[ovs-discuss] How to make Open vSwitch a router

Jesse Gross jesse at nicira.com
Wed Nov 10 04:31:55 UTC 2010


On Tue, Nov 9, 2010 at 7:52 PM, Derek Cormier
<derek.cormier at lab.ntt.co.jp> wrote:
> *My apologies, the formatting of my diagram got messed up after I sent it. I
> think it still gets the point across thought, vm1 and vm2 are connected to
> br0 and vm3 is connected to br1.
>
> @Martin: I see. Do you know if anyone has tried this before?

I doubt it.  For one thing, OpenFlow 1.0 doesn't provide the ability
to modify the TTL, so it's not actually possible to create a standards
compliant router, short of sending all packets to the controller.

>
> Something I'm a bit confused about: When you plug an Ethernet cable into a
> router, the router's NIC has an IP address. In the case of Open vSwitch,
> does that interface correspond to the IP address of the bridge?

Open vSwitch is modeling a switch and switches don't have IP addresses
on their ports.  The IP address of the bridge is essentially a switch
port that is directly attached to the host OS.

A router, on the other hand, would need an IP address on each subnet
that you want to route between.  Those IP addresses would need to be
configured on the controller, which it would use to know what traffic
is directed to the router to respond to ARP requests, etc.




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