OVS Offload Using ASAP² Direct

Linux Kernel Upstream Release Notes v5.17
Warning

Supported on ConnectX-5 and above adapter cards.

Open vSwitch (OVS) allows Virtual Machines (VMs) 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.
NVIDIA Accelerated Switching And Packet Processing (ASAP2) technology allows OVS offloading by handling OVS data-plane in ConnectX-5 onwards NIC hardware (Embedded Switch or eSwitch) while maintaining OVS control-plane unmodified. As a result, we observe significantly higher OVS performance without the associated CPU load.

As of v5.0, OVS-DPDK became part ofMLNX_OFED package. OVS-DPDK supports ASAP2 just as the OVS-Kernel (Traffic Control (TC) kernel-based solution) does, yet with a different set of features.

The traditional ASAP2 hardware data plane is built over SR-IOV virtual functions (VFs), so that the VF is passed through directly to the VM, with the NVIDIA driver running within the VM. An alternate approach that is also supported is vDPA (vhost Data Path Acceleration). vDPA allows the connection to the VM to be established using VirtIO, so that the data-plane is built between the SR-IOV VF and the standard VirtIO driver within the VM, while the control-plane is managed on the host by the vDPA application. Two flavors of vDPA are supported, Software vDPA; and Hardware vDPA. Software vDPA management functionality is embedded into OVS-DPDK, while Hardware vDPA uses a standalone application for management, and can be run with both OVS-Kernel and OVS-DPDK. For further information, please see sections VirtIO Acceleration through VF Relay (Software vDPA) and VirtIO Acceleration through Hardware vDPA.

Install the required packages. For the complete solution, you need to install supporting MLNX_OFED(v4.4 and above), iproute2, and openvswitch packages.

Run:

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./mlnxofedinstall --ovs-dpdk –upstream-libs

Warning

Note that this section applies to both OVS-DPDK and OVS-Kernel similarly.

To set up SR-IOV:

Procedure_Heading_Icon.PNG

  1. 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).

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    # lspci -nn | grep Mellanox   0a:00.0 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017] 0a:00.1 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017]   0a:00.2 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function] [15b3:1018]

    Warning

    Enabling SR-IOV and creating VFs is done by the firmware upon admin directive as explained in Step 5 below.

  2. Identify the NVIDIA NICs and locate net-devices which are on the NIC PCI BDF.

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    # ls -l /sys/class/net/ | grep 04:00   lrwxrwxrwx 1 root root 0 Mar 27 16:58 enp4s0f0 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.0/net/enp4s0f0 lrwxrwxrwx 1 root root 0 Mar 27 16:58 enp4s0f1 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.1/net/enp4s0f1 lrwxrwxrwx 1 root root 0 Mar 27 16:58 eth0 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.2/net/eth0 lrwxrwxrwx 1 root root 0 Mar 27 16:58 eth1 -> ../../devices/pci0000:00/0000:00:03.0/0000:04:00.3/net/eth1

    The PF NIC for port #1 is enp4s0f0, and the rest of the commands will be issued on it.

  3. Check the firmware version.
    Make sure the firmware versions installed are as state in the Release Notes document.

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    # ethtool -i enp4s0f0 | head -5 driver: mlx5_core version: 5.0-5  firmware-version: 16.21.0338 expansion-rom-version: bus-info: 0000:04:00.0

  4. Make 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 "NVIDIA Firmware Tools" below for more details.

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    # cat /sys/class/net/enp4s0f0/device/sriov_totalvfs 4

  5. Turn ON SR-IOV on the PF device.

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    # echo 2 > /sys/class/net/enp4s0f0/device/sriov_numvfs

  6. Provision the VF MAC addresses using the IP tool.

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    # ip link set enp4s0f0 vf 0 mac e4:11:22:33:44:50 # ip link set enp4s0f0 vf 1 mac e4:11:22:33:44:51

  7. Verify the VF MAC addresses were provisioned correctly and SR-IOV was turned ON.

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    # cat /sys/class/net/enp4s0f0/device/sriov_numvfs 2   # ip link show dev enp4s0f0 256: enp4s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master ovs-system state UP mode DEFAULT group default qlen 1000 link/ether e4:1d:2d:60:95:a0 brd ff:ff:ff:ff:ff:ff vf 0 MAC e4:11:22:33:44:50, spoof checking off, link-state auto vf 1 MAC e4:11:22:33:44:51, spoof checking off, link-state auto

    In the example above, the maximum number of possible VFs supported by the firmware is 4 and only 2 are enabled.

  8. 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 support.mellanox.com/s/article/HowTo-Configure-SR-IOV-for-ConnectX-4-ConnectX-5-ConnectX-6-with-KVM-Ethernet.

OVS-Kernel Hardware Offloads

SwitchDev Configuration

  1. Unbind the VFs.

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    echo 0000:04:00.2 > /sys/bus/pci/drivers/mlx5_core/unbind echo 0000:04:00.3 > /sys/bus/pci/drivers/mlx5_core/unbind

    Warning

    VMs with attached VFs must be powered off to be able to unbind the VFs.

  2. Change the eSwitch mode from Legacy to SwitchDev on the PF device.
    This will also create the VF representor netdevices in the host OS.

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    # devlink dev eswitch set pci/0000:3b:00.0 mode switchdev

    Warning

    Before changing the mode, make sure that all VFs are unbound.

    Warning

    To go back to SR-IOV legacy mode, run:
    # devlink dev eswitch set pci/0000:3b:00.0 mode legacy
    This will also remove the VF representor netdevices.

    On old OSs or kernels that do not support Devlink, moving to SwitchDev mode can be done using sysfs.

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    # echo switchdev > /sys/class/net/enp4s0f0/compat/devlink/mode

  3. At this stage, VF representors have been created. To map representor to its VF, make sure to obtain the representor's switchid and portname from:

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    # ip -d link show eth4 41: enp0s8f0_1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether ba:e6:21:37:bc:d4 brd ff:ff:ff:ff:ff:ff promiscuity 0 addrgenmode eui64 numtxqueues 10 numrxqueues 10 gso_max_size 65536 gso_max_segs 65535 portname pf0vf1 switchid f4ab580003a1420c

    switchid - used to map representor to device, both device PFs have the same switchid.
    portname - used to map representor to PF and VF, value returned is pfXvfY, where X is the PF number and Y is the number of VF.
    On old kernels, switchid and portname can be acquired through sysfs:

SwitchDev Performance Tuning

SwitchDev performance can be further improved by tuning it.

Steering Mode

OVS-kernel supports two steering modes for rules insertion into hardware.

  1. SMFS – Software Managed Flow Steering (as of MLNX_OFED v5.1, this is the default mode)

    Rules are inserted directly to the hardware by the software (driver). This mode is optimized for rules insertion.

  2. DMFS – Device Managed Flow Steering

    Rules insertion is done using firmware commands. This mode is optimized for throughput with a small amount of rules in the system.

    The mode can be controlled via sysfs or devlink API in kernels that support it:

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    Sysfs: # echo smfs > /sys/class/net/<PF netdev>/compat/devlink/steering_mode   Devlink: # devlink dev param set pci/0000:00:08.0 name flow_steering_mode value "smfs" cmode runtime   Replace smfs param with dmfs for device managed flow steering

Notes:

  • The mode should be set prior to moving to SwitchDev, by echoing to the sysfs or invoking the devlink command.

  • Only when moving to SwitchDev will the driver use the mode set by the previous step.

  • Mode cannot be changed after moving to SwitchDev.

  • The steering mode is applicable for SwitchDev mode only, meaning it does not affect legacy SR-IOV or other configurations.

vPort Match Mode

OVS-kernel support two modes that define how the rules on match on vport.

  1. Metadata – rules match on metadata instead of vport number (default mode).

    This mode is needed in order to support SR-IOV Live migration and Dual port RoCE features.

    Matching on Metadata can have a performance impact.

  2. Legacy – rules match on vport number.

    In this mode, performance can be higher in comparison to Metadata. It can still be used only if none of the above features (SR-IOV Live migration and Dual port RoCE) is enabled/used.

