Samsung Ubigate iBG2016, Руководство по настройке

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Ubigate iBG2016 Configuration Guide/Ed.00
© SAMSUNG Electronics Co., Ltd.
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A single class by itself should not be allowed to borrow all of the available
common pool buffers. So we need to enforce a maximum limit on the buffer
consumption of each class. Since we have allocated(10 * BCR average_
packet_size) buffers for the entire interface, we should, at least, allow each
class to use its fair share of(10 * bcr / average_packet_size) buffers(out of
which [6 * bcr / average_packet_size] have been reserved for it). However, the
buffer allocation for a class should also take into consideration the Burst
Rate(BR) configured for the class. If classes are configured with a very small
CR but BR = interface bandwidth, the above amount of buffers might not be
enough for the classes. Therefore, we allow a class to use up to a maximum
of(3 * bbr / average_packet_size) buffers by borrowing from the common
pool. In addition to supporting the BR, this will accommodate a burst of
(2 * scheduler interval) 10 ms at a rate of BR kbps.(For packet sizes larger
than average_packet_size bytes, the burst duration
will be even longer). In this case the maximum buffers that a traffic class can
loan from the common pool is as shown below.
Max loaned buffers = (3*bbr / average_packet_size) – reserved_buffers
For a class with BR = interface BR and CR~0,
Max loaned buffers = (3*BCR / average_packet_size) –QOS_MIN_RES_
CLASS_Q_SIZE
Max loaned buffers ~ (3*BCR / average_packet_size)
Note that a single class can still not consume all the buffers in the common
buffer pool. There will be(BCR / average_packet_size) buffers still remaining
for the other classes(which is enough to support a rate of up to the interface
bandwidth).
The following sums up the maximum buffer limit calculation for a class.
max1 = (3 * bbr) / average_packet_size;
max2 = (10 * bcr) / average_packet_size;
Max Buffers = MAX(max1, max2, QOS_MAX_CLASS_Q_LIMIT_MIN);
Where, QOS_MAX_CLASS_Q_LIMIT_MIN is 10.
It is important to note that, the buffer requirement for traffic classes is
(10 *BCR/100) buffers irrespective of the number of classes.