Configuring Congestion Management; Overview - HP MSR4080 Configuration Manual

Configuring congestion management

In this chapter, "MSR1000" refers to MSR1002-4. "MSR2000" refers to MSR2003, MSR2004-24,
MSR2004-48. "MSR3000" collectively refers to MSR3012, MSR3024, MSR3044, MSR3064.
"MSR4000" collectively refers to MSR4060 and MSR4080.

Overview

Congestion occurs on a link or node when traffic size exceeds the processing capability of the link or
node. It is typical of a statistical multiplexing network and can be caused by link failures, insufficient
resources, and various other causes.
Figure 13 Traffic congestion causes
Congestion produces 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 system breakdown.
Congestion is unavoidable in switched networks or multiuser application environments. To improve the
service performance of your network, implement congestion management policies.
For example, congestion management defines a resource dispatching policy to prioritize packets for
forwarding when congestion occurs.
Congestion management involves queue creating, traffic classification, packet enqueuing, and queue
scheduling.
Queuing is a common congestion management technique. It classifies traffic into queues and picks out
packets from each queue by using an algorithm. Various queuing algorithms are available, and each
addresses a particular network traffic problem. Your choice of algorithm significantly affects bandwidth
assignment, delay, and jitter.
This section describes several common queue-scheduling mechanisms.
Figure 13 shows common congestion scenarios.
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