    The mode can be controlled via sysfs:

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    Set Legacy: # echo legacy > /sys/class/net/<PF netdev>/compat/devlink/vport_match_mode   Set metadata: Devlink: # echo metadata > /sys/class/net/<PF netdev>/compat/devlink/vport_match_mode

    Note: This mode should be set prior to moving to SwitchDev, by echoing to the sysfs.

Flow Table Large Group Number

Offloaded flows, including Connection Tracking, are added to Virtual Switch Forwarding Data Base (FDB) flow tables. FDB tables have a set of flow groups, where each flow group saves the same traffic pattern flows. E.g, for connection tracking offloaded flow, TCP and UDP are different traffic patterns which will end up in two different flow groups.

A flow group has a limited size to save flow entries. As default, the driver has 15 big FDB flow groups. Each of these big flow groups can save 4M / ( 15 + 1) = 256k different 5-tuple flow entries at most. For scenarios with more than 15 traffic patterns, the driver provides a module parameter (num_of_groups) to allow customization and performance tuning.

The mode can be controlled via module param or devlink API for kernels that support it:

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Module param: # echo <num_of_groups> > /sys/module/mlx5_core/parameters/num_of_groups   Devlink: # devlink dev param set pci/0000:82:00.0 name fdb_large_groups \ cmode driverinit value 20

Notes:

  • In MLNX_OFED v5.1, the default value was changed from 4 to 15.

  • 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.
    If there are still offloaded flows residual when changing this parameter, it will only take effect after all flows have aged out.

Open vSwitch Configuration

Open vSwitch configuration is a simple OVS bridge configuration with SwitchDev.

  1. Run the openvswitch service.

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    # systemctl start openvswitch

  2. Create an OVS bridge (here it's named ovs-sriov).

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    # ovs-vsctl add-br ovs-sriov

  3. Enable hardware offload (disabled by default).

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    # ovs-vsctl set Open_vSwitch . other_config:hw-offload=true

  4. Restart the openvswitch service. This step is required for HW offload changes to take effect.

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    # systemctl restart openvswitch

    Warning

    HW 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.

  5. Add the PF and the VF representor netdevices as OVS ports.

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    # 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.

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    # 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).

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    # ovs-dpctl show system@ovs-system: lookups: hit:0 missed:192 lost:1 flows: 2 masks: hit:384 total:2 hit/pkt:2.00 port 0: ovs-system (internal) port 1: ovs-sriov (internal) port 2: enp4s0f0 port 3: enp4s0f0_0 port 4: enp4s0f0_1

  6. Run traffic from the VFs and observe the rules added to the OVS data-path.

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    # 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:2   recirc_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:3

    In 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 by adding type=offloaded to the command. For example:

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    # ovs-appctl dpctl/dump-flows type=offloaded

Open vSwitch Performance Tuning

Flow Aging

The aging timeout of OVS is given in ms and can be controlled using the following command.

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# ovs-vsctl set Open_vSwitch . other_config:max-idle=30000


TC Policy

Specifies the policy used with HW offloading.

  • 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

Example:

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# ovs-vsctl set Open_vSwitch . other_config:tc-policy=skip_sw

Note: TC policy should only be used for debugging purposes.

Max-Revalidator

Specifies the maximum time (in ms) that revalidator threads will wait for kernel statistics before executing flow revalidation.

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# ovs-vsctl set Open_vSwitch . other_config:max-revalidator=10000


n-handler-threads

Specifies the number of threads for software datapaths to use for handling new flows.
The default value is the number of online CPU cores minus the number of revalidators.

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# ovs-vsctl set Open_vSwitch . other_config:n-handler-threads=4


n-revalidator-threads

Specifies the number of threads for software datapaths to use for revalidating flows in the datapath.

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# ovs-vsctl set Open_vSwitch . other_config:n-revalidator-threads=4


vlan-limit

Limits the number of VLAN headers that can be matched to the specified number.

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# ovs-vsctl set Open_vSwitch . other_config:vlan-limit=2

Basic TC Rules Configuration

Offloading rules can also be added directly, and not only through OVS, using the tc utility.

To create an offloading rule using TC:

Procedure_Heading_Icon.PNG

  1. Create an ingress qdisc (queueing discipline) for each interface that you wish to add rules into.

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    # tc qdisc add dev enp4s0f0 ingress # tc qdisc add dev enp4s0f0_0 ingress # tc qdisc add dev enp4s0f0_1 ingress

  2. Add TC rules using flower classifier in the following format.

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    # tc filter add dev NETDEVICE ingress protocol PROTOCOL prio PRIORITY \ [chain CHAIN] flower [ MATCH_LIST ] [ action ACTION_SPEC ]

    Note: List of supported matches (specifications) and actions can be found in Classification Fields (Matches) section.

  3. Dump the existing tc rules using flower classifier in the following format.

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    # tc [ -s ] filter show dev NETDEVICE ingress

SR-IOV VF LAG

SR-IOV VF LAG allows the NIC’s physical functions (PFs) 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

  • XOR

  • LACP

SR-IOV VF LAG enables complete offload of the LAG functionality to the hardware. The bonding creates a single bonded PF port. Packets from up-link can arrive from any of the physical ports, and will be forwarded to the bond device.

When hardware offload is used, packets from both ports can be forwarded to any of the VFs. Traffic from the VF can be forwarded to both ports according to the bonding state. Meaning, when in active-backup mode, only one PF is up, and traffic from any VF will go through this PF. When in XOR or LACP mode, if both PFs are up, traffic from any VF will split between these two PFs.

SR-IOV VF LAG Configuration on ASAP2

To enable SR-IOV VF 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:

  1. Load bonding device and enslave the up-link representor (currently PF) net-device devices.

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    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 bond0

  2. Add the VF representor net-devices as OVS ports. If tunneling is not used, add the bond device as well.

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    ovs-vsctl add-port ovs-sriov bond0 ovs-vsctl add-port ovs-sriov enp4s0f0_0 ovs-vsctl add-port ovs-sriov enp4s0f1_0

  3. Make sure to bring up the PF and the representor netdevices.

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    ip link set dev bond0 up ip link set dev enp4s0f0_0 up ip link set dev enp4s0f1_0 up

Warning

Once SR-IOV VF LAG is configured, all VFs of the two PFs will become part of the bond, and will behave as described above.


Limitations

  • In VF LAG mode, outgoing traffic in load balanced mode is according to the origin ring, thus, half of the rings will be coupled with port 1 and half with port 2. All the traffic on the same ring will be sent from the same port.

  • VF LAG configuration is not supported when the NUM_OF_VFS configured in mlxconfig is higher than 64.

Using TC with VF LAG

Both rules can be added using either of the following.

  1. Shared block (supported from kernel 4.16 and RHEL/CentOS 7.7 and above).

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    # tc qdisc add dev bond0 ingress_block 22 ingress # tc qdisc add dev ens4p0 ingress_block 22 ingress # tc qdisc add dev ens4p1 ingress_block 22 ingress

    1. Add drop rule.

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      # tc filter add block 22 protocol arp parent ffff: prio 3 \ flower \ dst_mac e4:11:22:11:4a:51 \ action drop

    2. Add redirect rule from bond to representor.

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      # tc filter add block 22 protocol arp parent ffff: prio 3 \ flower \ dst_mac e4:11:22:11:4a:50 \ action mirred egress redirect dev ens4f0_0

    3. Add redirect rule from representor to bond.

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      # 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

  2. Without shared block (supported from kernel 4.15 and below).

    1. Add redirect rule from bond to representor.

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      # 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_0

    2. Add redirect rule from representor to bond.

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      # 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

Classification Fields (Matches)

OVS-Kernel supports multiple classification fields which packets can fully or partially match.

Ethernet Layer 2

  • Destination MAC

  • Source MAC

  • Ethertype

Supported on all kernels.

In OVS dump flows:

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skb_priority(0/0),skb_mark(0/0),in_port(eth6),eth(src=00:02:10:40:10:0d ,dst=68:54:ed:00:af:de),eth_type(0x8100), packets:1981, bytes:206024, used:0.440s, dp:tc, actions:eth7

Using TC rules:

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tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action mirred egress redirect dev $NIC


IPv4/IPv6

  • Source address

  • Destination address

  • Protocol

    • TCP/UDP/ICMP/ICMPv6

  • TOS

  • TTL (HLIMIT)

Supported on all kernels.

