The silicon vendor provided SDK needs to be integrated with the NOS. Now for the smooth and easy integration, vendors provide standard interfaces to access its silicon. The standard interface is well accepted and widely used by the various open sourced NOS. Since it is standard, the developer should only need to know the standard APIs which is vendor neutral.
By using SAI, the developer can integrate the silicon vendor’s software with any open source NOS very smoothly and faster. This means one has options to select NOS which has SAI as southbound interface to vendor’s SDK. There are various open sourced NOS available in the market which uses SAI. Let us look at one example of SONiC used with SAI.
Here SONiC is used as NOS on various platforms and SAI is used as a standard interface between SONiC and silicon vendor software. Apart from SONiC, NOS can be an open switch (OPX), dNOS, ONL etc. Now that we understand why and how of the SAI, let us look into what SAI actually is?