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Internet Engineering Task Force                           S.W. Handelman
INTERNET-DRAFT                                                       IBM
                                                       Hawthorne, NY USA

                                                          Nevil Brownlee
                                              The University of Auckland
                                                             New Zealand

                                                               Greg Ruth
                                                     GTE Internetworking
                                                         Waltham, MA USA

                                                              S. Stibler
                                                                     IBM
                                                       Hawthorne, NY USA

                                                          September 2000
                                                      Expires March 2000

           RTFM: New Attributes for Traffic Flow Measurement

               <draft-ietf-rtfm-new-traffic-flow-10.txt>

Abstract

The RTFM Traffic Measurement Architecture provides a general framework
for describing and measuring network traffic flows.  Flows are defined
in terms of their Address Attribute values and measured by a 'Traffic
Meter.'  This document discusses RTFM flows and the attributes which
they can have, so as to provide a logical framework for extending the
architecture by adding new attributes.

Extensions described include Address Attributes such as DSCodePoint,
SourceASN and DestASN, and Group Attributes such as short-term bit rates
and turnaround times.  Quality of Service parameters for Integrated
Services are also discussed.

INTERNET-DRAFT              RTFM: New Attributes          September 2000

Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC 2026.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups.  Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time.  It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

This Internet Draft is a product of the Realtime Traffic Flow
Measurement Working Group of the IETF.

Contents

1  Introduction                                                        3
   1.1 RTFM's Definition of Flows  . . . . . . . . . . . . . . . . .   3
   1.2 RTFM's Current Definition of Flows and their Attributes . . .   4
   1.3 RTFM Flows, Integrated Services, IPPM and Research in Flows .   5

2  Flow Abstractions                                                   6
   2.1 Meter Readers and Meters   .. . . . . . . . . . . . . . . . .   6
   2.2 Attribute Types  . . . . . .. . . . . . . . . . . . . . . . .   6
   2.3 Packet Traces  . . . . . . .. . . . . . . . . . . . . . . . .   8
   2.4 Aggregate Attributes . . . .. . . . . . . . . . . . . . . . .   8
   2.5 Group Attributes . . . .. . . . . . . . . . . . . . . . . . .   9
   2.6 Actions on Exceptions  . . .. . . . . . . . . . . . . . . . .  10

3  Extensions to the 'Basic' RTFM Meter                               11
   3.1 Flow table extensions  . . .. . . . . . . . . . . . . . . . .  11
   3.2 Specifying Distributions in RuleSets  . . . . . . . . . . . .  11
   3.3 Reading Distributions  . . .. . . . . . . . . . . . . . . . .  13

4  Extensions to the Rules Table, Attribute Numbers                   13

5  Security Considerations                                            15

6  References                                                         15

7  Author's Addresses                                                 16

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1  Introduction

The Real-Time Flow Measurement (RTFM) Working Group (WG) has developed a
system for measuring and reporting information about traffic flows in
the Internet.  This document explores the definition of extensions to
the flow measurements as currently defined in [RTFM-ARC]. The new
attributes described in this document will be useful for monitoring
network performance and will expand the scope of RTFM beyond simple
measurement of traffic volumes.  A companion document to this draft will
be written to define MIB structures for the new attributes.

This draft was started in 1996 to advance the work of the RTFM group.
The goal of this work is to produce a simple set of abstractions, which
can be easily implemented and at the same time enhance the value of RTFM
Meters.  This document also defines a method for organizing the flow
abstractions to augment the existing RTFM flow table.

Implementations of the RTFM Meter have been done by Nevil Brownlee in
the University of Auckland, NZ, and Stephen Stibler and Sig Handelman at
IBM in Hawthorne, NY, USA. The RTFM WG has also defined the role of the
Meter Reader whose role is to retrieve flow data from the Meter.

Note on flows and positioning of meters:

    A flow as it traverses the Internet may have some of its
    characteristics altered as it travels through Routers,
    Switches, and other network units.  It is important to note the
    spatial location of the Meter when referring to attributes of a
    flow.  An example, a server may send a sequence of packets with
    a definite order, and inter packet timing with a leaky bucket
    algorithm.  A meter reading downstream of the leaky bucket
    would record a set with minimal inter packet timing due to the
    leaky bucket.  At the client's location, the packets may arrive
    out of sequence, with the timings altered.  A meter at the
    client's location would record different attributes for the
    same flow.

