As per Relevance of the word terminology, we have this rfc below:
Network Working Group K.
Request for Comments: 2432 IronBridge
Category: Informational October 1998
Terminology for IP Multicast
Status of this
This memo provides information for the Internet community. It
not specify an Internet standard of any kind. Distribution of
memo is unlimited
Copyright
Copyright (C) The Internet Society (1998). All Rights Reserved
The purpose of this document is to define terminology specific to
benchmarking of multicast IP forwarding devices. It builds upon
tenets set forth in RFC 1242, RFC 2285, and other IETF
Methodology Working Group (BMWG) efforts. This document seeks
extend these efforts to the multicast paradigm
The BMWG produces two major classes of documents:
Terminology documents and Benchmarking Methodology documents.
Terminology documents present the benchmarks and other related terms
The Methodology documents define the procedures required to
the benchmarks cited in the corresponding Terminology documents
1.
Network forwarding devices are being required to take a single
and support delivery to a number of destinations having membership
a particular group. As such, multicast support may place a
burden on the resources of these network forwarding devices than
unicast or broadcast traffic types
Such burdens may not be readily apparent at first glance - the
multicast packet's Class D address may be the only
difference from an IP unicast packet. However, there are
factors that may impact the treatment of IP multicast packets
Consider how a device's architecture may impact the handling of
multicast frame. For example, is the multicast packet subject to
same processing as its unicast analog? Or is the multicast
treated as an exeception and processed on a different data path
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Consider, too, how a shared memory architecture may demonstrate
different performance profile than an architecture which
passes each individual packet between the processing entities
In addition to forwarding device architecture, there are
factors that may impact a device's or system's multicast
performance. Protocol requirements may demand that routers
switches consider destination and source addressing in its
forwarding decisions. Capturing multicast source/
addressing information may impact forwarding table size and
lookups. Topological factors such as the degree of
replication, the number of multicast groups being supported by
system, or the placement of multicast packets in unicast wrappers
span non-multicast network paths may all potentially affect
system's multicast related performance. For an overall
of IP multicasting, the reader is directed to [Se98], [Hu95],
[Mt98].
By clearly identifying IP multicast benchmarks and
terminology in this document, it is hoped that detailed
can be generated in subsequent documents. Taken in tandem, these
efforts endeavor to assist the clinical, empirical, and
characterization of certain aspects of multicast technologies
their individual implementations. Understanding the
profile of multicast forwarding devices may assist the
designer to better deploy multicast in his or her
environment
Moreover, this document focuses on one source to many
profiling. Elements of this document may require extension
considering multiple source to multiple destination IP
communication
2. Definition
This section cites the template suggested by RFC 1242 in
specification of a term to be defined
Term to be defined
Definition
The specific definition for the term
Discussion
A brief discussion of the term, its application, or
information that would build understanding
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Measurement units
Units used to record measurements of this term, if applicable
[Issues:]
List of issues or conditions that affect this term. This field
present items the may impact the term's related methodology
otherwise restrict its measurement procedures. This field
optional in this document
[See Also:]
List of other terms that are relevant to the discussion of
term. This field is optional in this document
2.1 Existing
This document draws on existing terminology defined in other
work. Examples include, but are not limited to
Throughput [RFC 1242, section 3.17]
Latency [RFC 1242, section 3.8]
Constant Load [RFC 1242, section 3.4]
Frame Loss Rate [RFC 1242, section 3.6]
Overhead behavior [RFC 1242, section 3.11]
Forwarding Rates [RFC 2285, section 3.6]
Loads [RFC 2285, section 3.5]
Device Under Test (DUT) [RFC 2285, section 3.1.1]
System Under Test (SUT) [RFC 2285, section 3.1.2]
