[ovs-discuss] Forwarding between Multiple interfaces Openflow

Aaron Rosen arosen at clemson.edu
Tue Mar 1 04:04:36 UTC 2011


Thanks Ben,

Any idea what could be going on here:

>From 130.127.39.173 I'm pinging 192.168.1.2 (I've setup routes on the
network so that packets get to the right end points)

I have dp1 (130.127.39.235) and dp0 (192.168.1.2) on the same computer. If I
run tcpdump on dp1 (which is the interface directly connected to the
internet) I see these packets .

22:58:17.462526 IP 130.127.39.173 > 192.168.1.2: ICMP echo request, id
16684, seq 113, length 64
22:58:17.613943 IP 130.127.39.173 > 192.168.1.2: ICMP echo request, id
30764, seq 13, length 64


Though If I run tcpdump at dp0 I don't see these packets nor do I get
packet-in events for them. You said before that Open vSwitch isn't an IP
stack so does that mean tcpdump isn't going to be working there? Any idea
what I need to do to get packets to route between the two interfaces?
Shouldn't the linux routing tables handle this or not at all?

Thanks,

Aaron

On Mon, Feb 28, 2011 at 10:58 PM, Ben Pfaff <blp at nicira.com> wrote:

> On Mon, Feb 28, 2011 at 7:39 PM, Aaron Rosen <arosen at clemson.edu> wrote:
> > I have one more question, If dp0 receives a packet that is not ip
> > protocol 0x800 but instead is an IPIP packet would there be any reason
> > why it wouldn't forward the packet to the controller as a packet-in
> > event rather than sending an ICMP protocol not support packet?
>
> Open vSwitch isn't an IP stack, so it is not going to send back
> an ICMP protocol not supported response on its own.  Something else
> must be generating that; for example, if the controller is causing
> packets to be directed to the Linux IP stack (e.g. by sending them to
> eth local port) but the Linux IP stack is not configured to handle IPIP
> packets, then this seems like plausible behavior.
> --
> "I don't normally do acked-by's.  I think it's my way of avoiding
> getting blamed when it all blows up."               Andrew Morton
>



-- 
Aaron O. Rosen
Masters Student - Network Communication
306B Fluor Daniel
843.425.9777
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