1.1  RTFM's Definition of Flows

The RTFM Meter architecture views a flow as a set of packets between two
endpoints (as defined by their source and destination attribute values
and start and end times), and as BI-DIRECTIONAL (i.e. the meter
effectively monitors two sub-flows, one in each direction).

Reasons why RTFM flows are bi-directional:

  - The WG is interested in understanding the behavior of sessions
    between endpoints.

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  - The endpoint attribute values (the "Address" and "Type" ones) are
    the same for both directions; storing them in bi-directional flows
    reduces the meter's memory demands.

  - 'One-way' (uni-directional) flows are a degenerate case.  Existing
    RTFM meters can handle this by using one of the computed attributes
    (e.g. FlowKind) to indicate direction.

1.2  RTFM's Current Definition of Flows and their Attributes

Flows, as described in the "Architecture" document [RTFM-ARC] have the
following properties:

a. They occur between two endpoints, specified as sets of attribute
   values in the meter's current rule set.  A flow is completely
   identified by its set of endpoint attribute values.

b. Each flow may also have values for "computed" attributes (Class
   and Kind).  These are directly derived from the endpoint
   attribute values.

c. A new flow is created when a packet is to be counted that does
   not match the attributes of an existing flow. The meter records
   the time when this new flow is created.

d. Attribute values in (a), (b) and (c) are set when the meter sees
   the first packet for the flow, and are never changed.

e. Each flow has a "LastTime" attribute, which indicates the time
   the meter last saw a packet for the flow.

f. Each flow has two packet and two byte counters, one for each
   flow direction (Forward and Backward).  These are updated as
   packets for the flow are observed by the meter.

g. ALL the attributes have (more or less) the same meaning for a
   variety of protocols; IPX, AppleTalk, DECnet and CLNS as well
   as TCP/IP.

Current flow attributes - as described above - fit very well into the
SNMP data model.  They are either static, or are continuously updated
counters.  They are NEVER reset.  In this document they will be referred
to as "old-style" attributes.

It is easy to add further "old-style" attributes, since they don't
require any new features in the architecture.  For example:

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  - Count of the number of "lost" packets (determined by watching
    sequence number fields for packets in each direction; only
    available for protocols which have such sequence numbers).

  - In the future, RTFM could coordinate directly with the Flow Label
    from the IPv6 header.

1.3  RTFM Flows, Integrated Services, IPPM and Research in Flows

The concept of flows has been studied in various different contexts.
For the purpose of extending RTFM, a starting point is the work of the
Integrated Services WG. We will measure quantities that are often set by
Integrated Services configuration programs.  We will look at the work of
the Benchmarking / IP Performance Metrics Working Group, and also look
at the work of Claffy, Braun and Polyzos [C-B-P]. We will demonstrate
how RTFM can compute throughput, packet loss, and delays from flows.

An example of the use of capacity and performance information is found
in "The Use of RSVP with IETF Integrated Services" [IIS-RSVP]. RSVP's
use of Integrated Services revolves around Token Bucket Rate, Token
Bucket Size, Peak Data Rate, Minimum Policed Unit, Maximum Packet Size,
and the Slack term.  These are set by TSpec, ADspec and FLowspec
(Integrated Services Keywords), and are used in configuration and
operation of Integrated Services.  RTFM could monitor explicitly Peak
Data Rate, Minimum Policed Unit, Maximum Packet Size, and the Slack
term.  RTFM could infer details of the Token Bucket.  The WG will
develop measures to work with these service metrics.  An initial
implementation of IIS Monitoring has been developd at CEFRIEL in Italy
[IIS-ACCT].

RTFM will work with several traffic measurements identified by IPPM
[IPPM-FRM]. There are three broad areas in which RTFM is useful for
IPPM.

  - An RTFM Meter could act as a passive device, gathering traffic and
    performance statistics at appropriate places in networks (server or
    client locations).

