3com 3031 Instruccion De Instalación

This chapter tells you the following:

■

Introduction to Managing Congestion 

■

How To Configure Congestion Management Technologies

■

Typical Configuration Examples

As to a network device, congestion will occur on the interface where the arrival 
rate of packets is faster than the sending rate. If there is no enough memory 
capacity to store those packets and then a part of them will be lost, which may 
cause the packet retransmission from the hosts or Router because of timeout, and 
lead to a vicious circle.

The key to congestion management is how to define a dispatching policy for 
resources to decide the forwarding order of packets when congestion occurs.

In general, congestion management adopts queuing technology. The system 
classifies traffic using a kind of queuing algorithm, and then it will send out the 
traffic with a certain preference algorithm. Each queuing algorithm is used to 
handle a particular network traffic problem and has great impacts on bandwidth 
resource assignment, delay, and jitter.

The following sections describe several common queue-scheduling mechanisms. 

Figure 233   FIFO queuing diagram 

As shown in Figure 233, FIFO organises the forwarding order of packets 
depending upon their arrival time. On a Router, the resources assigned for data 
traffic of users based on the arrival time of packets and the current load status of 
the network. Best-Effort services use FIFO queuing policy.

incoming packets

queue

outgoing packets

transmit

queue

interface