Technical Summary
Measuring network capacity is a task that sounds simple, but in
reality can be quite complex. In addition, the lack of a unified
nomenclature on this subject makes it increasingly difficult to
properly build, test, and use techniques and tools built around
these constructs. This document provides definitions for the terms
'Capacity' and 'Available Capacity' related to IP traffic traveling
between a source and destination in an IP network, to provide a
common framework for the discussion and analysis of a diverse set
of current and future measurement and estimation techniques.
Working Group Summary
The working group has supported the document through the last
five revisions, and it has been uncontroversial.
Protocol Quality
The document has been given thorough review by the group over its
revisions, and in particular Joseph Kopena and Dan Romanescu have
given thorough reviews improving document quality.
Personnel
Document Shepherd: Matt Zekauskas (matt@internet2.edu)
Responsible Area Director: Lars Eggert (lars.eggert@nokia.com)
RFC Editor Note
Expand the first use of the acronym IPPM as "IP Performance Metrics".
Section 2.1., paragraph 1:
OLD:
To define capacity, we need to broaden the notions of link and path
found in the IPPM framework document [RFC2330] to include network
devices that can impact IP capacity without being IP aware. For
example, consider an Ethernet switch that can operate ports at
different speeds.
NEW:
To define capacity, we need to broaden the notions of link and path
found in the IP Performance Metrics (IPPM) framework document
[RFC2330] to include network devices that can impact IP capacity
without being IP aware. For example, consider an Ethernet switch
that can operate ports at different speeds.
To be inserted as the last paragraph in Section 2.3.1.2:
As a practical matter, it should be noted that some providers may
treat packets with certain characteristics differently than other
packets. For example, access control lists, routing policies, and
other mechanisms may be used to filter ICMP packets or packets
with certain IP options through different routes. If a
capacity-measurement tool uses these special packets and they are
included in the "Type P" designation, the tool may not be
measuring the path that it was intended to measure. Tool authors,
as well as users may wish to check this point with their service
providers.
To be inserted as the last paragraph in Section 2.3.2:
As mentioned earlier, this definition is impacted by many factors
that may change over time. For example, a device's ability to
process and forward IP packets for a particular link may have
varying impact on capacity depending on the amount or type of
traffic being processed.