Open vSwitch (OVS) allows Virtual Machines (VM) to communicate with each other and with the outside world. OVS traditionally resides in the hypervisor and switching is based on twelve tuple matching on flows. The OVS software based solution is CPU intensive, affecting system performance and preventing full utilization of the available bandwidth. The current OVS supported is OVS running in Linux Kernel.
Mellanox Accelerated Switching And Packet Processing (ASAP2) technology allows OVS offloading by handling OVS data-plane in Mellanox ConnectX-5 onwards NIC hardware (Mellanox Embedded Switch or eSwitch) while maintaining OVS control-plane unmodified. As a result, we observe significantly higher OVS performance without the associated CPU load.
The current actions supported by ASAP2 include packet parsing and matching, forward, drop along with VLAN push/pop or VXLAN encapsulation/decapsulation.
Install the required packages. For the complete solution, you need to install supporting MLNX_EN (v4.4 and above), iproute2, and openvswitch packages.
To set up SR-IOV:
Choose the desired card.
The example below shows a dual-ported ConnectX-5 card (device ID 0x1017) and a single SR-IOV VF (Virtual Function, device ID 0x1018).
In SR-IOV terms, the card itself is referred to as the PF (Physical Function).# lspci -nn | grep Mellanox 0a:
00.0Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017] 0a:00.1Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017] 0a:00.2Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5Virtual Function] [15b3:1018]WarningEnabling SR-IOV and creating VFs is done by the firmware upon admin directive as explained in Step 5 below.
Identify the Mellanox NICs and locate net-devices which are on the NIC PCI BDF.
# ls -l /sys/
class/net/ | grep04:00lrwxrwxrwx1root root0Mar2716:58enp4s0f0 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.0/net/enp4s0f0 lrwxrwxrwx1root root0Mar2716:58enp4s0f1 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.1/net/enp4s0f1 lrwxrwxrwx1root root0Mar2716:58eth0 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.2/net/eth0 lrwxrwxrwx1root root0Mar2716:58eth1 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.3/net/eth1The PF NIC for port #1 is enp4s0f0, and the rest of the commands will be issued on it.
Check the firmware version.
Make sure the firmware versions installed are as state in the Release Notes document.# ethtool -i enp4s0f0 | head -
5driver: mlx5_core version:5.0-5firmware-version:16.21.0338expansion-rom-version: bus-info:0000:04:00.0Make sure SR-IOV is enabled on the system (server, card).
Make sure SR-IOV is enabled by the server BIOS, and by the firmware with up to N VFs, where N is the number of VFs required for your environment. Refer to "Mellanox Firmware Tools" below for more details.# cat /sys/
class/net/enp4s0f0/device/sriov_totalvfs4Turn ON SR-IOV on the PF device.
# echo
2> /sys/class/net/enp4s0f0/device/sriov_numvfsProvision the VF MAC addresses using the IP tool.
# ip link set enp4s0f0 vf
0mac e4:11:22:33:44:50# ip link set enp4s0f0 vf1mac e4:11:22:33:44:51Verify the VF MAC addresses were provisioned correctly and SR-IOV was turned ON.
# cat /sys/
class/net/enp4s0f0/device/sriov_numvfs2# ip link show dev enp4s0f0256: enp4s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu1500qdisc mq master ovs-system state UP mode DEFAULT groupdefaultqlen1000link/ether e4:1d:2d:60:95:a0 brd ff:ff:ff:ff:ff:ff vf0MAC e4:11:22:33:44:50, spoof checking off, link-state auto vf1MAC e4:11:22:33:44:51, spoof checking off, link-state autoIn the example above, the maximum number of possible VFs supported by the firmware is 4 and only 2 are enabled.
Provision the PCI VF devices to VMs using PCI Pass-Through or any other preferred virt tool of choice, e.g virt-manager.
For further information on SR-IOV, refer to https://support.mellanox.com/docs/DOC-2386.
Unbind the VFs.
echo
0000:04:00.2> /sys/bus/pci/drivers/mlx5_core/unbind echo0000:04:00.3> /sys/bus/pci/drivers/mlx5_core/unbindWarningVMs with attached VFs must be powered off to be able to unbind the VFs.