  - RTFM could give detailed analyses of IPPM test flows that pass
    through the Network segment that RTFM is monitoring.

  - RTFM could be used to identify the most-used paths in a network
    mesh, so that detailed IPPM work could be applied to these most
    used paths.

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2  Flow Abstractions

Performance attributes include throughput, packet loss, delays, jitter,
and congestion measures.  RTFM will calculate these attributes in the
form of extensions to the RTFM flow attributes according to three
general classes:

  - 'Trace,'  attributes of individual packets in a flow or a segment
          of a flow (\eg last packet size, last packet arrival time).

  - 'Aggregate,'  attributes derived from the flow taken as a whole
          (e.g. mean rate, max packet size, packet size distribution).

  - 'Group,' attributes that depend on groups of packet values within
          the flow (\eg inter-arrival times, short-term traffic rates).

Note that attributes within each of these classes may have various types
of values - numbers, distributions, time series, and so on.

2.1  Meter Readers and Meters

A note on the relation between Meter Readers and Meters ..

Several of the measurements enumerated below can be implemented by a
Meter Reader that is tied to a meter with very short response time and
very high bandwidth.  If the Meter Reader and Meter can be arranged in
such a way, RTFM could collect Packet Traces with time stamps and
provide them directly to the Meter Reader for further processing.

A more useful alternative is to have the Meter calculate some flow
statistics locally.  This allows a looser coupling between the Meter and
Meter Reader.  RTFM will monitor an 'extended attribute' depending upon
settings in its Rule table.  RTFM will not create any "extended
attribute" data without explicit instructions in the Rule table.

2.2  Attribute Types

Section 2.  described three different classes of attributes; this
section considers the "data types" of these attributes.

Packet Traces (as described below) are a special case in that they are
tables with each row containing a sequence of values, each of varying
type.  They are essentially 'compound objects' i.e. lists of attribute
values for a string of packets.

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Aggregate attributes are like the 'old-style' attributes.  Their types
are

  - Addresses, represented as byte strings (1 to 20 bytes long)

  - Counters, represented as 64-bit unsigned integers

  - Times, represented as 32-bit unsigned integers

Addresses are saved when the first packet of a flow is observed.  They
do not change with time, and they are used as a key to find the flow's
entry in the meter's flow table.

Counters are incremented for each packet, and are never reset.  An
analysis application can compute differences between readings of the
counters, so as to determine rates for these attributes.  For example,
if we read flow data at five-minute intervals, we can calculate
five-minute packet and byte rates for the flow's two directions.

Times are derived from the FirstTime for a flow, which is set when its
first packet is observed.  LastTime is updated as each packet in the
flow is observed.

All the above types have the common feature that they are expressed as
single values.  At least some of the new attributes will require
multiple values.  If, for example, we are interested in inter-packet
time intervals, we can compute an interval for every packet after the
first.  If we are interested in packet sizes, a new value is obtained as
each packet arrives.  When it comes to storing this data we have two
options:

  - As a distribution, i.e. in an array of 'buckets.'  This method is a
    compact representation of the data, with the values being stored as
    counters between a minimum and maximum, with defined steps in each
    bucket.  This fits the RTFM goal of compact data storage.

  - As a sequence of single values.  This saves all the information,
    but does not fit well with the RTFM goal of doing as much data
    reduction as possible within the meter.

Studies which would be limited by the use of distributions might well
use packet traces instead.

A method for specifying the distribution parameters, and for encoding
the distribution so that it can be easily read, is described in section
3.2.

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2.3  Packet Traces

The simplest way of collecting a trace in the meter would be to have a
new attribute called, say, "PacketTrace." This could be a table, with a
column for each property of interest.  For example, one could trace

  - Packet Arrival time (TimeTicks from sysUpTime, or microseconds from
    FirstTime for the flow).

  - Packet Direction (Forward or Backward)

  - Packet Sequence number (for protocols with sequence numbers)

  - Packet Flags (for TCP at least)

Note:  The following implementation proposal is for the user who is
familiar with the writing of rule sets for the RTFM Meter.

