3com 3031 Instruccion De Instalación
Several Traffic Control Technologies
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Impact
Congestion may cause the following negative effects:
■
Increase the delay and jitter of packet transmission
■
Packet re-transmission caused by high delay
■
Decrease the efficient throughput of network and waste the network resources
■
Intensified congestion can occupy too many network resources (especially in
memory), and the irrational assignment of resources even can lead to resource
block and breakdown for the system.
memory), and the irrational assignment of resources even can lead to resource
block and breakdown for the system.
It’s obvious that congestion will make the traffic unable to obtain the resources in
time and degrade the service performance accordingly. No one wants congestion,
but it occurs frequently in complex environments where packet switching and
multi-users applications coexist. So it needs to be treated cautiously.
time and degrade the service performance accordingly. No one wants congestion,
but it occurs frequently in complex environments where packet switching and
multi-users applications coexist. So it needs to be treated cautiously.
Countermeasure
A direct way to solve resources deficient problem is to increase the bandwidth of
network; however, it cannot resolve all the problems concerning congestion.
network; however, it cannot resolve all the problems concerning congestion.
A more effective method to solve the problem of QoS is to enhance the functions
of traffic control and resource allocation at network layer, and to provide
differentiated services for applications with different service requirement in order
to allocate and use resources rightly. During the process of resources allocation
and traffic control, the direct or indirect factors that might cause network
congestion should be controlled with best effort to reduce the probability of
congestion. As congestion occurs, resource allocation should be balanced
according to features and demands of applications, to minimize the effects on
QoS by congestion.
of traffic control and resource allocation at network layer, and to provide
differentiated services for applications with different service requirement in order
to allocate and use resources rightly. During the process of resources allocation
and traffic control, the direct or indirect factors that might cause network
congestion should be controlled with best effort to reduce the probability of
congestion. As congestion occurs, resource allocation should be balanced
according to features and demands of applications, to minimize the effects on
QoS by congestion.
Several Traffic Control
Technologies
Technologies
Traffic classification, traffic policing, traffic shaping, congestion management and
congestion avoidance are the foundations for the network to provide
differentiated services. Mainly they implement the following functions:
congestion avoidance are the foundations for the network to provide
differentiated services. Mainly they implement the following functions:
■
Traffic Classification: It is a prerequisite for differentiated service, to identify the
interested objects based on a certain matching rule.
interested objects based on a certain matching rule.
■
Traffic Policing: To police the specification of particular traffic entering the
router. When the traffic exceeds the specification then some restriction or
punishment measures can be taken to protect the commercial benefits of
carriers and to prevent network resources from being damaged.
router. When the traffic exceeds the specification then some restriction or
punishment measures can be taken to protect the commercial benefits of
carriers and to prevent network resources from being damaged.
■
Congestion Management: A necessary measure to handle the resource
competition problem during network congestion. Generally, it stores the
packets in the queue first, and then takes a dispatching algorithm to assign the
forwarding sequence of packets.
competition problem during network congestion. Generally, it stores the
packets in the queue first, and then takes a dispatching algorithm to assign the
forwarding sequence of packets.
■
Congestion Avoidance: Exceeding congestion can waste the network
resources. Congestion avoidance can monitor the usage status of network
resources, and as congestion becomes worse actively take the policy of
dropping packets through adjusting traffic to resolve the overloading of the
network.
resources. Congestion avoidance can monitor the usage status of network
resources, and as congestion becomes worse actively take the policy of
dropping packets through adjusting traffic to resolve the overloading of the
network.
■
Traffic Shaping: A traffic control measure of actively adjusting the output speed
of traffic, generally it can enable the traffic to adapt to the network resources
supplied by the downstream router, to prevent the unwanted packet dropping
and congestion.
of traffic, generally it can enable the traffic to adapt to the network resources
supplied by the downstream router, to prevent the unwanted packet dropping
and congestion.