[ovs-discuss] OVN load balancing on same subnet failing

Numan Siddique nusiddiq at redhat.com
Fri Mar 2 10:57:55 UTC 2018


On Fri, Mar 2, 2018 at 10:39 AM, Anil Venkata <anilvenkata at redhat.com>
wrote:

>
>
> On Fri, Mar 2, 2018 at 7:23 AM, Guru Shetty <guru at ovn.org> wrote:
>
>>
>>
>> On 27 February 2018 at 03:13, Anil Venkata <anilvenkata at redhat.com>
>> wrote:
>>
>>> For example, I have a 10.1.0.0/24 network and a load balancer is added
>>> to it with 10.1.0.10 as VIP and 10.1.0.2(MAC 50:54:00:00:00:01),
>>> 10.1.0.3(MAC 50:54:00:00:00:02) as members.
>>> ovn-nbctl  create load_balancer vips:10.1.0.10="10.1.0.2,10.1.0.3"
>>>
>>
>> We currently need the VIP to be in a different subnet. You should connect
>> switch it to a dummy logical router (or connect it to a external router).
>> Since a VIP is in a different subnet, it sends an ARP for logical router IP
>> and then things will work.
>>
>>
>
> Thanks Guru. Any reason for introducing this constraint(i.e VIP to be in a
> different subnet)? Can we address this limitation?
>
>
For OpenStack I think this is a valid use case and I think we should
support it.

Thanks
Numan


>>>  When I try to send a request from client within the subnet(i.e
>>> 10.1.0.33) its not reaching any load balancer members.
>>> I noticed ARP not resolved for VIP 10.1.0.10.
>>>
>>> I tried to resolve this in two ways
>>> 1) Adding a new ARP reply ovs flow for VIP 10.1.0.10 with router port's
>>> MAC. When client tries to connect VIP, it will use router's MAC. Now router
>>> gets the packet after load balancing, and will forward the packet to
>>> appropriate member.
>>>
>>> 2) Second approach,
>>>    a) Using a new MAC(example, 50:54:00:00:00:ab) for VIP 10.1.0.10, and
>>> adding a new ARP reply flow with this MAC.
>>>    b) As we are not using router, when load balancing changes
>>> destination ip, VIP MAC has to be replaced with corresponding member's MAC
>>> i.e
>>>       sudo ovs-ofctl add-flow br-int "table=24,ip,priority=150,dl_d
>>> st=50:54:00:00:00:ab,nw_dst=10.1.0.2,action=mod_dl_dst:50:54
>>> :00:00:00:01,load:0x1->NXM_NX_REG15[],resubmit(,32)"
>>> sudo ovs-ofctl add-flow br-int "table=24,ip,priority=150,dl_d
>>> st=50:54:00:00:00:ab,nw_dst=10.1.0.3,action=mod_dl_dst:50:54
>>> :00:00:00:02,load:0x2->NXM_NX_REG15[],resubmit(,32)"
>>>
>>> Which approach will be better or is there any alternate solution?
>>>
>>> Thanks
>>> Anil
>>>
>>>
>>> _______________________________________________
>>> discuss mailing list
>>> discuss at openvswitch.org
>>> https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>>>
>>>
>>
>
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