Knowledge Base

SD-WAN WAN Link Optimise algorithm

Last updated: Jul 06, 2026
1. Packet Cloning (Packet Duplication) Sends the same packet over multiple WAN links at the same time. The receiver keeps the first...
1. Packet Cloning (Packet Duplication)
  • Sends the same packet over multiple WAN links at the same time.
  • The receiver keeps the first packet that arrives and ignores duplicates.
  • Best for: VoIP calls, video conferencing, and critical applications that need smooth communication.
  • Pros: Prevents packet loss, improves call and video quality.
  • Cons: Uses more bandwidth.

 

2. Session-Based Weighted Load Balancing
  • Assigns new network connections (sessions) to different WAN links based on their assigned weight.
  • Once a session starts on a link, it stays there until it ends.
  • Best for: Web browsing, cloud apps, streaming services.
  • Pros: Keeps connections stable, avoids packet reordering.
  • Cons: If a WAN link slows down, the session remains stuck on it until it finishes.

 

3. Per-Packet Weighted Load Balancing
  • Splits individual packets across multiple WAN links instead of full sessions.
  • The weight assigned to each link decides how many packets go through it.
  • Best for: Large file transfers, streaming media, bulk data sync.
  • Pros: Maximizes bandwidth use and balances traffic.
  • Cons: Can cause packet reordering, which may slow down TCP traffic.

 

4. Best Path Selection
  • Monitors latency, jitter, packet loss, and bandwidth on each WAN link.
  • Always picks the best-performing link for traffic.
  • Best for: VoIP, video calls, financial transactions, cloud applications.
  • Pros: Ensures smooth and high-quality performance.
  • Cons: Needs constant network monitoring.
Comparison Table
Method How It Works Best For Pros Cons
Packet Cloning Sends duplicate packets on multiple links VoIP, video calls No packet loss, better quality High bandwidth usage
Session-Based Load Balancing Sends entire sessions over different links Web, cloud apps, streaming Stable connections Cannot switch mid-session
Per-Packet Load Balancing Sends individual packets over different links Large file transfers, streaming Maximizes bandwidth Can cause packet reordering
Best Path Selection Chooses the best WAN link in real time VoIP, critical apps Best performance Needs continuous monitoring
Key Takeaways
  • For VoIP & Video Calls → Use Packet Cloning + Best Path Selection
  • For Web & Cloud Apps → Use Session-Based Load Balancing
  • For Large File Transfers → Use Per-Packet Load Balancing
  • For Overall Optimization → Use Best Path Selection

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