What is Propagation Delay

When we call someone over the Internet using a service such as Skype or Google talk, we may experience certain undesirable problems. For instance, we may not be able to hear the other person very well, or even worse, the call may be dropped. In order to eliminate these problems, the underlying IP network has to be able to provide quality of service guarantees. Several schemes have been developed that enable the IP network to provide such guarantees. Of these schemes, the Multi-Protocol Label Switching (MPLS) and the Differentiated Services (DiffServ) are the most widely used. In this article, some of the salient features of MPLS and DiffServ are reviewed.