Internet Draft Anwar Siddiqui
Avaya Inc.
Dan Romascanu
Avaya Inc.
Eugene Golovinsky
BMC Software
22 Oct 2002
Real-time Application Quality of Service
Monitoring (RAQMON) Framework
<draft-siddiqui-rmonmib-raqmon-framework-00.txt>
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
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Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
There is a need to extend the RMON framework [RFC2819] to monitor end
devices such as IP phones, pagers, Instant Message Clients, mobile
phones, and PDA devices. This memo proposes an extension of RMON
Framework to allow Real-time Application QoS information of these
types of end devices to be retrieved with SNMP, independent of the
technology used to perform the measurements. An end-to-end user
experience of the quality of service (QoS) and performance for such
an application is a combination of device performance, transport
network performance and specific application context.
The memo also defines a common framework to identify a set of
application QoS parameters and a reporting mechanism using a common
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protocol data unit (PDU) format used between RAQMON Data Source (RDS)
and RAQMON Report Collector (RRC) to report QOS statistics using RTCP
and SNMP as underlying transport protocol.
The original RAQMON draft <draft-siddiqui-rmonmib-raqmon-mib-01.txt>
is split into 3 parts namely RAQMON Framework, RAQMON QOS PDU and
RAQMON MIB. This memo only defines the RAQMON Framework along with
companion drafts <draft-siddiqui-rmonmib-raqmon-mib-02.txt> that
defines a portion of the Management Information Base (MIB) and
<draft-siddiqui-rmonmib-raqmon-pdu-00.txt> that defines RAQMON PDUs.
Distribution of this memo is unlimited.
Table of Contents
Status of this Memo 1
Abstract 1
1 Introduction 2
2 RAQMON Framework Overview 3
3 A Simple Metrics 7
4 RAQMON Framework 13
5 References 22
6 Intellectual Property 24
7 Security Considerations 24
8 IANA Considerations 26
9 Authors' Addresses 26
A Full Copyright Statement 26
1. Introduction
There is a need to extend the RMON framework [RFC2819] to monitor end
devices such as IP Phones, pagers, Instant Message Clients, Cell
Phones, and PDA devices. This memo proposes an extension of RMON
Framework to allow Real-time Application QoS information of these
types of end devices to be retrieved with SNMP, independent of the
technology used to perform the measurements. An end-to-end user
experience of the quality of service (QoS) and performance for such
an application is a combination of device performance, transport
network performance and specific application context.
This memo defines a Real-Time Application QOS Monitoring (RAQMON)
Framework that extends the RMON Framework to allow Real-time
Application QoS information of these types of end devices as outlined
by RAQMON Charter of the RMON Workgroup.
The original RAQMON draft [SIDDIQUI1] is split into 3 parts to
identify the RAQMON Framework, RAQMON QOS PDU and RAQMON MIB.
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The memo [SIDDIQUI2] takes a portion of [SIDDIQUI1] that defined
RAQMON QOS PDU and describes how various PDUs can be transported over
existing Application level transport protocol like the Real Time
Communication protocol (RTCP) and the Simple Network Management
Protocol (SNMP) to transport statistics between RDS and RRC.
The memo [SIDDIQUI3] updates [SIDDIQUI1] that defined the Management
Information Base (MIB) for use with network management protocols in
the Internet community. The document proposes an extension to the
Remote Monitoring MIB [RFC2819] to accommodate RAQMON solution.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. RAQMON Framework Overview
This document continues the architecture created in the RMON MIB
[RFC2819] by providing analysis of application performance as
experienced by end-users on a specific IP end point and correlating
such performance statistics to its underlying transport network
characteristics. This memo is written with following assumptions:
+ All IP end points and applications are producers and consumers of
IP Traffic.
+ The design of the RAQMON QOS PDUs are such that, it can be used by
many Real-Time Applications like Voice over IP, Fax over IP, Video
over IP, IP Short Messaging Services (SMS), Instant Messaging, Email,
chats, ftp/tftp based downloads, e-business style transactions, web
access etc.
