Traffic Management; Traffic Management Capabilities; Traffic Descriptors - Cabletron Systems SmartSwitch 6500 User Manual

7 TRAFFIC MANAGEMENT

7.1

TRAFFIC MANAGEMENT CAPABILITIES

This section describes how the SmartSwitch 6500 manages bandwidth and congestion. It briefly describes console
commands that affect how the SmartSwitch 6500 manages traffic. This section also provides guidelines for setting
some traffic control parameters.
The SmartSwitch 6500 has extensive abilities for managing the flow of traffic. Traffic management includes all
operations performed by the SmartSwitch 6500 that ensure optimum switch throughput, where throughput is based on
rate of packet loss, available bandwidth, and traffic processing overhead. Under most conditions, the SmartSwitch
6500 can efficiently and automatically manage switch traffic. However, if necessary, you can adjust the switch traffic
management parameters. For example, it might be necessary to adjust parameters for a port that carries a large amount
of CBR traffic or a very large number of simultaneous connections.
The SmartSwitch 6500 provides console commands that affect traffic flow on a global, port, or category of service
level. These console commands affect switch traffic flow by controlling
•
Bandwidth allocation
•
Call Admission Control (CAC) policies
•
The service category for a connection
•
Buffer memory allocation
•
Threshold settings for anti-congestion routines
Caution Do not change traffic control settings unless you have expert-level experience
with ATM switching. Back up the switch configuration before making changes.
Also, make notes of the changes you make to the traffic control parameters.
7.1.1

Traffic Descriptors

Traffic characteristics of an ATM source are signaled through a set of traffic descriptors during connection
establishment. The SmartSwitch 6500 uses traffic descriptors for resource allocation during call set up and guarantees
the Quality of Service (QoS) across the connection. The source traffic descriptor is a set of parameters that describes
the expected bandwidth utilization of a connection. You can set these parameters,
•
Peak Cell Rate (PCR)
•
Sustainable Cell Rate (SCR) and Maximum Burst Size (MBS)
•
Minimum Cell Rate (MCR) — signaled through UNI4.0 signaling only
Traffic descriptors vary for each QoS. If a connection is bi-directional, a traffic descriptor has to be assigned to each
direction and need not be the same in both directions.
SmartSwitch 6500 User Guide 7-1