Cisco WS-C2960-24TC-S Software Guide - Page 41

Chapter 1 Overview Features QoS and CoS Features These are the QoS and CoS features: • Automatic QoS (auto-QoS) to simplify the deployment of existing QoS features by classifying traffic and configuring egress queues • Classification - IP type-of-service/Differentiated Services Code Point (IP ToS/DSCP) and IEEE 802.1p CoS marking priorities on a per-port basis for protecting the performance of mission-critical applications - IP ToS/DSCP and IEEE 802.1p CoS marking based on flow-based packet classification (classification based on information in the MAC, IP, and TCP/UDP headers) for high-performance quality of service at the network edge, allowing for differentiated service levels for different types of network traffic and for prioritizing mission-critical traffic in the network - Trusted port states (CoS, DSCP, and IP precedence) within a QoS domain and with a port bordering another QoS domain - Trusted boundary for detecting the presence of a Cisco IP Phone, trusting the CoS value received, and ensuring port security • Policing - Traffic-policing policies on the switch port for managing how much of the port bandwidth should be allocated to a specific traffic flow - In Cisco IOS Release 12.2(25)SED and later, if you configure multiple class maps for a hierarchical policy map, each class map can be associated with its own port-level (second-level) policy map. Each second-level policy map can have a different policer. - Aggregate policing for policing traffic flows in aggregate to restrict specific applications or traffic flows to metered, predefined rates • Out-of-Profile - Out-of-profile markdown for packets that exceed bandwidth utilization limits • Ingress queueing and scheduling - Two configurable ingress queues for user traffic (one queue can be the priority queue) - Weighted tail drop (WTD) as the congestion-avoidance mechanism for managing the queue lengths and providing drop precedences for different traffic classifications - Shaped round robin (SRR) as the scheduling service for specifying the rate at which packets are sent to the internal ring (sharing is the only supported mode on ingress queues) • Egress queues and scheduling - Four egress queues per port - WTD as the congestion-avoidance mechanism for managing the queue lengths and providing drop precedences for different traffic classifications - SRR as the scheduling service for specifying the rate at which packets are dequeued to the egress interface (shaping or sharing is supported on egress queues). Shaped egress queues are guaranteed but limited to using a share of port bandwidth. Shared egress queues are also guaranteed a configured share of bandwidth, but can use more than the guarantee if other queues become empty and do not use their share of the bandwidth. OL-8603-04 Catalyst 2960 Switch Software Configuration Guide 1-9