+ RAQMON Framework is agnostic to the underlying measurement
methodology used to quantify a PDU parameter.
RAQMON PDUs offer an entry (a.k.a. "Name") to be filled in by
application specific software which with a specific "value". Since
RAQMON PDUs are common data formats commonly understood by RDS and
RRC to exchange RAQMON Statistics (i.e. "Name" and "Value" pair),
measurement methodologies are out of the scope of RAQMON
specification. It is also out of the scope of PDU specification to
validate specific measurement methodology used to gather a "value".
However set of "Name" entries specified in RAQMON PDU in this draft
can be filled in with a "value" using IPPM WG recommended measurement
methodologies.
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+ In order to facilitate complete End-to-End view and to portray end
user experience, the RAQMON Framework SHOULD be able to handle
statistics that relate to:
i. "User, Application, Session" specific parameters - e.g. Instant
Message vs. VoIP
ii. "IP end device" specific parameters during a session (e.g. CPU
Usage)
iii. "Transport network" specific parameter during a session (e.g.
End-to-End Delay, Jitter)
User experience of an application running on a specific IP end point
has lot to do with the type of application an user is running, local
end device resources available as well as the underlying transport
network capabilities.
+ RAQMON "Names" are selectable by the RDS and Application
implementation.
End-to-End QOS view is sensitive to application type, device and
transport network. Though RAQMON PDUs are capable of carrying various
pre-specified parameters but, it is expected that proposed PDUs MUST
provide options to select a sub-set of those parameters from the
metrics definition list, to fit the needs of the application-context.
The Application implementer controlling the RDS will be responsible
for choosing a set of parameters, as "monitoring context" is
application specific.
For example an IP Soft Phone application running on a PC probably be
willing to report "Jitter" to RRC however an Email Application
running on the same host may not use the "Jitter" parameter to report
to RRC as Jitter is deemed to be not so critical for E-mail
Application.
+ List of "Names" used by the RAQMON PDU MUST be extensible to
accommodate application and vendor specific implementations.
+ Monitored statistics is reported by the RAQMON Data Source (RDS) at
will.
Content Parameters, Transmission timing, frequency of RAQMON PDUs
etc. will be completely controlled by the RDSs to provide ease of
administration
Though monitoring is a useful function but there are various
operation scenarios where monitoring could be expensive and degrade
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the QOS of an application. There are also restrictions imposed on
end devices based on the administrative domains. For example, an
Enterprise IP Phone user is managed by the enterprise Telecom
manager, but the Service Level Agreements is monitored by the
Enterprise and ISP IT Managers. In such an environment, IP Phones may
be required to report QOS Problems to various administrative
authorities restricted by the administration domain policy. A RDS
Driven reporting mechanism allows enough flexibility to accommodate
various administrative constraints.
+ Quality of service parameters of each communication session should
be captured and stored "completely".
A communication session may consist of one or more combinations of
transaction-oriented, throughput-oriented, or streaming-oriented
operations. For example, the quality-of-service definition of a Video
over IP call using Video Phones involves:
- Caller Video Phone signaling for call setup that includes a
transaction with a session processing server which locates/connects
the callee using a protocols like SIP, H.323 or MGCP.
- Eventually the video phone source/sinks media streams between two
IP end points using RTP as a result of successful session setup
transaction
In this particular application scenario, the session set up timing is
as critical as the end-to-end delay per packet of media streams. The
RAQMON PDUs should provide a capability to capture such session
specific data.
RAQMON draft would use the following definitions of transactions as
defined in the APM MIB [WALDBUSSER]:
Transaction-Oriented: These transactions have a fairly constant
workload to perform for all transactions. The responsiveness metric
for transaction-oriented applications is application response time,
the elapsed time between the user's request for service (e.g. pushing
the submit button or pressing DTMF in IP Phones) and the completion
of the request (e.g. displaying the results or getting a ring back).
Throughput-Oriented: These transactions have widely varying workloads
based on the amount of data requested. The metric for throughput-
oriented applications are expressed in is Kilobits per second (Kbps)
or Mega bits per second (Mbps).