In OVS dump flows:

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Ipv4: ipv4(src=0.0.0.0/0.0.0.0,dst=0.0.0.0/0.0.0.0,proto=17,tos=0/0,ttl=0/0,frag=no) Ipv6: ipv6(src=::/::,dst=1:1:1::3:1040:1008,label=0/0,proto=58,tclass=0/0x3,hlimit=64),

Using TC rules:

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IPv4: tc filter add dev $rep parent ffff: protocol ip pref 1 \ flower \ dst_ip 1.1.1.1 \ src_ip 1.1.1.2 \ ip_proto TCP \ ip_tos 0x3 \ ip_ttl 63 \ action mirred egress redirect dev $NIC     IPv6: tc filter add dev $rep parent ffff: protocol ipv6 pref 1 \ flower \ dst_ip 1:1:1::3:1040:1009 \ src_ip 1:1:1::3:1040:1008 \ ip_proto TCP \ ip_tos 0x3 \ ip_ttl 63\ action mirred egress redirect dev $NIC


TCP/UDP Source and Destination ports & TCP Flags

  • TCP/UDP source and destinations ports

  • TCP flags

Supported kernels are kernel > 4.13 and RHEL > 7.5

In OVS dump flows:

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TCP: tcp(src=0/0,dst=32768/0x8000), UDP: udp(src=0/0,dst=32768/0x8000), TCP flags: tcp_flags(0/0)

Using TC rules:

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tc filter add dev $rep parent ffff: protocol ip pref 1 \ flower \ ip_proto TCP \ dst_port 100 \ src_port 500 \ tcp_flags 0x4/0x7 \ action mirred egress redirect dev $NIC


VLAN

  • ID

  • Priority

  • Inner vlan ID and Priority

Supported kernels: All (QinQ: kernel 4.19 and higher, and RHEL 7.7 and higher)

In OVS dump flows:

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eth_type(0x8100),vlan(vid=2347,pcp=0),

Using TC rules:

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tc filter add dev $rep parent ffff: protocol 802.1Q pref 1 \ flower \ vlan_ethtype 0x800 \ vlan_id 100 \ vlan_prio 0 \ action mirred egress redirect dev $NIC QinQ: tc filter add dev $rep parent ffff: protocol 802.1Q pref 1 \ flower \ vlan_ethtype 0x8100 \ vlan_id 100 \ vlan_prio 0 \ cvlan_id 20 \ cvlan_prio 0 \ cvlan_ethtype 0x800 \ action mirred egress redirect dev $NIC


Tunnel

  • ID (Key)

  • Source IP address

  • Destination IP address

  • Destination port

  • TOS (supported from kernel 4.19 and above & RHEL 7.7 and above)

  • TTL (support from kernel 4.19 and above & RHEL 7.7 and above)

  • Tunnel options (Geneve)

Supported kernels:

  • VXLAN: All

  • GRE: Kernel > 5.0, RHEL 7.7 and above

  • Geneve: Kernel > 5.0, RHEL 7.7 and above

In OVS dump flows:

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tunnel(tun_id=0x5,src=121.9.1.1,dst=131.10.1.1,ttl=0/0,tp_dst=4789,flags(+key))

Using TC rules:

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# tc filter add dev $rep protocol 802.1Q parent ffff: pref 1  flower \ vlan_ethtype 0x800 \ vlan_id 100 \ vlan_prio 0 \ action mirred egress redirect dev $NIC QinQ: # tc filter add dev vxlan100 protocol ip 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

Supported Actions

Forward

Forward action allows for packet redirection:

  • From VF to wire

  • Wire to VF

  • VF to VF

Supported on all kernels.

In OVS dump flows:

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skb_priority(0/0),skb_mark(0/0),in_port(eth6),eth(src=00:02:10:40:10:0d ,dst=68:54:ed:00:af:de),eth_type(0x8100), packets:1981, bytes:206024, used:0.440s, dp:tc, actions:eth7

Using TC rules:

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tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action mirred egress redirect dev $NIC


Drop

Drop action allows to drop incoming packets.

Supported on all kernels.

In OVS dump flows:

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skb_priority(0/0),skb_mark(0/0),in_port(eth6),eth(src=00:02:10:40:10:0d ,dst=68:54:ed:00:af:de),eth_type(0x8100), packets:1981, bytes:206024, used:0.440s, dp:tc, actions:drop

Using TC rules:

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tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action drop


Statistics

By default, each flow collects the following statistics:

  • Packets – number of packets which hit the flow

  • Bytes – total number of bytes which hit the flow

  • Last used – the amount of time passed since last packet hit the flow

Supported on all kernels.

In OVS dump flows:

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skb_priority(0/0),skb_mark(0/0),in_port(eth6),eth(src=00:02:10:40:10:0d ,dst=68:54:ed:00:af:de),eth_type(0x8100), packets:1981, bytes:206024, used:0.440s, dp:tc, actions:drop

Using TC rules:

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#tc -s filter show dev $rep ingress   filter protocol ip pref 2 flower chain 0 filter protocol ip pref 2 flower chain 0 handle 0x2 eth_type ipv4 ip_proto tcp src_ip 192.168.140.100 src_port 80 skip_sw in_hw action order 1: mirred (Egress Redirect to device p0v11_r) stolen index 34 ref 1 bind 1 installed 144 sec used 0 sec Action statistics: Sent 388344 bytes 2942 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0 

Tunnels (Encapsulation/Decapsulation)

OVS-kernel supports offload of tunnels using encapsulation and decapsulation actions.

  • Encapsulation – pushing of tunnel header is supported on Tx

  • Decapsulation – popping of tunnel header is supported on Rx

Supported Tunnels:

  • VXLAN (IPv4/IPv6) – supported on all Kernels

  • GRE (IPv4/IPv6) – supported on kernel 5.0 and above & RHEL 7.6 and above

  • Geneve (IPv4/IPv6) - supported on kernel 5.0 and above & RHEL 7.6 and above

OVS configuration:
In case of offloading tunnel, the PF/bond should not be added as a port in the OVS datapath. It should 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:

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    # ip addr add 1.1.1.177/24 dev enp4s0f1   # ovs-vsctl add-port ovs-sriov vxlan0 -- set interface vxlan0 type=vxlan options:local_ip=1.1.1.177 options:remote_ip=1.1.1.75 options:key=98

  • On the second host:

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    # ip addr add 1.1.1.75/24 dev enp4s0f1   # ovs-vsctl add-port ovs-sriov vxlan0 -- set interface vxlan0 type=vxlan options:local_ip=1.1.1.75 options:remote_ip=1.1.1.177 options:key=98     • for GRE IPv4 tunnel need use type=gre • for GRE IPv6 tunnel need use type=ip6gre • for GENEVE tunnel need use type=geneve

Warning

When encapsulating guest traffic, the VF’s device MTU must be reduced to allow the host/HW to add the encap headers without fragmenting the resulted packet. As such, the VF’s MTU must be lowered by 50 bytes from the uplink MTU for IPv4 and 70 bytes for IPv6.

Tunnel offload using TC rules:

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Encapsulation: # 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   Decapsulation: # 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


VLAN Push/Pop

OVS-kernel supports offload of vlan header push/pop actions.

  • Push - pushing of vlan header is supported on Tx

  • Pop - popping of tunnel header is supported on Rx

OVS Configuration

Add a tag=$TAG section for the OVS command line that adds the representor ports. For example, VLAN ID 52 is being used here.

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# 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.

Dump Flow Example

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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

VLAN Offload using TC Rules Example

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# 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 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

Header Rewrite

This action allows for modifying packet fields.

