vmxnet3.rst revision 6b3e017e
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30
31Poll Mode Driver for Paravirtual VMXNET3 NIC
32============================================
33
34The VMXNET3 adapter is the next generation of a paravirtualized NIC, introduced by VMware* ESXi.
35It is designed for performance, offers all the features available in VMXNET2, and adds several new features such as,
36multi-queue support (also known as Receive Side Scaling, RSS),
37IPv6 offloads, and MSI/MSI-X interrupt delivery.
38One can use the same device in a DPDK application with VMXNET3 PMD introduced in DPDK API.
39
40In this chapter, two setups with the use of the VMXNET3 PMD are demonstrated:
41
42#.  Vmxnet3 with a native NIC connected to a vSwitch
43
44#.  Vmxnet3 chaining VMs connected to a vSwitch
45
46VMXNET3 Implementation in the DPDK
47----------------------------------
48
49For details on the VMXNET3 device, refer to the VMXNET3 driver's vmxnet3 directory and support manual from VMware*.
50
51For performance details, refer to the following link from VMware:
52
53`http://www.vmware.com/pdf/vsp_4_vmxnet3_perf.pdf <http://www.vmware.com/pdf/vsp_4_vmxnet3_perf.pdf>`_
54
55As a PMD, the VMXNET3 driver provides the packet reception and transmission callbacks, vmxnet3_recv_pkts and vmxnet3_xmit_pkts.
56
57The VMXNET3 PMD handles all the packet buffer memory allocation and resides in guest address space
58and it is solely responsible to free that memory when not needed.
59The packet buffers and features to be supported are made available to hypervisor via VMXNET3 PCI configuration space BARs.
60During RX/TX, the packet buffers are exchanged by their GPAs,
61and the hypervisor loads the buffers with packets in the RX case and sends packets to vSwitch in the TX case.
62
63The VMXNET3 PMD is compiled with vmxnet3 device headers.
64The interface is similar to that of the other PMDs available in the DPDK API.
65The driver pre-allocates the packet buffers and loads the command ring descriptors in advance.
66The hypervisor fills those packet buffers on packet arrival and write completion ring descriptors,
67which are eventually pulled by the PMD.
68After reception, the DPDK application frees the descriptors and loads new packet buffers for the coming packets.
69The interrupts are disabled and there is no notification required.
70This keeps performance up on the RX side, even though the device provides a notification feature.
71
72In the transmit routine, the DPDK application fills packet buffer pointers in the descriptors of the command ring
73and notifies the hypervisor.
74In response the hypervisor takes packets and passes them to the vSwitch, It writes into the completion descriptors ring.
75The rings are read by the PMD in the next transmit routine call and the buffers and descriptors are freed from memory.
76
77Features and Limitations of VMXNET3 PMD
78---------------------------------------
79
80In release 1.6.0, the VMXNET3 PMD provides the basic functionality of packet reception and transmission.
81There are several options available for filtering packets at VMXNET3 device level including:
82
83#.  MAC Address based filtering:
84
85    *   Unicast, Broadcast, All Multicast modes - SUPPORTED BY DEFAULT
86
87    *   Multicast with Multicast Filter table - NOT SUPPORTED
88
89    *   Promiscuous mode - SUPPORTED
90
91    *   RSS based load balancing between queues - SUPPORTED
92
93#.  VLAN filtering:
94
95    *   VLAN tag based filtering without load balancing - SUPPORTED
96
97.. note::
98
99
100    *   Release 1.6.0 does not support separate headers and body receive cmd_ring and hence,
101        multiple segment buffers are not supported.
102        Only cmd_ring_0 is used for packet buffers, one for each descriptor.
103
104    *   Receive and transmit of scattered packets is not supported.
105
106    *   Multicast with Multicast Filter table is not supported.
107
108Prerequisites
109-------------
110
111The following prerequisites apply:
112
113*   Before starting a VM, a VMXNET3 interface to a VM through VMware vSphere Client must be assigned.
114    This is shown in the figure below.
115
116.. _figure_vmxnet3_int:
117
118.. figure:: img/vmxnet3_int.*
119
120   Assigning a VMXNET3 interface to a VM using VMware vSphere Client
121
122.. note::
123
124    Depending on the Virtual Machine type, the VMware vSphere Client shows Ethernet adaptors while adding an Ethernet device.
125    Ensure that the VM type used offers a VMXNET3 device. Refer to the VMware documentation for a listed of VMs.
126
127.. note::
128
129    Follow the *DPDK Getting Started Guide* to setup the basic DPDK environment.
130
131.. note::
132
133    Follow the *DPDK Sample Application's User Guide*, L2 Forwarding/L3 Forwarding and
134    TestPMD for instructions on how to run a DPDK application using an assigned VMXNET3 device.
135
136VMXNET3 with a Native NIC Connected to a vSwitch
137------------------------------------------------
138
139This section describes an example setup for Phy-vSwitch-VM-Phy communication.
140
141.. _figure_vswitch_vm:
142
143.. figure:: img/vswitch_vm.*
144
145   VMXNET3 with a Native NIC Connected to a vSwitch
146
147.. note::
148
149    Other instructions on preparing to use DPDK such as, hugepage enabling, uio port binding are not listed here.
150    Please refer to *DPDK Getting Started Guide and DPDK Sample Application's User Guide* for detailed instructions.
151
152The packet reception and transmission flow path is::
153
154    Packet generator -> 82576
155                     -> VMware ESXi vSwitch
156                     -> VMXNET3 device
157                     -> Guest VM VMXNET3 port 0 rx burst
158                     -> Guest VM 82599 VF port 0 tx burst
159                     -> 82599 VF
160                     -> Packet generator
161
162VMXNET3 Chaining VMs Connected to a vSwitch
163-------------------------------------------
164
165The following figure shows an example VM-to-VM communication over a Phy-VM-vSwitch-VM-Phy communication channel.
166
167.. _figure_vm_vm_comms:
168
169.. figure:: img/vm_vm_comms.*
170
171   VMXNET3 Chaining VMs Connected to a vSwitch
172
173.. note::
174
175    When using the L2 Forwarding or L3 Forwarding applications,
176    a destination MAC address needs to be written in packets to hit the other VM's VMXNET3 interface.
177
178In this example, the packet flow path is::
179
180    Packet generator -> 82599 VF
181                     -> Guest VM 82599 port 0 rx burst
182                     -> Guest VM VMXNET3 port 1 tx burst
183                     -> VMXNET3 device
184                     -> VMware ESXi vSwitch
185                     -> VMXNET3 device
186                     -> Guest VM VMXNET3 port 0 rx burst
187                     -> Guest VM 82599 VF port 1 tx burst
188                     -> 82599 VF
189                     -> Packet generator
190