Congestion Management Configuration; Congestion Management Overview; Causes, Impacts, And Countermeasures; Congestion Management Techniques - HP A5120 EI Series Configuration Manual

Congestion management configuration

Congestion management overview

Causes, impacts, and countermeasures

Network congestion degrades service quality on a traditional network. Congestion is a situation where
the forwarding rate decreases due to insufficient resources, and results in extra delay.
Congestion is more likely to occur in complex packet switching circumstances.
common cases:
Figure 12 Traffic congestion causes
100M
100M > 10M
(1)
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 system breakdown
Congestion is unavoidable in switched networks and multi-user application environments. To improve the
service performance of your network, you must take proper measures to address the congestion issues.
The key to congestion management is defining 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, and SP+WRR queuing.
SP queuing
SP queuing is designed for mission-critical applications that require preferential service to reduce the
response delay when congestion occurs.
100M
10M
10M
50M
(100M + 10M + 50M) > 100M
(2)
100M
39
Figure 12 shows the