Learn network fundamentals to have cutting-edge skills and hands-on experience to excel in any DevOps role.

DevOps for Developers

Learn network fundamentals essential for any DevOps specialist. You'll explore socket programming, command-line tools, OSI layer protocols, and more.

Network Fundamentals

# Network Layer Imperfections
The transport layer must deal with the imperfections of the network layer service. There are three types of imperfections that must be considered by the transport layer:
1. Segments can be **corrupted** by transmission errors
2. Segments can be **lost**
3. Segments can be **reordered** or **duplicated**

Let's look at some workarounds for these problems that the transport layer employs.



# Checksums
The first imperfection of the network layer is that segments **may be corrupted by transmission errors**. The simplest error detection scheme is the **checksum**. 

A checksum can be based on a number of schemes. One possible scheme is an arithmetic sum of all the bytes of a segment. Checksums are computed by the sender and attached with the segment. The receiver verifies it upon reception and can choose what to do in case it is not valid. Quite often, the segments received with an invalid checksum are **discarded**. 



Principles of Reliable Data Transfer

Network Layer Imperfections