CCNA
Cisco Certified Network Associate certification resources
Serial Cable: Types, Pinouts, and DTE/DCE Connections
A serial cable is used to interconnect DTEs (Data Terminal Equipment) and DCEs (Data Communications Equipment). DTEs are the devices that actually generate or receive the data being communicated, such as a computer, router, or terminal. DCEs are the devices that facilitate and relay that data across the connection, such as a modem or CSU/DSU....
Statistical Time-Division Multiplexing (STDM): Complete Guide
Statistical Time-Division Multiplexing is an advanced multiplexing technique that dynamically allocates transmission time slots to active channels, eliminating the bandwidth waste inherent in standard Time-Division Multiplexing (TDM). Understanding STDM — how it differs from TDM and FDM, how its frame structure works, and where it is applied in real WAN protocols — is essential knowledge...
Time Division Multiplexing (TDM): Complete Guide
Multiplexing is a technique that allows multiple logical signals to share a single physical channel. The two most fundamental multiplexing techniques in telecommunications and networking are Time Division Multiplexing (TDM) and its dynamic counterpart, Statistical Time Division Multiplexing (STDM). This guide focuses on TDM, its frame structure, real-world implementations in T1 and E1 circuits, Cisco...
Point-to-Point Communication Links: A Complete Guide
A point-to-point link is used when a permanent, dedicated connection is required between two locations. It’s a pre-established WAN communications path that securely connects two or more locations for private data services, without sharing that specific physical or logical path with other customers’ traffic. Point-to-point links are also commonly known by other names in the...
Serial Communication: RS-232, V.35, and HSSI Explained
Serial communication is a widely used technique for transferring data between processing equipment and various peripherals, and it’s also commonly used to transfer data across WAN links. In a WAN context, the sending router encapsulates data using a communication protocol, sends the encapsulated data across the physical medium, and the receiving router de-encapsulates it on...
What Is a Parallel Port? History, Pinout, and How It Works
Parallel ports are typically used for connecting printers, and historically for other peripherals that needed relatively high throughput for their era. The port is also used for interconnection between internal components within some devices. A parallel port transmits multiple bits simultaneously over multiple wires, in contrast to a serial port, which sends one bit at...
Serial Port: How Serial Interfaces Work in Networking
A serial port allows a PC or network device to transmit or receive data one bit at a time over a single channel. Serial interfaces are the foundation of point-to-point WAN connections — the leased line links that connect remote sites across cities and countries. While USB has replaced serial ports on most PCs, serial...
VPN Technology: How Virtual Private Networks Work
VPN is the abbreviation for Virtual Private Network. VPN technology creates a safe, encrypted connection over an unsecured network, such as the Internet. It effectively extends a private network across a public network, letting remote users and offices communicate as if they were directly connected to the same private infrastructure. A virtual private network uses...
Cellular Network: How Cellular WAN Technology Works
Cellular networks are a type of wireless WAN technology. They provide connectivity to users and remote locations where no other WAN access technologies are available. Millions of users rely on cellular networks daily to email, browse the web, download apps, stream video, and make voice calls from smartphones, tablets, laptops, and even routers equipped with...
Wireless Internet: Wi-Fi, WiMAX, Satellite, and Cellular Explained
Wireless internet uses radio waves instead of physical wires to connect a personal computer, laptop, smartphone, or other device to the Internet. Early wireless technologies lacked the high speed of broadband connections like cable and DSL, but modern wireless technologies have largely closed that gap, and in some cases surpassed it. Wireless Internet Service Providers...