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.
What is lower BW when using lite mode? is it 200Mbs? 300Mbs? 1Gbs?
Greetings, As the documentations mentioned it depends like for example the Junos OS features that are configured and other factors, such as average packet size, etc so there is no fixed answer, however, you can get an idea/baseline of the variation once you add the minimum requirements for of mode in the equation:
Performance Mode: Enables vMX to run in performance mode. Performance mode needs more CPUs (check below for specifications ) and memory to run at a higher bandwidth. When you enable performance mode, make sure you have configured the proper number of vCPUs and memory for your VMs based on your use case. If you have not configured enough vCPUs, vMX runs in lite mode.
Lite Mode: Enables vMX to run in lite mode and disables performance mode. Lite mode needs fewer CPUs( check below for specifications ) and memory to run at lower bandwidth.
While the bandwidth varies upon how you deploy and what resources you use, there are a few things you might need to be mindful of while choosing between the modes:
1) Due to a DPDK version change in Junos OS Release 18.1R1 and later, ESXi 6.5 is the minimum version required to run the vMX router if you are operating in high-bandwidth mode (performance mode). If you are operating the vMX router in low-bandwidth (lite) mode, you can use ESXi 6.0 or ESXi 5.5.
NOTE: For performance mode, the minimum software requirement for ESXI 6.5 is Junos OS Release 18.1R1 and later.
2) If you are running virtio interfaces in lite mode, you can use up to 96 ports. Other configurations running in performance mode support up to 23 ports.
3) 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.
4) 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.
There is no direct correlation between the mode (lite or performance) and bandwidth, the different modes just define which features you can use. The more vCPUs memory you have, the more bandwidth you can use (up to 3 Gbps, then you have to change the NIC type)