    To add a row to the table, we only need a rule which PushPkts
    the PacketTrace attribute.  To use this, one would write a rule
    set which selected out a small number of flows of interest,
    with a 'PushPkt PacketTrace' rule for each of them.  A
    MaxTraceRows default value of 2000 would be enough to allow a
    Meter Reader to read one-second ping traces every 10 minutes or
    so.  More realistically, a MaxTraceRows of 500 would be enough
    for one-minute pings, read once each hour.

Packet traces are already implemented by the RMON MIB [RMON-MIB,
RMON2-MIB], in the Packet Capture Group.  They are therefore a low
priority for RTFM.

2.4  Aggregate Attributes

RTFM's "old-style" flow attributes count the bytes and packets for
packets which match the rule set for an individual flow.  In addition to
these totals, for example, RTFM could calculate Packet Size statistics.
This data can be stored as distributions, though it may sometimes be
sufficient to simply keep a maximum value.

As an example, consider Packet Size.  RTFM's packet flows can be
examined to determine the maximum packet size found in a flow.  This
will give the Network Operator an indication of the MTU being used in a
flow.  It will also give an indication of the sensitivity to loss of a
flow, for losing large packets causes more data to be retransmitted.

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Note that aggregate attributes are a simple extension of the 'old-style'
attributes; their values are never reset.  For example, an array of
counters could hold a 'packet size' distribution.  The counters continue
to increase, a meter reader will collect their values at regular
intervals, and an analysis application will compute and display
distributions of the packet size for each collection interval.

2.5  Group Attributes

The notion of group attributes is to keep simple statistics for measures
that involve more than one packet.  This section describes some group
attributes which it is feasible to implement in a traffic meter, and
which seem interesting and useful.

Short-term bit rate - The data could also be recorded as the maximum and
minimum data rate of the flow, found over specific time periods during
the lifetime of a flow; this is a special kind of 'distribution.'  Bit
rate could be used to define the throughput of a flow, and if the RTFM
flow is defined to be the sum of all traffic in a network, one can find
the throughput of the network.

If we are interested in '10-second' forward data rates, the meter might
compute this for each flow of interest as follows:

  - maintain an array of counters to hold the flow's 10-second data
    rate distribution.

  - every 10 seconds, compute and save 10-second octet count, and save
    a copy of the flow's forward octet counter.

To achieve this, the meter will have to keep a list of aggregate flows
and the intervals at which they require processing.  Careful programming
is needed to achieve this, but provided the meter is not asked to do it
for very large numbers of flows, it has been successfully implemented.

Inter-arrival times.  The Meter knows the time that it encounters each
individual packet.  Statistics can be kept to record the inter-arrival
times of the packets, which would give an indication of the jitter found
in the Flow.

Turn-around statistics.  Sine the Meter knows the time that it
encounters each individual packet, it can produce statistics of the time
intervals between packets in opposite directions are observed on the

network.  For protocols such as SNMP (where every packet elicits an
answering packet) this gives a good indication of turn-around times.

Subflow analysis.  Since the choice of flow endpoints is controlled by
the meter's rule set, it is easy to define an aggregate flow, e.g "all

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the TCP streams between hosts A and B." Preliminary implementation work
suggests that - at least for this case - it should be possible for the
meter to maintain a table of information about all the active streams.
This could be used to produce at least the following attributes:

  - Number of streams, e.g. streams active for n-second intervals.
    Determined for TCP and UDP using source-dest port number pairs.

  - Number of TCP bytes, determined by taking difference of TCP
    sequence numbers for each direction of the aggreagate flow.

