Redline Communications Inc. AN100UXA 用户手册
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AN-100U/UX Base Station
Manual
70-00058-01-04
Proprietary Redline Communications © 2010
Page 104 of 136
April 19, 2010
ongoing manual or automated operations. Any unused bandwidth available after
allocations to all active connections is also available.
allocations to all active connections is also available.
Important: This bandwidth is shared for all subscribers in the sector. Initiating multiple
management operations simultaneously (e.g., subscriber software upgrades) may have
a severe impact on any ongoing operator sessions (HTTP/TELNET) or automated
operations (SNMP, Syslog) during high traffic.
management operations simultaneously (e.g., subscriber software upgrades) may have
a severe impact on any ongoing operator sessions (HTTP/TELNET) or automated
operations (SNMP, Syslog) during high traffic.
6.3
Deficit Round Robin Algorithm
The sector controller uses Deficit Round Robin (DRR) scheduling. The DDR algorithm
provides a balance of efficiency and fairness for traffic sent over a wireless interface. In
summary, the opportunity to transmit packets is based on a combination of the minimum
reserved bandwidth, packet size, and elapsed time. DRR Scheduling has the following
characteristics.
provides a balance of efficiency and fairness for traffic sent over a wireless interface. In
summary, the opportunity to transmit packets is based on a combination of the minimum
reserved bandwidth, packet size, and elapsed time. DRR Scheduling has the following
characteristics.
6.3.1 New Connection
When a connection is created, the DRR scheduler uses the following components for
scheduling:
scheduling:
Deficit Counter (d): This counter is a threshold used to determine when a connection is
eligible to transmit data. When transmitting data, the counter indicates the minimum
amount of data to be transmitted for the qualifying connection. This counter can not be
less than zero.
eligible to transmit data. When transmitting data, the counter indicates the minimum
amount of data to be transmitted for the qualifying connection. This counter can not be
less than zero.
Quantum (Q): The quantum is a calculated value used to factor the deficit counter (d).
Q = Min. Reserved Rate * Frame Duration / 8
The connection is tagged as inactive until packets are queued to be transmitted over the
wireless interface.
wireless interface.
6.3.2 Packets in Queue
When packets are queued to be transmitted over the wireless interface, the connection
is tagged active and will be included in scheduling for the next wireless frame.
is tagged active and will be included in scheduling for the next wireless frame.
When evaluating the connections eligibility to be included in a wireless frame, the deficit
counter (d) is first increased by the quantum (Q). The result (d + Q) is compared to the
size of the next packet in the connection queue. Bandwidth is allocated in the current
wireless frame only when the deficit counter (d) is greater than the size of next queued
packet.
counter (d) is first increased by the quantum (Q). The result (d + Q) is compared to the
size of the next packet in the connection queue. Bandwidth is allocated in the current
wireless frame only when the deficit counter (d) is greater than the size of next queued
packet.
deficit < size_next_packet:
No packets are transmitted for the current frame. The deficit counter (d) value is carried
forward to scheduling for the next wireless frame. The value of the deficit counter (d) will
accumulate over multiple wireless frames until it meets or exceeds the size of the next
queued packet.
forward to scheduling for the next wireless frame. The value of the deficit counter (d) will
accumulate over multiple wireless frames until it meets or exceeds the size of the next
queued packet.
deficit ≥ size_next_packet:
Bandwidth up to the current value of the deficit counter (d) may be allocated in the
current wireless frame. Generally, only complete packets are transmitted. The total
number of bytes transmitted is subtracted from the deficit counter (d) and the difference
is carried forward to the next frame.
current wireless frame. Generally, only complete packets are transmitted. The total
number of bytes transmitted is subtracted from the deficit counter (d) and the difference
is carried forward to the next frame.
6.3.3 No Packets in Queue
The deficit counter is not modified when an active connection has no packets queued. If
no packets are queued for 16 consecutive wireless frames, the connection is tagged
inactive and the deficit counter is set to zero.
no packets are queued for 16 consecutive wireless frames, the connection is tagged
inactive and the deficit counter is set to zero.