Configuring Congestion Management; Overview; Causes, Impacts, And Countermeasures; Congestion Management Techniques - HP 5830 Series Configuration Manual

Configuring congestion management

This chapter describes how to configure congestion management.

Overview

This section describes why congestion occurs and the congestion management techniques.

Causes, impacts, and countermeasures

Network congestion degrades service quality. 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.
common cases:
Figure 13 Traffic congestion causes
Congestion can 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 multi-user application environments. To improve the
service performance of your network, you must take some proper 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.

Congestion management 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.
The following section describes in detail Strict Priority (SP) queuing, Weighted Fair Queuing (WFQ),
Weighted Round Robin (WRR) queuing, SP+WRR queuing, and SP+WFQ queuing.
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Figure 13 shows two