CCNA
Cisco Certified Network Associate certification resources
Leased Lines
Leased Lines are dedicated communication channels between two or more nodes. Usually, it is a pre-established WAN connection from the customer premises to the service provider network. The lines are usually leased from a service provider; they are called leased lines. The leased lines work as a dedicated tunnel from one point to another. It...
What is PDH?
PDH is the abbreviation of plesiochronous digital hierarchy. The term plesiochronous derives from two Greek words: ‘plesio’ means ‘near’ and ‘chronos’ means ‘time’. In the plesiochronous digital hierarchy, the clocks are running close but not exactly matched, so signal arrival times may be different when multiplexing, as the transmission rates are directly linked to the...
What Is SDH? Synchronous Digital Hierarchy Explained
SDH — Synchronous Digital Hierarchy — is the ITU-T standard for multiplexing and transporting digital signals over optical fibre networks. It defines a hierarchy of data rates, a frame structure for organizing those signals, and a set of management and overhead mechanisms that make large-scale optical transport networks manageable and resilient. SDH is interoperable with...
What Is SONET? Synchronous Optical Networking Explained
Synchronous Optical Networking is a standardized protocol for transmitting large volumes of data over long distances across fiber-optic media. For decades it has been a backbone technology of the global telecommunications network, carrying voice, data, and video traffic between cities and across continents on high-speed optical links. SONET was developed in the mid-1980s and standardized...
Circuit Switched vs Packet Switched
WAN devices discussed in the previous article are incomplete because other devices may be needed, depending on the chosen WAN access technology. WAN access technologies are either circuit-switched or packet-switched. Circuit Switched In a circuit-switched network, communications between end devices must be established before they can communicate. A circuit-switched network establishes a dedicated circuit (or...
WAN Devices
There are many types of specially designed WAN devices used in networks. These devices require expert skills for configuring and management. The important WAN devices are: Dialup modem Dialup Modems allow digital data to be sent over an analogue medium during the transmission and receiving of information. The dial-up modem is a legacy WAN technology....
Introduction to WAN Technologies
Wide-area networks (WANs) are used to connect different LANs together. They can bridge LANs within a city, country, or global region. For CCNA candidates, understanding WANs is crucial for the 200-301 exam’s Network Fundamentals domain (15-25% weightage). CCNP students dive deeper into scalable WAN designs via ENCOR (20-30% on WAN optimization). Here’s why WANs matter:...
Basic EIGRP Troubleshooting Commands – Exclusive Introduction
Due to the importance of EIGRP troubleshooting problems related to this protocol is an important ability for a network administrator. There are numerous commands that are important during EIGRP troubleshooting. The most used command for EIGRP troubleshooting is the “show ip eigrp neighbors”, “show ip route”, and “show ip protocols”. The commands can also be...
MD5 Routing Protocol Authentication – Exclusive Explanation
Network security is an important consideration for network administrators. The router install in a public network is at risk each time, anyone with a packet sniffer can read information propagating between routers. The router can be attacked through the interruption of peer devices or the falsifying of routing information. Interruption of peers is less critical...
How to Configure EIGRP Load Balancing for IPv4
EIGRP is a Cisco proprietary routing protocol. Router-enabled EIGRP calculates the best route to a destination using the metric value based on the link bandwidth and delay. The protocol selects the shortest path and installs that path in the routing table. If the destination has more than one path with the same administrative distance and...