From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jay Vosburgh Subject: Re: [PATCH v2] bonding: send IPv6 neighbor advertisement on failover Date: Fri, 10 Oct 2008 08:53:56 -0700 Message-ID: <29444.1223654036@death.nxdomain.ibm.com> References: Cc: Brian Haley , Alex Sidorenko , David Miller , Simon Horman , "netdev@vger.kernel.org" , netdev-owner@vger.kernel.org, YOSHIFUJI Hideaki To: David Stevens Return-path: Received: from e35.co.us.ibm.com ([32.97.110.153]:54771 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757858AbYJJPy2 (ORCPT ); Fri, 10 Oct 2008 11:54:28 -0400 In-reply-to: Sender: netdev-owner@vger.kernel.org List-ID: David Stevens wrote: >Brian Haley wrote on 10/10/2008 07:34:58 AM: > >> I don't really want to since this is bonding-specific behavior, and >> we're not performing DAD for the address. This is just another sysfs >> entry: /sys/class/net/bond*/bonding/num_unsol_na, not a sysctl. > > I think they really are the same case, and doing DAD >would solve the problem just as well. But I can hold my nose a >little bit and live with it. :-) Getting the problem solved is >more important than the details. If I'm reading things correctly, DAD sends neighbor solicitations, and we're sending neighbor advertisements, and not running the DAD logic. As a semi-related question, what does IPv6 do if it receives a gratutitous NA, and finds a duplicate? I agree that doing DAD would update the switches, peers, etc, but, if I'm reading the IPv6 code correctly, the delay between probes is one second (nd_tbl.retrans_time), and it looks like there's an initial delay of up to 1 second as well (in addrconf_dad_kick, the rtr_solicit_delay). For failover purposes, we want to issue the gratuitous ARP or NA packets immediately with a minimal delay between probes. Is my understanding of the DAD behavior correct? -J --- -Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com