Essential Principles of Network Design and Hardware

Criteria for Selecting Internetworking Devices

When selecting an internetworking device, the most important criteria include processing speed, the amount of latency, support for LAN and WAN technologies, ease of configuration, Mean Time Between Failure (MTBF), and Mean Time to Repair (MTTR).

Single-Mode vs. Multimode Fiber Optics

Single-mode fiber allows only one light path and has a low core diameter. It also supports higher bandwidth. Single-mode fiber is generally faster because its smaller core diameter ensures that only one path is taken, reducing signal dispersion.

The Importance of QoS in Modern Networks

Quality of Service (QoS) features are often necessary in LAN switches and routers because they provide reliable service between the sender and receiver, or the source and destination, by prioritizing critical traffic.

Why Ethernet Dominates Campus Networks

Modern campus networks are almost always built with Ethernet technology these days. Ethernet has successfully outlasted older technologies such as Token Ring, FDDI, and ATM LAN Emulation (LANE) due to its scalability and cost-effectiveness.

Five Goals for Network Design Testing

• Verify technical and business goals: Once a new network design has been created, it is essential to test whether it meets the required standards. Key technical issues must be checked before the network design is accepted.
• WAN/LAN validation: Any network design must support connectivity and communication with multiple devices. It is crucial to verify that the design supports the necessary WAN and LAN technologies.
• Analysis of failure: Any telecommunication network is susceptible to link failures; testing helps understand how the network handles these events.
• Robustness and applicability: Ensuring the network design is resilient and suitable for the intended environment.
• Identify connectivity problems: Proactively finding issues that could prevent devices from communicating.

Pros and Cons of Industry Network Tests

Advantages: Industry tests may be used for simple networks and can be helpful to convince a customer to use a particular network design or device.

Disadvantages: Results published by vendors in trade journals may be biased, and negative results are many times not published at all.

Testing Components on Production Networks

Advantages: Testing during normal business hours can increase the sample of parameters that control the performance of the component under real-world conditions.

Disadvantages: This approach may not provide an accurate estimate of performance during peak hours when traffic load is very high. Furthermore, it does not easily estimate the failure or crash point of the new component without risking business operations.