Change the e-switch mode from legacy to switchdev on the PF device.
This will also create the VF representor netdevices in the host OS.# echo switchdev > /sys/
class/net/enp4s0f0/compat/devlink/modeWarningBefore changing the mode, make sure that all VFs are unbound.
WarningTo go back to SR-IOV legacy mode:
# echo legacy > /sys/class/net/enp4s0f0/compat/devlink/mode
Running this command, will also remove the VF representor netdevices.Set the network VF representor device names to be in the form of $PF_$VFID where $PF is the PF netdev name, and $VFID is the VF ID=0,1,[..], either by:
* Using this rule in /etc/udev/rules.d/82-net-setup-link.rulesSUBSYSTEM==
"net", ACTION=="add", ATTR{phys_switch_id}=="e41d2d60971d", \ ATTR{phys_port_name}!="", NAME="enp4s0f1_$attr{phys_port_name}"Replace the phys_switch_id value ("e41d2d60971d" above) with the value matching your switch, as obtained from:
ip -d link show enp4s0f1
Example output of device names when using the udev rule:
ls -l /sys/
class/net/ens4* lrwxrwxrwx1root root0Mar2717:14enp4s0f0 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.0/net/enp4s0f0 lrwxrwxrwx1root root0Mar2717:15enp4s0f0_0 -> ../../devices/virtual/net/enp4s0f0_0 lrwxrwxrwx1root root0Mar2717:15enp4s0f0_1 -> ../../devices/virtual/net/enp4s0f0_1* Using the supplied 82-net-setup-link.rules and vf-net-link-name.sh script to set the VF representor device names.
From the scripts directory copy vf-net-link-name.sh to /etc/udev/ and 82-net-setup-link.rules to /etc/udev/rules.d/.
Make sure vf-net-link-name.sh is executable.Run the openvswitch service.
# systemctl start openvswitch
Create an OVS bridge (here it's named ovs-sriov).
# ovs-vsctl add-br ovs-sriov
Enable hardware offload (disabled by default).
# ovs-vsctl set Open_vSwitch . other_config:hw-offload=
trueRestart the openvswitch service. This step is required for HW offload changes to take effect.
# systemctl restart openvswitch
WarningHW offload policy can also be changed by setting the tc-policy using one on the following values:
* none - adds a TC rule to both the software and the hardware (default)
* skip_sw - adds a TC rule only to the hardware
* skip_hw - adds a TC rule only to the software
The above change is used for debug purposes.
Add the PF and the VF representor netdevices as OVS ports.
# ovs-vsctl add-port ovs-sriov enp4s0f0 # ovs-vsctl add-port ovs-sriov enp4s0f0_0 # ovs-vsctl add-port ovs-sriov enp4s0f0_1
Make sure to bring up the PF and representor netdevices.
# ip link set dev enp4s0f0 up # ip link set dev enp4s0f0_0 up # ip link set dev enp4s0f0_1 up
The PF represents the uplink (wire).
# ovs-dpctl show system
@ovs-system: lookups: hit:0missed:192lost:1flows:2masks: hit:384total:2hit/pkt:2.00port0: ovs-system (internal) port1: ovs-sriov (internal) port2: enp4s0f0 port3: enp4s0f0_0 port4: enp4s0f0_1Run traffic from the VFs and observe the rules added to the OVS data-path.
# ovs-dpctl dump-flows recirc_id(
0),in_port(3),eth(src=e4:11:22:33:44:50,dst=e4:1d:2d:a5:f3:9d), eth_type(0x0800),ipv4(frag=no), packets:33, bytes:3234, used:1.196s, actions:2recirc_id(0),in_port(2),eth(src=e4:1d:2d:a5:f3:9d,dst=e4:11:22:33:44:50), eth_type(0x0800),ipv4(frag=no), packets:34, bytes:3332, used:1.196s, actions:3In the example above, the ping was initiated from VF0 (OVS port 3) to the outer node (OVS port 2), where the VF MAC is e4:11:22:33:44:50 and the outer node MAC is e4:1d:2d:a5:f3:9d
As shown above, two OVS rules were added, one in each direction.
