From a088d1d73a4bcfd7bc482f8d08375b9b665dc3e5 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Linus=20L=C3=BCssing?= Date: Fri, 3 Feb 2017 08:11:03 +0100 Subject: [PATCH] ipv6: Fix IPv6 packet loss in scenarios involving roaming + snooping switches MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When for instance a mobile Linux device roams from one access point to another with both APs sharing the same broadcast domain and a multicast snooping switch in between: 1) (c) <~~~> (AP1) <--[SSW]--> (AP2) 2) (AP1) <--[SSW]--> (AP2) <~~~> (c) Then currently IPv6 multicast packets will get lost for (c) until an MLD Querier sends its next query message. The packet loss occurs because upon roaming the Linux host so far stayed silent regarding MLD and the snooping switch will therefore be unaware of the multicast topology change for a while. This patch fixes this by always resending MLD reports when an interface change happens, for instance from NO-CARRIER to CARRIER state. Signed-off-by: Linus Lüssing Signed-off-by: David S. Miller --- net/ipv6/addrconf.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index f60e88e56255..81f7b4ea4281 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -3386,9 +3386,15 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, } if (idev) { - if (idev->if_flags & IF_READY) - /* device is already configured. */ + if (idev->if_flags & IF_READY) { + /* device is already configured - + * but resend MLD reports, we might + * have roamed and need to update + * multicast snooping switches + */ + ipv6_mc_up(idev); break; + } idev->if_flags |= IF_READY; } -- 2.20.1