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Cisco Skills

  • 2 min read

Cisco Discovery Protocol

In today's post let's talk about CDP the Cisco Discovery Protocol. This protocol helps us in two ways, it first helps us verify that a connection between router or switch is set up correctly  at least up to layer two in the OSI model. This also helps us discover Cisco devices that are in are network and which interfaces these devices are connected too and from are Cisco equipment. The Cisco discovery protocol is Cisco proprietary  and before I go any further let me mention that CDP is a security risk because of the detailed information CDP gives out which helps you has a network administrator build a current network infrastructure, this can also hurt you because this information can easily be sniffed by programs that are easily searched on the internet. So what is the purpose of CDP? CDP can gather device information from neighboring switches and routers without the need for a password. Like mentioned before this is great for troubleshooting a problem, discovering new devices that are not documented in your network topology, and verifying that each device is physically connected to the correct interfaces according to network documentation. CDP can discover the following details from neighboring devices that support CDP:

  • 2 min read

Distance Vector Routing

Couple weeks ago I talked about routing protocols and in the post I mentioned two routing protocol features distance vector and link state. Although these protocols fundamentally do the same thing by getting information on remote networks they get this information in a different way. For today let's introduce distance vector routing. With a distance vector routing protocol, a router learns about a route to a different network (that's the purpose of a routing protocol) the router only knows the "distance" to get there this is usually called the metric.

  • 3 min read

Classful vs. Classless Routing

Before the internet and general networking become popular into what it is now, there were and still are routing protocols that only do classful routing. What is classful routing? When I was talking about Dynamic Routing earlier (See the post Dynamic Routing Protocols) I mentioned there was a difference between classful routing and classless routing. So in today's post let's focus on these two but important topics when using routing protocols.

  • 2 min read

Cisco IOS Commands

This is a master list of various Cisco IOS commands relevant to the CCNA track, along with brief descriptions of what each command does. Some commands may exceed CCNA requirements but provide valuable information.

  • 3 min read

Basic Wireless LAN Security

Although having a wireless LAN sounds like a wonderful idea, there are things that need to be implemented like security. A wireless LAN can be uncontrollable has it is just radio waves and anybody can receive them. Having and using good security practices can help you be under control of your wireless LAN. Not having any security in a wireless LAN environment will cause anybody to have access to the network. Some threats that lead to wireless LANs can be the following:

  • 3 min read

Understanding VTP

Some people hate it, some people love it. It's the Cisco proprietary VLAN Trunking Protocol (VTP) which in short means that Cisco switches can exchange VLAN configuration, instead of manually configuring each switch with the same VLANs. I also suggest if you don't know what a VLAN is check out the post Creating VLANs Let's get right into understanding VTP.

  • 3 min read

Dynamic Routing Protocols

If you ever wanted to set up a network manually, you will quickly find how much overhead is required to get PCs, printers, and other network equipment. That's where dynamic routing protocols come into play although they are helpful I strongly urge you to understand static routing first. (See the post Configure Static Routing) So for today's post let's get the foundation of understanding dynamic routing protocols. By definition a routing protocol is a set of messages, rules and algorithms used by routers for the overall purpose of learning routes to other networks not physically connected to it.

  • 4 min read

Configure Static Routing

Plugging Cisco routers together and hoping they work out of the box is not something you should hope for. A router can learn about networks in two ways, manually from configured static routers which we will talk about today and dynamic routing protocols which will talk about on Wednesday. Let's get started!

  • 3 min read

Understanding AAA

The wonderful AAA which in the Cisco world means, Authentication, Authorization, and Accounting but what does that really mean? In today's post that's what we are going to be talking about. What is AAA and what are the benefits of using it along with what is it?