Note that you can also verify offloaded packets using by adding type=offloaded to the command. For example:# ovs-dpctl dump-flows type=offloaded
Flow Statistics and Aging
The aging timeout of OVS is given is ms and can be controlled with this command:
# ovs-vsctl set Open_vSwitch . other_config:max-idle=30000
Offloading VLANs
It is common to require the VM traffic to be tagged by the OVS. Such that, the OVS adds tags (vlan push) to the packets sent by the VMs and strips (vlan pop) the packets received for this VM from other nodes/VMs.
To do so, add a tag=$TAG section for the OVS command line that adds the representor ports, for example here we use vlan ID 52.
# ovs-vsctl add-port ovs-sriov enp4s0f0
# ovs-vsctl add-port ovs-sriov enp4s0f0_0 tag=52
# ovs-vsctl add-port ovs-sriov enp4s0f0_1 tag=52
The PF port should not have a VLAN attached. This will cause OVS to add VLAN push/pop actions when managing traffic for these VFs.
To see how the OVS rules look with vlans, here we initiated a ping from VF0 (OVS port 3) to an outer node (OVS port 2), where the VF MAC is e4:11:22:33:44:50 and the outer node MAC is 00:02:c9:e9:bb:b2.
At this stage, we can see that two OVS rules were added, one in each direction.
recirc_id(0),in_port(3),eth(src=e4:11:22:33:44:50,dst=00:02:c9:e9:bb:b2),eth_type(0x0800),ipv4(frag=no), \
packets:0, bytes:0, used:never, actions:push_vlan(vid=52,pcp=0),2
recirc_id(0),in_port(2),eth(src=00:02:c9:e9:bb:b2,dst=e4:11:22:33:44:50),eth_type(0x8100), \
vlan(vid=52,pcp=0),encap(eth_type(0x0800),ipv4(frag=no)), packets:0, bytes:0, used:never, actions:pop_vlan,3
For outgoing traffic (in port = 3), the actions are push vlan (52) and forward to port 2
For incoming traffic (in port = 2), matching is done also on vlan, and the actions are pop vlan and forward to port 3
Offloading VXLAN Encapsulation/Decapsulation Actions
VXLAN encapsulation / decapsulation offloading of OVS actions is supported only in ConnectX-5 adapter cards.
In case of offloading VXLAN, the PF should not be added as a port in the OVS data-path but rather be assigned with the IP address to be used for encapsulation.
The example below shows two hosts (PFs) with IPs 1.1.1.177 and 1.1.1.75, where the PF device on both hosts is enp4s0f0 and the VXLAN tunnel is set with VNID 98:
On the first host:
# ip addr add
1.1.1.177/24dev enp4s0f1 # ovs-vsctl add-port ovs-sriov vxlan0 -- setinterfacevxlan0 type=vxlan options:local_ip=1.1.1.177options:remote_ip=1.1.1.75options:key=98On the second host:
# ip addr add
1.1.1.75/24dev enp4s0f1 # ovs-vsctl add-port ovs-sriov vxlan0 -- setinterfacevxlan0 type=vxlan options:local_ip=1.1.1.75options:remote_ip=1.1.1.177options:key=98
When encapsulating guest traffic, the VF’s device MTU must be reduced to allow the host/HW add the encap headers without fragmenting the resulted packet. As such, the VF’s MTU must be lowered to 1450 for IPv4 and 1430 for IPv6.
To see how the OVS rules look with vxlan encap/decap actions, here we initiated a ping from a VM on the 1st host whose MAC is e4:11:22:33:44:50 to a VM on the 2nd host whose MAC is 46:ac:d1:f1:4c:af
At this stage we see that two OVS rules were added to the first host; one in each direction.
