taikun.cloud

Taikun Logo

Taikun OCP Guide

Table of Contents

Open vSwitch hardware offloading

The purpose of this page is to describe how to enable Open vSwitch
hardware offloading functionality available in OpenStack (using
OpenStack Networking). This functionality was first introduced in the
OpenStack Pike release. This page intends to serve as a guide for how to
configure OpenStack Networking and OpenStack Compute to enable Open
vSwitch hardware offloading.

The basics

Open vSwitch is a production quality, multilayer virtual switch
licensed under the open source Apache 2.0 license. It is designed to
enable massive network automation through programmatic extension, while
still supporting standard management interfaces and protocols. Open
vSwitch (OVS) allows Virtual Machines (VM) to communicate with each
other and with the outside world. The OVS software based solution is CPU
intensive, affecting system performance and preventing fully utilizing
available bandwidth.

TermDefinition
PFPhysical Function. The physical Ethernet controller that supports
SR-IOV.
VFVirtual Function. The virtual PCIe device created from a physical
Ethernet controller.
Representor PortVirtual network interface similar to SR-IOV port that represents
Nova instance.
First Compute NodeOpenStack Compute Node that can host Compute instances (Virtual
Machines).
Second Compute NodeOpenStack Compute Node that can host Compute instances (Virtual
Machines).

Supported Ethernet
controllers

The following manufacturers are known to work:

  • Mellanox ConnectX-4 NIC (VLAN Offload)
  • Mellanox ConnectX-4 Lx/ConnectX-5 NICs (VLAN/VXLAN Offload)
  • Broadcom NetXtreme-S series NICs
  • Broadcom NetXtreme-E series NICs

For information on Mellanox Ethernet Cards, see Mellanox:
Ethernet Cards – Overview
.

Prerequisites

  • Linux Kernel >= 4.13

  • Open vSwitch >= 2.8

  • iproute >= 4.12

  • Mellanox or Broadcom NIC

    Note

    Mellanox NIC FW that supports Open vSwitch hardware offloading:

    ConnectX-5 >= 16.21.0338

    ConnectX-4 >= 12.18.2000

    ConnectX-4 Lx >= 14.21.0338

Using Open vSwitch
hardware offloading

In order to enable Open vSwitch hardware offloading, the following
steps are required:

  1. Enable SR-IOV
  2. Configure NIC to switchdev mode (relevant Nodes)
  3. Enable Open vSwitch hardware offloading

Note

Throughout this guide, enp3s0f0 is used as the PF and
eth3 is used as the representor port. These ports may vary
in different environments.

Note

Throughout this guide, we use systemctl to restart
OpenStack services. This is correct for systemd OS. Other
methods to restart services should be used in other environments.

Create Compute virtual
functions

Create the VFs for the network interface that will be used for
SR-IOV. We use enp3s0f0 as PF, which is also used as the
interface for the VLAN provider network and has access to the private
networks of all nodes.

Note

The following steps detail how to create VFs using Mellanox
ConnectX-4 and SR-IOV Ethernet cards on an Intel system. Steps may be
different for the hardware of your choice.

  1. Ensure SR-IOV and VT-d are enabled on the system. Enable IOMMU in
    Linux by adding intel_iommu=on to kernel parameters, for
    example, using GRUB.

  2. On each Compute node, create the VFs:

    # echo '4' > /sys/class/net/enp3s0f0/device/sriov_numvfs

    Note

    A network interface can be used both for PCI passthrough, using the
    PF, and SR-IOV, using the VFs. If the PF is used, the VF number stored
    in the sriov_numvfs file is lost. If the PF is attached
    again to the operating system, the number of VFs assigned to this
    interface will be zero. To keep the number of VFs always assigned to
    this interface, update a relevant file according to your OS. See some
    examples below:

    In Ubuntu, modifying the /etc/network/interfaces
    file:

    auto enp3s0f0
    iface enp3s0f0 inet dhcp
    pre-up echo '4' > /sys/class/net/enp3s0f0/device/sriov_numvfs

    In Red Hat, modifying the /sbin/ifup-local file:

    #!/bin/sh
    if [[ "$1" == "enp3s0f0" ]]
    then
        echo '4' > /sys/class/net/enp3s0f0/device/sriov_numvfs
    fi

    Warning

    Alternatively, you can create VFs by passing the max_vfs
    to the kernel module of your network interface. However, the
    max_vfs parameter has been deprecated, so the PCI /sys
    interface is the preferred method.

