From 0ef548b9c90da05b60b8bffe83680afd80b2d4cb Mon Sep 17 00:00:00 2001 From: Matthias Radestock Date: Tue, 6 Oct 2015 16:25:02 +0100 Subject: [PATCH] prevent dropping of large multicast packets Fixes #1507. --- weave | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/weave b/weave index ae1560e1..e051f096 100755 --- a/weave +++ b/weave @@ -543,8 +543,14 @@ attach() { # Route multicast packets across the weave network. # This must come last in 'attach'. If you change this, change weavewait to match. + # + # The MTU lock prevents PMTU discovery for multicast + # destinations. Without that, the kernel sets the DF flag on + # multicast packets. Since RFC1122 prohibits sending of ICMP + # errors for packets with multicast destinations, that causes + # packets larger than the PMTU to be dropped silently. if ! netnsenter ip route show | grep '^224\.0\.0\.0/4' >/dev/null ; then - netnsenter ip route add 224.0.0.0/4 dev $CONTAINER_IFNAME + netnsenter ip route add 224.0.0.0/4 dev $CONTAINER_IFNAME mtu lock $MTU fi }