Computer Networks: Topologies, Architectures, and Protocols
Network Topologies
Network topologies refer to the layout or arrangement of different elements (links, nodes, etc.) in a computer network. The main types of network topologies include:
Bus Topology: All devices share a single communication line or cable. It is easy to install but can be slow and prone to collisions as network traffic increases.
Ring Topology: Each device is connected to two other devices, forming a circular pathway for signals. Data travels in one direction, reducing collision risks
Network Media, Coding, Topology, and Ethernet Standards
Media Transmission
Wired (transmission signals via electricity):
- Balanced (2 conductors; if there is interference, the difference is used).
- Unbalanced (the modified signal is received).
Types of Wired Media:
- Stranded: 4 twisted pairs.
- UTP (Unshielded Twisted Pair) (digital): Twisted pairs.
- FTP (Foiled Twisted Pair) (digital): 4 twisted pairs with a mesh around them.
- STP (Shielded Twisted Pair) (digital): Shielding on each pair and all pairs.
- Coaxial (analog & digital): Central core conductor (copper)
ZeroMQ in Node.js: Examples & Patterns
ZeroMQ in Node.js: Practical Examples
This document provides practical examples of using ZeroMQ (zeromq
) in Node.js. It covers several common messaging patterns, including Publish/Subscribe, Push/Pull, Router/Dealer, and Request/Reply. Each example is presented with corrected code and explanations.
Publish/Subscribe Pattern (Pub/Sub)
This example demonstrates a publisher sending messages on different topics, and a subscriber listening to a specific topic (“Politica”).
const zmq = require('zeromq')
Read More
Java HashMap Implementation: Code and Explanation
Java HashMap Implementation
This document provides a detailed implementation of a HashMap in Java.
public class HashMap<K, V> implements Map<K, V> {
private int capacidad;
private int numElem;
private Lista<Map.Par<K, V>>[] arrayMapa;
public HashMap(int cap) throws IllegalArgumentException {
if (cap < 0) {
throw new IllegalArgumentException("NUMERO NEGATIVO");
} else {
this.capacidad = cap;
this.numElem
Read More
Understanding IP Address Spaces and Common Ports
Understanding IP Address Spaces
Private IPv4 Address Spaces
The following table lists the private IPv4 address spaces:
Address Block | Description |
127.0.0.0/8 | Loopback |
192.168.0.0/16 | Private Network |
10.0.0.0/8 | Private Network |
100.64.0.0/10 | Shared address space[4] carrier-grade NAT. |
172.16.0.0/12 | Private Network (172.16.0.0–172.31.255.255) |
Special Use IPv4 Addresses
These addresses are reserved for specific purposes:
Address Block | Description |
224.0.0.0/4 | IP multicast.[10] (Former Class D network.) |
240.0.0.0/4 | Reserved |
Communication Channels and Technologies
Communication Channels
A communication channel routes messages from sender to receiver. Channels can be guided (e.g., copper wires, optical fiber) or unguided (e.g., air, vacuum).
Types of Communication Channels
- Dedicated Links: Establish an exclusive channel between two interlocutors.
- Point-to-Point: One sender and one receiver.
- Multipoint: Multiple callers at either end.
- Shared Networks: Callers connect to a network node to contact others.
- Dissemination (Broadcast): Transmitter sends data to multiple