On Tue, Jun 16, 2015 at 06:31:39PM -0700, masoom alam wrote:
> I want to enable Promiscuous mode in OVS so that on a port of my choice I
> can listen to the traffic being passed through OVS. How is this possible?
This is a FAQ.
### Q: Does Open vSwitch support configuring a port in promiscuous mode?
A: Yes. How you configure it depends on what you mean by "promiscuous
mode":
- Conventionally, "promiscuous mode" is a feature of a network
interface card. Ordinarily, a NIC passes to the CPU only the
packets actually destined to its host machine. It discards
the rest to avoid wasting memory and CPU cycles. When
promiscuous mode is enabled, however, it passes every packet
to the CPU. On an old-style shared-media or hub-based
network, this allows the host to spy on all packets on the
network. But in the switched networks that are almost
everywhere these days, promiscuous mode doesn't have much
effect, because few packets not destined to a host are
delivered to the host's NIC.
This form of promiscuous mode is configured in the guest OS of
the VMs on your bridge, e.g. with "ifconfig".
- The VMware vSwitch uses a different definition of "promiscuous
mode". When you configure promiscuous mode on a VMware vNIC,
the vSwitch sends a copy of every packet received by the
vSwitch to that vNIC. That has a much bigger effect than just
enabling promiscuous mode in a guest OS. Rather than getting
a few stray packets for which the switch does not yet know the
correct destination, the vNIC gets every packet. The effect
is similar to replacing the vSwitch by a virtual hub.
This "promiscuous mode" is what switches normally call "port
mirroring" or "SPAN". For information on how to configure
SPAN, see "How do I configure a port as a SPAN port, that is,
enable mirroring of all traffic to that port?"
_______________________________________________
discuss mailing list
[email protected]
http://openvswitch.org/mailman/listinfo/discuss