Ethernet Layer 2

  • Destination MAC

  • Source MAC

Supported kernels: Kernel 4.14 and above & RHEL 7.5 and above

In OVS dump flows:

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skb_priority(0/0),skb_mark(0/0),in_port(eth6),eth(src=00:02:10:40:10:0d ,dst=68:54:ed:00:af:de),eth_type(0x8100), packets:1981, bytes:206024, used:0.440s, dp:tc, actions: set(eth(src=68:54:ed:00:f4:ab,dst=fa:16:3e:dd:69:c4)),eth7

Using TC rules:

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tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action pedit ex \ munge eth dst set 20:22:33:44:55:66 \ munge eth src set aa:ba:cc:dd:ee:fe \ action mirred egress redirect dev $NIC


IPv4/IPv6

  • Source address

  • Destination address

  • Protocol

  • TOS

  • TTL (HLIMIT)

Supported kernels: Kernel 4.14 and above & RHEL 7.5 and above

In OVS dump flows:

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Ipv4: set(eth(src=de:e8:ef:27:5e:45,dst=00:00:01:01:01:01)), set(ipv4(src=10.10.0.111,dst=10.20.0.122,ttl=63)) Ipv6: set(ipv6(dst=2001:1:6::92eb:fcbe:f1c8,hlimit=63)),

Using TC rules:

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IPv4: tc filter add dev $rep parent ffff: protocol ip pref 1 \ flower \ dst_ip 1.1.1.1 \ src_ip 1.1.1.2 \ ip_proto TCP \ ip_tos 0x3 \ ip_ttl 63 \ pedit ex \ munge ip src set 2.2.2.1 \ munge ip dst set 2.2.2.2 \ munge ip tos set 0 \ munge ip ttl dec \ action mirred egress redirect dev $NIC     IPv6: tc filter add dev $rep parent ffff: protocol ipv6 pref 1 \ flower \ dst_ip 1:1:1::3:1040:1009 \ src_ip 1:1:1::3:1040:1008 \ ip_proto tcp \ ip_tos 0x3 \ ip_ttl 63\ pedit ex \ munge ipv6 src set 2:2:2::3:1040:1009 \ munge ipv6 dst set 2:2:2::3:1040:1008 \ munge ipv6 hlimit dec \ action mirred egress redirect dev $NIC

Warning

IPv4 and IPv6 header rewrite is only supported with match on UDP/TCP/ICMP protocols.

TCP/UDP Source and Destination Ports

  • TCP/UDP source and destinations ports

Supported kernels: kernel > 4.16 & RHEL > 7.6

In OVS dump flows:

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TCP: set(tcp(src= 32768/0xffff,dst=32768/0xffff)), UDP:   set(udp(src= 32768/0xffff,dst=32768/0xffff)),

Using TC rules:

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TCP:   tc filter add dev $rep parent ffff: protocol ip pref 1 \ flower \ dst_ip 1.1.1.1 \ src_ip 1.1.1.2 \ ip_proto tcp \ ip_tos 0x3 \ ip_ttl 63 \ pedit ex \ pedit ex munge ip tcp sport set 200 pedit ex munge ip tcp dport set 200 action mirred egress redirect dev $NIC   UDP: tc filter add dev $rep parent ffff: protocol ip pref 1 \ flower \ dst_ip 1.1.1.1 \ src_ip 1.1.1.2 \ ip_proto udp \ ip_tos 0x3 \ ip_ttl 63 \ pedit ex \ pedit ex munge ip udp sport set 200 pedit ex munge ip udp dport set 200 action mirred egress redirect dev $NIC


VLAN

  • ID

Supported on all kernels.

In OVS dump flows:

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Set(vlan(vid=2347,pcp=0/0)),

Using TC rules:

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tc filter add dev $rep parent ffff: protocol 802.1Q pref 1 \ flower \ vlan_ethtype 0x800 \ vlan_id 100 \ vlan_prio 0 \ action vlan modify id 11 pipe action mirred egress redirect dev $NIC

Connection Tracking

The TC connection tracking action performs connection tracking lookup by sending the packet to netfilter conntrack module. Newly added connections may be associated, via the ct commit action, with a 32 bit mark, 128 bit label and source/destination NAT values.

The following example allows ingress tcp traffic from the uplink representor to vf1_rep, while assuring that egress traffic from vf1_rep is only allowed on established connections. In addition, mark and source IP NAT is applied.

In OVS dump flows:

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ct(zone=2,nat) ct_state(+est+trk) actions:ct(commit,zone=2,mark=0x4/0xffffffff,nat(src=5.5.5.5))

Using TC rules:

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# tc filter add dev $uplink_rep ingress chain 0 prio 1 proto ip \ flower \ ip_proto tcp \ ct_state -trk \ action ct zone 2 nat pipe action goto chain 2 # tc filter add dev $uplink_rep ingress chain 2 prio 1 proto ip \ flower \ ct_state +trk+new \ action ct zone 2 commit mark 0xbb nat src addr 5.5.5.7 pipe \ action mirred egress redirect dev $vf1_rep # tc filter add dev $uplink_rep ingress chain 2 prio 1 proto ip \ flower \ ct_zone 2 \ ct_mark 0xbb \ ct_state +trk+est \ action mirred egress redirect dev $vf1_rep   #Setup filters on $vf1_rep, allowing only established connections of zone 2 through, and reverse nat (dst nat in this case) # tc filter add dev $vf1_rep ingress chain 0 prio 1 proto ip \ flower \ ip_proto tcp \ ct_state -trk \ action ct zone 2 nat pipe \ action goto chain 1 # tc filter add dev $vf1_rep ingress chain 1 prio 1 proto ip \ flower \ ct_zone 2 \ ct_mark 0xbb \ ct_state +trk+est \ action mirred egress redirect dev eth0

Connection Tracking Performance Tuning

  • Max offloaded connections—specifies the limit on the number of offloaded connections.
    Example:

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    # devlink dev param set pci/${pci_dev} name ct_max_offloaded_conns value $max cmode runtime

  • Allow mixed NAT/non-NAT CT—allows offloading of the following scenario:

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    • cookie=0x0, duration=21.843s, table=0, n_packets=4838718, n_bytes=241958846, ct_state=-trk,ip,in_port=enp8s0f0 actions=ct(table=1,zone=2) • cookie=0x0, duration=21.823s, table=1, n_packets=15363, n_bytes=773526, ct_state=+new+trk,ip,in_port=enp8s0f0 actions=ct(commit,zone=2,nat(dst=11.11.11.11)),output:"enp8s0f0_1" • cookie=0x0, duration=21.806s, table=1, n_packets=4767594, n_bytes=238401190, ct_state=+est+trk,ip,in_port=enp8s0f0 actions=ct(zone=2,nat),output:"enp8s0f0_1"

    Example:

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    # echo enable > /sys/class/net/<device>/compat/devlink/ct_action_on_nat_conns

Forward to Chain (TC Only)

TC interface supports adding flows on different chains. Only chain 0 is accessed by default. Access to the other chains requires usafe of the goto action.

In this example, a flow is created on chain 1 without any match and redirect to wire.

The second flow is created on chain 0 and match on source MAC and action goto chain 1.

This example simulates simple MAC spoofing.

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#tc filter add dev $rep parent ffff: protocol all chain 1 pref 1 \ flower \ action mirred egress redirect dev $NIC   #tc filter add dev $rep parent ffff: protocol all chain 1 pref 1 \ flower \ src_mac aa:bb:cc:aa:bb:cc action goto chain 1

Port Mirroring (Flow Based VF Traffic Mirroring for ASAP²)

Unlike para-virtual configurations, when the VM traffic is offloaded to the hardware via SR-IOV 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:

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# 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: "2.14.1"

  • To set enp4s0f0_0 as the mirror port, and mirror all of the traffic:

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    # ovs-vsctl -- --id=@p get port enp4s0f0_0 \ -- --id=@m create mirror name=m0 select-all=true output-port=@p \ -- set bridge br-vxlan mirrors=@m

  • To set enp4s0f0_0 as the mirror port, and only mirror the traffic, the destination is enp4s0f0_1:

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    # ovs-vsctl -- --id=@p1 get port enp4s0f0_0 \ -- --id=@p2 get port enp4s0f0_1 \ -- --id=@m create mirror name=m0 select-dst-port=@p2 output-port=@p1 \ -- set bridge br-vxlan mirrors=@m

  • To set enp4s0f0_0 as the mirror port, and only mirror the traffic the source is enp4s0f0_1:

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    # ovs-vsctl -- --id=@p1 get port enp4s0f0_0 \ -- --id=@p2 get port enp4s0f0_1 \ -- --id=@m create mirror name=m0 select-src-port=@p2 output-port=@p1 \ -- set bridge br-vxlan mirrors=@m

  • To set enp4s0f0_0 as the mirror port and mirror, all the traffic on enp4s0f0_1:

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    # ovs-vsctl -- --id=@p1 get port enp4s0f0_0 \ -- --id=@p2 get port enp4s0f0_1 \ -- --id=@m create mirror name=m0 select-dst-port=@p2 select-src-port=@p2 output-port=@p1 \ -- set bridge br-vxlan mirrors=@m

To clear the mirror port:

Procedure_Heading_Icon.PNG

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# ovs-vsctl clear bridge br-vxlan mirrors

Mirroring using TC:

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Mirror to VF tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action mirred egress mirror dev $mirror_rep pipe \ action mirred egress redirect dev $NIC   Mirror to tunnel: tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action tunnel_key set \ src_ip 1.1.1.1 \ dst_ip 1.1.1.2 \ dst_port 4789 \ id 768 \ pipe \ action mirred egress mirror dev vxlan100 pipe \ action mirred egress redirect dev $NIC


sFLOW

This feature allows for monitoring traffic sent between two VMs on the same host using an sFlow collector.

