net/bridge: Add 'hairpin' port forwarding mode

This patch adds a 'hairpin' (also called 'reflective relay') mode
port configuration to the Linux Ethernet bridge kernel module.
A bridge supporting hairpin forwarding mode can send frames back
out through the port the frame was received on.

Hairpin mode is required to support basic VEPA (Virtual
Ethernet Port Aggregator) capabilities.

You can find additional information on VEPA here:
http://tech.groups.yahoo.com/group/evb/
http://www.ieee802.org/1/files/public/docs2009/new-hudson-vepa_seminar-20090514d.pdf
http://www.internet2.edu/presentations/jt2009jul/20090719-congdon.pdf

An additional patch 'bridge-utils: Add 'hairpin' port forwarding mode'
is provided to allow configuring hairpin mode from userspace tools.

Signed-off-by: Paul Congdon <paul.congdon@hp.com>
Signed-off-by: Anna Fischer <anna.fischer@hp.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index d5b5537272b4..8319247dad5d 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -81,6 +81,9 @@ struct net_bridge_port
         struct timer_list               message_age_timer;
         struct kobject                  kobj;
         struct rcu_head                 rcu;
+
+        unsigned long                   flags;
+#define BR_HAIRPIN_MODE         0x00000001
 };
 
 struct net_bridge