Oh dear, I referenced the wrong link on Scott Lowe's blog... The correct
one should be:
http://blog.scottlowe.org/2012/10/31/layer-3-routing-with-open-vswitch/

Thanks.


On Mon, Nov 19, 2012 at 10:21 PM, Willard Dennis
<[email protected]>wrote:

> Hello all,
>
> On the OVS homepage, under the heading "What is Open vSwitch?" it states:
> "Open vSwitch is a production quality, multilayer virtual switch [...]"
>
> My understanding of a multilayer switch is one that not only does
> traditional layer two switching, possibly with multiple VLANs (i.e
> maintains separate L2 forwarding tables for each VLAN) but that also can do
> routing between such VLANs (via virtual VLAN interfaces) without
> requiring an outboard router.
>
> In a testbed setup (comprised of a single Ubuntu Linux box) that I
> recently constructed to learn more about Open vSwitch (and OpenFlow, though
> that is ancillary to this discussion) I instantiated a OVS soft-switch that
> has three VLANs on it:
> VLAN 10 - actual physical ports (interfaces = eth0, eth1, etc.), used to
> communicate with physical infrastructure
> VLAN 20 - VM hosts (interfaces = vnet0, vnet1, etc - in this case, I'm
> using KVM with libvirt)
> VLAN 30 - connection to a router virtualization platform
> (Dynamips/Dynagen/GNS3) via a tuntap interface [see http://www.gns3.netfor 
> more detail if desired]
>
> In looking into how to then configure routing between the three VLANs
> within OVS, and not finding anything on the OVS site, I finally came upon
> this article:
> http://blog.scottlowe.org/2010/04/23/configuring-inter-vlan-routing/
>
> So, it seems that the (current) OVS switch implementation is not what I'd
> think of as a "multilayer" switch, as it seems that you have to use the
> Linux kernel routing to perform the routing between the "vlanX" interfaces
> (and this would be an "outboard" router to OVS to me.)
>
> Am I confused as to the nature of "multilayer" in the OVS context? And, is
> it true that routing between VLANs (at least at this point) be handled by
> an "outboard" router, or can OVS handle inter-VLAN routing "natively"
> somehow? Please do not interpret this as any sort of a "slam" on OVS, it's
> amazing software and quite useful to me just as it is... Just trying to
> understand.
>
> Thanks for reading and responding...
>
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