1-20 User Guide for the Avaya P580 and P882 Multiservice Switches, v6.1
Chapter 1
50-Series Buffers and Queues
Buffer and queue management relieves congestion in a network. Adding
gigabit speeds to existing networks means that there can be a hug e dispa rity
between link speeds. For example, anything more than a 1-perc ent load o n a
gigabit link could easily overwhelm a 10 Mb/s Ethernet link.
Each switch employs the following buffer and queue management
techniques:
■Configurable active backpressure:
—Half-duplex ports use active backpressure to jam input ports
when their frame buffers are full.
—Full-duplex links use IEEE 802.3z pause control frames to
pause traffic when buffers are full.
■Packed frame buffers for optimal memory utilization. The memory
management allows virtually 100% utilization of buffer memory.
■Two CoS priority queues for 50-Series modules and eight CoS
priority queues for 80-Series mod ules provide flexible queue
management algorithms to meet application requirements.
■Configurable queue depth for each prioritized packet queues.
■Configurable priority threshol d .
■Configurable service ratio tunes queue priority.
For more information on 50-series buffers and queues, see Chapter 24,
“Managing Buffers and Queues on 50-Series Modules.”
80-Series QoS
Quality of Service (QoS) is a set of tools that make it possible for you to
manage traffic across a switch or a network. These tools protect specific
traffic from the effects of network congestion. You can enable these features
for a module or individual ports on a module to control the flow of traffic
across your network. This control makes it possible for you to guarantee
that delay-sensitive traffic such as voice over IP (VoIP) receives the priori ty
it requires, while also ensuring t hat the switch services other low pr iority
data.
QoS makes it possible for you to prioritize time-sensitive traffic and assign
larger amounts of bandwidth to those applications that require it.
For more information on QoS, see Chapter 25, “80-Series QoS.”