Note: "DUT/SUT" refers to a metric that may be applicable to a DUT
SUT
3. Table of Defined
3.1 General
3.1.1 Traffic Class. (TC
3.1.2 Group Class. (GC
3.1.3 Service Class. (SC
3.2 Forwarding and
3.2.1 Mixed Class Throughput (MCT).
3.2.2 Scaled Group Forwarding Matrix (SGFM).
3.2.3 Aggregated Multicast Throughput (AMT
3.2.4 Encapsulation Throughput (ET
3.2.5 Decapsulation Throughput (DT
3.2.6 Re-encapsulation Throughput (RET
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3.3 Forwarding
3.3.1 Multicast Latency (ML
3.3.2 Min/Max Multicast Latency (Min/Max ML
3.4
3.4.1 Group Join Delay. (GJD
3.4.2 Group Leave Delay. (GLD
3.5
3.5.1 Multicast Group Capacity. (MGC
3.6
3.6.1 Burdened
3.6.2 Forwarding Burdened Multicast Latency (FBML
3.6.3 Forwarding Burdened Join Delay (FBJD
3.1 General
This section will present general terminology to be used in this
other documents
3.1.1 Traffic Class. (TC
Definition
An equivalence class of packets comprising one or more
streams
Discussion
In the scope of this document, Traffic Class will be considered
logical identifier used to discriminate between a set or sets
packets offered the DUT
For example, one Traffic Class may identify a set of
packets offered to the DUT. Another Traffic Class
differentiate the multicast packets destined to multicast group X
Yet another Class may distinguish the set of multicast
destined to multicast group Y
Unless otherwise qualified, the usage of the word "Class" in
document will refer simply to a Traffic Class
Measurement units
Not applicable
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3.1.2 Group Class. (GC
Definition
A specific type of Traffic Class where the packets comprising
Class are destined to a particular multicast group
Discussion
Measurement units
Not applicable
3.1.3 Service Class. (SC
Definition
A specific type of Traffic Class where the packets comprising
Class require particular treatment or treatments by the
forwarding devices along the path to the packets' destination(s).
Discussion
Measurement units
Not applicable
3.2 Forwarding and Throughput
This section presents terminology related to the characterization
the packet forwarding ability of a DUT/SUT in a
environment. Some metrics extend the concept of throughput
in RFC 1242. The notion of Forwarding Rate is cited in RFC 2285.
3.2.1 Mixed Class Throughput (MCT).
Definition
The maximum rate at which none of the offered frames,
from a unicast Class and a multicast Class, to be forwarded
dropped by the device across a fixed number of ports
Discussion
Often times, throughput is collected on a homogenous traffic
- the offered load to the DUT is either singularly unicast
singularly multicast. In most networking environments,
traffic mix is seldom so uniformly distributed
Based on the RFC 1242 definition for throughput, the Mixed
Throughput benchmark attempts to characterize the DUT's ability
process both unicast and multicast frames in the same
traffic stream
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Measurement units
Frames per
Issues
Related methodology may have to address the ratio of
packets to multicast packets
Since frame size can sometimes be a factor in frame
benchmarks, the corresponding methodology for this metric
need to consider frame size distribution(s).
3.2.2 Scaled Group Forwarding Matrix (SGFM).
Definition
A table that demonstrates Forwarding Rate as a function of
multicast groups for a fixed number of tested DUT/SUT ports
Discussion
A desirable attribute of many Internet mechanisms is the
to "scale." This benchmark seeks to demonstrate the ability of
SUT to forward as the number of multicast groups is
upwards
Measurement units
Packets per second, with corresponding tested multicast group
port configurations
Issues
The corresponding methodology may have to reflect the impact
the pairing (source, group) has on many multicast
protocols
Since frame size can sometimes be a factor in frame
benchmarks, the corresponding methodology for this metric
need to consider frame size distribution(s).
