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

Anil Venkata anilvenkata at redhat.com
Fri Mar 2 05:09:57 UTC 2018


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?


>>  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
>>
>>
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>>
>>
>
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