Netgear GSM4248P User Manual - Page 771

AV Line of Fully Managed Switches M4250 Series Main User Manual The IP ACL in this example matches all packets with the source IP address and subnet mask of the Finance department's network and deny it on interfaces 2, 3, and 4 of the switch. The second rule permits all non-Finance traffic on the ports. The second rule is required because an explicit deny all rule exists as the lowest priority rule. Differentiated Services (DiffServ) Standard IP-based networks are designed to provide best effort data delivery service. Best effort service implies that the network delivers the data in a timely fashion, although there is no guarantee that it does. During times of congestion, packets might be delayed, sent sporadically, or dropped. For typical Internet applications, such as email and file transfer, a slight degradation in service is acceptable and in many cases unnoticeable. However, any degradation of service can negatively affect applications with strict timing requirements, such as voice or multimedia. Quality of Service (QoS) can provide consistent, predictable data delivery by distinguishing between packets with strict timing requirements from those that are more tolerant of delay. Packets with strict timing requirements are given special treatment in a QoS-capable network. With this in mind, all elements of the network must be QoS capable. If one node cannot meet the necessary timing requirements, this creates a deficiency in the network path and the performance of the entire packet flow is compromised. There are two basic types of QoS: • Integrated Services: Network resources are apportioned based on request and are reserved (resource reservation) according to network management policy (RSVP, for example). • Differentiated Services: Network resources are apportioned based on traffic classification and priority, giving preferential treatment to data with strict timing requirements. The switch supports DiffServ. The DiffServ feature contains a number of conceptual QoS building blocks that you can use to construct a differentiated service network. Use these same blocks in different ways to build other types of QoS architectures. You must configure three key QoS building blocks for DiffServ: • Class • Policy • Service (the assignment of a policy to a directional interface) Configuration Examples 771 Main User Manual