[ovs-discuss] [OVN] router-preference in non periodic RA

Gabriele Cerami gcerami at redhat.com
Fri Jun 5 15:26:28 UTC 2020

On 02 Jun, Numan Siddique wrote:
> If you want to address this, then you should include router-preference in
> the put_nd_ra_opts(),
> something like
> reg1[0] = put_nd_ra_opts(addr_mode = "slaac", mtu = 1500, prefix =
> aef0::/64, slla = ae:01:02:03:04:05, router-preference=true);

Thanks for the explanation and the pointers, I think I understand a lot
more what is happening here, and what the northd produces.

Unfortunately router-preference is not an option like the others, the
priority of the preference takes two bits out of the flags byte in the
RA message header, which is mapped in the mo_flags field of the
ovs_ra_msg struct.

The ra->mo_flags is hard coded as 0 in encode_PUT_ND_RA_OPS.
I think I can easily put options like dnssl and rdss which are also
missing, but preference requires a slightly different treatment.

This is already correctly managed in ipv6_ra_update_config for the
periodic RAs.
As we dicussed, I'll fix the code to close the bug, then work to unify
these two RA packet handling methods.

Thanks Numan and Lorenzo!

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