a very fast Virtual Local Ethernet using the netmap
is a feature of the
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.
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.
dynamically creates switches and ports
as clients connect to it using the
ports are named
is the prefix indicating a VALE switch
rather than a standard interface, SSS
indicates a specific switch (the colon is a separator), and
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
for details on the API.
currently supports up to 4 switches, 16
ports per switch, with 1024 buffers per port. These hard limits will be
changed to sysctl variables in future releases.
uses the following sysctl variables to
- The maximum number of packets processed internally in each iteration.
Defaults to 1024, use lower values to trade latency with throughput.
- Set to non-zero values to enable in-kernel diagnostics.
Create one switch, with a traffic generator connected to one port, and a
netmap-enabled tcpdump instance on another port:
tcpdump -ni valea:1 &
pkt-gen -i valea:0 -f tx &
Create two switches, each connected to two qemu machines on different ports.
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 ... &
Luigi Rizzo, Giuseppe Lettieri: VALE, a switched ethernet for virtual machines,
June 2012, http://info.iet.unipi.it/~luigi/vale/
switch was designed and implemented
in 2012 by Luigi Rizzo
at the Universita` di
was funded by the European Commission
within FP7 Projects CHANGE (257422) and OPENLAB (287581).