netdev - Re: [PATCH v2] bonding: send IPv6 neighbor advertisement on failover

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 10 Oct 2008 12:04:15 -0400
From:	Brian Haley <brian.haley@...com>
To:	Jay Vosburgh <fubar@...ibm.com>
CC:	David Stevens <dlstevens@...ibm.com>,
	Alex Sidorenko <alexandre.sidorenko@...com>,
	David Miller <davem@...emloft.net>,
	Simon Horman <horms@...ge.net.au>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	netdev-owner@...r.kernel.org,
	YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
Subject: Re: [PATCH v2] bonding: send IPv6 neighbor advertisement on failover

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
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html