Having established that a network needs to implement QoS to be able to support different types of traffic on the network, it is also important to understand what impact the network has on application performance. In this section, we will discuss the impact that the network can have on different types of applications, and how we can classify the applications into groups that need to be treated in a similar manner over the network.

Let's start by discussing the impact that the network has on the packets as they travel from source to destination across a series of network devices and links. We have discussed in Chapter 3, Components of the Enterprise Network, how a router processes the packets received on the interfaces. We have also discussed additional processing that is done by the router in terms of ACLs in Chapter 8, Understanding and Configuring...