• In Routing Tables part one, we covered the basic purpose of a routing table and how an end device or intermediate device such as a router or multilayer switch can route based off its table. We also viewed different routing tables and how they are used to find a given destination network. In this blog, …   Read More

  • Welcome back! This time, we’ll take a look at access control lists, often referred to as “access lists” or “ACLs” (sometimes pronounced “ackels”). In Cisco IOS, ACLs are used for many things, including but not limited to: Filtering data packets (“firewalling”) Controlling Telnet or SSH access to a router or switch Filtering routing protocols Specifying …   Read More

  • In VLSM – Part 1, we looked at a quick way to do VLSM. This time, we’ll look at some more VLSM exercises, as well as examples in which VLSM won’t solve the problem. Of...

  • Welcome back! In this installment, we’re going to examine VLSM (Variable-Length Subnet Masking, RFC 1878), and how to use the subnetting shortcuts to solve VLSM problems. I’m sure that it won’t surprise you to know that we’ll need the powers of two chart: n = 8 7 6 5 4 3 2 1 2n = …   Read More