The example below shows the creation of port mirroring on the following configuration.

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# 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: "2.14.1"

To sample all traffic over the OVS bridge:

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# ovs-vsctl -- --id=@sflow create sflow agent=\"$SFLOW_AGENT\" \ target=\"$SFLOW_TARGET:$SFLOW_PORT\" header=$SFLOW_HEADER \ sampling=$SFLOW_SAMPLING polling=10 \ -- set bridge br-vxlan sflow=@sflow

Parameter

Description

SFLOW_AGENT

Indicates that the sFlow agent should send traffic from SFLOW_AGENT’s IP address

SFLOW_TARGET

Remote IP address of the sFLOW collector

SFLOW_PORT

Size of packet header to sample (in bytes)

SFLOW_SAMPLING

Sample rate

To clear the sFLOW configuration:

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# ovs-vsctl clear bridge br-vxlan mirrors

sFLOW using TC:

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Sample to VF tc filter add dev $rep parent ffff: protocol arp pref 1 \ flower \ dst_mac e4:1d:2d:5d:25:35 \ src_mac e4:1d:2d:5d:25:34 \ action sample rate 10 group 5 trunc 96 \ action mirred egress redirect dev $NIC

Warning

Userspace application is needed in order to process to sampled packet from the kernel. Example: https://github.com/Mellanox/libpsample


Rate Limit

OVS-kernel supports offload of VF rate limit using OVS configuration and TC.

The example below sets a rate limit to the VF related to representor eth0 to 10Mbps.

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OVS: # ovs-vsctl set interface eth0 ingress_policing_rate=10000   tc: # tc_filter add dev eth0 root prio 1 protocol ip matchall skip_sw action police rate 10mbit burst 20k


Kernel Requirements

This kernel config should be enabled in order to support switchdev offload.

  • CONFIG_NET_ACT_CSUM – needed for action csum

  • CONFIG_NET_ACT_PEDIT – needed for header rewrite

  • CONFIG_NET_ACT_MIRRED – needed for basic forward

  • CONFIG_NET_ACT_CT – needed for connection tracking (supported from kernel 5.6)

  • CONFIG_NET_ACT_VLAN - needed for action vlan push/pop

  • CONFIG_NET_ACT_GACT

  • CONFIG_NET_CLS_FLOWER

  • CONFIG_NET_CLS_ACT

  • CONFIG_NET_SWITCHDEV

  • CONFIG_NET_TC_SKB_EXT - needed for connection tracking (supported from kernel 5.6)

  • CONFIG_NET_ACT_CT - needed for connection tracking (supported from kernel 5.6)

  • CONFIG_NFT_FLOW_OFFLOAD

  • CONFIG_NET_ACT_TUNNEL_KEY

  • CONFIG_NF_FLOW_TABLE - needed for connection tracking (supported from kernel 5.6)

  • CONFIG_SKB_EXTENSIONS - needed for connection tracking (supported from kernel 5.6)

  • CONFIG_NET_CLS_MATCHALL

  • CONFIG_NET_ACT_POLICE

  • CONFIG_MLX5_ESWITCH

VF Metering

OVS-kernel supports offloading of VF metering (TX and RX) using sysfs. Metering of number of packets per second (PPS) and bytes per second (BPS) is supported.

The example bellow sets Rx meter on VF 0 with value 10Mbps BPS.

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echo 10000000 > /sys/class/net/enp4s0f0/device/sriov/0/meters/rx/bps/rate echo 65536 > /sys/class/net/enp4s0f0/device/sriov/0/meters/rx/bps/burst

The example bellow sets Tx meter on VF 0 with value 1000 PPS.

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echo 1000 > /sys/class/net/enp4s0f0/device/sriov/0/meters/tx/pps/rate echo 100 > /sys/class/net/enp4s0f0/device/sriov/0/meters/tx/pps/burst

Warning

Both rate and burst must not be zero and burst may need to be adjusted according to the requirements.

The following counters can be used to query the number dropped packet/bytes:

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#cat /sys/class/net/enp8s0f0/device/sriov/0/meters/rx/pps/packets_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/rx/pps/bytes_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/rx/bps/packets_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/rx/bps/bytes_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/tx/pps/packets_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/tx/pps/bytes_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/tx/bps/packets_dropped #cat /sys/class/net/enp8s0f0/device/sriov/0/meters/tx/bps/bytes_dropped


Representor Metering

Metering for uplink and VF representors traffic support has been added.

Traffic going to a representor device can be a result of a miss in the embedded switch (eSwitch) FDB tables. This means that a packet which arrived from that representor into the eSwitch was not matched against the existing rules in the hardware FDB tables and needs to be forwarded to software to be handled there and is, therefore, forwarded to the originating representor device driver.

The meter allows to configure the max rate [packets/sec] and max burst [packets] for traffic going to the representor driver. Any traffic exceeding values provided by the user will be dropped in hardware. There are statistics that show number of dropped packets.

The configuration of a representors metering is done via a new sysfs called miss_rl_cfg.

  • Full path of the miss_rl_cfg parameter: /sys/class/net//rep_config/miss_rl_cfg

  • Usage: echo ”<rate> <burst>” > /sys/class/net//rep_config/miss_rl_cfg. Rate is the max rate of packets allowed for this representor (in packets/sec units) and burst is the max burst size allowed for this representor (in packets units). Both values must be specified. The default is 0 for both, meaning unlimited rate and burst.

To view the amount of packets and bytes that were dropped due to traffic exceeding the user-provided rate and burst, two read-only sysfs for statistics are exposed.

  • /sys/class/net//rep_config/miss_rl_dropped_bytes counts how many FDB-miss bytes were dropped due to reaching the miss limits

  • /sys/class/net//rep_config/miss_rl_dropped_packets counts how many FDB-miss packets were dropped due to reaching the miss limits

OVS-DPDK Hardware Offloads

OVS-DPDK Hardware Offloads Configuration

To configure OVS-DPDK HW offloads:

Procedure_Heading_Icon.PNG

  1. Unbind the VFs.

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    echo 0000:04:00.2 > /sys/bus/pci/drivers/mlx5_core/unbind echo 0000:04:00.3 > /sys/bus/pci/drivers/mlx5_core/unbind

    Note: VMs with attached VFs must be powered off to be able to unbind the VFs.

  2. Change the e-switch mode from Legacy to SwitchDev on the PF device (make sure all VFs are unbound). This will also create the VF representor netdevices in the host OS.

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    echo switchdev > /sys/class/net/enp4s0f0/compat/devlink/mode

    To revert to SR-IOV Legacy mode:

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    echo legacy > /sys/class/net/enp4s0f0/compat/devlink/mode

    Note that running this command will also result in the removal of the VF representor netdevices.

