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 5.10							    29 Sep 2004 						     tokenmt(7ipp)