DiffServ

Differentiated Services (DiffServ) is a computer networking architecture designed to provide Quality of Service (QoS) by classifying and managing network traffic. Here are the key features and concepts of DiffServ: 

Traffic Classification: DiffServ classifies network traffic into different classes using a 6-bit Differentiated Services Code Point (DSCP) in the IP header1. This classification allows the network to treat packets differently based on their class.

Per-Hop Behaviors (PHBs): Routers and switches in the network apply specific behaviors to packets based on their DSCP value. Common PHBs include:

Default PHB: Best-effort service with no special treatment.

Expedited Forwarding (EF): Low-latency, low-loss service suitable for real-time applications like VoIP.

Assured Forwarding (AF): Provides different levels of assurance for delivery, useful for applications requiring reliable delivery.

Scalability: DiffServ is designed to be scalable by performing complex classification and policing at the network edge, while core routers handle packets based on their DSCP values without needing to maintain per-flow state1.

QoS Policies: Network administrators can define QoS policies to prioritize critical traffic, ensuring that important applications receive the necessary bandwidth and low latency2.

Backward Compatibility: DiffServ maintains backward compatibility with older QoS mechanisms by using class selectors that map to the former IP precedence field1.

DiffServ is widely used in modern IP networks to ensure that critical applications receive the necessary network resources, improving overall performance and reliability.