Network Working Group S. Shenker
Request for Comments: 2215 J. Wroclawski
Category: Standards Track Xerox PARC/MIT LCS
General Characterization Parameters for
Integrated Service Network Elements
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
This memo defines a set of general control and characterization
parameters for network elements supporting the IETF integrated
services QoS control framework. General parameters are those with
common, shared definitions across all QoS control services.
This memo defines the set of general control and characterization
parameters used by network elements supporting the integrated
services framework. "General" means that the parameter has a common
definition and shared meaning across all QoS control services.
Control parameters are used by applications to provide information to
the network related to QoS control requests. An example is the
traffic specification (TSpec) generated by application senders and
Characterization parameters are used to discover or characterize the
QoS management environment along the path of a packet flow requesting
active end-to-end QoS control. These characterizations may
eventually be used by the application requesting QoS control, or by
other network elements along the path. Examples include information
about which QoS control services are available along a network path
and estimates of the available path bandwidth.
Individual QoS control service specifications may refer to these
parameter definitions as well as defining additional parameters
specific to the needs of that service.
Shenker & Wroclawski Standards Track [Page 1]RFC 2215 General Characterization Parameters September 1997
Parameters are assigned machine-oriented ID's using a method
described in [RFC 2216] and summarized here. These ID's may be used
within protocol messages (e.g., as described in [RFC 2210]) or
management interfaces to describe the parameter values present. Each
parameter ID is composed from two numerical fields, one identifying
the service associated with the parameter (the <service_number>), and
the other (the <parameter_number>) identifying the parameter itself.
Because the definitions of the parameters defined in this note are
common to all QoS control services, the <parameter_number> values for
the parameters defined here are assigned from the "general
parameters" range (1 - 127).
NOTE: <parameter_numbers> in the range 128 - 254 name parameters
with definitions specific to a particular QoS control service. In
contrast to the general parameters described here, it is necessary
to consider both the <service_number> and <parameter_number> to
determine the meaning of the parameter.
Service number 1 is reserved for use as described in Section 2 of
this note. Service numbers 2 through 254 will be allocated to
individual QoS control services. Currently, Guaranteed service
[RFC 2212] is allocated number 2, and Controlled-load service [RFC
2211] is allocated number 5.
In this note, the textual form
is used to write a service_number, parameter_number pair. The range
of possible of service_number and parameter_number values specified
in [RFC 2216] allow the parameter ID to directly form the tail
portion of a MIB object ID representing the parameter. This
simplifies the task of making parameter values available to network
The definition of each parameter used to characterize a path through
the network describes two types of values; local and composed. A
Local value gives information about a single network element.
Composed values reflect the running composition of local values along
a path, specified by some composition rule. Each parameter
definition specifies the composition rule for that parameter. The
composition rule tells how to combine an incoming composed value
(from the already-traversed portion of the path) and the local value,
to give a new composed value which is passed to the next network