'
>>> +
>>> +AT_CHECK([ovn-sbctl dump-flows | grep ls_in_arp_rsp | grep
>>> "169.254.239.2" | wc -l], [0], [dnl
>>> +0
>>> +])
>>> +
>>> +# Add the flows back send arp request and check we see an ARP response
>>> +ovn-nbctl --wait=hv add Logical_Switch_Port rp-ls1 \
>>> +options arp_proxy='"169.254.239.254,169.254.239.2"'
>>> +
>>> +ls1_p1_mac=00:00:00:01:02:03
>>> +ls1_p1_ip=192.16.1.6
>>> +
>>> +ls1_ro_mac=00:00:00:01:02:f1
>>> +ls1_ro_ip=192.168.1.1
>>> +
>>> +proxy_ip1=169.254.239.254
>>> +proxy_ip2=169.254.239.2
>>> +
>>> +bcast_mac=ff:ff:ff:ff:ff:ff
>>> +
>>> +# Send ARP request for 169.254.239.254
>>> +packet="inport==\"ls1-lp1\" && eth.src==$ls1_p1_mac &&
>>> eth.dst==$bcast_mac &&
>>> +       arp.op==1 && arp.sha==$ls1_p1_mac && arp.spa==$ls1_p1_ip &&
>>> +       arp.tha==$bcast_mac && arp.tpa==$proxy_ip1"
>>> +
>>> +as pa-hv ovs-appctl -t ovn-controller inject-pkt "$packet"
>>> +
>>> +ovs-ofctl dump-flows br-int| grep 169.254.239.254 | grep priority=50
>>>> debug1
>>> +AT_CAPTURE_FILE([debug1])
>>> +
>>> +
>>> +# Check if packet hit the ARP reply ovs flow
>>> +AT_CHECK([ovs-ofctl dump-flows br-int | \
>>> +    grep "169.254.239.254" | \
>>> +    grep "priority=50" | \
>>> +    grep "arp_op=1" | \
>>> +    grep "n_packets=1" | wc -l], [0], [dnl
>>> +1
>>> +])
>>> +
>>> +# Check that the HV gets an ARP reply
>>> +expected="eth.src==$ls1_ro_mac && eth.dst==$ls1_p1_mac &&
>>> +       arp.op==2 && arp.sha==$ls1_ro_mac && arp.spa==$proxy_ip1 &&
>>> +       arp.tha==$ls1_p1_mac && arp.tpa==$ls1_p1_ip"
>>> +echo $expected | ovstest test-ovn expr-to-packets > expected
>>> +
>>> +OVN_CHECK_PACKETS([pa-hv/vif1-tx.pcap], [expected])
>>> +
>>> +OVN_CLEANUP([pa-hv])
>>> +AT_CLEANUP
>>> +])
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