[ovs-discuss] Help in understanding the code

[sujith p s]

Need a hand here..Please..

Installed OpenvSwitch at first.Worked as expected.
Later made a few, small changes (basically, inserting printk statements) in
the ovs_dp_process_received_packet() of datapath.c in datapath directory.

I compile using following commands:
sudo kill `cd /usr/local/var/run/openvswitch && cat ovsdb-server.pid
ovs-vswitchd.pid`
./boot.sh
./configure
./configure --with-linux=/lib/modules/3.5.0-17-generic/build
make
sudo make install
sudo make modules_install
sudo /sbin/modprobe openvswitch
lsmod --> shows openvswitch


Then start daemons using commands:
sudo ovsdb-tool convert /usr/local/etc/openvswitch/conf.db
vswitchd/vswitch.ovsschema
sudo ovsdb-server --remote=punix:/usr/local/var/run/openvswitch/db.sock <
etc > < etc > --pidfile --detach
sudo ovs-vsctl --no-wait init
sudo ovs-vswitchd --pidfile --detach

Everything goes fine.

But I am unable to see my changes after running the "$sudo mn
--switch=ovsk" and tried ping command in mininet.
mininet> h1 ping -c5 h2
Checked dmesg and syslog.
Am I going wrong somewhere in dealing with ovs kernel modules?
( printk statements are having KERN_INFO severity. Ex: printk(KERN_INFO
"Received packet..Trying to match the flow.."); )

Thanks in advance,
Sujith


On Wed, Jul 10, 2013 at 10:12 PM, sujith p s <sujithpandels at gmail.com>wrote:

> Thanks for the quick reply!
>
> Regarding the reason for not getting error for VLOG_INFO in my datapath
> module:
> Backtracing my steps, I found out that i missed configuring/make-ing the
> kernel modules after the code changes.
> Thanks for suggesting printk option.
>
>
> Regards,
> Sujith
>
>
> On Wed, Jul 10, 2013 at 8:08 PM, Andy Zhou <azhou at nicira.com> wrote:
>
>> The remaining icmp packets are indeed processed in the kernel (via
>> ovs_dp_process_received_packet()). ovs-vswitchd will install a flow entry
>> in the kernel to handle those packets.
>> You can inspect kernel flows with "ovs-dpctl dump-flows".
>>
>> VLOG_INFO is only for user space programs. I am surprised it compiled
>> with kernel module. printk may work better.
>>
>> --andy
>>
>>
>>  On Wed, Jul 10, 2013 at 4:20 AM, sujith p s <sujithpandels at gmail.com>wrote:
>>
>>>  Hi everyone!
>>> I'm a newcomer to OpenvSwitch. I installed it in mininet-VM using the
>>> INSTALL guide provided.
>>> I am curious to understand the flow of the code in case of ping.
>>>
>>> Example topology:
>>> $ sudo mn --switch=ovsk --topo linear
>>>
>>>  h1 -- s1 -- s2 -- h2
>>>
>>> command:
>>> mininet> h1 ping -c5 h2
>>>
>>> ofproto_run recognises a new flow ( 1st ping packet - icmp echo from h1
>>> to h2 ) and send it as PACKET_IN to the controller.
>>> Controller sends back the respective FLOW_MOD back to switch s1.
>>> handle_openflow() function takes care of these things.
>>> Similarly above 2 steps happens for icmp echo reply from h2 to h1.
>>>
>>> Now, I understand that since flow_mods are already installed in the flow
>>> table, there's no need to contact the controller once again for the 2nd
>>> icmp-echo packet from h1 to h2.
>>>
>>> What I wanted to know is which module(s) manages the remaining icmp
>>> packets, i.e. checking for a match and do the forwarding of these packets
>>> through mentioned port of the switch.
>>>
>>> It looks like ovs_dp_process_received_packet() in datapath.c So I tried
>>> checking by inserting VLOG_INFO statements in the module and installed it
>>> again. Looks like I was wrong about that.
>>>
>>> I wanted to make sure that I am in the correct path.
>>>
>>> Can anyone help me please!
>>>
>>> Thanks in advance
>>> Sujith
>>>
>>> _______________________________________________
>>> discuss mailing list
>>> discuss at openvswitch.org
>>> http://openvswitch.org/mailman/listinfo/discuss
>>>
>>>
>>
>
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