In my training classes, I go to great lengths to teach when and why proxy arp is necessary on an interface. I have seen (and answered) numerous questions on my mailing lists regarding proxy arp and it seems it is time to create an article that I can just point people to. I will focus this article on Mikrotik RouterOS (as many of my articles are), but it should be noted that proxy arp is not unique to Mikrotik.
It’s a question that I get from time to time and it’s time to answer here. If you understand the fundamental principles of networking, then all the other parts of building and maintaining an ISP network (wired OR wireless) are much simpler. In this series of articles we will discuss the processes that make IP networking function by delving into the fundamentals of how subnetting works, how a router USES subnet information and the very important arp process.
This topic is an easy topic to understand, but it is difficult to organize the materials and ideas needed to easily explain. This is because there are so many pieces that are related and understanding one part is necessary to understand the next. You, as a reader, may need to read this article more than once in order to fully understand all of the parts. We will use the following “talking points” to cover this topic: