Subject: Re: [PATCH] bonding: send IPv6 neighbor advertisement on failover

From: Brian Haley <[email-masked]>
Date: Wed, 08 Oct 2008 22:08:42 -0400

Sridhar Samudrala wrote:
> On Wed, 2008-10-08 at 15:01 -0400, Brian Haley wrote:
>> David Stevens wrote:
>>> Well, actually, it looks like I'm suggesting you to re-use something that 
>>> doesn't
>>> exist. :-)
>>>
>>> MLD (and IGMP) has such a thing where unsolicited advertisements are sent
>>> multiple times, with delays in between, to account for lossy networks 
>>> possibly
>>> dropping the first one. There are configurable counts associated with 
>>> probes
>>> and retransmit intervals for solicits, but I don't see the equivalent yet 
>>> for
>>> unsolicited NA's.
>> I don't see an equivalent either, since the only unsolicited NA the 
>> kernel sends is for DAD, which uses dad_transmits.
> 
> Doesn't DAD use neighbor solicitation rather than unsolicited NA?

Yes.  There is one case in the NS code that will respond with an 
unsolicited NA if we get a NS doing DAD.  I guess I should have made it 
clearer that it's when we're defending our address during a DAD probe.

> Can we use NS in the bonding failover scenario too?

Both and NS and NA seemed to update the switch, so either one can be 
sent on a failover event.  It seemed to be the consensus that the NA was 
more appropriate, especially since we can send it without the solicited 
bit set.

-Brian