Date: Tue, 9 Jul 2013 07:55:47 +0000 (UTC) From: Hiroki Sato <hrs@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r253060 - head/share/man/man4 Message-ID: <201307090755.r697tls1002774@svn.freebsd.org>
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Author: hrs Date: Tue Jul 9 07:55:47 2013 New Revision: 253060 URL: http://svnweb.freebsd.org/changeset/base/253060 Log: Document IPv6 support. Modified: head/share/man/man4/bridge.4 Modified: head/share/man/man4/bridge.4 ============================================================================== --- head/share/man/man4/bridge.4 Tue Jul 9 07:51:11 2013 (r253059) +++ head/share/man/man4/bridge.4 Tue Jul 9 07:55:47 2013 (r253060) @@ -35,7 +35,7 @@ .\" .\" $FreeBSD$ .\" -.Dd January 9, 2010 +.Dd July 3, 2013 .Dt IF_BRIDGE 4 .Os .Sh NAME @@ -142,6 +142,79 @@ This can be used to multiplex the input stream. This is useful for reconstructing the traffic for network taps that transmit the RX/TX signals out through two separate interfaces. +.Sh IPV6 SUPPORT +.Nm +supports the +.Li AF_INET6 +address family on bridge interfaces. +The following +.Xr rc.conf 5 +variable configures an IPv6 link-local address on +.Li bridge0 +interface: +.Bd -literal -offset indent +ifconfig_bridge0_ipv6="up" +.Ed +.Pp +or in a more explicit manner: +.Bd -literal -offset indent +ifconfig_bridge0_ipv6="inet6 auto_linklocal" +.Ed +.Pp +However, the +.Li AF_INET6 +address family has a concept of scope zone. +Bridging multiple interfaces change the zone configuration because +multiple links are merged to each other and form a new single link +while the member interfaces still work individually. +This means each member interface still has a separate link-local scope +zone and the +.Nm +interface has another single, +aggregated link-local scope zone at the same time. +This situation is clearly against the description +.Qq zones of the same scope cannot overlap +in Section 5, +RFC 4007. +Although it works in most cases, +it can cause some conterintuitive or undesirable behavior in some +edge cases when both of the +.Nm +interface and one of the member interface have an IPv6 address +and applications use both of them. +.Pp +To prevent this situation, +.Nm +checks whether an link-local scoped IPv6 address is configured on +a member interface to be added and the +.Nm +interface. +When the +.Nm +interface has IPv6 addresses, +IPv6 addresses on the member interface will be automatically removed +before the interface is added. +When both +.Nm +interface and the existing member interfaces do not have one, +adding an interface with IPv6 addresses as a new member interface is allowed. +These means only one interface in the link-local scope zone where the +.Nm +interface forms can have link-local scoped IPv6 addresses. +.Pp +Note that +.Li ACCEPT_RTADV +and +.Li AUTO_LINKLOCAL +interface flag are not enabled by default on +.Nm +interface even when +.Va net.inet6.ip6.accept_rtadv +and/or +.Va net.inet6.ip6.auto_linklocal +is set to +.Li 1 . +.Ed .Sh SPANNING TREE The .Nm
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