# ovs-dpctl show
system@ovs-system:
lookups: hit:7869 missed:241 lost:2
flows: 2
masks: hit:13726 total:10 hit/pkt:1.69
port 0: ovs-system (internal)
port 1: ovs-sriov (internal)
port 2: vxlan_sys_4789 (vxlan)
port 3: enp4s0f1_0
port 4: enp4s0f1_1
# ovs-dpctl dump-flows
recirc_id(0),in_port(3),eth(src=e4:11:22:33:44:50,dst=46:ac:d1:f1:4c:af),eth_type(0x0800),ipv4(tos=0/0x3,frag=no),
packets:4, bytes:392, used:0.664s, actions:set(tunnel(tun_id=0x62,dst=1.1.1.75,ttl=64,flags(df,key))),2
recirc_id(0),tunnel(tun_id=0x62,src=1.1.1.75,dst=1.1.1.177,ttl=64,flags(-df-csum+key)),
in_port(2),skb_mark(0),eth(src=46:ac:d1:f1:4c:af,dst=e4:11:22:33:44:50),eth_type(0x0800),ipv4(frag=no), packets:5, bytes:490, used:0.664s, actions:3
For outgoing traffic (in port = 3), the actions are set vxlan tunnel to host 1.1.1.75 (encap) and forward to port 2
For incoming traffic (in port = 2), matching is done also on vxlan tunnel info which was decapsulated, and the action is forward to port 3
Manually Adding TC Rules
Offloading rules can also be added directly, and not just through OVS, using the tc utility.
To enable TC ingress on both the PF and the VF.
# tc qdisc add dev enp4s0f0 ingress
# tc qdisc add dev enp4s0f0_0 ingress
# tc qdisc add dev enp4s0f0_1 ingress
Examples
L2 Rule
# tc filter add dev ens4f0_0 protocol ip parent ffff: \
flower \
skip_sw \
dst_mac e4:11:22:11:4a:51 \
src_mac e4:11:22:11:4a:50 \
action drop
VLAN Rule
# tc filter add dev ens4f0_0 protocol 802.1Q parent ffff: \
flower \
skip_sw \
dst_mac e4:11:22:11:4a:51 \
src_mac e4:11:22:11:4a:50 \
action vlan push id 100 \
action mirred egress redirect dev ens4f0
# tc filter add dev ens4f0 protocol 802.1Q parent ffff: \
flower \
skip_sw \
dst_mac e4:11:22:11:4a:51 \
src_mac e4:11:22:11:4a:50 \
vlan_ethtype 0x800 \
vlan_id 100 \
vlan_prio 0 \
action vlan pop \
action mirred egress redirect dev ens4f0_0
VXLAN Rule
# tc filter add dev ens4f0_0 protocol 0x806 parent ffff: \
flower \
skip_sw \
dst_mac e4:11:22:11:4a:51 \
src_mac e4:11:22:11:4a:50 \
action tunnel_key set \
src_ip 20.1.12.1 \
dst_ip 20.1.11.1 \
id 100 \
action mirred egress redirect dev vxlan100
# tc filter add dev vxlan100 protocol 0x806 parent ffff: \
flower \
skip_sw \
dst_mac e4:11:22:11:4a:51 \
src_mac e4:11:22:11:4a:50 \
enc_src_ip 20.1.11.1 \
enc_dst_ip 20.1.12.1 \
enc_key_id 100 \
enc_dst_port 4789 \
action tunnel_key unset \
action mirred egress redirect dev ens4f0_0
Bond Rule
Bond rules can be added in one of the following methods:
Using shared block (requires kernel support):
# tc qdisc add dev bond0 ingress_block
22ingress # tc qdisc add dev ens4p0 ingress_block22ingress # tc qdisc add dev ens4p1 ingress_block22ingressAdd drop rule:
# tc filter add block
22protocol arp parent ffff: prio3\ flower \ dst_mac e4:11:22:11:4a:51\ action dropAdd redirect rule from bond to representor:
# tc filter add block
22protocol arp parent ffff: prio3\ flower \ dst_mac e4:11:22:11:4a:50\ action mirred egress redirect dev ens4f0_0Add redirect rule from representor to bond:
# tc filter add dev ens4f0_0 protocol arp parent ffff: prio
3\ flower \ dst_mac ec:0d:9a:8a:28:42\ action mirred egress redirect dev bond0
Without using shared block:
Add redirect rule from bond to representor:
# tc filter add dev bond0 protocol arp parent ffff: prio
1\ flower \ dst_mac e4:11:22:11:4a:50\ action mirred egress redirect dev ens4f0_0Add redirect rule from representor to bond:
# tc filter add dev ens4f0_0 protocol arp parent ffff: prio
3\ flower \ dst_mac ec:0d:9a:8a:28:42\ action mirred egress redirect dev bond0
VLAN Modify
VLAN Modify rules can be added in one of the following methods:
tc filter add dev $REP_DEV1 protocol 802.1q ingress prio 1 flower \
vlan_id 10 \
action vlan modify id 11 pipe \
action mirred egress redirect dev $REP_DEV2
tc filter add dev $DEV_REP1 protocol 802.1q ingress prio 1 flower \
vlan_id 10 \
action vlan pop pipe action vlan push id 11 pipe \
action mirred egress redirect dev $REP_DEV2
SR-IOV VF LAG
SR-IOV VF LAG allows the NIC’s physical functions to get the rules that the OVS will try to offload to the bond net-device, and to offload them to the hardware e-switch. Bond modes supported are:
Active-Backup
Active-Active
LACP
To enable SR-IOV LAG, both physical functions of the NIC should first be configured to SR-IOV switchdev mode, and only afterwards bond the up-link representors.