Streaming-Oriented: These transactions deliver data at a constant
metered rate of speed regardless of excess capacity in the networking
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and computing infrastructure. However, when the infrastructures
cannot deliver data at this speed, interruption of service or
degradation of service can result.
+ A report on a communication session between users should capture
the entire session by keeping records of all the sub-sessions
performed within that session.
A generic communication session between two users can be modeled as
multiple sub-sessions within a communication session. For example a
video call between two users would capture Quality of Service
parameters of a session for Audio, Video and Data separately but
within one compound report as it reflects the true nature of the
communication session. It is easier for an end device to correlate
between these sub-sessions and report the End-to-End QOS parameters
of that session in a compound report.
+ The monitoring functionality must run in real-time during each
communication session and consume very minimal device resources.
Many of the IP end points that runs applications like Voice over IP,
Fax over IP, Video over IP, Short Messaging Services (SMS), Instant
Messaging, Email, chats, ftp/tftp based downloads, e-business style
transactions, web access are embedded devices with resources
constraints.
Monitoring of these devices and applications is performed for all
communication session as QOS of each session is dependent on the time
when monitoring was performed.
+ RAQMON Framework requires a simple, easy to understand and simple
to implement metrics definition.
Metrics definitions need to be simple and intuitive to Application
Service Providers, IT Managers, network operators, equipment vendors
etc.
+ RAQMON Framework design should be embedded device friendly.
The applications covered under the RAQMON Charter have become such a
commodity in our everyday lives that there are lots of simple
embedded smart devices being developed by various vendors at an
enormous rate. Application Service Providers, Network Service
Providers, Enterprise operators, IT Managers etc. have an inherent
need to gather QOS Reports of these devices and applications to
manage there networks and services. It is the objective of this draft
to deliver a simple but easy to deploy monitoring solution.
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+ RAQMON MIB is agnostic to the transport protocol used to carry
RAQMON PDUs between RDS and RRC.
3. A Simple Metrics
The objectives set in the previous section dictates that the RAQMON
framework ought to provide a simple metrics definition. It is an
extremely challenging task to define "appropriate metrics" as metrics
are context-sensitive. However one can also notice that there are
enough commonalities between the various QOS parameters associated to
various applications such that the task of defining a "simple
metrics" is feasible. This document defines a simple metric that in
essence captures the performance and associated quality-of-service
parameters of a communication session. RAQMON framework also provides
a mechanism to add and drop various parameters to this metrics as
defined in Table 1 below to accommodate application context
sensitivity:
1. Data Source Name (DN)
2. Receiver Name (RN)
3. Data Source Address (DA)
4. Receiver Address (RA)
5. Data Source Device Port used
6. Receiver Device Port used
7. Session Setup Date/Time
8. Session Setup delay
9. Session duration
10. Session Setup Status
11. End-to-End Delay
12. Inter Arrival Jitter
13. Total number of Packets Received
14. Total number of Packets Sent
15. Total number of Octets Received
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16. Total number of Octets Sent
17. Cumulative Packet Loss
18. Packet Loss in Fraction
19. Source Payload Type
20. Receiver Payload Type
21. Source Layer 2 Priority
22. Destination Layer 2 Priority
23. Source Layer 3 Priority
24. Destination Layer 3 Priority
25. CPU utilization in Fraction
26. Memory utilization in Fraction
27. Application Name/version
28. RAQMON Optional Flags (ROF)
Table 1: RAQMON Metrics Definition
Various parameters listed in table 1 are defined below. The
definition presented here is meant to provide guidance to
implementers. No claim is made that the definitions presented here
are appropriate for a particular application need.
Data Source Name (DN): The DN item could be of various formats as
needed by the application. Few instances of DN could be but not
restricting to
* "user@host", or "host" if a user name is not available as on
single-user systems. For both formats, "host" is either the fully
qualified domain name of the host from which the payload originates,
formatted according to the rules specified in [RFC1034], [RFC1035]
and Section 2.1 of [RFC1123]; The DN value is expected to remain
constant for the duration of a session. Examples are "big-guy@ip-
phone.bigcompany.com" or "big-guy@135.8.45.178" for a multi-user
system. On a system with no user name, examples would be "ip-
phone4630.bigcompany.com". It is recommended that the standard host's
numeric address not be reported via DN parameter as Data Source
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Address (DA) parameter is used for that purpose.
