Juniper JUNOSE 11.1.X - QUALITY OF SERVICE CONFIGURATION GUIDE 3-21-2010, Руководство по настройке

Страница: 127 / 398

Sample Process for Controlling the Simple Shared Shaper Algorithm
The simple shared shaper in this example contains two constituents, best-effort and
video. The shared-shaping rate is 15 Mbps, and the video rate is 4 Mbps.
The example contains two parts: when the video flow is turned on, and then turned
off.
NOTE: The rates in this example are approximate and for illustrative purposes only.
Your configuration might yield different results based on network variables.
Starting Video Flow
Table 9 on page 95 lists the dynamic rate when the video flow is turned on for the
five classes of simple shared shaper variables. Results vary because the amount of
video measured in the first rising period is random, in the range 0–4 Mbps
non-inclusive.
Table 9: Rising Edge Sample When Video Flow Starts
Period of Dynamic Rate, in Kbps
10 9 8 7 6 5 4 3 2 1 Control
11000 11000 11000 11000 11000 11000 11000 11000 13080 15000 Most
liberal
10994 10998 10994 10979 10972 10867 10470 8880 9542 15000 Liberal
10953 10967 10814 10628 10329 9651 8303 5606 6510 15000 Moderate
9735 9300 8733 7978 7038 5714 3953 1604 6022 15000 Conservative
– – – – – – – – – – Most
conservative
In this example, a liberal maximum VOQL value is ineffective because the 15 Mbps
shared-shaping rate is much higher than the 4 Mbps video rate. The video rate divided
by the shared shaping rate is 26.6 percent, so any value higher than this has no
effect.
NOTE: The rates in this example represent approximate egress-queue enqueue rates
on an Ethernet line module; therefore, there is no ATM SAR or downstream devices
are not used. More liberal configurations can be inappropriate when there might be
queuing between the scheduler and the destination. VLAN queuing is used, and
saturation rates are offered.
Sample Process for Controlling the Simple Shared Shaper Algorithm
■ 95
Chapter 11: Configuring Variables in the Simple Shared Shaping Algorithm