Memory Requirements For Queue And Buffers; Guidelines For Managing Queue Thresholds; Guidelines For Configuring A Maximum Threshold; Table 5: Egress Memory And Region Size On Asic Line Modules - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - QUALITY OF SERVICE CONFIGURATION GUIDE 2010-09-22 Configuration Manual

Memory Requirements for Queue and Buffers

Related
Documentation

Guidelines for Managing Queue Thresholds

Guidelines for Configuring a Maximum Threshold

Copyright © 2010, Juniper Networks, Inc.
RED and WRED Overview on page 26
JunosE Software uses 128-byte buffers.
The egress memory available for queues available depends on the ASIC and the line
module. Table 5 on page 19 lists the egress memory.

Table 5: Egress Memory and Region Size on ASIC Line Modules

ASIC Line Module
EFA All EFA line modules
FFA GE-2 and GE-HDE
OC48
ES2 4G LM
TFA ES2 10G LM
To identify the type of ASIC used by a line module, see the ERX Module Guide and the
E120 and E320 Module Guide
Guidelines for Managing Queue Thresholds on page 19
Guidelines for Managing Buffers on page 20
To prevent the router from setting queue thresholds too low or too high, you can specify
minimum and maximum queue thresholds. You can also specify the conformed length
and exceeded length as percentages of the committed length.
We recommend that you constrain queue thresholds using committed or conformed
threshold settings; any unused memory is redistributed to queues whose thresholds are
not constrained. This use of thresholds is analogous to the way that shaping rates
constrain bandwidth and cause bandwidth redistribution to unconstrained queues.
For example, voice queues are scheduled at strict priority; therefore, they require very
little buffering. Configuring a maximum queue threshold enables the system to allocate
more buffers to other queues in the system. Video queues are similar but because they
are higher bandwidth, they might require higher maximum committed thresholds.
Chapter 3: Configuring Queue Profiles for Buffer Management
Egress Memory
(MB)
32
64
128
128
96
Region Size
(MB)
4
8
16
16
12
19