Red Parameters - Avaya P550R User Manual

RED Parameters

Avaya P550R/P580/P880/P882 Multiservice Switch ATM Uplink Module User Guide, Version 2.0
Figure 0-1. RED Deployment
Host A
Host B
Host C
VCI 1
Offered
VCI 2
Traffic
Load
VCI 3
Consider three flows to different destinations on shaped
connections. If any queue is allowed to grow uncontrolled, it will
exhaust all packet memory for that traffic class. If an application's
flow is not controlled, a badly behaving application, (one offering
more load than was apportioned for it's data) can cause packet loss
on an application that is not exceeding its bandwidth allocation.
Under these conditions, RED may be provisioned for the flows,
without further rate limiting, to ensure that well behaved flows do
not suffer for the sins of others.
* Note: Due to the additional checks that must be done when
packets arrive at the queue, the implementation of RED
can cause a degradation in total system throughput.
RED, as implemented on the ATM Uplink Module, provides four
parameters that are used to modify packet discard. The
implementation of RED, on the ATM Uplink Module has been
optimized for application to frames at wires speeds of up to OC12.
These parameters, exported to the user for modification, do not
correspond exactly to the parameters as presented in the RED
document published by Floyd & Jacobson.
ATM Uplink
Module
Avaya Switch
ATM Up
RED
CBR VCI
CBR VCI
CBR VCI
Memory Buffer
For CBR Traffic
A-3