[src/trunk]: src/share/man/man4 Note that opening and closing the tun/tap dev...

[roy <roy%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/befd97580608
branches:  trunk
changeset: 939694:befd97580608
user:      roy <roy%NetBSD.org@localhost>
date:      Sun Sep 27 19:36:54 2020 +0000

description:
Note that opening and closing the tun/tap devices affects link state.

And how this influences Duplicate Address Detection.

diffstat:

 share/man/man4/tap.4 |  10 +++++++++-
 share/man/man4/tun.4 |  12 ++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diffs (57 lines):

diff -r 31ea14b99fad -r befd97580608 share/man/man4/tap.4
--- a/share/man/man4/tap.4      Sun Sep 27 19:25:54 2020 +0000
+++ b/share/man/man4/tap.4      Sun Sep 27 19:36:54 2020 +0000
@@ -1,4 +1,4 @@
-.\" $NetBSD: tap.4,v 1.14 2020/09/27 15:19:04 roy Exp $
+.\" $NetBSD: tap.4,v 1.15 2020/09/27 19:36:54 roy Exp $
 .\"
 .\"  Copyright (c) 2004, 2005 The NetBSD Foundation.
 .\"  All rights reserved.
@@ -159,6 +159,14 @@
 .Dv PF_LINK
 socket, as it is not available on
 the ioctl handler of the character device interface.
+.Ss LINK STATE
+When an application has opened the
+.Nm
+character device the link is considered up, otherwise down.
+As such, it is best to open the character device once connectivity has
+been established so that Duplicate Address Detection, if applicable,
+can be performed.
+If connectivity is lost, the character device should be closed.
 .Sh FILES
 .Bl -tag -compact -width /dev/tap[0-9]*
 .It Pa /dev/tap
diff -r 31ea14b99fad -r befd97580608 share/man/man4/tun.4
--- a/share/man/man4/tun.4      Sun Sep 27 19:25:54 2020 +0000
+++ b/share/man/man4/tun.4      Sun Sep 27 19:36:54 2020 +0000
@@ -1,4 +1,4 @@
-.\" $NetBSD: tun.4,v 1.24 2019/03/26 09:58:20 pgoyette Exp $
+.\" $NetBSD: tun.4,v 1.25 2020/09/27 19:36:54 roy Exp $
 .\"
 .\" Copyright (c) 1996-2006 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd April 8, 2006
+.Dd September 27, 2020
 .Dt TUN 4
 .Os
 .Sh NAME
@@ -272,6 +272,14 @@
 If the interface is up when the data device is not open
 output packets are always thrown away rather than letting
 them pile up.
+.Ss LINK STATE
+When an application has opened the
+.Nm
+character device the link is considered up, otherwise down.
+As such, it is best to open the character device once connectivity has
+been established so that Duplicate Address Detection, if applicable,
+can be performed.
+If connectivity is lost, the character device should be closed.
 .Sh SEE ALSO
 .Xr inet 4 ,
 .Xr intro 4