User's Manual
Table Of Contents
- 1 Preface
- 2 Overview
- 3 Features
- 3.1 Main Features
- 3.2 Adaptive Coding and Modulation (ACM)
- 3.3 Transmit Power Control (TPC)
- 3.4 2x2 Multiple-input and Multiple-output (2x2 MIMO)
- 3.5 Dynamic Frequency Selection (DFS)
- 3.6 Dynamic Channel Selection (DCS)
- 3.7 Retransmission
- 3.8 Configurable Uplink/Downlink Ratio
- 3.9 Quality of Service (QoS)
- 3.10 Power over Ethernet
- 3.11 Synchronization
- 3.12 Co-site Synchronization
- 3.13 OFDM Modulation
- 3.14 Low-density Parity Check (LDPC) Encoding
- 3.15 LLDP
- 3.16 Radio Port Performance Monitoring
- 3.17 Adaptive Noise Immunity (ANI)
- 4 Mechanical Structure and Interfaces
- 5 Product Structure
- 6 Management
- 7 Technical Specification
- 8 Standards
21
DragonWave Inc. Features
• Weighted round robin (WRR)
WRR is used to allocate a bandwidth per queue to ensure that each queue gets the
amount of bandwidth determined by the weighing assigned.
The available bandwidth is distributed to the queues in need of bandwidth propor-
tional to the assigned weight.
Once every WRR minimum bandwidth per queue has been satisfied, excess band-
width is allocated in proportion to the weights of the queues competing for the
excess bandwidth.
The weight of each queue can be configurable from 1 to 127.
• Deficit Weighted Round Robin (DWRR)
An inherent limitation of WRR mode is that the actual bandwidth allocated to a
queue depends on the frame size, but as frame sizes are not known to the sched-
uler, it is hard to control the bandwidth allocated to a queue.
To address this issue, DWRR is invented. It is a modified version of WRR.
DWRR has two parameters, credit counter (also called deficit counter) and quantum.
DWRR serves the frames at the head of every non-empty queue whose credit
counter is greater than the frame’s size. If the credit counter is lower, the queue is
skipped and its credit is increased by a given value called quantum. Hence, the
function of quantum is somewhat like weight but is in bytes. This increased value is
used to calculate the credit counter the next time around when the scheduler
examines this queue for serving its head-of-line frame. If the queue is served, the
credit is decremented by the size of frame being served.
• SP + WRR/DWRR
The combination of SP and WRR/DWRR method is supported. In this method, a
certain number of CoS queues (out of 8) on an egress port work in SP mode, while
the rest of the queues on the same port work in WRR/DWRR mode. it is possible to
enable all CoS queues either in SP or WRR/DWRR mode, or some with SP and the
rest with WRR/DWRR. However, the queues configured for SP mode must have a
higher index value than those for WRR/DWRR mode. The SP mode iindices must
also be consecutive.
Up to 8 queues (starting from Q8) can be configured for strict priority queues (see
Table 3). SP queues use SP based on CoS values to assign bandwidth ahead of
other WRR or DWRR queues.
Number of SP Queues Configured Corresponding SP Queues
1Q8
2Q7, Q8
3 Q6, Q7, Q8
4 Q5, Q6, Q7, Q8
5 Q4, Q5, Q6, Q7, Q8
6 Q3, Q4, Q5, Q6, Q7, Q8
7 Q2,Q3, Q4, Q5, Q6, Q7, Q8
8 Q1, Q2,Q3, Q4, Q5, Q6, Q7, Q8
Table 3 SP Queues Configuration