3.2.3 Aggregated Multicast Throughput (AMT
Definition
The maximum rate at which none of the offered frames to
forwarded through N destination interfaces of the same
group are dropped
Discussion
Another "scaling" type of exercise, designed to identify
DUT/SUT's ability to handle traffic as a function of the
destination ports it is required to support
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Measurement units
The ordered pair (N,t) where
N = the number of destination ports of the multicast group
t = the throughput, in frames per second, relative to
source stream
Issues
Since frame size can sometimes be a factor in frame
benchmarks, the corresponding methodology for this metric
need to consider frame size distribution(s).
3.2.4 Encapsulation Throughput (ET
Definition
The maximum rate at which frames offered a DUT are
and correctly forwarded by the DUT without loss
Discussion
A popular technique in presenting a frame to a device that may
support a protocol feature is to encapsulate, or tunnel,
packet containing the unsupported feature in a format that
supported by that device
More specifically, encapsulation refers to the act of taking
frame or part of a frame and embedding it as a payload of
frame. This benchmark attempts to characterize the
behavior associated with that translational process
Measurement units
Frames per second
Issues
Consideration may need to be given with respect to the impact
different frame formats on usable bandwidth
Since frame size can sometimes be a factor in frame
benchmarks, the corresponding methodology for this metric
need to consider frame size distribution(s).
3.2.5 Decapsulation Throughput (DT
Definition
The maximum rate at which frames offered a DUT are
and correctly forwarded by the DUT without loss
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Discussion
A popular technique in presenting a frame to a device that may
support a protocol feature is to encapsulate, or tunnel,
packet containing the unsupported feature in a format that
supported by that device. At some point, the frame may be
to be returned its orginal format from its encapsulation
for use by the frame's next destination
More specifically, decapsulation refers to the act of taking
frame or part of a frame embedded as a payload of another
and returning it to the payload's appropriate format.
benchmark attempts to characterize the overhead
associated with that translational process
Measurement units
Frames per second
Issues
Consideration may need to be given with respect to the impact
different frame formats on usable bandwidth
Since frame size can sometimes be a factor in frame
benchmarks, the corresponding methodology for this metric
need to consider frame size distribution(s).
3.2.6 Re-encapsulation Throughput (RET
Definition
The maximum rate at which frames of one encapsulated
offered a DUT are converted to another encapsulated format
correctly forwarded by the DUT without loss
Discussion
A popular technique in presenting a frame to a device that may
support a protocol feature is to encapsulate, or tunnel,
packet containing the unsupported feature in a format that
supported by that device. At some point, the frame may be
to be converted from one encapsulation format to
encapsulation format
More specifically, re-encapsulation refers to the act of taking
encapsulated payload of one format and replacing it with
encapsulated format - all the while preserving the
payload's contents. This benchmark attempts to characterize
overhead behavior associated with that translational process
Measurement units
Frames per second
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Issues
Consideration may need to be given with respect to the impact
different frame formats on usable bandwidth
Since frame size can sometimes be a factor in frame
benchmarks, the corresponding methodology for this metric
need to consider frame size distribution(s).
3.3 Forwarding Latency
This section presents terminology relating to the characterization
the forwarding latency of a DUT/SUT in a multicast environment.
extends the concept of latency presented in RFC 1242.