IIS attributes.  Work at CEFRIEL [IIS-ACCT] has produced a traffic meter
with a rule set modified 'on the fly' so as to maintain a list of
RSVP-reserved flows.  For such flows the following attributes have been
implemented (these quantities are defined in [GUAR-QOS]):

   - QoSService:          Service class for the flow
                            (guaranteed, controlled load)
   - QoSStyle:            Reservation setup style
                            (wildcard filter, fixed filter,
                            shared explicit)
   - QoSRate:             [byte/s] rate for flows with
                            guaranteed service
   - QoSSlackTerm:        [microseconds] Slack Term QoS parameter
                            for flows with guaranteed service
   - QoSTokenBucketRate:  [byte/s] Token Bucket Rate QoS parameter
                            for flows with guaranteed or
                            controlled load service

   The following are also being considered:

   - QoSTokenBucketSize:  [byte] Size of Token Bucket

   - QoSPeakDataRate:     [byte/s] Maximum rate for incoming data

   - QoSMinPolicedUnit:   [byte] IP datagrams less than this are
                            counted as being this size
   - QoSMaxDatagramSize:  [byte] Size of biggest datagram which
                            conforms to the traffic specification

2.6  Actions on Exceptions

Some users of RTFM have requested the ability to mark flows as having
High Watermarks.  The existence of abnormal service conditions, such as
non-ending flow, a flow that exceeds a given limit in traffic (e.g. a
flow that is exhausting the capacity of the line that carries it) would

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cause an ALERT to be sent to the Meter Reader for forwarding to the
Manager.  Operations Support could define service situations in many
different environments.  This is an area for further discussion on Alert
and Trap handling.

3  Extensions to the 'Basic' RTFM Meter

The Working Group has agreed that the basic RTFM Meter will not be
altered by the addition of the new attributes of this document.  This
section describes the extensions needed to implement the new attributes.

3.1  Flow table extensions

The architecture of RTFM has defined the structure of flows, and this
draft does not change that structure.  The flow table could have
ancillary tables called "Distribution Tables" and "Trace Tables," these
would contain rows of values and or actions as defined above.  Each
entry in these tables would be marked with the number of its
corresponding flow in the RTFM flow table.

Note:  The following section is for the user who is familiar with the
writing of rule sets for the RTFM Meter.

    In order to identify the data in a Packet Flow Table, the
    attribute name could be pushed into a string at the head of
    each row.  For example, if a table entry has "To Bit Rate" for
    a particular flow, the "ToBitRate" string would be found at the
    head of the row.  (An alternative method would be to code an
    identification value for each extended attribute and push that
    value into the head of the row.)  See section 4.  for an inital
    set of ten extended flow attributes.

3.2  Specifying Distributions in RuleSets

At first sight it would seem neccessary to add extra features to the
RTFM Meter architecture to support distributions.  This, however, is not
neccessarily the case.

What is actually needed is a way to specify, in a ruleset, the
distribution parameters.  These include the number of counters, the
lower and upper bounds of the distribution, whether it is linear or
logarithmic, and any other details (e.g. the time interval for
short-term rate attributes).

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Any attribute which is distribution-valued needs to be allocated a
RuleAttributeNumber value.  These will be chosen so as to extend the
list already in the RTFM Meter MIB document [RTFM-MIB].

Since distribution attributes are multi-valued it does not make sense to
test them.  This means that a PushPkt (or PushPkttoAct) action must be
executed to add a new value to the distribution.  The old-style
attributes use the 'mask' field to specify which bits of the value are
required, but again, this is not the case for distributions.  Lastly,
the MatchedValue ('value') field of a PushPkt rule is never used.
Overall, therefore, the 'mask' and 'value' fields in the PushPkt rule
are available to specify distribution parameters.

Both these fields are at least six bytes long, the size of a MAC
address.  All we have to do is specify how these bytes should be used!
As a starting point, the following is proposed (bytes are numbered
left-to-right.

Mask bytes:
     1    Transform        1 = linear, 2 = logarithmic
     2    Scale Factor     Power of 10 multiplier for Limits
                               and Counts
   3-4    Lower Limit      Highest value for first bucket
   5-6    Upper Limit      Highest value for last bucket

Value bytes:
     1    Buckets          Number of buckets.  Does not include
                               the 'overflow' bucket
     2    Parameter-1      } Parameter use depends
   3-4    Parameter-2      } on distribution-valued
   5-6    Parameter-3      } attribute

For example, experiments with NeTraMet have used the following
rules:

  FromPacketSize     & 1.0.25!1500 = 60.0!0:   PushPkttoAct, Next;

  ToInterArrivalTime &  2.3.1!1800 = 60.0.0!0: PushPkttoAct, Next;

  FromBitRate        & 2.3.1!10000 = 60.5.0!0: PushPkttoAct, Next;

In these mask and value fields a dot indicates that the preceding number
is a one-byte integer, the exclamation marks indicate that the preceding
number is a two-byte integer, and the last number is two bytes wide
since this was the width of the preceding field.  (Note that this
convention follows that for IP addresses - 130.216 means 130.216.0.0).