  3. Bind the VFs.

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    echo 0000:04:00.2 > /sys/bus/pci/drivers/mlx5_core/bind echo 0000:04:00.3 > /sys/bus/pci/drivers/mlx5_core/bind

  4. Run the Open vSwitch service.

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    systemctl start openvswitch

  5. Enable hardware offload (disabled by default).

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    ovs-vsctl --no-wait set Open_vSwitch . other_config:dpdk-init=true ovs-vsctl set Open_vSwitch . other_config:hw-offload=true

  6. Configure the DPDK white list.

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    ovs-vsctl --no-wait set Open_vSwitch . other_config:dpdk-extra="-w 0000:01:00.0,representor=[0],dv_flow_en=1,dv_esw_en=1,dv_xmeta_en=1"

  7. Restart the Open vSwitch service. This step is required for HW offload changes to take effect.

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    systemctl restart openvswitch

  8. Create OVS-DPDK bridge.

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    ovs-vsctl --no-wait add-br br0-ovs -- set bridge br0-ovs datapath_type=netdev

  9. Add PF to OVS.

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    ovs-vsctl add-port br0-ovs pf -- set Interface pf type=dpdk options:dpdk-devargs=0000:88:00.0

  10. Add representor to OVS.

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    ovs-vsctl add-port br0-ovs representor -- set Interface representor type=dpdk options:dpdk-devargs=0000:88:00.0,representor=[$rep]

Offloading VXLAN Encapsulation/Decapsulation Actions

vSwitch in userspace rather than kernel-based Open vSwitch requires an additional bridge. The purpose of this bridge is to allow use of the kernel network stack for routing and ARP resolution.

The datapath needs to look-up the routing table and ARP table to prepare the tunnel header and transmit data to the output port.

Configuring VXLAN Encap/Decap Offloads

Warning

The configuration is done with:

  • PF on 0000:03:00.0 PCI and MAC 98:03:9b:cc:21:e8

  • Local IP 56.56.67.1 - br-phy interface will be configured to this IP

  • Remote IP 56.56.68.1

To configure OVS-DPDK VXLAN:

Procedure_Heading_Icon.PNG

  1. Create a br-phy bridge.

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    ovs-vsctl add-br br-phy -- set Bridge br-phy datapath_type=netdev -- br-set-external-id br-phy bridge-id br-phy -- set bridge br-phy fail-mode=standalone other_config:hwaddr=98:03:9b:cc:21:e8

  2. Attach PF interface to br-phy bridge.

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    ovs-vsctl add-port br-phy p0 -- set Interface p0 type=dpdk options:dpdk-devargs=0000:03:00.0

  3. Configure IP to the bridge.

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    ip addr add 56.56.67.1/24 dev br-phy

  4. Create a br-ovs bridge.

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    ovs-vsctl add-br br-ovs -- set Bridge br-ovs datapath_type=netdev -- br-set-external-id br-ovs bridge-id br-ovs -- set bridge br-ovs fail-mode=standalone

  5. Attach representor to br-ovs.

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    ovs-vsctl add-port br-ovs pf0vf0 -- set Interface pf0vf0 type=dpdk options:dpdk-devargs=0000:03:00.0,representor=[0]

  6. Add a port for the VXLAN tunnel.

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    ovs-vsctl add-port ovs-sriov vxlan0 -- set interface vxlan0 type=vxlan options:local_ip=56.56.67.1 options:remote_ip=56.56.68.1 options:key=45 options:dst_port=4789

Connection Tracking Offload

Connection tracking enables stateful packet processing by keeping a record of currently open connections.
OVS flows using connection tracking can be accelerated using advanced Network Interface Cards (NICs) by offloading established connections.

To view offloaded connections, run:

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ovs-appctl dpctl/offload-stats-show


SR-IOV VF LAG

To configure OVS-DPDK SR-IOV VF LAG:

Procedure_Heading_Icon.PNG

  1. Enable SR-IOV on the NICs.

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    mlxconfig -d <PCI> set SRIOV_EN=1

  2. Allocate the desired number of VFs per port.

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    echo $n > /sys/class/net/<net name>/device/sriov_numvfs

  3. Unbind all VFs.

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    echo <VF PCI> >/sys/bus/pci/drivers/mlx5_core/unbind

  4. Change both NICs' mode to SwitchDev.

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    devlink dev eswitch set pci/<PCI> mode switchdev

  5. Create Linux bonding using kernel modules.

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    modprobe bonding mode=<desired mode>

    Note: Other bonding parameters can be added here. The supported Bond modes are: Active-Backup, XOR and LACP.

  6. Bring all PFs and VFs down.

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    ip link set <PF/VF> down

  7. Attach both PFs to the bond.

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    ip link set <PF> master bond0

  8. To work with VF-LAG with OVS-DPDK, add the bond master (PF) to the bridge.

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    ovs-vsctl add-port br-phy p0 -- set Interface p0 type=dpdk options:dpdk-devargs=0000:03:00.0 options:dpdk-lsc-interrupt=true

  9. Add representor $N of PF0 or PF1 to a bridge.

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    ovs-vsctl add-port br-phy rep$N -- set Interface rep$N type=dpdk options:dpdk-devargs=<PF0 PCI>,representor=pf0vf$N   OR   ovs-vsctl add-port br-phy rep$N -- set Interface rep$N type=dpdk options:dpdk-devargs=<PF0 PCI>,representor=pf1vf$N

VirtIO Acceleration through VF Relay (Software & Hardware vDPA)

Warning

Hardware vDPA is supported on ConnectX-6 Dx, ConnectX-6 Lx & BlueField-2 cards and above only.

Warning

Hardware vDPA is enabled by default. In case your hardware does not support vDPA, the driver will fall back to Software vDPA.

To check which vDPA mode is activated on your driver, run: ovs-ofctl -O OpenFlow14 dump-ports br0-ovs and look for hw-mode flag.

Warning

This feature has not been accepted to the OVS-DPDK Upstream yet, making its API subject to change.

In user space, there are two main approaches for communicating with a guest (VM), either through SR-IOV, or through virtIO.

Phy ports (SR-IOV) allow working with port representor, which is attached to the OVS and a matching VF is given with pass-through to the guest. HW rules can process packets from up-link and direct them to the VF without going through SW (OVS). Therefore, using SR-IOV achieves the best performance.

However, SR-IOV architecture requires the guest to use a driver specific to the underlying HW. Specific HW driver has two main drawbacks:

  1. Breaks virtualization in some sense (guest is aware of the HW). It can also limit the type of images supported.

  2. Gives less natural support for live migration.

Using virtIO port solves both problems. However, it reduces performance and causes loss of some functionalities, such as, for some HW offloads, working directly with virtIO. To solve this conflict, a new netdev type- dpdkvdpa has been created. The new netdev is similar to the regular DPDK netdev, yet introduces several additional functionalities.

dpdkvdpa translates between phy port to virtIO port. It takes packets from the Rx queue and sends them to the suitable Tx queue, and allows transfer of packets from virtIO guest (VM) to a VF, and vice-versa, benefitting from both SR-IOV and virtIO.

To add vDPA port:

Procedure_Heading_Icon.PNG

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ovs-vsctl add-port br0 vdpa0 -- set Interface vdpa0 type=dpdkvdpa \ options:vdpa-socket-path=<sock path> \ options:vdpa-accelerator-devargs=<vf pci id> \ options:dpdk-devargs=<pf pci id>,representor=[id] \ options: vdpa-max-queues =<num queues> \ options: vdpa-sw=<true/false>

Note: vdpa-max-queues is an optional field. When the user wants to configure 32 vDPA ports, the maximum queues number is limited to 8.

vDPA Configuration in OVS-DPDK Mode

Prior to configuring vDPA in OVS-DPDK mode, follow the steps below.

  1. Generate the VF.

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    echo 0 > /sys/class/net/enp175s0f0/device/sriov_numvfs echo 4 > /sys/class/net/enp175s0f0/device/sriov_numvfs

  2. Unbind each VF.

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    echo <pci> > /sys/bus/pci/drivers/mlx5_core/unbind

  3. Switch to SwitchDev mode.

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    echo switchdev >> /sys/class/net/enp175s0f0/compat/devlink/mode

  4. Bind each VF.

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    echo <pci> > /sys/bus/pci/drivers/mlx5_core/bind

  5. Initialize OVS with:

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    ovs-vsctl --no-wait set Open_vSwitch . other_config:dpdk-init=true ovs-vsctl --no-wait set Open_vSwitch . other_config:hw-offload=true

To configure vDPA in OVS-DPDK mode on ConnectX-5 cards and above:

Procedure_Heading_Icon.PNG

  1. Open vSwitch configuration.

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    ovs-vsctl --no-wait set Open_vSwitch . other_config:dpdk-extra="-w 0000:01:00.0,representor=[0],dv_flow_en=1,dv_esw_en=1,dv_xmeta_en=1" /usr/share/openvswitch/scripts/ovs-ctl restart

  2. Create OVS-DPDK bridge.

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    ovs-vsctl add-br br0-ovs -- set bridge br0-ovs datapath_type=netdev ovs-vsctl add-port br0-ovs pf -- set Interface pf type=dpdk options:dpdk-devargs=0000:01:00.0

  3. Create vDPA port as part of the OVS-DPDK bridge.

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    ovs-vsctl add-port br0-ovs vdpa0 -- set Interface vdpa0 type=dpdkvdpa options:vdpa-socket-path=/var/run/virtio-forwarder/sock0 options:vdpa-accelerator-devargs=0000:01:00.2 options:dpdk-devargs=0000:01:00.0,representor=[0] options: vdpa-max-queues=8

To configure vDPA in OVS-DPDK mode on BlueField cards:

Procedure_Heading_Icon.PNG

Set the bridge with the software or hardware vDPA port:

  • On the ARM side:

    Create the OVS-DPDK bridge.

