Quality of Service | 851
Figure 41-1.  Dell Force10 QoS Architecture
Implementation Information
Dell Force10 QoS implementation complies with IEEE 802.1p User Priority Bits for QoS Indication. It 
also implements these Internet Engineering Task Force (IETF) documents:
• RFC 2474, Definition of the Differentiated Services Field (DS Field) in the IPv4 Headers
• RFC 2475, An Architecture for Differentiated Services
• RFC 2597, Assured Forwarding PHB Group
• RFC 2598, An Expedited Forwarding PHB
You cannot configure port-based and policy-based QoS on the same interface, and SONET line cards 
support only port-based QoS.
Packet
Classification
(ACL) 
Ingress
Packet
Processing 
Marking
(DiffServ,
802.1p, Exp) 
Rate Policing
Buffers 
Class-based
Queues 
Congestion 
Avoidance
(WRED)
Egress
Packet
Processing 
Traffic
Shaping 
Egress
Congestion Management
(WFQ Scheduling)
Rate Limiting
Buffers  
Class-based
Queues
Switching