3.3.1 Multicast Latency. (ML
Definition
The set of individual latencies from a single input port on
DUT or SUT to all tested ports belonging to the
multicast group
Discussion
This benchmark is based on the RFC 1242 definition of latency
While it is useful to collect latency between a pair of source
destination multicast ports, it may be insightful to collect
same type of measurements across a range of ports supporting
Group Class
A variety of statistical exercises can be applied to the set
latencies measurements
Measurement units
Time units with enough precision to reflect a latency measurement
3.3.2 Min/Max Multicast Latency. (Min/Max ML
Definition
The difference between the maximum latency measurement and
minimum latency measurement from the set of latencies produced
the Multicast Latency benchmark
Discussion
This statistic may yield some insight into how a
implementation handles its multicast traffic. This may be
to users of multicast synchronization types of applications
Measurement units
Time units with enough precision to reflect latency measurement
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3.4
This section presents terminology relating to the characterization
the overhead delays associated with explicit operations found
multicast environments
3.4.1 Group Join Delay. (GJD
Definition
The time duration it takes a DUT to start forwarding
packets from the time a successful IGMP group membership
has been issued to the DUT
Discussion
Many factors can contribute to different results, such as
number or type of multicast-related protocols configured on
device under test. Other factors are physical topology and "tree
configuration
Because of the number of variables that could impact this metric
the metric may be a better characterization tool for a
rather than a basis for comparisons with other devices
Issues
A consideration for the related methodology: possible need
differentiate a specifically-forwarded multicast frame from
sprayed by protocols implementing a flooding tactic to
prune feedback
While this metric attempts to identify a simple delay,
underlying and contributing delay components (e.g.,
delay, frame processing delay, etc.) make this a less than
measurement. The corresponding methodology will need to
this and similar factors to ensure a consistent and precise
result
Measurement units
Microseconds
3.4.2 Group Leave Delay. (GLD
Definition
The time duration it takes a DUT to cease forwarding
packets after a corresponding IGMP "Leave Group" message has
successfully offered to the DUT
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Discussion
While it is important to understand how quickly a device
process multicast frames; it may be beneficial to understand
quickly that same device can stop the process as well
Because of the number of variables that could impact this metric
the metric may be a better characterization tool for a
rather than a basis for comparisons with other devices
Measurement units
Microseconds
Issues
The Methodology may need to consider protocol-specific
values
While this metric attempts to identify a simple delay,
underlying and contributing delay components (e.g.,
delay, frame processing delay, etc.) make this a less than
measurement. Moreover, the cessation of traffic is a
unobservable event (i.e., at what point is the multicast
considered stopped on the DUT interface processing the Leave?).
The corresponding methodology will need to consider this
similar factors to ensure a consistent and precise metric result
3.5
This section offers terms relating to the identification of
group limits of a DUT/SUT
3.5.1 Multicast Group Capacity. (MGC
Definition
The maximum number of multicast groups a SUT/DUT can support
maintaining the ability to forward multicast frames to
multicast groups registered to that SUT/DUT
Discussion
Measurement units
Multicast groups
Issues
The related methodology may have to consider the impact
multicast sources per group on the ability of a SUT/DUT to "
up" the number of supportable multicast groups
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3.6
Network forwarding devices are generally required to provide
functionality than than the forwarding of traffic. Moreover,
forwarding devices may be asked to provide those functions in
variety of environments. This section offers terms to assist in
charaterization of DUT/SUT behavior in consideration of
interacting factors
3.6.1 Burdened Response
Definition
A measured response collected from a DUT/SUT in light
interacting, or potentially interacting, distinct stimulii
Discussion
Many metrics provide a one dimensional view into an
characteristic of a tested system. For example, the
rate metric may yield information about the packet
ability of a device. Collecting that same metric in view
another control variable can oftentimes be very insightful.