* Another instance of a DN could a valid E.164 phone number, a SIP
URI or any other form of telephone or pager numbers. It is
recommended that the phone number should be formatted with the plus
sign replacing the international access code. For example, "+88 02
123 45678" for a number in Bangladesh.
It is expected that a Data Source Name (DN) will remain constant
within a communication session.
Receiver Name (RN): Same as Data Source Name (DN).
Data Source Address (DA): Data Source Address (DA) parameter should
be represented as the standard ASCII representation of the host's
numeric address. This could be an IPv4 Address, IPv6 Address, network
address assignments such as the Net-10 assignment proposed in
[RFC1597] or any other form of numeric address represented in ASCII.
It is expected that a Data Source Name (DN) would remain constant
within a communication session.
DN and DA are intended to give the application writers an opportunity
to uniquely identify a record associated to a session. However
application writers should be aware that private network address
assignments such as the Net-10 assignment may create network
addresses that are not globally unique. To handle this case, the
burden is on the application either by converting private addresses
to public addresses if necessary to keep private addresses from being
exposed or by creating an application specific extension.
Receiver Address (RA): Same as Data Source Address
Data Source Device Ports used: This parameter is used to indicate the
port used for a particular session or sub-session used for
communication. Example of port includes TCP Port, UDP Port, RTP Port
etc. It is not expected that a Data Source Device Ports would remain
constant within a communication session.
Receiver Device Ports used: Same as Data Source Device Ports used.
Session Setup Date/Time Indicates the wallclock time when the RAQMON
packet was sent so that it may be used by the RRC to store Date/Time.
Wallclock time (absolute time) is represented using the timestamp
format of the Network Time Protocol (NTP), which is in seconds
relative to 0h UTC on 1 January 1900 [RFC1305].
Session Setup delay: Session setup delay indicates the duration of
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time required by a network communication controller to set a media
path between the communicating entities or the end devices. For
example in VoIP systems a session setup time can be measured as the
last DTMF button pushed to the first ring back tone that indicates
that the far end is ringing. However as these definitions are very
specific to the type of system used and implementation details of
such system, no claim is made about the definition presented here are
appropriate for a particular application need and left upon the
implementers to define.
Session duration: This parameter describes how long a session or a
sub-session lasted.
Session Setup Status: This parameter is intended to report status of
a session in order to support applications those need to display
status in realtime. For example a debugging tool that captures the
status of a call setup as soon as a call is established or a tool
that captures why a session failed or how many RSVP sessions failed
etc.
End-to-End Delay: End-to-End delay is a key parameter for Application
QOS Monitoring. Some applications do not perform well (or at all) if
end-to-end delay between hosts is large relative to some threshold
value. Erratic variation in delay makes it difficult (or impossible)
to support many real-time applications like Voice over IP, Video over
IP, Fax over IP etc.
There are many measurement methodologies available to fill this
parameter but this parameter is intended to capture the End-to-End
delay as observed by the IP devices at the application layer
pertaining to a specific operation environment. While appropriate, it
is recommended that specific application layer delays like play out
delay, packet sequencing delays, coding, decoding delays be added to
transport network delay to report End-to-End delay under RAQMON
Framework.
End-to-End delay of underlying transport network can be measured
using various methodologies as described in [RFC2681], [RFC2679],
[RFC1889] depending on the application needs and left upon the
implementers based on their applications.
Inter-arrival Jitter: Inter-arrival jitter field provides a short-
term measure of congestion. The definition of Jitter is context
sensitive and measurement specific. Measurement of inter-arrival
Jitter is beyond the scope of this document. The jitter measure
indicates congestion before it leads to packet loss. Inter-arrival
jitter of underlying transport network can be measured using various
methodologies and left upon the implementers based on there
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application need. VoIP Systems can readily acquire Inter-arrival
Jitter calculations from RTCP measurements as described in [RFC1889].
