NAT – network address translation
How NAT Works The networks under RFC1918 which are considered private do NOT work on the internet. Well, they could theoretically but if you get internet from an ISP then those ISP have a ACL…
Configuring Router Interfaces
Understanding Basic Interface Counters What we see in the picture above: Under the total Packets input Packets output Understanding Interface Speed 1 byte = 1 character -> e 1 bit = a 0 or a…
Configuring Switch Interfaces
It is a plus to always use global templates for ports, so every switch you touch has your own style and navigation and troubleshooting gets easier because you are familiar with your environment. There are…
Defining Networks with Subnet Masks
Subnetmask is the definer of networks. What part represents the network itself, and what part of the ip address represents the host in the network. There are 3 classes The first octet defines the class…
Review, Why Routers Exist
Every interface on a router is a network. A router stops broadcasts. If those would get out to the internet, the internet would be a flood. Inside of these routers is a routing table. Which…
Why do we need ip addresses?
If you are in the network 192.168.1.0/24 and try to ping 192.168.1.50 the client sends an ARP request. But if we try to ping 192.168.3.10 the client gets so smart, that it is not trying…
How to track down a device in a network
What is given? We normally start off with a ping request to the device. So if we don’t have this device already in our CAM table, we will see it there after the ARP request…
How do switches do what they do?
When we send a ping request, the whole process with the OSI model starts. So we have the destination ip address but now we have to find the the desination mac address with only a…
Cisco Packet Tracer
Cisco Packet Tracer is a network simulation tool we are going to use to get familiar to simulate our first network. The essentials First of all the workspace has to work with you. For me…
Cable types
Ethernet cables Inside the outer jacket are for twisted pairs, eight copper wires total, and those twists are not there for decoration. They help fight two major enemies, electromagnetic interference (or EMI) and crosstalk, which…