[ovs-dev] MacVTap support in OVS

Balaji.P at freescale.com Balaji.P at freescale.com
Thu May 8 10:04:19 UTC 2014


Hi Jesse,

IMHO, MacVTap support in OVS will give a performance boost for the VM traffic.

Regards,
Balaji.P

> -----Original Message-----
> From: dev [mailto:dev-bounces at openvswitch.org] On Behalf Of Jesse Gross
> Sent: Friday, May 02, 2014 11:33 PM
> To: Suresh Kumar Reddy Reddygari
> Cc: dev at openvswitch.org
> Subject: Re: [ovs-dev] MacVTap support in OVS
> 
> On Fri, May 2, 2014 at 3:04 AM, Suresh Kumar Reddy Reddygari
> <Suresh.Reddy at emulex.com> wrote:
> >
> >
> >> -----Original Message-----
> >> From: Jesse Gross [mailto:jesse at nicira.com]
> >> Sent: Thursday, May 01, 2014 10:07 PM
> >> To: Suresh Kumar Reddy Reddygari
> >> Cc: dev at openvswitch.org
> >> Subject: Re: [ovs-dev] MacVTap support in OVS
> >>
> >> On Thu, May 1, 2014 at 2:00 AM, Suresh Kumar Reddy Reddygari
> >> <Suresh.Reddy at emulex.com> wrote:
> >> > Hi,
> >> >
> >> > Is MacVTap support there in OVS. If not, is there any plan to
> support it.
> >>
> >> No.
> >>
> >> What are you trying to do?
> >
> > Hi Jesse,
> >
> > As you know, Hypervisors like Xen/Citrix/KVM typically host one or
> > more virtual machines (VMs) and provide network connectivity to the VMs
> by connecting to the uplink Ethernet interface via a bridge module such
> as Linux Bridge or Open vSwitch (OVS.)  The Hypervisors (citrix)
> configure the uplink interface in MAC and VLAN promiscuous mode. But the
> MacVTap driver does not configure the up-link Ethernet interface in
> promiscuous mode. Instead, it programs the up-link Ethernet interface
> with the MAC addresses and VLANs used by the virtual NICs in the VMs.
> > Please correct me if I am wrong.
> >
> > There are some advantages by using MacVTap. Hence I am looking for
> MacVTap support in OVS.
> >
> > Why are we not supporting MacVTap in OVS ? Are there any disadvantages
> ?
> 
> macvtap is a parallel mechanism for connecting VMs. It does not make
> sense to "support" it in OVS.
> 
> It is theoretically possible to have OVS configure MAC and VLAN filters
> in the NIC. However, in most cases the upstream switch will flood
> relatively few unknown packets so the advantages are minimal.
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