When AND Why Proxy-ARP

Tuesday, June 1st, 2010
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. (more…)

So, how does routing work, anyway? (Part 1)

Thursday, September 11th, 2008
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:
  1. Networking basics - what is needed to make two or more computers communicate?
  2. What is a router and why is it a necessary component in a  network?
  3. Subnet masks and what they mean.  What, exactly, IS a subnet address and why do I care?
  4. ARP - what is it and what does it do?
  5. Wrap up and tying up the loose ends.
(more…)