[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 network and a load balancer is added
>> to it with as VIP and 50:54:00:00:00:01),
>> 50:54:00:00:00:02) as members.
>> ovn-nbctl  create load_balancer vips:","
> 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
>> its not reaching any load balancer members.
>> I noticed ARP not resolved for VIP
>> I tried to resolve this in two ways
>> 1) Adding a new ARP reply ovs flow for VIP 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, 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=,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=,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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>> discuss at openvswitch.org
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