IEC 61850 is becoming a cornerstone standard defining communication protocols and common data and device models for ensuring critical real-time monitoring and control of smart grids. Although the interoperability can be achieved by conforming to this standard, the underlying communication network still needs, however, careful configuration and dimensioning for guaranteeing reliable and real-time data exchanges. In this paper, we focus on the substation automation part of electric smart grids where data communication requires milliseconds order delay and full reliability guarantees. This arises challenging issues on the underlying Ethernet-based network architecture design, especially concerning its performance evaluation. The contributions of this paper are threefold. First, it proposes a tutorial introduction to IEC 61850 international standard for communication within substations. Second, it surveys the performance evaluation of switched Ethernet for IEC 61850 substation automation with the analysis of both network calculus and simulation based state-of-the-art approaches. Third, it discusses future research directions such as the need of in-depth traffic scheduling analysis, the potentials of introducing the Time Sensitive Networking standard into substation automation and the co-simulation of both electric grid and communication network. This paper can serve as a basis for understanding the challenging issues for modern smart Substation Communication Network design through performance evaluation approaches and how the current state-of-the-art solutions can be used or should be further extended.