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    ovs-vsctl add-br br0-ovs -- set bridge br0-ovs datapath_type=netdev ovs-vsctl add-port br0-ovs pf -- set Interface pf type=dpdk options:dpdk-devargs=0000:af:00.0 ovs-vsctl add-port br0-ovs rep-- set Interface rep type=dpdk options:dpdk-devargs=0000:af:00.0,representor=[0]

  • On the host side:

    Create the OVS-DPDK bridge.

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    ovs-vsctl add-br br1-ovs -- set bridge br1-ovs datapath_type=netdev protocols=OpenFlow14 ovs-vsctl add-port br0-ovs vdpa0 -- set Interface vdpa0 type=dpdkvdpa options:vdpa-socket-path=/var/run/virtio-forwarder/sock0 options:vdpa-accelerator-devargs=0000:af:00.2

    Note: To configure SW vDPA, add "options:vdpa-sw=true" to the end of the command.

Software vDPA Configuration in OVS-Kernel Mode

SW vDPA can also be used in configurations where the HW offload is done through TC and not DPDK.

  1. Open vSwitch configuration.

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    ovs-vsctl set Open_vSwitch . other_config:dpdk-extra="-w 0000:01:00.0,representor=[0],dv_flow_en=1,dv_esw_en=0,idv_xmeta_en=0,isolated_mode=1" /usr/share/openvswitch/scripts/ovs-ctl restart

  2. Create OVS-DPDK bridge.

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    ovs-vsctl add-br br0-ovs -- set bridge br0-ovs datapath_type=netdev

  3. Create vDPA port as part of the OVS-DPDK bridge.

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    ovs-vsctl add-port br0-ovs vdpa0 -- set Interface vdpa0 type=dpdkvdpa options:vdpa-socket-path=/var/run/virtio-forwarder/sock0 options:vdpa-accelerator-devargs=0000:01:00.2 options:dpdk-devargs=0000:01:00.0,representor=[0] options: vdpa-max-queues=8

  4. Create Kernel bridge.

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    ovs-vsctl add-br br-kernel

  5. Add representors to Kernel bridge.

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    ovs-vsctl add-port br-kernel enp1s0f0_0 ovs-vsctl add-port br-kernel enp1s0f0

Large MTU/Jumbo Frame Configuration

To configure MTU/jumbo frames:

Procedure_Heading_Icon.PNG

  1. Verify that the Kernel version on the VM is 4.14 or above.

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    cat /etc/redhat-release

  2. Set the MTU on both physical interfaces in the host.

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    ifconfig ens4f0 mtu 9216

  3. Send a large size packet and verify that it is sent and received correctly.

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    tcpdump -i ens4f0 -nev icmp & ping 11.100.126.1 -s 9188 -M do -c 1

  4. Enable host_mtu in xml, and add the following values to xml.

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    host_mtu=9216,csum=on,guest_csum=on,host_tso4=on,host_tso6=on

    Example:

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    <qemu:commandline> <qemu:arg value='-chardev'/> <qemu:arg value='socket,id=charnet1,path=/tmp/sock0,server'/> <qemu:arg value='-netdev'/> <qemu:arg value='vhost-user,chardev=charnet1,queues=16,id=hostnet1'/> <qemu:arg value='-device'/> <qemu:arg value='virtio-net-pci,mq=on,vectors=34,netdev=hostnet1,id=net1,mac=00:21:21:24:02:01,bus=pci.0,addr=0xC,page-per-vq=on,rx_queue_size=1024,tx_queue_size=1024,host_mtu=9216,csum=on,guest_csum=on,host_tso4=on,host_tso6=on'/> </qemu:commandline>

  5. Add mtu_request=9216 option to the OvS ports inside the container and restart the OVS:

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    ovs-vsctl add-port br0-ovs pf -- set Interface pf type=dpdk options:dpdk-devargs=0000:c4:00.0 mtu_request=9216

    OR:

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    ovs-vsctl add-port br0-ovs vdpa0 -- set Interface vdpa0 type=dpdkvdpa options:vdpa-socket-path=/tmp/sock0 options:vdpa-accelerator-devargs=0000:c4:00.2 options:dpdk-devargs=0000:c4:00.0,representor=[0] mtu_request=9216 /usr/share/openvswitch/scripts/ovs-ctl restart

  6. Start the VM and configure the MTU on the VM.

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    ifconfig eth0 11.100.124.2/16 up ifconfig eth0 mtu 9216 ping 11.100.126.1 -s 9188 -M do -c1

E2E Cache

Warning

This feature is at beta level.

OVS offload rules are based on a multi-table architecture. E2E cache feature enables merging the multi-table flow matches and actions into one joint flow.

This improves connection tracking performance by using a single-table when exact match is detected.

To s

Procedure_Heading_Icon.PNG

et the E2E cache size (default = 4k):

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ovs-vsctl set open_vswitch . other_config:e2e-size=<size> systemctl restart openvswitch

Note: Make sure to restart the openvswitch service in order for the configuration to take effect.

To e

Procedure_Heading_Icon.PNG

nable/disable E2E cache (default = disabled) :

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ovs-vsctl set open_vswitch . other_config:e2e-enable=<true/false> systemctl restart openvswitch

Note: Make sure to restart the openvswitch service in order for the configuration to take effect.

To run

Procedure_Heading_Icon.PNG

E2E cache statistics:

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ovs-appctl dpctl/dump-e2e-stats

To run E2E cache flows:

Procedure_Heading_Icon.PNG

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ovs-appctl dpctl/dump-e2e-flows


Geneve Encapsulation/Decapsulation

Geneve tunneling offload feature support includes matching on extension header.

To configure OVS-DPDK Geneve encap/decap:

Procedure_Heading_Icon.PNG

  1. Create a br-phy bridge.

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    ovs-vsctl --may-exist add-br br-phy -- set Bridge br-phy datapath_type=netdev -- br-set-external-id br-phy bridge-id br-phy -- set bridge br-phy fail-mode=standalone

  2. Attach PF interface to br-phy bridge.

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    ovs-vsctl add-port br-phy pf -- set Interface pf type=dpdk options:dpdk-devargs=<PF PCI>

  3. Configure IP to the bridge.

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    ifconfig br-phy <$local_ip_1> up

  4. Create a br-int bridge.

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    ovs-vsctl --may-exist add-br br-int -- set Bridge br-int datapath_type=netdev -- br-set-external-id br-int bridge-id br-int -- set bridge br-int fail-mode=standalone

  5. Attach representor to br-int.

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    ovs-vsctl add-port br-int rep$x -- set Interface rep$x type=dpdk options:dpdk-devargs=<PF PCI>,representor=[$x]

  6. Add a port for the GENEVE tunnel.

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    ovs-vsctl add-port br-int geneve0 -- set interface geneve0 type=geneve options:key=<VNI> options:remote_ip=<$remote_ip_1> options:local_ip=<$local_ip_1>

Parallel Offloads

OVS-DPDK supports parallel insertion and deletion of offloads (flow & CT). While multiple threads are supported, by default only one is used.

To c

Procedure_Heading_Icon.PNG

onfigure multiple threads:

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ovs-vsctl set Open_vSwitch . other_config:hw-offload-thread-nb=3

Make sure to restart the openvswitch service in order for the configuration to take effect.

