.TH LIBVDEPLUG_MULTI 1 "April 30, 2017" "Virtual Distributed Ethernet"
.SH NAME
libvdeplug_multi - multiplexing vdeplug module: multilink
.SH SYNOPSIS
libvdeplug_multi.so
.SH DESCRIPTION
This is a libvdeplug multiplex module implementing a multilink.

The common usage of this module is to support (usually temporary) multiple links between
virtual machines or switches. This module can be used to implement hand-offs betweek links:
a new link can be set-up and then the old one is closed.
When both links are active, packets can be duplicated.

This module of libvdeplug4 can be used in any program supporting vde like
\fBvde_plug\fR, \fBkvm\fR, \fBqemu\fR, \fBuser-mode-linux\fR and \fBvirtualbox\fR.

The vde_plug_url syntax of this module is the following:
.RS
.B multi://\fR[\fIpath\fR]
.br
.B multi://\fR[\fIpath\fR]\fB[\fR[\fIOPTION\fR][\fB/\fIOPTION\fR][\fB/\fIOPTION\fR]...\fB]
.br
.RE

If \fIpath\fR is omitted the path of the multi is /tmp/vdenode_$USERNAME (e.g. /tmp/vdenode_john
if the username is john).

.SH OPTIONS
.TP
\fBmode=\fR\fIMODE
define the permissions for the multilink (see chmod). MODE is an octal number.
The standard permission mask is: 0600 (only processes owning to the same user can join the network).
.TP
\fBdirmode=\fR\fIDIRMODE
define the permissions for the multilink control directory(see chmod). MODE is an octal number.
If omitted, is computed from mode.
.TP
\fBgrp=\fR\fIGROUP
define the group ownership of the multilink.
.SH EXAMPLES
.B multi:///tmp/multi
.br
Other virtual machines, namespaces or vde_plug can join this multilink using \fBvde:///tmp/hub\fR or simply \fB/tmp/hub\fR
.br
Given two virtual machines using \fBmulti:///tmp/vm1\fR and \fBmulti:///tmp/vm2\fR respectively, it is possible to 
connect them using \fBvde_plug /tmp/vm1 /tmp/vm2\fR. If the second virtual machine is running on a remote hosts; 
\fBip1.vm2.domain.org\fR and \fBip2.vm2.domain.org\fR are two ip addresses permitting to reach that remote host using
different paths, the command \fBvde_plug /tmp/vm1 = ssh ip1.vm2.domain.org vde_plug /tmp/vm2\fR connects the two vms.
In a second time is possible to run \fBvde_plug /tmp/vm1 = ssh ip2.vm2.domain.org vde_plug /tmp/vm2\fR to create another
channel on the other path. When both connections are in place packets can arrive duplicated (the upper protocols can
manage the problem). Then the process connecting the remotevm using \fBip1.vm2.domain.org\fR can be killed, completing
in this way the (hiccup-less) handoff.
.br
.B multi:///tmp/multi[mode=0666]
.br
It is the same multilink, but everybody is allowed to connect their processes.
.SH NOTICE
Virtual Distributed Ethernet is not related in any way with
www.vde.com ("Verband der Elektrotechnik, Elektronik und Informationstechnik"
i.e. the German "Association for Electrical, Electronic & Information
Technologies").
.SH SEE ALSO
\fBvde_plug\fP(1),