Regards _Sugesh
From: Advith Nagappa [mailto:advith.naga...@gmail.com] Sent: Wednesday, October 19, 2016 11:11 AM To: Chandran, Sugesh <sugesh.chand...@intel.com> Cc: discuss@openvswitch.org Subject: Re: [ovs-discuss] OVS - Userspace packet processing Thank you again. [Sugesh] I guess this must be something to do with how mininet configure OVS. Please have a look at the ovs-vswitchd.log file for more details(this shows how OVS is being configured by mininet). Also check if ovs-vswitchd and ovsdb-servers are running on the machine Funnily enough, after you mentioned, I stopped the ovs-vswitchd and ovsdb-servers and ran mn --user switch. And it still runs! pingall works too.. So I tend to think that "mn --switch user" doesn't really use OVS (because the daemon and ovsdb servers are down!). OK, to surmise, the user switch used by mininet has a kernel to user space transition of packets. (but this is not the ovs kernel module , rather the kernel of the underlying hypervisor/guest OS). And this is clearly not the same as user space OVS that is often discussed in the OVS community. I think the question remains is what is OVS user space switch? What happens when a bridge is set with datapath_type=netdev? (In this case, I think the entry point is /lib/dpif_netdev.c -- dp_netdev_process_rxq_port ?) Is there a document resource which explains this datapath type? [Sugesh] Yes(Only for the userspace interfaces) and No(there is no document that explains the datapath type) Also, with DPDK + OVS, I believe the entry point would be /lib/dpif_netdev.c -- dp_netdev_process_rxq_port, right? [Sugesh] Yes And another question would be if userspace OVS is even supported by mininet? (I suppose this question should be discussed in the mininet forum.) [Sugesh] Yes, you must post this question in mininet forum. Best Regards Advith Nagappa On Wed, Oct 19, 2016 at 11:13 AM, Chandran, Sugesh <sugesh.chand...@intel.com<mailto:sugesh.chand...@intel.com>> wrote: Regards _Sugesh From: Advith Nagappa [mailto:advith.naga...@gmail.com<mailto:advith.naga...@gmail.com>] Sent: Wednesday, October 19, 2016 9:15 AM To: Chandran, Sugesh <sugesh.chand...@intel.com<mailto:sugesh.chand...@intel.com>> Cc: discuss@openvswitch.org<mailto:discuss@openvswitch.org> Subject: Re: [ovs-discuss] OVS - Userspace packet processing Thank you again, I am using a mininet set up (mn --switch user), which I think uses the userspace ovs switch. (Is this assumption right? All available documentation uses wording which gives this impression.) [Sugesh] I haven’t used mininet for traffic generation yet so can’t comment on what ‘mn –switch user’ does internally. However from the mininet wiki, its clear that the packets are still comes from the kernel. Read the ‘other switch types’ in http://mininet.org/walkthrough/ And answering your question, the packets from the kernel interfaces are handled by the ovs-vswitchd main thread itself and they may not hit dp_netdev_process_rxq_port. Also your finding is right on the entry point for the packet from kernel interface. To confirm this, I also have removed the openvswitch.ko in my VM. But curiously though, ovs-vsctl show doesn't show any topology: root@cep-VirtualBox:/home/cep# ovs-vsctl show 204aa7ac-2ac9-4277-afcf-e7a3f17fc7c1 This is weird because, mininet initializes two hosts (h1, h2) and one OVS switch s1. And the ping all works fine. [Sugesh] I guess this must be something to do with how mininet configure OVS. Please have a look at the ovs-vswitchd.log file for more details(this shows how OVS is being configured by mininet). Also check if ovs-vswitchd and ovsdb-servers are running on the machine. and to contrast things, I loaded the openvswith.ko (./configure --with-Linux/.... , make install, make modules_install, /sbin/modprobe openvswitch) and ran mininet with the loaded kernel module (sudo mn) root@cep-VirtualBox:/home/cep# ovs-vsctl show 6d14e9f4-de26-4332-93fe-b87e33c532f9 Bridge "s1" Controller "ptcp:6634" Controller "tcp:127.0.0.1:6633<http://127.0.0.1:6633>" is_connected: true fail_mode: secure Port "s1-eth2" Interface "s1-eth2" Port "s1" Interface "s1" type: internal Port "s1-eth1" Interface "s1-eth1" Regards Advith On Wed, Oct 19, 2016 at 9:30 AM, Chandran, Sugesh <sugesh.chand...@intel.com<mailto:sugesh.chand...@intel.com>> wrote: Regards _Sugesh From: Advith Nagappa [mailto:advith.naga...@gmail.com<mailto:advith.naga...@gmail.com>] Sent: Wednesday, October 19, 2016 1:02 AM To: Chandran, Sugesh <sugesh.chand...@intel.com<mailto:sugesh.chand...@intel.com>> Cc: discuss@openvswitch.org<mailto:discuss@openvswitch.org> Subject: Re: [ovs-discuss] OVS - Userspace packet processing Hello Sugesh, Thank you for the response. I am using userspace OVS without DPDK. I do plan to use DPDK at a future point, but currently am trying to understand the behavior of a pure userspace ovs switch. I have put in custom DBG messages in /lib/dpif_netdev. (specifically dp_netdev_process_rxq_port) but this dbg message doesn't get triggered when I ping between two hosts connected by a OVS capable switch. I do see that in this case, the netdev_linux.c module is called, but I don't know who is calling this module (i.e the entry point to the ovs code base) [Sugesh]It looks to me you are using kernel interfaces in your setup, which is not ‘pure’ userspace openvswitch. Can you share the setup details? What type of interface you used to connect hosts to OVS? Any input is appreciated. Best Regards Advith On Tue, Oct 18, 2016 at 10:37 AM, Chandran, Sugesh <sugesh.chand...@intel.com<mailto:sugesh.chand...@intel.com>> wrote: Regards _Sugesh From: discuss [mailto:discuss-boun...@openvswitch.org<mailto:discuss-boun...@openvswitch.org>] On Behalf Of Advith Nagappa Sent: Sunday, October 16, 2016 1:33 AM To: discuss@openvswitch.org<mailto:discuss@openvswitch.org> Subject: [ovs-discuss] OVS - Userspace packet processing Hello, I am running OVS in userspace (rmmod openvswitch.ko). I wanted to the entry point for a packet within the OVS code base. I.e which module first 'sees' the packet in pure userspace OVS. [Sugesh] [Sugesh] Look at the INSTALL.DPDK.md<http://INSTALL.DPDK.md> and INSTALL.DPDK-advanced.md<http://INSTALL.DPDK-advanced.md> for the set up guide. You can start looking at the lib/dpif-netdev.c. mainly the functions such as dp_netdev_process_rxq_port, dp_netdev_input etc. Best Regards Advith
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