Dell PowerConnect M6220 Configuration Manual

Also see for PowerConnect M6220: Release notes Configuration guide Cli reference guide Configuration guide Release note

Contents

Quality of Service 1097Quality of ServiceThis section includes the following subsections:• "Class of Service Queuing" on page 109• "Differentiated Services" on page 113Class of Service QueuingThe Class of Service (CoS) feature lets you give preferential treatment to certain types of traffic overothers. To set up this preferential treatment, you can configure the ingress ports, the egress ports,and individual queues on the egress ports to provide customization that suits your environment.The level of service is determined by the egress port queue to which the traffic is assigned. Whentraffic is queued for transmission, the rate at which it is serviced depends on how the queue isconfigured and possibly the amount of traffic present in other queues for that port.Some traffic is classified for service (i.e., packet marking) before it arrives at the switch. If you decideto use these classifications, you can map this traffic to egress queues by setting up a CoS Mappingtable.Each ingress port on the switch has a default priority value (set by configuring VLAN Port Priority inthe Switching sub-menu) that determines the egress queue its traffic gets forwarded to. Packets thatarrive without a priority designation, or packets from ports you’ve identified as “untrusted,” getforwarded according to this default.Ingress Port ConfigurationTrusted and Untrusted Ports/CoS Mapping TableThe first task for ingress port configuration is to specify whether traffic arriving on a given port is“trusted” or “untrusted.”A trusted port means that the system will accept at face value a priority designation within arrivingpackets. You can configure the system to trust priority designations based on one of the followingfields in the packet header:• 802.1 Priority: values 0-7• IP DSCP: values 0-63• IP Precedence: values 0-7You can also configure an ingress port as untrusted, where the system ignores priority designations ofincoming packets and sends the packet to a queue based on the ingress port’s default priority.