From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Haley Subject: Re: [PATCH v2] bonding: send IPv6 neighbor advertisement on failover Date: Fri, 10 Oct 2008 12:04:15 -0400 Message-ID: <48EF7CFF.4050405@hp.com> References: <29444.1223654036@death.nxdomain.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Stevens , Alex Sidorenko , David Miller , Simon Horman , "netdev@vger.kernel.org" , netdev-owner@vger.kernel.org, YOSHIFUJI Hideaki To: Jay Vosburgh Return-path: Received: from g5t0009.atlanta.hp.com ([15.192.0.46]:48472 "EHLO g5t0009.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760942AbYJJQES (ORCPT ); Fri, 10 Oct 2008 12:04:18 -0400 In-Reply-To: <29444.1223654036@death.nxdomain.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: Jay Vosburgh wrote: > As a semi-related question, what does IPv6 do if it receives a > gratutitous NA, and finds a duplicate? If a node has an IPv6 neighbor entry and receives an unsolicited NA it will change it's state to stale, forcing a re-lookup on the next transmit. An un-solicited NA will change the state to reachable. > 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. Right, and since a bond failover event should be rare, I think sending the NA immediately is OK. All those random delays are meant to cover the case, for example, when a router sends an advertisement with a new prefix - you don't want everyone that receives it to do DAD immediately since it could overwhelm the network. -Brian