Configuring Hardware Congestion Management; Overview; Techniques - HP A6600 Configuration Manual

Configuring hardware congestion management

The features in this chapter are available only on routers with a SAP interface card working in bridge mode.

Overview

Network congestion degrades service quality on a traditional network. Congestion is a situation where the
forwarding rate decreases due to insufficient resources, resulting in extra delay.
Congestion is more likely to occur in complex packet switching circumstances.
cases.
Figure 23 Traffic congestion causes
100M
100M > 10M
(1)
Congestion may bring the following negative results:
Increased delay and jitter during packet transmission

 Decreased network throughput and resource use efficiency
 Network resource (memory, in particular) exhaustion and even system breakdown
Congestion is unavoidable in switched networks and multiuser application environments. To improve the
service performance of your network, you must take measures to address the congestion issues.
The key to congestion management is how to define a dispatching policy for resources to decide the order
of forwarding packets when congestion occurs.

Techniques

Congestion management uses queuing and scheduling algorithms to classify and sort traffic leaving a port.
Each queuing algorithm addresses a particular network traffic problem, and has a different impact on
bandwidth resource assignment, delay, and jitter.
Queue scheduling processes packets by their priorities, preferentially forwarding high-priority packets. This
section describes SP queuing, WFQ, WRR queuing, and CBQ.
100M
10M
10M
50M
(100M + 10M + 50M) > 100M
(2)
100M
69
Figure 23 shows two common