    You can determine the maximum number of VFs a PF can support:

    # cat /sys/class/net/enp3s0f0/device/sriov_totalvfs
    8
  3. Verify that the VFs have been created and are in up
    state:

    Note

    The PCI bus number of the PF (03:00.0) and VFs (03:00.2 .. 03:00.5)
    will be used later.

    # lspci | grep Ethernet
    03:00.0 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5]
    03:00.1 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5]
    03:00.2 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
    03:00.3 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
    03:00.4 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
    03:00.5 Ethernet controller: Mellanox Technologies MT27800 Family [ConnectX-5 Virtual Function]
    # ip link show enp3s0f0
    8: enp3s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT qlen 1000
       link/ether a0:36:9f:8f:3f:b8 brd ff:ff:ff:ff:ff:ff
       vf 0 MAC 00:00:00:00:00:00, spoof checking on, link-state auto
       vf 1 MAC 00:00:00:00:00:00, spoof checking on, link-state auto
       vf 2 MAC 00:00:00:00:00:00, spoof checking on, link-state auto
       vf 3 MAC 00:00:00:00:00:00, spoof checking on, link-state auto

    If the interfaces are down, set them to up before
    launching a guest, otherwise the instance will fail to spawn:

    # ip link set enp3s0f0 up

Configure Open
vSwitch hardware offloading

  1. Change the e-switch mode from legacy to switchdev on the PF
    device. This will also create the VF representor network devices in the
    host OS.

    # echo 0000:03:00.2 > /sys/bus/pci/drivers/mlx5_core/unbind

    This tells the driver to unbind VF 03:00.2

    Note

    This should be done for all relevant VFs (in this example
    0000:03:00.2 .. 0000:03:00.5)

  2. Enable Open vSwitch hardware offloading, set PF to switchdev mode
    and bind VFs back.

    # sudo devlink dev eswitch set pci/0000:03:00.0 mode switchdev
    # sudo ethtool -K enp3s0f0 hw-tc-offload on
    # echo 0000:03:00.2 > /sys/bus/pci/drivers/mlx5_core/bind

    Note

    This should be done for all relevant VFs (in this example
    0000:03:00.2 .. 0000:03:00.5)

  3. Restart Open vSwitch

    # sudo systemctl enable openvswitch.service
    # sudo ovs-vsctl set Open_vSwitch . other_config:hw-offload=true
    # sudo systemctl restart openvswitch.service

    Note

    The given aging of OVS is given in milliseconds and can be controlled
    with:

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

Configure Nodes (VLAN
Configuration)

  1. Update /etc/neutron/plugins/ml2/ml2_conf.ini on
    Controller nodes

    [ml2]
    tenant_network_types = vlan
    type_drivers = vlan
    mechanism_drivers = openvswitch
  2. Update /etc/neutron/neutron.conf on Controller
    nodes

    [DEFAULT]
    core_plugin = ml2
  3. Update /etc/nova/nova.conf on Controller nodes

    [filter_scheduler]
    enabled_filters = PciPassthroughFilter
  4. Update /etc/nova/nova.conf on Compute nodes

    [pci]
    #VLAN Configuration passthrough_whitelist example
    passthrough_whitelist ={"'"address"'":"'"*:'"03:00"'.*"'","'"physical_network"'":"'"physnet2"'"}

Configure Nodes (VXLAN
Configuration)

  1. Update /etc/neutron/plugins/ml2/ml2_conf.ini on
    Controller nodes

    [ml2]
    tenant_network_types = vxlan
    type_drivers = vxlan
    mechanism_drivers = openvswitch
  2. Update /etc/neutron/neutron.conf on Controller
    nodes

    [DEFAULT]
    core_plugin = ml2
  3. Update /etc/nova/nova.conf on Controller nodes

    [filter_scheduler]
    enabled_filters = PciPassthroughFilter
  4. Update /etc/nova/nova.conf on Compute nodes

    Note

    VXLAN configuration requires physical_network to be null.

    [pci]
    #VLAN Configuration passthrough_whitelist example
    passthrough_whitelist ={"'"address"'":"'"*:'"03:00"'.*"'","'"physical_network"'":null}
  5. Restart nova and neutron services

    # sudo systemctl restart openstack-nova-compute.service
    # sudo systemctl restart openstack-nova-scheduler.service
    # sudo systemctl restart neutron-server.service

Validate Open vSwitch
hardware offloading

Note

In this example we will bring up two instances on different Compute
nodes and send ICMP echo packets between them. Then we will check TCP
packets on a representor port and we will see that only the first packet
will be shown there. All the rest will be offloaded.

