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

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Date:	Thu, 09 Oct 2008 20:52:34 -0400
From:	Brian Haley <brian.haley@...com>
To:	Jay Vosburgh <fubar@...ibm.com>,
	David Miller <davem@...emloft.net>,
	YOSHIFUJI Hideaki <yoshfuji@...ux-ipv6.org>
CC:	Simon Horman <horms@...ge.net.au>,
	Alex Sidorenko <alexandre.sidorenko@...com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH v2] bonding: send IPv6 neighbor advertisement on failover

Updated to address Vlad's comment about storing the link-local IPv6 
address in the bond/vlan structure, I no longer overwrite the existing 
address with a newer one.  Also added missed locking for the inet6_dev.

I don't see any way to address David Steven's comment since there is 
currently no NA tunable in the IPv6 code.

---

This patch adds better IPv6 failover support for bonding devices,
especially when in active-backup mode and there are only IPv6 addresses
configured, as reported by Alex Sidorenko.

- Creates a new file, net/drivers/bonding/bond_ipv6.c, for the
   IPv6-specific routines.  Both regular bonds and VLANs over bonds
   are supported.

- Adds a new tunable, num_unsol_na, to limit the number of unsolicited
   IPv6 Neighbor Advertisements that are sent on a failover event.
   Default is 1.

- Creates two new IPv6 neighbor discovery functions:

   ndisc_build_skb()
   ndisc_send_skb()

   These were required to support VLANs since we have to be able to
   add the VLAN id to the skb since ndisc_send_na() and friends
   shouldn't be asked to do this.  These two routines are basically
   __ndisc_send() split into two pieces, in a slightly different order.

- Updates Documentation/networking/bonding.txt and bumps the rev of bond
   support to 3.4.0.

On failover, this new code will generate one packet:

- An unsolicited IPv6 Neighbor Advertisement, which helps the switch
   learn that the address has moved to the new slave.

Testing has shown that sending just the NA results in pretty good
behavior when in active-back mode, I saw no lost ping packets for example.

-Brian

Signed-off-by: Brian Haley <brian.haley@...com>
---

View attachment "bonding-ipv6.patch" of type "text/x-patch" (19674 bytes)