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Day 21 – SD-WAN (Software-Defined WAN) - Coggle Diagram
Day 21 – SD-WAN (Software-Defined WAN)
SD-WAN Overview
What is SD-WAN
Software-defined way to manage multiple WAN links
Intelligent traffic steering based on rules and link quality
Replaces static routing limitations
Why SD-WAN is Needed
Traditional WAN cannot react to link quality
Static routing causes poor performance
No application awareness in legacy WAN
Benefits of SD-WAN
Automatic failover
Load balancing across links
Application-aware routing
Improved user experience
Common Use Cases
DIA (Direct Internet Access)
Branch users access Internet directly
Better cloud and SaaS performance
Site-to-Site Connectivity
SD-WAN tunnels between locations
Dynamic path selection between sites
SD-WAN Components
SD-WAN Members
Physical WAN interfaces (WAN1, WAN2)
Logical interfaces (VLANs, VPN tunnels)
Represent actual internet or WAN links
SD-WAN Zones
Logical grouping of WAN members
Simplifies firewall policies
Used as single interface in rules
Benefits of Zones
Cleaner configurations
Easier scaling when adding new links
Centralized traffic steering
SD-WAN Rules
What are SD-WAN Rules
Define how traffic is steered
Processed top to bottom
First match wins
Rule Matching Criteria
Source address or subnet
Destination address or subnet
Internet service (Google, Microsoft, Facebook)
Application (Zoom, Teams, YouTube)
Rule Priority
Order matters
Specific rules placed above general rules
Example Rules
Zoom traffic uses best quality link
Backup traffic uses lowest cost link
Traffic Steering Strategies
Manual Strategy
Interface preference based
Administrator defines link priority
Simple but not dynamic
Best Quality Strategy
Uses SLA measurements
Latency
Jitter
Packet loss
Selects healthiest link
Best for voice and video
Lowest Cost Strategy
Uses cheapest available link
Avoids expensive links like LTE
Best for non-critical traffic
Monitoring SD-WAN
Traffic Logs
Shows which rule matched
Shows which WAN link was used
Useful for troubleshooting
Link Usage Monitoring
Displays bandwidth usage per link
Helps identify overloaded links
Quality Status Monitoring
Monitors SLA metrics
Latency, jitter, packet loss
Health status (Up, Degraded, Down)
Importance of Monitoring
Validates SD-WAN behavior
Helps tune rules and SLAs
Detects ISP or link issues early