3com WX3000 Manuel D’Utilisation

 

1-8 

Protocol packets carry their own priority. You can modify the priority of a protocol packet to implement 

QoS.  

The priority marking function is to use ACL rules in traffic classification and reassign the priority for the 

packets matching the ACL rules. 

The network will be made more congested by plenty of continuous burst packets if the traffic of each 

user is not limited. The traffic of each user must be limited in order to make better use of the limited 

network resources and provide better service for more users. For example, a traffic flow can be limited 

to get only its committed resources during a time period to avoid network congestion caused by 

excessive bursts. 

Traffic policing and traffic shaping is each a kind of traffic control policy used to limit the traffic and the 

resource occupied by supervising the traffic. The regulation policy is implemented according to the 

evaluation result on the premise of knowing whether the traffic exceeds the specification when traffic 

policing or traffic shaping is performed. Normally, token bucket is used for traffic evaluation. 

The token bucket can be considered as a container with a certain capacity to hold tokens. The system 

puts tokens into the bucket at the set rate. When the token bucket is full, the extra tokens will overflow 

and the number of tokens in the bucket stops increasing. 

Figure 1-5 Evaluate the traffic with the token bucket 

Token bucket

Drop

Packet 

classification

Packets to be sent 

through this port

Continue to send

Put tokens in the bucket at the set rate