Enabling Performance Mode or Lite Mode
vMX can be configured to run in two modes depending on the use case.
Lite mode—Needs fewer resources in terms of CPU and memory to run at lower bandwidth.
Performance mode—Needs higher resources in terms of CPU and memory to run at higher bandwidth.
Starting in Junos OS Release 15.1F6 and later releases performance mode is enabled implicitly by default.
When you enable performance mode, make sure you have configured the proper number of vCPUs (four or more VPCUs) and memory for your VMs based on your use case.
You can explicitly enable lite-mode. If you are using paravirtualized network interfaces such as virtio (for KVM) or VMXNET3 (for VMware) for lab simulation use cases, you can disable performance mode by including the lite-mode statement at the [edit chassis fpc 0] hierarchy level.
user@vmx# set chassis fpc 0 lite-mode
You can explicitly enable performance mode by including the performance-mode statement at the [edit chassis fpc 0] hierarchy level.
user@vmx# set chassis fpc 0 performance-mode
We recommend that you enable hyperthreading in BIOS. We recommend that you verify the process with the vendor because different systems have different methods to enable hyperthreading.
Starting with Junos OS Release 17.3R1, the show chassis hardware command displays the mode in which vMX is running in the part number field for the FPC. RIOT-PERF indicates performance mode and RIOT-LITE indicates lite mode. For example, this output indicates that vMX is running in lite mode.
user@vmx> show chassis hardware
Hardware inventory: Item Version Part number Serial number Description Chassis VM54599D128A VMX Midplane Routing Engine 0 RE-VMX CB 0 VMX SCB CB 1 VMX SCB FPC 0 Virtual FPC CPU Rev. 1.0 RIOT-LITE BUILTIN MIC 0 Virtual PIC 0 BUILTIN BUILTIN Virtual
Table 1 highlights some of the challenging features which are supported in the Fast Path and some which are not supported. Features which are not supported in the Fast Path still work but they get less than 100K PPS per worker vCPU.
Table 1: Features Support in Fast Path
Support in Fast Path
Pseudowire Headend Termination (PWHT) (Layer 2 VPN)
Ethernet VPN (EVPN)
Virtual Extensible LAN protocol (VXLAN)
Pseudowire Headend Termination (PWHT) (Layer 3 VPN and IP )
logical tunnel interfaces (lt)