Total number of Packets Received: The total number of packets
received by the data source since starting transmission up until the
time this RAQMON packet was generated.
Total number of Packets Sent: Similar to total number of packets
received.
Total number of Octets Received: The total number of payload octets
received in packets by the sender since starting transmission up
until the time this RAQMON packet was generated.
Total number of Octets Sent: Similar to total number of octets
received.
Cumulative Packet Loss: Packet loss tracks persistent congestion
while the jitter measure tracks transient congestion. Since the
interarrival jitter field is only a snapshot of the jitter at the
time of a report, packet loss indicates the network environment as
well as local device losses over time. Packet loss of underlying
transport network can be measured using various methodologies e.g. as
described in [RFC2680], [RFC1889] and local device level packet
losses ought to be captured by the local device specific algorithms.
Measurement methodologies are left upon the implementers based on
their application need.
Packet loss in Fraction: Same as Packets loss but expressed in
percentage
Source Payload Type: Defines payload formats (e.g. media encodings)
as sent by the data source. e.g. ITU G.711-(law, ITU G.729B, H.263,
MPEG-2, ASCII etc. This document follows the same payload type
constants as defined in [RFC1890].
Destination Payload Type: Similar to Source Payload Type.
Source Layer 2 Priority: Many devices use Layer 2 technologies to
prioritize certain type of traffic in the Local Area Network
environment. For example the 1998 Edition of IEEE 802.1D [IEEE802.1D]
"Media Access Control" Bridges contains expedited traffic
capabilities to support transmission of time critical information and
many devices use the standard to mark Ethernet frames according to
IEEE 802.1p standard. Details on these can be found in IEEE 802.1Q
"Virtual Bridged LAN" specifications. 802.1p has been Incorporated
into ISO/IEC 15802-3 1998 [IEEE802.1Q]. Source Layer 2 RAQMON field
indicates Layer 2 values used by the Data Source to prioritize these
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packets in the Local Area Networks environment.
Source Layer 3 Priority: Various Layer 3 technologies are in place to
prioritize certain type of traffic in the internet. For example
traditional IP Precedence [RFC791], Type Of Service (TOS)
[RFC1349],[RFC1812] or more recent technologies like Differentiated
Service [RFC2474][RFC2475] is achieved by using the TOS octet in IPv4
and the Traffic class Octet in IPv6 are used to prioritize traffic.
Source Layer 3 RAQMON field indicates appropriate Layer 3 values used
by the Data Source to prioritize these packets.
Destination Layer 2 Priority: Same as Source Layer 2 Priority.
Destination Layer 3 Priority: Same as Source Layer 3 Priority.
CPU utilization in Fraction: This parameter captures the IP Device
CPU usage rate to indicate current state of the local IP Device
resource which has a very critical implications on QOS implications
of an end device. e.g. x % CPU busy averaged over session duration.
Memory utilization in Fraction: This parameter captures the IP Device
Memory usage rate to indicate current state of the local IP Device
resource which has a very critical implications on QOS implications
of an end device. e.g. y % memory utilized over session duration.
Application Name/version Application Name/version parameter gives the
name and possibly version of the application associated to that
session or sub-session, e.g., "XYZ VoIP Agent 1.2". This information
may be useful for scenarios where end device is running multiple
applications with various priorities and could be very handy for
debugging purposes.
RAQMON Optional Flags (ROF): These flags are open to various vendors
to be used for application specific bit level signaling. For example
RDS can report various numeric status code to RRCs using these bits.
For example, the end devices that support RSVP to setup a
communication session would be successful in acquiring RSVP
reservation in one direction but not the other. A specific 8-bit
failure code can be used to indicate each failure code. One could
also use these bits to indicate RAQMON packet sequence number. These
8-bit Optional Flags are interpreted by the application, not by the
RRC and usage of these left at the application developer's
discretion.