The example below shows the creation of bond interface on two PFs:
Load bonding device and enslave the up-link representor (currently PF) net-device devices.
modprobe bonding mode=
802.3ad Ifup bond0 (make sure ifcfg file is present with desired bond configuration) ip link set enp4s0f0 master bond0 ip link set enp4s0f1 master bond0Add the VF representor net-devices as OVS ports. If tunneling is not used, add the bond device as well.
ovs-vsctl add-port ovs-sriov bond0 ovs-vsctl add-port ovs-sriov enp4s0f0_0 ovs-vsctl add-port ovs-sriov enp4s0f1_0
Make sure to bring up the PF and the representor netdevices.
ip link set dev bond0 up ip link set dev enp4s0f0_0 up ip link set dev enp4s0f1_0 up
Port Mirroring (Flow Based VF Traffic Mirroring for ASAP²)
Port Mirroring is currently supported in ConnectX-5 adapter cards only.
Unlike para-virtual configurations, when the VM traffic is offloaded to the hardware via SRIOV VF, the host side Admin cannot snoop the traffic (e.g. for monitoring).
ASAP² uses the existing mirroring support in OVS and TC along with the enhancement to the offloading logic in the driver to allow mirroring the VF traffic to another VF.
The mirrored VF can be used to run traffic analyzer (tcpdump, wireshark, etc) and observe the traffic of the VF being mirrored.
The example below shows the creation of port mirror on the following configuration:
# ovs-vsctl show
09d8a574-9c39-465c-9f16-47d81c12f88a
Bridge br-vxlan
Port "enp4s0f0_1"
Interface "enp4s0f0_1"
Port "vxlan0"
Interface "vxlan0"
type: vxlan
options: {key="100", remote_ip="192.168.1.14"}
Port "enp4s0f0_0"
Interface "enp4s0f0_0"
Port "enp4s0f0_2"
Interface "enp4s0f0_2"
Port br-vxlan
Interface br-vxlan
type: internal
ovs_version: "2.8.90"
If we want to set enp4s0f0_0 as the mirror port, and mirror all of the traffic, set it as follow:
# ovs-vsctl -- --id=
@pget port enp4s0f0_0 \ -- --id=@mcreate mirror name=m0 select-all=trueoutput-port=@p\ -- set bridge br-vxlan mirrors=@mIf we want to set enp4s0f0_0 as the mirror port, and only mirror the traffic, the destination is enp4s0f0_1, set it as follow:
# ovs-vsctl -- --id=
@p1get port enp4s0f0_0 \ -- --id=@p2get port enp4s0f0_1 \ -- --id=@mcreate mirror name=m0 select-dst-port=@p2output-port=@p1\ -- set bridge br-vxlan mirrors=@mIf we want to set enp4s0f0_0 as the mirror port, and only mirror the traffic the source is enp4s0f0_1, set it as follow:
# ovs-vsctl -- --id=
@p1get port enp4s0f0_0 \ -- --id=@p2get port enp4s0f0_1 \ -- --id=@mcreate mirror name=m0 select-src-port=@p2output-port=@p1\ -- set bridge br-vxlan mirrors=@mIf we want to set enp4s0f0_0 as the mirror port and mirror, all the traffic on enp4s0f0_1, set it as follow:
# ovs-vsctl -- --id=
@p1get port enp4s0f0_0 \ -- --id=@p2get port enp4s0f0_1 \ -- --id=@mcreate mirror name=m0 select-dst-port=@p2select-src-port=@p2output-port=@p1\ -- set bridge br-vxlan mirrors=@m
# ovs-vsctl clear bridge br-vxlan mirrors
Performance Tuning Based on Traffic Patterns
Offloaded flows (including connection tracking) are added to virtual switch FDB flow tables. FDB tables have a set of flow groups. Each flow group saves the same traffic pattern flows. For example, for connection tracking offloaded flow, TCP and UDP are different traffic patterns which end up in two different flow groups.