that same forwarding rate measurement, for instance, while
device's address table is injected with an additional 50,000
entries may yield a different perspective
Measurement units
A burdened response is a type of metric. Metrics of this
type must follow guidelines when reporting results
The metric's principal result MUST be reported in conjunction
the contributing factors
For example, in reporting a Forwarding Burdened Latency,
latency measurement should be reported with respect
corresponding Offered Load and Forwarding Rates
Issues: A Burdened response may be very illuminating when trying
characterize a single device or system. Extreme care must
exercised when attempting to use that characterization as a
of comparison with other devices or systems. Test agents
ensure that the measured response is a function of the
stimulii, and not secondary factors. An example of of such
interfering factor would be configuration mismatch of a
impacting a response process
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3.6.2 Forwarding Burdened Multicast Latency. (FBML
Definition
A multicast latency taken from a DUT/SUT in the presence of
traffic forwarding requirement
Discussion
This burdened response metric builds on the Multicast
definition offered in section 3.3.1. It mandates that the DUT
subjected to an additional measure of traffic not required by
non-burdened metric
This metric attempts to provide a means by which to evaluate
traffic load may or may not impact a device's or system's
processing delay
Measurement units
Time units with enough precision to reflect the
measurements
Latency measurements MUST be reported with the
sustained Forwarding Rate and associated Offered Load
3.6.3 Forwarding Burdened Group Join Delay. (FBGJD
Definition
A multicast Group Join Delay taken from a DUT in the presence of
traffic forwarding requirement
Discussion
This burdened response metric builds on the Group Join
definition offered in section 3.4.1. It mandates that the DUT
subjected to an additional measure of traffic not required by
non-burdened metric
Many factors can contribute to different results, such as
number or type of multicast-related protocols configured on
device under test. Other factors could be physical topology or
logical multicast "tree" configuration
Because of the number of variables that could impact this metric
the metric may be a better characterization tool for a
rather than a basis for comparisons with other devices
Measurement units
Time units with enough precision to reflect the
measurements
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RFC 2432 Terminology for IP Multicast Benchmarking October 1998
Delay measurements MUST be reported with the
sustained Forwarding Rate and associated Offered Load
Issues
While this metric attempts to identify a simple delay,
underlying and contributing delay components (e.g.,
delay, frame processing delay, etc.) make this a less than
measurement. The corresponding methodology will need to
this and similar factors to ensure a consistent and precise
result
4. Security
This document addresses metrics and terminology relating to
performance benchmarking of IP Multicast forwarding devices.
information contained in this document does not impact the
of the Internet
Methodologies regarding the collection of the metrics
within this document may need to cite security considerations.
document does not address methodological issues
5.
The IETF BMWG participants have made several comments and
regarding this work. Particular thanks goes to Harald Alvestrand
Scott Bradner, Brad Cain, Eric Crawley, Bob Mandeville, David Newman
Shuching Sheih, Dave Thaler, Chuck Winter, Zhaohui Zhang, and
Galgay for their insightful review and assistance
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RFC 2432 Terminology for IP Multicast Benchmarking October 1998
6.
[Br91] Bradner, S., "Benchmarking Terminology for
Interconnection Devices", RFC 1242, July 1991.
[Br96] Bradner, S., and J. McQuaid, "Benchmarking Methodology
Network Interconnect Devices", RFC 1944, May 1996.
[Hu95] Huitema, C. "Routing in the Internet." Prentice-Hall, 1995.
[Se98] Semeria, C. and Maufer, T. "Introduction to IP
Routing." http://www.3com.com/nsc/501303.html 3Com Corp.,
1998.
[Ma98] Mandeville, R., "Benchmarking Terminology for LAN
Devices", RFC 2285, February 1998.
[Mt98] Maufer, T. "Deploying IP Multicast in the Enterprise."
Prentice-Hall, 1998.
7. Author's
Kevin
IronBridge
55 Hayden
Lexington, MA 02421
Phone: 781 372 8118
EMail: kdubray@ironbridgenetworks.
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RFC 2432 Terminology for IP Multicast Benchmarking October 1998
8. Full Copyright
Copyright (C) The Internet Society (1998). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
and distributed, in whole or in part, without restriction of
kind, provided that the above copyright notice and this paragraph
included on all such copies and derivative works. However,
document itself may not be modified in any way, such as by
the copyright notice or references to the Internet Society or
Internet organizations, except as needed for the purpose
developing Internet standards in which case the procedures
copyrights defined in the Internet Standards process must
followed, or as required to translate it into languages other
English
The limited permissions granted above are perpetual and will not
revoked by the Internet Society or its successors or assigns
This document and the information contained herein is provided on
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED,
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
Dubray Informational [Page 16]
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just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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