On Multus CNI

         as everyone knows ,Kubernetes Support single network interface ！Kubernetes Implementation of network model , We need some network methods with unique multi network characteristics to realize multiple network interfaces . 

         You can use Multus CNI As in Kubernetes Method of realizing multi network interface in . Basically ,Multus CNI It's a Kubernetes CNI plug-in unit , Can be in Kubernetes Create additional pod Network interface , With the help of Kubernetes Medium CRD Object supports multiple network functions .Multus Container network interface management Kubernetes Multiple container network interfaces in .  
 
Multus CNI The role of ：  
        Multus CNI Is an open source plug-in , It helps realize multi interface support by acting as a supplementary layer in the container network . It attaches multiple network interfaces to Kubernetes Medium pod. You may know Kubernetes There is only one network interface by default ！ adopt Multus, You can easily create a multi homed with multiple network interfaces Pod.  

• Multus CNI It helps to manage the connection between the container runtime and plug-ins . 
• Multus Network configuration is not allowed by itself , It depends on other types of plug-ins . 

• It supports almost all types of reference plug-ins , Including the realization CNI canonical Flannel.  
• It also supports third-party plug-ins , Include Weave、Calico、Contiv and Cilium. 
• Besides , It allows DPDK/SRIOV Interface attached to pod To support network intensive workloads  

Multus CNI Operation and work ：  
        Multus Acting as other CNI The arbiter of plug-ins . It calls Flannel、Calico、vHost CNI or SR-IOV To create a network interface . however , In the configuration Multus when , A plug-in should be identified as the main plug-in to configure and manage eth0（ Main network interface ）. 

         To understand Multus How it works , Deepen understanding Kubernetes The way network functions work is crucial . There are two available network plug-ins , for example CNI plug-in unit （ Realization CNI Specification to provide interoperability ） and Kubelet（ Use the host - Local CNI The plug-in implements the basic bridge cbr0 Principal agent of ）.    
        Kubelet stay Kubernetes Run on each node in the cluster .Kubelet Allow nodes to be registered to Kubernetes Control panel , And plan to run one by one on this node Pod Provide effective lifecycle management . It's also for everyone pod Establish network interface . 
        Kubelet Use Multus CNI Configuration file to set each pod Network of . ad locum ,Kubelet Is configured to use the container network interface as its network plug-in .Kubelet Call it to set Pod Will call its container runtime . For network configuration ,Kubelet A network plug-in wrapper is provided for the container runtime （Multus CNI plug-in unit ）. 
        Multus CNI Can interact with network objects 、 Configuration files or combinations of files and objects . It reads the configuration and unloads the network setup task to another CNI plug-in unit , That is, commission .  

About Multus CNI Installation and use , You can refer to ：multus-cni/quickstart.md at master · k8snetworkplumbingwg/multus-cni · GitHub