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traffic-control: add TBF chapter to Makefile

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Stefano Avallone
2018-03-16 09:44:12 +01:00
parent 0d5b1028cb
commit 2909ec18fd
3 changed files with 16 additions and 15 deletions
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1
doc/models/Makefile
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@@ -82,6 +82,7 @@ SOURCES = \
$(SRC)/traffic-control/doc/queue-discs.rst \
$(SRC)/traffic-control/doc/pfifo-fast.rst \
$(SRC)/traffic-control/doc/fifo.rst \
$(SRC)/traffic-control/doc/tbf.rst \
$(SRC)/traffic-control/doc/red.rst \
$(SRC)/traffic-control/doc/codel.rst \
$(SRC)/traffic-control/doc/fq-codel.rst \

1
doc/models/source/traffic-control.rst
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@@ -7,6 +7,7 @@ Traffic Control Layer
queue-discs
fifo
pfifo-fast
tbf
red
codel
fq-codel

29
src/traffic-control/doc/tbf.rst
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@@ -18,22 +18,21 @@ bytes. If yes, then the tokens are removed and the packet is passed for transmis
packets will have to wait until there are sufficient tokens in the bucket. This data conformance
can be thus put into three possible scenarios [Ref3]_:
1. Data rate = Token rate : Packets pass without delay
2. Data rate < Token rate : Few tokens are depleted.
* Burst Condition : So the tokens might accumulate and the bucket might become
full. Then, the next packets to enter TBF will be transmitted right away without
having any limit applied to them, until the bucket is empty. This is called a burst
condition and in TBF the burst parameter defines the size of the bucket. In order
to overcome this problem and provide better control over the bursts, TBF
implements a second bucket which is smaller and generally the same size as the
MTU. This second bucket cannot store large amount of tokens, but its
replenishing rate will be a lot faster than the one of the big bucket. This second
rate is called 'peakRate' and it will determine the maximum rate of a burst.
1. Data rate = Token rate : Packets pass without delay.
2. Data rate < Token rate : The tokens might accumulate and the bucket might become
full. Then, the next packets to enter TBF will be transmitted right away without
having any limit applied to them, until the bucket is empty. This is called a burst
condition and in TBF the burst parameter defines the size of the bucket. In order
to overcome this problem and provide better control over the bursts, TBF
implements a second bucket which is smaller and generally the same size as the
MTU. This second bucket cannot store large amount of tokens, but its
replenishing rate will be a lot faster than the one of the big bucket. This second
rate is called 'peakRate' and it will determine the maximum rate of a burst.
3. Data rate > Token rate : This causes the TBF algorithm to throttle itself for a while as
soon as the bucket gets empty. This is called an 'overlimit situation' [Ref2]_. In this situation,
some of the packets will be blocked until enough tokens are available at which time a schedule for
the waking of the queue will be done. If packets keep coming in, at a larger rate, then the
packets will start to get dropped when the total number of bytes exceeds the QueueLimit.
soon as the bucket gets empty. This is called an 'overlimit situation' [Ref2]_. In this situation,
some of the packets will be blocked until enough tokens are available at which time a schedule for
the waking of the queue will be done. If packets keep coming in, at a larger rate, then the
packets will start to get dropped when the total number of bytes exceeds the QueueLimit.
Model Description
*****************