RFC 2698 (rfc2698) - Page 2 of 5

A Two Rate Three Color Marker

RFC 2698             A Two Rate Three Color Marker        September 1999


   The Meter meters each packet and passes the packet and the metering
   result to the Marker:

                            +------------+
                            |   Result   |
                            |            V
                        +-------+    +--------+
                        |       |    |        |
      Packet Stream ===>| Meter |===>| Marker |===> Marked Packet Stream
                        |       |    |        |
                        +-------+    +--------+
   The Meter operates in one of two modes.  In the Color-Blind mode, the
   Meter assumes that the packet stream is uncolored.  In the Color-
   Aware mode the Meter assumes that some preceding entity has pre-
   colored the incoming packet stream so that each packet is either
   green, yellow, or red.  The details of the pre-coloring process,
   including handling of error scenarios, and how the Meter determines
   the color of a pre-colored packet are DS domain specific and outside
   the scope of this document.

   The Marker (re)colors an IP packet according to the results of the
   Meter.  The color is coded in the DS field [RFC 2474] of the packet in
   a PHB specific manner (see section 4 for an example).

   A companion document [RFC 2697] describes another three color marker,
   called a Single Rate Three Color Maker (srTCM), where packets are
   marked based on a single rate and two burst sizes.

2. Configuration

   The trTCM is configured by setting its mode and by assigning values
   to four traffic parameters: a Peak Information Rate (PIR) and its
   associated Peak Burst Size (PBS) and a Committed Information Rate
   (CIR) and its associated Committed Burst Size (CBS).

   The PIR and CIR are measured in bytes of IP packets per second, i.e.,
   it includes the IP header, but not link specific headers.  The PIR
   must be equal to or greater than the CIR.

   The PBS and the CBS and are measured in bytes and both of them must
   be configured to be greater than 0.  It is recommended that they be
   configured to be equal to or greater than the size of the largest
   possible IP packet in the stream.








Heinanen & Guerin            Informational