3.1 Measurement Methodology
It is not the intent of this document to recommend a methodology to
measure any of the QOS parameters defined in table 1. Measurement
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algorithms are left upon the implementers and equipment vendors to
choose. There are many different measurement methodologies available
for measuring application performance (e.g., probe-based, client-
based, synthetic-transaction, etc.). This specification does not
mandate a particular methodology - it is open to any that meet the
minimum requirements. Conformance to this specification requires that
the collected data match the semantics described herein.
4. RAQMON Framework
RAQMON framework is based on three entities:
- RAQMON Data Source (RDS)
- RAQMON Report Collector (RRC)
- RAQMON MIB Structure
In addition, the framework contains requirements for a protocol by
which RDS exchange RAQMON information with the RRC. Several proposals
for protocols which can fulfill this role. Few of these options have
been rolled out in this draft to evaluate feasibility of a protocol
between the RDS and RRC.
+----------------------+ +---------------------------+
| IP End Device | | IP End Device >----+ |
|+--------------------+| |+--------------------+ | |
|| APPLICATION || || APPLICATION | | |
|| -Voice over IP <----(1)----> -Voice over IP >- + | |
|| -Instant Messaging|| || -Instant Messaging| | 3 |
|| -Email || || -Email | 2 | |
|+--------------------+| |+--------------------+ | | |
| | | | | |
| | | +------------------+ | | |
+----------------------+ | |RAQMON Data Source|<-+ | |
| | (RDS) |<---+ |
| +------------------+ |
+-----------|---------------+
|
4
|
+----------------------------+
| |
|/ |/
+------------------+ +------------------+ +-------------+
|RAQMON Report | .. |RAQMON Report | |Network Alarm|
|Collector (RRC) #n| |Collector (RRC) #1|<--5-->| Manager |
+------------------+ +------------------+ +-------------+
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Figure 1 - RAQMON Framework.
(1) Communication Session between IP end devices/apps affected by
underlying transport network
(2) Context-Sensitive transport network Specific Metrics
(3) Device State Specific Metrics
(4) RAQMON packets transmitted over this interface (IP Address, port)
(5) RAQMON MIB sent within SNMP notifications.
4.1 RAQMON Data Source (RDS)
RAQMON Data Source is "a source of data for monitoring purposes". This
term is used exactly as defined in the RMON-2 MIB [RFC2021]. In the
RAQMON Framework, RDS is an element that may or may not co-reside on
an IP end point depending on the architecture. However RDS is primarily
responsible for abstracting IP end-devices for the purpose of monitoring.
The RDS gathers the parameters defined in table 1 for a particular
communication session, and forwards them to the RRC. It is envisioned
that the RDS function can be implemented on a (potentially small,
low powered) end device.
Under this framework it is required that an RDS be configured with
the following parameters:
1. The interval in which to send report PDUs
2. The RRC address
3. The encryption/authentication scheme required and its parameters (
if used).
Such configuration can be performed either by administering the devices
manually or statically updating them with some configuration files that
uses web style user interface or by using some distributed protocols
like tftp or DHCP. However it is beyond the scope of this draft to
describe a configuration mechanism.
4.2 RAQMON Report Collector (RRC)
A RAQMON Report Collector (RRC) receives RAQMON statistics from multiple
RDSs, analyzes it, and stores it in RAQMON MIB.
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The RRC is envisioned as a device of some power, providing a storage and
aggregation point for a set of RDSs. A high-level management application
will analyze information retrieved using SNMP from RAQMON MIBs on multiple
RRCs.
4.3 RAQMON Protocol Data Unit
There are 2 types of RAQMON PDUs used by the RDS to report various QOS
parameters to RRC.
BASIC: For reporting monitored data from an RDS to RRC which include QOS
parameters defined in table 1. Application developers have the flexibility
to report a sub-set of these pre-set parameters to RRC appropriate for an
application context.
APP: These APP PDUs can define Application specific information and
provided for further extension required to convey Application specific or
vendor specific parameters for future extension.
