[ovs-discuss] Set up OpenFlow using OpenvSwitch

Yue ZHANG cassidy.zy at gmail.com
Thu Nov 11 03:41:57 UTC 2010


Dear Jesse,


Thanks very much for looking at it, I've just made it work following the INSTALL.KVM very exactly.
There should be something wrong with my KVM configuration before, since I did not use ovs-ifup & ovs-ifdown scripts, just connect the port after qemu started.
I don't know what's the difference between them, but it could work. It's very kind of you, thanks.


        2010-11-11
        Yue ZHANG
        cassidy.zy at gmail.com





2010/11/9 Yue ZHANG <cassidy.zy at gmail.com>: 
> Hi, dear, 
> 
> 
> Thanks for your quickly reply. 
> 
> I've insmod the OvS to replace original kernal bridge in the KVM host, and 
> configured br0 and vif1(qemu param:-net tap,vlan=0,ifname=vif1) which is the 
> interface of the KVM guest. 
> 
> #ovs-vsctl add-br br0 
> #ovs-vsctl add-port br0 vif1 
> 
> Then it seems like that: 
> #ovs-dpctl show br0 
> system at dp0: 
>  flows: xxxx 
>       ?... 
>       ?port 0: br0 (internal) 
>       ?port 1: vif1               <--- The KVM guest interface 
> 
> 
> Then I ifconfig br0 with 192.168.2.1 in the KVM host, and ifconfig eth0 with 
> 192.168.2.2 in the KVM guest. 
> 
> I think the KVM guest(192.168.2.2) and br0(192.168.2.1) should be connected 
> automatically, is it? But the tcpdump result is strange that the vif1 could 
> send packet to br0, but could not receive any incoming packet. 
> 
> If ping from kvm guest(2.2) to br0(2.1), br0 will receive arp request and 
> return mac addr correctly, but the guest(2.2) will not receive the returned 
> mac addr. 
> If ping from br0 to kvm guest, br0 sent arp request, but kvm guest(2.2) 
> still received no packet. 
> 
> There maybe something wrong, either the configuration of OvS or the KVM, it 
> will be great help if you have some ideas, or give me some suggestions on 
> how to debug, thanks! 

Hmm, normally traffic should be able to flow in both directions, 
assuming a default configuration. Are you using an OpenFlow 
controller? 

Assuming not, there are a few things that I would look at: 
ovs-ofctl dump-flows br0 (this will give the high level OpenFlow flows) 
ovs-dpctl dump-flows br0 (this will show how the OpenFlow flows are 
applied to the current traffic) 
tcpdump on the various interfaces: br0, vif1, eth0 in the guest to see 
where traffic is getting dropped or if it is making it through but the 
OS is not responding 
. 
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