[ovs-dev] [PATCH v1 ovn 0/1] Forwarding group to load balance l2 traffic with liveness detection

Numan Siddique numans at ovn.org
Tue Jan 14 07:37:08 UTC 2020

On Sat, Jan 11, 2020 at 6:31 AM Manoj Sharma <manoj.sharma at nutanix.com> wrote:
> Thank you for the review Numan.
> On 1/8/20, 11:14 PM, "Numan Siddique" <numans at ovn.org> wrote:
>     Hi Manoj,
>     Thanks for the patch. I didn't look into the complete patch. I have
>     initial few comments.
>     The patch fails to compile when --enable-Werror and --enable-sparse
>     are enabled during configuration.
> I sent the v2 that has the fix for the compilation issue.

Thanks for v2. I will take a look at it.

I have few follow up questions.

>     Can you please include the description in Patch 0 in the actual patch
>     commit message ?
>     The commit message in the patch doesn't have much details.
> Done
>     In your above description, does the logical switch (with logical ports
>     lsp1 and lsp2) has a localnet port ?
> It does not matter if the switch has localnet port or not. You are only putting
> the logical switch ports in an openflow group so that traffic can be load balanced
> across them.
>     I am confused how the packet goes out of the logical switch to the
>     external network ?
>     Does lsp1 and lsp2 bound to any VM/VIF ?
>     From the test case you have written I see that lsp21 and lsp22 are
>     part of forward group and they
>     have VIF ports as well. So the packet destined to the VIP will be
>     delivered to one of the VIF ?
>     And the VIF/VM takes care of sending the traffic to external routers ?
> We can model an external router as an OVN chassis. For HA, you will need more than one external router
> and bind the lsp1 and lsp2 to these chassis (lsp1 <> chassis1, lsp2 <> chassis2). If we want
> to load balance across these external routers then just send the traffic to the VIP.

Does ovn-controller run on these external router hosts ? I presume so,
otherwise there will be no
chassis entry in the SB Chassis table.
I am curious on how the packet will go out of br-int ?

You must be aware that we already have native load balancer feature in
OVN which does almost exactly the same
thing. The forward groups you proposed here and the OVN load balancer
uses the same mechanism.
But probably load balancer don't use BFD mechanism to check the liveliness.

Can the native load balancer be used instead ? It does have health
check feature now. If it's possible, then
definitely I would avoid adding forward groups.

> Since I also wanted to include --liveness in the unit tests, I put the VIFs, bound to lsp1 and lsp2,
> on different hypervisors so that there is a tunnel interface from the source hypervisor to these
> two VIFs. For liveness, you need BFD running on the tunnel interface.
> Thanks,
> Manoj
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