DELL 8132 ユーザーズマニュアル

QoS Commands

Quality of Service (QoS) technologies are intended to provide guaranteed 

timely delivery of specific application data to a particular destination. In 

contrast, 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. During times of 

congestion, packets may be delayed, sent sporadically, or dropped. For typical 

Internet applications, such as electronic mail and file transfer, a slight 

degradation in service is acceptable and, in many cases, unnoticeable.
Conversely, any degradation of service has undesirable effects on applications 

with strict timing requirements, such as voice or multimedia. 
QoS is a means of providing consistent, predictable data delivery by 

distinguishing between packets that have 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. To accomplish this, all 

elements of the network must be QoS-capable. If one node is unable to meet 

the necessary timing requirements, this creates a deficiency in the network 

path and the performance of the entire packet flow is compromised.

The PowerConnect ACL feature allows classification of packets based upon 

Layer 2 through Layer 4 header information. An Ethernet IPv6 packet is 

distinguished from an IPv4 packet by its unique Ether-type value; thus, all 

IPv4 and IPv6 classifiers include the Ether-type field.
Multiple ACLs per interface are supported. The ACLs can be combination of 

Layer 2 and/or Layer 3/4 ACLs.
ACL assignment is appropriate for both physical ports and LAGs.

2CSPC4.X8100-SWUM102.book  Page 635  Friday, March 15, 2013  8:56 AM