A flow group has a limited size to save flow entries. By default, the driver has 4 big FDB flow groups. Each of these big flow groups can save at most 4000000/(4+1)=800k different 5-tuple flow entries. For scenarios with more than 4 traffic patterns, the driver provides a module parameter (num_of_groups) to allow customization and performance tune.
The size of each big flow group can be calculated according to the following formula.
size = 4000000/(num_of_groups+1)
To change the number of big FDB flow groups, run:
$ echo <num_of_groups> > /sys/module/mlx5_core/parameters/num_of_groups
The change takes effect immediately if there is no flow inside the FDB table (no traffic running and all offloaded flows are aged out), and it can be dynamically changed without reloading the driver.
The module parameter can be set statically in /etc/modprobe.d/mlnx.conf file. This way the administrator will not be required to set it via sysfs each time the driver is reloaded.
If there are residual offloaded flows when changing this parameter, then the new configuration only takes effect after all flows age out.
Download and install the MFT package corresponding to your computer’s operating system. You would need the kernel-devel or kernel-headers RPM before the tools are built and installed.
The package is available at http://www.mellanox.com => Products => Software => Firmware Tools.Start the mst driver.
# mst start Starting MST (Mellanox Software Tools) driver set Loading MST PCI module - Success Loading MST PCI configuration module - Success Create devices
Show the devices status.
ST modules: ------------ MST PCI module loaded MST PCI configuration module loaded PCI devices: ------------ DEVICE_TYPE MST PCI RDMA NET NUMA ConnectX4lx(rev:
0) /dev/mst/mt4117_pciconf0.104:00.1net-enp4s0f1 NA ConnectX4lx(rev:0) /dev/mst/mt4117_pciconf004:00.0net-enp4s0f0 NA # mlxconfig -d /dev/mst/mt4117_pciconf0 q | head -16Device #1: ---------- Device type: ConnectX4lx PCI device: /dev/mst/mt4117_pciconf0 Configurations: Current SRIOV_EN True(1) NUM_OF_VFS8PF_LOG_BAR_SIZE5VF_LOG_BAR_SIZE5NUM_PF_MSIX63NUM_VF_MSIX11LINK_TYPE_P1 ETH(2) LINK_TYPE_P2 ETH(2)Make sure your configuration is as follows:
* SR-IOV is enabled (SRIOV_EN=1)
* The number of enabled VFs is enough for your environment (NUM_OF_VFS=N)
* The port’s link type is Ethernet (LINK_TYPE_P1/2=2) when applicable
If this is not the case, use mlxconfig to enable that, as follows:Enable SR-IOV.
# mlxconfig -d /dev/mst/mt4115_pciconf0 s SRIOV_EN=
1Set the number of required VFs.
# mlxconfig -d /dev/mst/mt4115_pciconf0 s NUM_OF_VFS=
8Set the link type to Ethernet.
# mlxconfig -d /dev/mst/mt4115_pciconf0 s LINK_TYPE_P1=
2# mlxconfig -d /dev/mst/mt4115_pciconf0 s LINK_TYPE_P2=2
Reset the firmware.
# mlxfwreset -d /dev/mst/mt4115_pciconf0 reset
Query the firmware to make sure everything is set correctly.
# mlxconfig -d /dev/mst/mt4115_pciconf0 q