What is Source-Based Routing?

In contrast to destination-based routing, source-based routing (also known as path addressing) flips the script on how data packets find their way through a network. Instead of relying solely on the destination IP address, source-based routing allows the sender of the packet to partially or completely specify the route the packet takes.

Here’s a breakdown of source-based routing:

1. Sender Takes Control: The device sending the data packet includes a list of hops (routers) the packet should traverse in the packet header. This list acts as a roadmap for the packet’s journey.
2. Partial vs. Full Control: Source-based routing can be either strict or loose. Strict source-based routing dictates the exact path, while loose source-based routing specifies some waypoints but allows the network to fill in the gaps for optimal routing.
3. Less Common Approach: While technically possible, source-based routing isn’t as widely used as destination-based routing due to its complexity and potential drawbacks.

Characteristics of Source-Based Routing

• Routing Decision: Based on the source address of data packets.
• Forwarding Decision: Made at the source node, determining the path the packet will take from the outset.
• Routing Protocol Examples: Source-Initiated Routing Protocol (SIRP).
• Flexibility: Limited flexibility compared to destination-based routing.
• Load Balancing: Load balancing may be more challenging to implement.
• Efficiency: Efficient for specific scenarios or small-scale networks.
• Scalability: May face scalability challenges in large networks.

Advantages of Source-Based Routing

• Control over Routing Paths: Provides the source node with direct control over the route taken by data packets, potentially allowing for more customized routing decisions.
• Reduced Overhead: Source-based routing may result in reduced routing protocol overhead compared to destination-based routing, as routing decisions are made at the source node.
• Enhanced Privacy: Source-based routing can potentially offer enhanced privacy by allowing the source node to select routing paths that minimize exposure of sensitive data to intermediate nodes.

Disadvantages of Source-Based Routing

• Complexity: Source-based routing can be more complex to implement and manage, particularly in larger networks with dynamic topologies.
• Limited Load Balancing: Load balancing may be more challenging to achieve in source-based routing, as all routing decisions are made at the source node.
• Dependency on Source Node: The reliability and performance of source-based routing are heavily dependent on the source node’s ability to make informed routing decisions.
• Suboptimal Routing: Without complete knowledge of network topology, source-based routing may result in suboptimal routing paths, potentially leading to increased latency or inefficient resource utilization.
• Scalability Challenges: Source-based routing may face scalability challenges in large networks with a high volume of traffic or complex routing requirements.

Destination-based vs source-based routing is like choosing a destination on a road trip. In destination-based routing, you focus on where you’re going, taking the fastest or shortest route. Source-based routing, however, is like considering where you’re coming from. You might choose different roads based on your starting point. In computer networks, destination-based routing sends data based on where it’s headed, while source-based routing considers where it’s coming from.