4.4 RDS/RRC Network Transport Protocol interface
Network Transport of RAQMON PDUs from RDS to RRC is network and transport
protocol agnostic. Though the choice of network and transport protocol
would have affects on the reliability of these PDUs.
This section describes issues specific to carrying RAQMON packets within
particular network and transport protocols. The following rules apply
unless superseded by protocol-specific definitions outside this
specification.
RAQMON PDUs relies on the underlying protocol(s) to provide a length
indication. The maximum length of the RAQMON data packet is limited only by
the underlying protocols.
If RAQMON PDUs from RDS to RRC are to be carried in an underlying protocol
that provides the abstraction of a continuous octet stream rather than
messages (packets), an encapsulation of the RAQAMON packets must be defined
to provide a framing mechanism. Framing is also needed if the underlying
protocol may contain padding so that the extent of the RAQMON payload
cannot be determined. The framing mechanism is not defined in this
document. Carrying several RAQMON packets in one network or transport
packet reduces header overhead.
The memo [SIDDIQUI2] defines the RAQMON QOS PDU and describes how various
PDUs can be transported over existing Application level transport protocol
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like Real Time Communication protocol (RTCP) and Simple Network Management
Protocol (SNMP) between RDS and RRC.
4.4.1 Design Considerations for the RDS/RRC Network Transport Protocol interface
The Protocol should be:
1. Lightweight - RDSs will be implemented on low powered embedded devices
with limited device resources such as IP Phones, Hand held computing devices,
cellular phones, pagers etc. It is a requirement that the protocol be simple
and flexible.
2. Scalable - Since RRCs need to interact with very large number of RDSs,
it is a requirement that the protocol be highly scalable.
3. Security - Since RAQMON statistics may contain sensitive system
information it is imperative that the protocol provides a strong security
solution.
4. It is recommended that no more than 10% network bandwidth in a
system be used for RDS/RRC reporting. More frequent reports from
an RDS to RRC would imply requirements for higher network bandwidth usage.
5. NAT Friendly - Comply with [RFC3235], so that an RDS could communicate
with an RRC through a Firewall/Network Address Translation device.
6. The protocol may be lossy, as RAQMON deals with getting statistics
rather than billing type critical functionalities.
4.5 Mapping RAQMON PDUs in existing Transport Protocol
Both RTCP and SNMP can be used as an underlying transport protocol to
carry RAQMON PDUs between RDS and RRC. Section 5.4.1 describes a
transport protocol that uses SNMP Inform PDUs and section 5.4.2
borrows heavily from RTCP-like reports to carry RAQMON PDUs.
4.5.1 SNMP Inform PDUs as RDS/RRC Network Transport Protocol
The idea is to re-use SNMP INFORM PDU. This proposal suggest that:
+ RDSs implement the capability of embedding RAQMON information in
SNMP INFORM and thus re-using well-known SNMP mechanisms
to report RAQMON statistics.
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+ To keep the RDS realization simple and keep the protocol lightweight,
the RDSs will not be REQUIRED to respond to SNMP requests like get, set,
etc., as an SNMP compliant responder would.
+ If the RRC chooses to implement an SNMP manager, an SNMP INFORM Response
could be sent for each associated SNMP INFORM originated by the RDS.
+ The RDS may ignore the SNMP INFORM Responses, or, if better
reliability is required, will wait for the Inform response, retransmitting
the original Inform PDU every M seconds until it has been sent N times.
+ The SNMP INFORM transport for RAQMON PDUs can use one of the two
UDP ports assignments:
- Standard UDP port 162 used for SNMP Notifications, if full SNMP
entities implementations are present in the RRC and RDS
- IANA assigned UDP port 5YYYY for RAQMON PDUs carried over SNMP, for the
cases when at least one of the RRC and RDS does not support a
full implementation of the SNMP entities.
The benefits of using SNMP Informs are:
- Using a well-known protocol.
- Privacy and authentication are covered by SNMPv3
- Limited or no need for specific RAQMON-protocol code in the
RRC, as it can use an SNMP manager implementation to process Informs.
