TCP Segment Retransmission Timers and the Retransmission Queue 

TCP Transaction Example with Retransmission Let’s use an example to clarify how acknowledgments and retransmissions work in TCP (illustrated in Figure 223, to which you may wish to refer as you read on). Suppose the server in a connection sends out four contiguous segments (numbered starting with 1 for clarity): Segment #1:Sequence Number field is 1 and segment length is 80. So… Read more →

IP address classes and structure

IP address classes and structure When the IEEE committee sat down to sort out the range of numbers that were going to be used by all computers, they came up with five different ranges or, as we call them, “classes” of IP addresses. When someone applies for IP addresses they are given a certain range within a specific class depending… Read more →

General Overview of Layer 2

General Overview of Layer 2 Layer 2 is Data Link Layer (DLL) as per OSI Model. As we know function of each layer is to provide services to above layer, so DLL provide various services to Layer 3: Network Layer. Various services which DLL provides are: Framing network layer data packets. Flow Control Multiple Access control using CSMA/CD (Carrier Sense… Read more →

The Routing Table

Here we are going to look at the routing table. All network devices that use the TCP/IP protocol have a routing table, even your Windows PC has one. ALL devices use their routing table to determine where to send packets. Without a routing table your PC wouldn’t even be able to communicate with computers on the same subnet. Here is… Read more →

How IP Routing Works

An Important Fact About IP Routing Most People Forget When packets take a certain route to their destination they DO NOT have to take the same route back. I can’t stress this enough, packets DO NOT record the route they take. This is a big misconception among some IT professionals. Let’s say you are playing an online game, you have… Read more →