From 88f9c8ccf815fdc170e0f160335acdaacadc669e Mon Sep 17 00:00:00 2001
From: Phil Sutter <psutter@redhat.com>
Date: Wed, 20 Jul 2016 22:59:33 +0200
Subject: [PATCH] ip-address.8: Document autojoin flag

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1333513
Upstream Status: iproute2.git commit 6acf086c2bf3e

commit 6acf086c2bf3e94ceed984acd39936e216342e16
Author: Phil Sutter <phil@nwl.cc>
Date:   Tue Jul 12 09:56:16 2016 +0200

    ip-address.8: Document autojoin flag

    Description copied from related kernel support commit message with a
    little tailoring to fit.

    While at it, fix font of non-terminal CONFFLAG-LIST in synopsis.

    Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 man/man8/ip-address.8.in | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/man/man8/ip-address.8.in b/man/man8/ip-address.8.in
index 8d34adb..c954ab3 100644
--- a/man/man8/ip-address.8.in
+++ b/man/man8/ip-address.8.in
@@ -75,14 +75,15 @@ ip-address \- protocol address management
 .IR FLAG " := "
 .RB "[ " permanent " | " dynamic " | " secondary " | " primary " |"
 .RB [ - ] tentative " | [" - ] deprecated " | [" - ] dadfailed " |"
-.BR temporary " | " CONFFLAG-LIST " ]"
+.BR temporary " |"
+.IR CONFFLAG-LIST " ]"
 
 .ti -8
 .IR CONFFLAG-LIST " := [ "  CONFFLAG-LIST " ] " CONFFLAG
 
 .ti -8
 .IR CONFFLAG " := "
-.RB "[ " home " | " mngtmpaddr " | " nodad " | " noprefixroute " ]"
+.RB "[ " home " | " mngtmpaddr " | " nodad " | " noprefixroute " | " autojoin " ]"
 
 .ti -8
 .IR LIFETIME " := [ "
@@ -244,6 +245,26 @@ address, and don't search for one to delete when removing the address. Changing
 an address to add this flag will remove the automatically added prefix route,
 changing it to remove this flag will create the prefix route automatically.
 
+.TP
+.B autojoin
+Joining multicast groups on Ethernet level via
+.B "ip maddr"
+command does not work if connected to an Ethernet switch that does IGMP
+snooping since the switch would not replicate multicast packets on ports that
+did not have IGMP reports for the multicast addresses.
+
+Linux VXLAN interfaces created via
+.B "ip link add vxlan"
+have the
+.B group
+option that enables them to do the required join.
+
+Using the
+.B autojoin
+flag when adding a multicast address enables similar functionality for
+Openvswitch VXLAN interfaces as well as other tunneling mechanisms that need to
+receive multicast traffic.
+
 .SS ip address delete - delete protocol address
 .B Arguments:
 coincide with the arguments of
-- 
1.8.3.1