The first rule specifies that a distribution of packet sizes is to be
built.  It uses an array of 60 buckets, storing values from 1 to 1500

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bytes (i.e. linear steps of 25 bytes each bucket).  Any packets with
size greater than 1500 will be counted in the 'overflow' bucket, hence
there are 61 counters for the distribution.

The second rule specifies an interarrival-time distribution, using a
logarithmic scale for an array of 60 counters (and an overflow bucket)
for rates from 1 ms to 1.8 s.  Arrival times are measured in
microseconds, hence the scale factor of 3 indicates that the limits are
given in milliseconds.

The third rule specifies a bit-rate distribution, with the rate being
calculated every 5 seconds (parameter 1).  A logarithmic array of 60
counters (and an overflow bucket) are used for rates from 1 kbps to 10
Mbps.  The scale factor of 3 indicates that the limits are given in
thousands of bits per second (rates are measured in bps).

These distribution parameters will need to be stored in the meter so
that they are available for building the distribution.  They will also
need to be read from the meter and saved together with the other flow
data.

3.3  Reading Distributions

Since RTFM flows are bi-directional, each distribution-valued quantity
(e.g. packet size, bit rate, etc.)  will actually need two sets of
counters, one for packets travelling in each direction.  It is tempting
to regard these as components of a single 'distribution,' but in many
cases only one of the two directions will be of interest; it seems
better to keep them in separate distributions.  This is similar to the
old-style counter-valued attributes such as toOctets and fromOctets.

A distribution should be read by a meter reader as a single, structured
object.  The components of a distribution object are

  - 'mask' and 'value' fields from the rule which created the
    distribution

  - sequence of counters ('buckets' + overflow)

These can be easily collected into a BER-encoded octet string, and would
be read and referred to as a 'distribution.'

4  Extensions to the Rules Table, Attribute Numbers

The Rules Table of "old-style" attributes will be extended for the new
flow types.  A list of actions, and keywords, such as "ToBitRate",

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"ToPacketSize", etc.  will be developed and used to inform an RTFM meter
to collect a set of extended values for a particular flow (or set of
flows).

Note.  An implementation suggestion.

    Value 65 is used for 'Distributions,' which has one bit set for
    each distribution-valued attribute present for the flow, using
    bit 0 for attribute 66, bit 1 for attribute 67, etc.

Here are ten possible distribution-valued attributes numbered according
to RTFM WG consensus at the 1997 meeting in Munich:

   ToPacketSize(66)         size of PDUs in bytes (i.e. number
   FromPacketSize(67)         of bytes actually transmitted)

   ToInterarrivalTime(68)   microseconds between successive packets
   FromInterarrivalTime(69)   travelling in the same direction

   ToTurnaroundTime(70)     microseconds between successive packets
   FromTurnaroundTime(71)     travelling in opposite directions

   ToBitRate(72)            short-term flow rate in bits per second
   FromBitRate(73)            Parameter 1 = rate interval in seconds

   ToPDURate(74)            short-term flow rate in PDUs per second
   FromPDURate(75)            Parameter 1 = rate interval in seconds

   (76 .. 97)               other distributions

   It seems reasonable to allocate a further group of numbers
   for the IIS attributes described above -

   QoSService(98)
   QoSStyle(99)
   QoSRate(100)
   QoSSlackTerm(101)
   QoSTokenBucketRate(102)
   QoSTokenBucketSize(103)
   QoSPeakDataRate(104)
   QoSMinPolicedUnit(105)
   QoSMaxPolicedUnit(106)

The following attributes have also been implemented in NetFlowMet, a
version of the RTFM traffic meter -

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   MeterID(112)      Integer identifying the router producing
                        NetFlow data (needed when NetFlowMet takes
                        data from several routers)
   SourceASN(113)    Autonomous System Number for flow's source
   SourcePrefix(114) CIDR width used by router for determining
                        flow's source network
   DestASN(115)      Autonomous System Number for flow's destination
   DestPrefix(116)   CIDR width used by router for determining
                        flow's destination network

Some of the above, e.g. SourceASN and DestASN, might sensibly be
allocated attribute numbers below 64, making them part of the 'base'
RTFM meter attributes.

