or any part of the network infrastructure.
of the IP packet (see Figure 14-18). Seven of these bits enable classification of traffic across an
IP network. The eighth bit is not used and is set to 0. The first three bits are used to set
precedence. The next four bits specify the type of service (ToS). Up to six classes of service can
be partitioned using the ToS bits. As soon as this traffic is classified as important, queuing
technologies in the network use these bits to apply the appropriate expedited handling across
the network.
offers considerable flexibility for precedence assignment, down to the user or application level.
Another option is to classify packets by source and destination, source subnet, and so on.
Normally, this is done closest to the source, whether at the edge or near the core.
and low priorities to classify traffic into service-level criteria. When packets are classified from
the endpoint, they keep their service-level definitions as they move from network hop to
network hop.