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systemctl restart openvswitch

Warning

For more information, see the OvS user manual.

sFlow

This feature allows for monitoring traffic sent between two VMs on the same host using an sFlow collector.

To sample all traffic over the OVS bridge, run the following:

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# ovs-vsctl -- --id=@sflow create sflow agent=\"$SFLOW_AGENT\" \ target=\"$SFLOW_TARGET:$SFLOW_PORT\" header=$SFLOW_HEADER \ sampling=$SFLOW_SAMPLING polling=10 \ -- set bridge sflow=@sflow

Parameter

Description

SFLOW_AGENT

Indicates that the sFlow agent should send traffic from SFLOW_AGENT’s IP address

SFLOW_TARGET

Remote IP address of the sFLOW collector

SFLOW_PORT

Remote IP destination port of the sFlow collector

SFLOW_HEADER

Size of packet header to sample (in bytes)

SFLOW_SAMPLING

Sample rate

To clear the sFLOW configuration, runt he following:

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# ovs-vsctl clear bridge br-vxlan mirrors

Warning

Currently sFlow for OVS-DPDK is supported without CT.


CT CT NAT

To enable ct-ct-nat offloads in OvS-DPDK, execute the following command (deafult value is false):

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ovs-vsctl set open_vswitch . other_config:ct-action-on-nat-conns=true

If disabled, ct-ct-nat configurations will not be fully offloaded, improving connection offloading rate for
other cases (ct and ct-nat).

If enabled, ct-ct-nat configurations will be fully offloaded but ct and ct-nat offloading
will be slower to be created.

Hardware vDPA Installation

Hardware vDPA requires QEMU v4.0.0 and DPDK v20.02 as minimal versions.

To install QEMU:

Procedure_Heading_Icon.PNG

  1. Clone the sources:

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    git clone https://git.qemu.org/git/qemu.git cd qemu git checkout v4.0.0

  2. Build QEMU:

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    mkdir bin cd bin ../configure --target-list=x86_64-softmmu --enable-kvm make -j24

To install DPDK:

Procedure_Heading_Icon.PNG

  1. Clone the sources:

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    git clone git://dpdk.org/dpdk cd dpdk git checkout v20.02

  2. Install dependencies (if needed):

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    yum install cmake gcc libnl3-devel libudev-devel make pkgconfig valgrind-devel pandoc libibverbs libmlx5 libmnl-devel -y

  3. Configure DPDK:

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    export RTE_SDK=$PWD make config T=x86_64-native-linuxapp-gcc cd build sed -i 's/\(CONFIG_RTE_LIBRTE_MLX5_PMD=\)n/\1y/g' .config sed -i 's/\(CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD=\)n/\1y/g' .config

  4. Build DPDK:

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    make -j

  5. Build the vDPA application:

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    cd $RTE_SDK/examples/vdpa/ make -j

Hardware vDPA Configuration

To configure huge pages:

Procedure_Heading_Icon.PNG

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mkdir -p /hugepages mount -t hugetlbfs hugetlbfs /hugepages echo <more> > /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/nr_hugepages echo <more> > /sys/devices/system/node/node1/hugepages/hugepages-1048576kB/nr_hugepages

To configure a vDPA VirtIO interface in an existing VM's xml file (using libvirt):

Procedure_Heading_Icon.PNG

  1. Open the VM's configuration xml for editing:

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    virsh edit <domain name>

  2. Modify/add the following:

    1. Change the top line to:

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      <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>

    2. Assign a memory amount and use 1GB page size for hugepages (size must be the same as used for the vDPA application), so that the memory configuration looks like the following.

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      <memory unit='KiB'>4194304</memory> <currentMemory unit='KiB'>4194304</currentMemory> <memoryBacking> <hugepages> <page size='1048576' unit='KiB'/> </hugepages> </memoryBacking>

    3. Assign an amount of CPUs for the VM CPU configuration, so that the vcpu and cputune configuration looks like the following.

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      <vcpu placement='static'>5</vcpu> <cputune> <vcpupin vcpu='0' cpuset='14'/> <vcpupin vcpu='1' cpuset='16'/> <vcpupin vcpu='2' cpuset='18'/> <vcpupin vcpu='3' cpuset='20'/> <vcpupin vcpu='4' cpuset='22'/> </cputune>

    4. Set the memory access for the CPUs to be shared, so that the cpu configuration looks like the following.

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      <cpu mode='custom' match='exact' check='partial'> <model fallback='allow'>Skylake-Server-IBRS</model> <numa> <cell id='0' cpus='0-4' memory='8388608' unit='KiB' memAccess='shared'/> </numa> </cpu>

    5. Set the emulator in use to be the one built in step "2. Build QEMU" above, so that the emulator configuration looks as follows.

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      <emulator><path to qemu executable></emulator>

    6. Add a virtio interface using qemu command line argument entries, so that the new interface snippet looks as follows.

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      <qemu:commandline> <qemu:arg value='-chardev'/> <qemu:arg value='socket,id=charnet1,path=/tmp/sock-virtio0'/> <qemu:arg value='-netdev'/> <qemu:arg value='vhost-user,chardev=charnet1,queues=16,id=hostnet1'/> <qemu:arg value='-device'/> <qemu:arg value='virtio-net-pci,mq=on,vectors=6,netdev=hostnet1,id=net1,mac=e4:11:c6:d3:45:f2,bus=pci.0,addr=0x6, page-per-vq=on,rx_queue_size=1024,tx_queue_size=1024'/> </qemu:commandline>

      Note: In this snippet, the vhostuser socket file path, the amount of queues, the MAC and the PCI slot of the VirtIO device can be configured.

Running Hardware vDPA

Warning

Hardware vDPA supports SwitchDev mode only.

Create the ASAP2 environment:

Procedure_Heading_Icon.PNG

  1. Create the VFs.

  2. Enter switchdev mode.

  3. Set up OVS.

the vDPA application.

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cd $RTE_SDK/examples/vdpa/build ./vdpa -w <VF PCI BDF>,class=vdpa --log-level=pmd,info -- -i

Create a vDPA port via the vDPA application CLI.

Procedure_Heading_Icon.PNG

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create /tmp/sock-virtio0 <PCI DEVICE BDF>

Note: The vhostuser socket file path must be the one used when configuring the VM.

Start the VM.

Procedure_Heading_Icon.PNG

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virsh start <domain name>

For further information on the vDPA application, please visit: https://doc.dpdk.org/guides/sample_app_ug/vdpa.html.

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 nvidia.com/en-us/networking/ → Products → Software → Firmware Tools.

  1. Start the mst driver.

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    # mst start Starting MST (Mellanox Software Tools) driver set Loading MST PCI module - Success Loading MST PCI configuration module - Success Create devices

  2. Show the devices status.

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    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_pciconf0.1 04:00.1 net-enp4s0f1 NA ConnectX4lx(rev:0) /dev/mst/mt4117_pciconf0 04:00.0 net-enp4s0f0 NA     # mlxconfig -d /dev/mst/mt4117_pciconf0 q | head -16   Device #1: ----------   Device type: ConnectX4lx PCI device: /dev/mst/mt4117_pciconf0   Configurations: Current SRIOV_EN True(1) NUM_OF_VFS 8 PF_LOG_BAR_SIZE 5 VF_LOG_BAR_SIZE 5 NUM_PF_MSIX 63 NUM_VF_MSIX 11 LINK_TYPE_P1 ETH(2) LINK_TYPE_P2 ETH(2)

  3. 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:

    1. Enable SR-IOV.

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      # mlxconfig -d /dev/mst/mt4115_pciconf0 s SRIOV_EN=1

    2. Set the number of required VFs.

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      # mlxconfig -d /dev/mst/mt4115_pciconf0 s NUM_OF_VFS=8 

    3. Set the link type to Ethernet.

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      # mlxconfig -d /dev/mst/mt4115_pciconf0 s LINK_TYPE_P1=2 # mlxconfig -d /dev/mst/mt4115_pciconf0 s LINK_TYPE_P2=2

  4. Reset the firmware.

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    # mlxfwreset -d /dev/mst/mt4115_pciconf0 reset

  5. Query the firmware to make sure everything is set correctly.

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    # mlxconfig -d /dev/mst/mt4115_pciconf0 q

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