Re: ipv6 addresses on vifX.Y interfaces and bridges

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Jan 07, 2008 at 09:26:43AM +1100, James Harper wrote:
> The network scripts appear to set noarp on all the vifX.Y and xen-brX
> interfaces, but I also need to remove the IPv6 address and stop the
> interfaces participating in autoconfiguration...
> 
> Has anyone done this already?

You don't need to remove the link-local IPv6 addresses, they are harmless.
The key is to stop auto-conf taking place on the bridge. The way todo
this is to set the mtu of the bridge to something tiny (eg 68) before
bringing the interface up, and then once it is up, restore the mtu to
its normal 1500. 

This was previously merged in xen-unstable, in 13364

diff -r c71fe03f086f -r c2fd75d7e2b7 tools/examples/xen-network-common.sh
--- a/tools/examples/xen-network-common.sh      Fri Jan 12 15:19:23 2007 +0000
+++ b/tools/examples/xen-network-common.sh      Fri Jan 12 15:23:07 2007 +0000
@@ -117,7 +117,12 @@ create_bridge () {
         ip link set ${bridge} arp off
         ip link set ${bridge} multicast off
     fi
+
+    # A small MTU disables IPv6 (and therefore IPv6 addrconf).
+    mtu=$(ip link show ${bridge} | sed -n 's/.* mtu \([0-9]\+\).*/\1/p')
+    ip link set ${bridge} mtu 68
     ip link set ${bridge} up
+    ip link set ${bridge} mtu ${mtu:-1500}
 }
 
 # Usage: add_to_bridge bridge dev


But for some reason got chopped out in changeset 15203

Dan.
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