Thanks, Ben, for your response. This clears things up for me. The routing function must be provided by an outside means, whether an OF controller, or a host-based or perhaps external router (trunk connection to external router, what is called "router-on-a-stick" in some circles.) I was just trying to determine if OVS itself had a routing function "built-in" (static or perhaps even dynamic) that I was missing.
Best, Will On Nov 19, 2012, at 11:47 PM, Ben Pfaff <[email protected]> wrote: > On Mon, Nov 19, 2012 at 10:21:50PM -0500, Willard Dennis wrote: >> 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.net for >> 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.) > > I'm not sure what the exact intent of that claim is. It may simply mean > that Open vSwitch can match and act based on multiple layers > (specifically, L2, L3, and L4). But I believe that it is still correct, > even if one takes the narrower meaning that you suggest, because there > are at least two ways that you can implement routing with OVS. One is > to use OpenFlow, with a controller. Another is to use the Linux TCP/IP > stack, on the same box running Open vSwitch, possibly with network > namespaces to implement separation. _______________________________________________ discuss mailing list [email protected] http://openvswitch.org/mailman/listinfo/discuss
