SD-WAN, SD-Access, QoS: Core Network Technologies Explained

Posted on Sep 11, 2025 in Communications Electronic Engineering

SD-WAN: Software-Defined Wide Area Networking

What is SD-WAN?

SD-WAN is a modern networking technology that enables organizations to manage and optimize their Wide Area Networks (WANs) using software-based controllers. It separates the network control function from the underlying hardware, allowing centralized and intelligent traffic routing over multiple types of connections such as MPLS, broadband, and 4G/5G.

Key Features of SD-WAN

  1. Centralized Control – A single dashboard to manage all WAN devices and connections.

  2. Transport Agnostic – Works with any internet link (MPLS, LTE, broadband).

  3. Dynamic Path Selection – Chooses the best route for traffic based on performance and policy.

  4. Enhanced Security – Built-in encryption (IPsec), firewalls, and secure access.

  5. Application-Aware Routing – Prioritizes critical applications (e.g., VoIP, video conferencing).

Benefits of SD-WAN Deployment

  • Cost-Efficient – Reduces dependency on expensive MPLS links.

  • Improved Performance – Ensures better cloud and SaaS app delivery.

  • Scalable – Easily adds new branches without complex configurations.

SD-Access: Cisco’s Software-Defined Access Solution

What is Cisco SD-Access?

SD-Access is Cisco’s enterprise networking solution that provides automated end-to-end segmentation, policy enforcement, and simplified network management using a software-defined approach. It extends the benefits of SDN (Software-Defined Networking) to the enterprise access layer (LAN and WLAN).

SD-Access Key Components

  1. Cisco DNA Center – The centralized controller and management platform.

  2. Fabric – A logical overlay network that separates user, device, and application traffic.

  3. ISE (Identity Services Engine) – Manages user identities and policies.

  4. Edge Nodes – Access switches and wireless controllers that connect endpoints.

  5. Control Plane Nodes – Use LISP (Locator/ID Separation Protocol) for routing in the fabric.

SD-Access Main Features

  • Automated Provisioning – Configures devices and policies automatically.

  • Policy-Based Segmentation – Uses Scalable Group Tags (SGTs) to enforce access control.

  • Seamless Mobility – Maintains user policies as users move across the network.

  • Integrated Security – Built-in threat detection and segmentation to prevent lateral attacks.

Benefits of Cisco SD-Access

  • Simplified Network Management – Central GUI for managing wired and wireless devices.

Quality of Service (QoS): Ensuring Network Performance

What is Quality of Service (QoS)?

Quality of Service (QoS) refers to a set of techniques and mechanisms used in computer networks to manage network resources by prioritizing specific types of traffic, ensuring reliable and predictable performance, especially for critical or time-sensitive applications like VoIP, video conferencing, and online gaming.

Key Objectives of QoS

  1. Bandwidth Management – Allocate network capacity efficiently.

  2. Traffic Prioritization – Ensure high-priority traffic (e.g., voice, video) is transmitted first.

  3. Latency Control – Reduce delay in time-sensitive data transmission.

  4. Jitter Reduction – Maintain steady data flow for smooth media delivery.

  5. Packet Loss Prevention – Ensure data reaches its destination reliably.

Essential QoS Parameters

  1. Bandwidth – The data rate supported by a network connection.

  2. Latency – Delay between data transmission and reception.

  3. Jitter – Variation in delay of packet delivery.

  4. Packet Loss – Percentage of packets lost during transmission.