.\" Copyright (c) 2012 Luigi Rizzo, Universita` di Pisa
.\" All rights reserved.
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.\" This document is derived in part from the enet man page (enet.4)
.\" distributed with 4.3BSD Unix.
.\" $Id: $
.\"
.Dd August 30, 2024
.Dt VALE 4
.Os
.Sh NAME
.Nm vale
.Nd a very fast Virtual Local Ethernet using the netmap API
.Sh SYNOPSIS
.Cd device netmap
.Sh DESCRIPTION
.Nm
is a feature of the
.Xr netmap 4
module that implements multiple Virtual switches that can
be used to interconnect netmap clients, including traffic
sources and sinks, packet forwarders, userspace firewalls,
and so on.
.Pp
.Nm
is implemented completely in software, and is extremely fast.
On a modern machine it can move almost 20 Million packets per
second (Mpps) per core with small frames, and about 70 Gbit/s
with 1500 byte frames.
.Sh OPERATION
.Nm
dynamically creates switches and ports as clients connect
to it using the
.Xr netmap 4
API.
.Pp
.Nm
ports are named
.Pa valeSSS:PPP
where
.Pa vale
is the prefix indicating a VALE switch rather than a standard interface,
.Pa SSS
indicates a specific switch (the colon is a separator),
and
.Pa PPP
indicates a port within the switch.
Both SSS and PPP have the form [0-9a-zA-Z_]+ , the string cannot
exceed IFNAMSIZ characters, and PPP cannot be the name of any
existing OS network interface.
.Pp
See
.Xr netmap 4
for details on the API.
.Ss LIMITS
.Nm
currently supports up to 254 ports per switch. The maximum
number of switches is provided by the max_bridges sysctl variable.
.Sh SYSCTL VARIABLES
See
.Xr netmap 4
for a list of sysctl variables that affect
.Nm
bridges.
.Sh EXAMPLES
Create one switch, with a traffic generator connected to one
port, and a netmap-enabled tcpdump instance on another port:
.Bd -literal -offset indent
tcpdump -ni valea:1 &
pkt-gen  -i valea:0 -f tx &
.Ed
.Pp
Create two switches,
each connected to two qemu machines on different ports.
.Bd -literal -offset indent
qemu -net nic -net netmap,ifname=vale1:a ... &
qemu -net nic -net netmap,ifname=vale1:b ... &
qemu -net nic -net netmap,ifname=vale2:c ... &
qemu -net nic -net netmap,ifname=vale2:d ... &
.Ed
.Sh SEE ALSO
.Xr netmap 4 ,
.Xr valectl 8
.Pp
Luigi Rizzo, Giuseppe Lettieri: VALE, a switched ethernet for virtual machines,
June 2012, http://info.iet.unipi.it/~luigi/vale/
.Sh AUTHORS
.An -nosplit
The
.Nm
switch was designed and implemented in 2012 by
.An Luigi Rizzo
and
.An Giuseppe Lettieri
at the Universita` di Pisa.
.Pp
.Nm
was funded by the European Commission within FP7 Projects
CHANGE (257422) and OPENLAB (287581).