To support use of the RTFM meter as an 'Edge Device' for implementing
Differentiated Services, and/or for metering traffic carried via such
services, one more attribute will be useful:

   DSCodePoint(118)  DS Code Point (6 bits) for packets in this flow

Since the DS Code Point is a single field within a packet's IP header,
it is not possible to have both Source- and Dest- CodePoint attributes.
Possible uses of DSCodePoint include aggregating flows using the same
Code Points, and separating flows having the same end-point addresses
but using different Code Points.

5  Security Considerations

The attributes considered in this document represent properties of
traffic flows; they do not present any security issues in themselves.
The attributes may, however, be used in measuring the behaviour of
traffic flows, and the collected traffic flow data could be of
considerable value.  Suitable precautions should be taken to keep such
data safe.

6  References

[C-B-P]    Claffy, K., Braun, H-W, Polyzos, G., "A Parameterizable
           Methodology for Internet Traffic Flow Profiling,"
           IEEE Journal on Selected Areas in Communications,
           Vol. 13, No. 8, October 1995.

Handelman, Brownlee, Ruth, Stibler                             [Page 15]


INTERNET-DRAFT              RTFM: New Attributes          September 2000

[GUAR-QOS] Shenker, S., Partridge, C., Guerin, R.: "Specification of
           Guaranteed Quality of Service," RFC 2212, 1997.

[IIS-ACCT] Maiocchi, S: "NeTraMet & NeMaC for IIS Accounting:
           Users' Guide", CEFRIEL, Milan, 5 May 1998.
           (See also http://www.cefriel.it/ntw)

[IIS-RSVP] Wroclawski, J., "The Use of RSVP with IETF Integrated
           Services," RFC 2210, September 1997.

[IPPM-FRM] Paxson, V., Almes, G., Mahdavi, J. and  Mathis, M.,
           "Framework for IP Performance Metrics," RFC 2330, May 1998.

[RMON-MIB] Waldbusser, S., "Remote Network Monitoring Management
           Information Base,"  RFC 1757, February 1995.

[RMON2-MIB] Waldbusser, S., "Remote Network Monitoring Management
           Information Base Version 2 using SMIv2,"
           RFC 2021, January 1997.

[RTFM-ARC] Brownlee, N., Mills, C. and G. Ruth, "Traffic Flow
           Measurement: Architecture", RFC 2063, January 1997.

[RTFM-MIB] Brownlee, N., "Traffic Flow Measurement: Meter MIB",
           RFC 2064, January 1997.

7  Author's Addresses

    Sig Handelman
    IBM Research Division
    T.J. Watson Research Center
    P.O. Box 704
    Yorktown Heights, NY 10598

    Phone: +1 914 784 7626
    E-mail: swhandel@us.ibm.com

    Nevil Brownlee
    Information Technology Systems & Services
    The University of Auckland
    Private Bag 92-019
    Auckland, New Zealand

    Phone: +64 9 373 7599 x8941
    E-mail: n.brownlee@auckland.ac.nz

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INTERNET-DRAFT              RTFM: New Attributes          September 2000

    Greg Ruth
    GTE Internteworking
    3 Van de Graaff Drive
    P.O. Box 3073
    Burlington, MA 01803, U.S.A.

    Phone: +1 781 262 4831
    E-mail: grr1@gte.com

    Stephen Stibler
    IBM Research Division
    T.J. Watson Research Center
    P.O. Box 704
    Yorktown Heights, NY 10598

    Phone: +1 914 784 7191
    E-mail: stibler@us.ibm.com

                                                      Expires March 2000

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