QoS Commands 64531QoS CommandsQuality of Service (QoS) technologies are intended to provide guaranteedtimely delivery of specific application data to a particular destination. Incontrast, standard IP-based networks are designed to provide best effort datadelivery service. Best effort service implies that the network delivers the datain a timely fashion, although there is no guarantee. During times ofcongestion, packets may be delayed, sent sporadically, or dropped. For typicalInternet applications, such as electronic mail and file transfer, a slightdegradation in service is acceptable and, in many cases, unnoticeable.Conversely, any degradation of service has undesirable effects on applicationswith strict timing requirements, such as voice or multimedia.QoS is a means of providing consistent, predictable data delivery bydistinguishing between packets that have strict timing requirements fromthose that are more tolerant of delay. Packets with strict timing requirementsare given special treatment in a QoS-capable network. To accomplish this, allelements of the network must be QoS-capable. If one node is unable to meetthe necessary timing requirements, this creates a deficiency in the networkpath and the performance of the entire packet flow is compromised.Access Control ListsThe PowerConnect ACL feature allows classification of packets based uponLayer 2 through Layer 4 header information. An Ethernet IPv6 packet isdistinguished from an IPv4 packet by its unique Ether-type value; thus, allIPv4 and IPv6 classifiers include the Ether-type field.Multiple ACLs per interface are supported. The ACLs can be combination ofLayer 2 and/or Layer 3/4 ACLs.ACL assignment is appropriate for both physical ports and LAGs.