  1. Create a port direct on private
    network

    # openstack port create --network private --vnic-type=direct direct_port1
  2. Create an instance using the direct port on ‘First Compute
    Node’

    # openstack server create --flavor m1.small --image cloud_image --nic port-id=direct_port1 vm1
  3. Repeat steps above and create a second instance on ‘Second
    Compute Node’

    # openstack port create --network private --vnic-type=direct direct_port2
    # openstack server create --flavor m1.small --image mellanox_fedora --nic port-id=direct_port2 vm2

    Note

    You can use –availability-zone nova:compute_node_1 option to set the
    desired Compute Node

  4. Connect to instance1 and send ICMP Echo Request packets to
    instance2

    # vncviewer localhost:5900
    vm_1# ping vm2
  5. Connect to ‘Second Compute Node’ and find representor port of the
    instance

    Note

    Find a representor port first, in our case it’s eth3

    compute_node2# ip link show enp3s0f0
    6: enp3s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master ovs-system state UP mode DEFAULT group default qlen 1000
       link/ether ec:0d:9a:46:9e:84 brd ff:ff:ff:ff:ff:ff
       vf 0 MAC 00:00:00:00:00:00, spoof checking off, link-state enable, trust off, query_rss off
       vf 1 MAC 00:00:00:00:00:00, spoof checking off, link-state enable, trust off, query_rss off
       vf 2 MAC 00:00:00:00:00:00, spoof checking off, link-state enable, trust off, query_rss off
       vf 3 MAC fa:16:3e:b9:b8:ce, vlan 57, spoof checking on, link-state enable, trust off, query_rss off
    
    compute_node2# ls -l /sys/class/net/
    lrwxrwxrwx 1 root root 0 Sep 11 10:54 eth0 -> ../../devices/virtual/net/eth0
    lrwxrwxrwx 1 root root 0 Sep 11 10:54 eth1 -> ../../devices/virtual/net/eth1
    lrwxrwxrwx 1 root root 0 Sep 11 10:54 eth2 -> ../../devices/virtual/net/eth2
    lrwxrwxrwx 1 root root 0 Sep 11 10:54 eth3 -> ../../devices/virtual/net/eth3
    
    compute_node2# sudo ovs-dpctl show
    system@ovs-system:
      lookups: hit:1684 missed:1465 lost:0
      flows: 0
      masks: hit:8420 total:1 hit/pkt:2.67
      port 0: ovs-system (internal)
      port 1: br-enp3s0f0 (internal)
      port 2: br-int (internal)
      port 3: br-ex (internal)
      port 4: enp3s0f0
      port 5: tapfdc744bb-61 (internal)
      port 6: qr-a7b1e843-4f (internal)
      port 7: qg-79a77e6d-8f (internal)
      port 8: qr-f55e4c5f-f3 (internal)
      port 9: eth3
  6. Check traffic on the representor port. Verify that only the first
    ICMP packet appears.

    compute_node2# tcpdump -nnn -i eth3
    
    tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
    listening on eth3, link-type EN10MB (Ethernet), capture size 262144 bytes
    17:12:41.220447 ARP, Request who-has 172.0.0.10 tell 172.0.0.13, length 46
    17:12:41.220684 ARP, Reply 172.0.0.10 is-at fa:16:3e:f2:8b:23, length 42
    17:12:41.260487 IP 172.0.0.13 > 172.0.0.10: ICMP echo request, id 1263, seq 1, length 64
    17:12:41.260778 IP 172.0.0.10 > 172.0.0.13: ICMP echo reply, id 1263, seq 1, length 64
    17:12:46.268951 ARP, Request who-has 172.0.0.13 tell 172.0.0.10, length 42
    17:12:46.271771 ARP, Reply 172.0.0.13 is-at fa:16:3e:1a:10:05, length 46
    17:12:55.354737 IP6 fe80::f816:3eff:fe29:8118 > ff02::1: ICMP6, router advertisement, length 64
    17:12:56.106705 IP 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 62:21:f0:89:40:73, length 300

taikun-logo-icon

Explore Taikun CloudWorks in 2 Minutes!