tokenmt(7ipp)						   IP Quality of Service Modules					     tokenmt(7ipp)

NAME

       tokenmt - Single and Two Rate Three Conformance Level Meter

DESCRIPTION

       The tokenmt module can be configured as a Single or a Two Rate meter. Packets are deemed to belong to one of the three levels - Red, Yellow
       or Green - depending on the configured rate(s) and the burst sizes. When configured as a Single Rate meter, tokenmt can operate	with  just
       the Green and Red levels.

       Configuration parameters for tokenmt correspond to definitions in RFC- 2697 and RFC- 2698 as follows:

       Configuring tokenmt as a Single Rate meter (from RFC- 2697):
	 committed_rate - CIR
	 committed_burst - CBS
	 peak_burst - EBS

       (thus  'peak_burst'  for  a  single  rate meter is actually the 'excess	burst' in the RFC. However, throughout the text the parameter name
       "peak burst" is used.)

       Configuring tokenmt as a Two Rate meter (from RFC- 2698):
	 committed_rate - CIR
	 peak_rate - PIR
	 committed_burst - CBS
	 peak_burst - PBS

       The meter is implemented using token buckets C and P, which initially hold tokens equivalent to	committed  and	peak  burst  sizes  (bits)
       respectively. When a packet of size  B bits arrive at time  t, the following occurs:

	 When operating as a Single Rate meter, the outcome (level)
	 is decided as follows:
		 - Update tokens in C and P
		       o Compute no. of tokens accumulated since the
			 last time packet was seen at the committed rate as
			 T(t) = committed rate * (t - t')
			 (where t' is the time the last packet was seen)
		       o Add T tokens to C up to a maximum of committed burst
			 size. Add remaining tokens ((C+T) - Commited Burst),
			 if any, to P, to a maximum of peak burst size.
		 - Decide outcome
		       o If not color aware
			       o If B <= C, outcome is GREEN and C -= B.
			       o Else, if B <= P, outcome is YELLOW and P -= B.
			       o Else, outcome is Red.
		       o Else,
			       o obtain DSCP from packet
			       o obtain color from color_map, color_map[DSCP]
			       o if (color is GREEN) and (B <= C), outcome is
				 GREEN and C -= B.
			       o Else, if (color is GREEN or YELLOW) and
				 (B <= P), outcome is YELLOW and  P -= B.
			       o Else, outcome is RED.
	      Note that if peak_burst and yellow_next_actions are
	      not specified (that is, a single rate meter with two
	      outcomes), the outcome is never YELLOW.

       When operating as a Two Rate meter, the outcome (level) is decided as follows:

	 - Update tokens in C and P
			   o Compute no. of tokens accumulated since the last time a
			     packet was seen at the committed and peak rates as
			     Tc(t) = committed rate * (t - t')
			     Tp(t) = peak rate * (t - t')
			     (where t' is the time the last packet was seen)
			   o Add Tc to C up to a maximum of committed burst size
			   o Add Tp to P up to a maximum of peak burst size
		      - Decide outcome
			   o If not color aware
				 o If B > P, outcome is RED.
				 o Else, if B > C, outcome is YELLOW and P -= B
				 o Else, outcome is GREEN and C -= B & P -= B
			   o Else,
				 o obtain DSCP from packet
				 o obtain color from color_map, color_map[DSCP]
				 o if (color is RED) or (B > P), outcome is RED
				 o Else, if (color is YELLOW) or (B > C),
				   outcome is YELLOW and P -= B
				 o Else, outcome is GREEN and C -= B & P -= B

STATISTICS

       The tokenmt module exports the following statistics through kstat:

       Global statistics:

	 module: tokenmt			  instance: <action id>
	   name: tokenmt statistics		  class <action name>
		 epackets			  <number of packets in error>
		 green_bits			  <number of bits in green>
		 green_packets			  <number of packets in green>
		 red_bits			  <number of bits in red>
		 red_packets			  <number of packets in red>
		 yellow_bits			  <number of bits in yellow>
		 yellow packets 		  <number of packets in yellow>

FILES

       /kernel/ipp/sparcv9/tokenmt

	   64-bit module (SPARC only.)

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWqos			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ipqosconf(1M), dlcosmk(7ipp), dscpmk(7ipp), flowacct(7ipp), ipqos(7ipp), ipgpc(7ipp), tswtclmt(7ipp)

       RFC 2697, A Single Rate Three Color Marker J. Heinanen, R. Guerin -- The Internet Society, 1999

       RFC 2698, A Two Rate Three Color Marker J. Heinanen, R. Guerin -- The Internet Society, 1999

SunOS 5.11							    29 Sep 2004 						     tokenmt(7ipp)