Technical data

BLADE OS 5.1 Application Guide
98
 Chapter 7: Quality of Service BMD00136, November 2009
Figure 13 QoS Model
The G8000 uses the Differentiated Services (DiffServ) architecture to provide QoS functions.
DiffServ is described in IETF RFC 2474 and RFC 2475.
With DiffServ, you can establish policies to direct traffic. A policy is a traffic-controlling
mechanism that monitors the characteristics of the traffic, (for example, its source, destination, and
protocol) and performs a controlling action on the traffic when certain characteristics are matched.
The G8000 can classify traffic by reading the DiffServ Code Point (DSCP) or IEEE 802.1p priority
value, or by using filters to match specific criteria. When network traffic attributes match those
specified in a traffic pattern, the policy instructs the G8000 to perform specified actions on each
packet that passes through it. The packets are assigned to different Class of Service (COS) queues
and scheduled for transmission.
The basic G8000 QoS model works as follows:
 Classify traffic:
 Read DSCP
 Read 802.1p Priority
 Match ACL filter parameters
 Meter traffic:
 Define bandwidth and burst parameters
 Select actions to perform on in-profile and out-of-profile traffic
 Perform actions:
 Drop packets
 Pass packets
 Mark DSCP or 802.1p Priority
 Set COS queue (with or without re-marking)
 Queue and schedule traffic:
 Place packets in one of two COS queues
 Schedule transmission based on the COS queue weight
Ports
ACL
Filter
Permit/Deny
Classify
Packets
Perform
Actions
Egress
Ingress
COS
Queue
Queue and
Schedule