The drawback of this approach is the overhead SNMP puts on
low-powered RDSs, for instance - BER encoding.
4.5.2 RTCP like protocol as RDS/RRC Network Transport Protocol
The protocol is comprised of unidirectional exchange of PDUs between RDSs
and an RRC. The protocol data units are mapped to a connectionless
datagram service (UDP).
RRC interface of RTCP based transport need to deal with one simple RDS
Report (i.e. like RTCP reports).
+ During a monitored real-time session, the RDS emits a Report PDU
every M seconds toward the RRC as provisioned by the RDS.
+ Since the PDUs are required to carry "complete" set of information,
the reporting between RDS and RRC is stateless.
Though this is a simple one-way send protocol, the RDSs will not be capable
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of inferring whether a PDU was received by the RRC as Report PDUs are
transmitted over a lossy network.
So one uses proposed RTCP like protocol as RDS/RRC Network Transport
Protocol each Report PDU must contain enough information to uniquely
Identify the PDUs and correlate to an ongoing session. RRCs could use
DSRC field and a unique device ID (i.e. like 6 Octet MAC address or
IP Address) to define a unique session.
However this will cause 6-octet overhead worth wasted bandwidth per
PDU which could result in a significant wasted bandwidth.
4.5.2.1 - Pseudo code for RDS & RRC
RDS:
when (session starts} {
report.identifier = session.endpoints, session.starttime;
report.timestamp = 0;
while (session in progress) {
wait interval;
report.statistics = update statistics;
report.curtimestamp += interval;
if encryption required
report_data = encrypt(report, encrypt parameters);
else
report_data = report;
raqmon_pdu = header, report_data;
send raqmon-pdu;
}
}
RRC:
listen on raqmon port
when ( raqmon_pdu received ) {
decrypt raqmon_pdu.data if needed
if report.identifier in database
if report.current_time_stamp > last update
update session statistics from report.statistics
else
discard report
}
4.5.2.2 Port Assignment
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As specified in the previous sections that Transport of RAQMON PDUs
can be performed using various underlying network transport protocol
like TCP and UDP.
Applications operating under RAQMON Framework may use any unreserved
UDP port. For example, a session management program can allocate the
port randomly. A single fixed port cannot be required because multiple
applications using RAQMON are likely to run on the same host, and
there are some operating systems that do not allow multiple processes
to use the same UDP port with different multicast addresses.
However, port numbers 5XXX have been registered with IANA for use with
those applications that choose to use them as the default port
for RAQMON PDUs over RTCP. Hosts that run multiple applications may use
this port as an indication to have used RAQMON if they are not subject
to the constraint of the previous paragraph.
Applications need not have a default and may require that the port be
explicitly specified. The particular port number was chosen to lie in
the range above 5000 to accommodate port number allocation practice
within the Unix operating system, where privileged processes can only
use port numbers below 1024 and port numbers between 1024 and 5000 are
automatically assigned by the operating systems.
4.5.2.3 Reliability
RAQMON framework will allow an RDS to report QOS Parameters to multiple
RRCs. Such mechanism would allow better chances of backup and restore
QOS parameters. However backup, synchronization of multiple RRCs are
beyond the scope of this document is left to the discretion of system
designers and implementers.
4.6 Report Aggregation and Statistical Data processing
The RAQMON MIB is designed to provide very simple and minimal aggregations
of various RAQMON Parameters defined in table 1. RAQMON MIB is designed to
not to provide extensive aggregations like APM MIB [29] or TPM MIB [30]
and one should use APM and TPM MIBs to aggregate based on protocols (e.g.
Performance of HTTP, RTP) or based on application (e.g. Performance of
VoIP, Video Applications).
In RAQMON Framework, RDSs are not burdened by statistical data processing
as RDSs may be co-resident in end-devices and could be resource constrained.
Various aggregations are performed by the RRC.
Aggregation of RAQMON parameters collected over a period of time is
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dependent on aggregation algorithms. In the RAQMON MIB, aggregation
can be performed only on specific RAQMON metrics parameters specified
below:
End-to-End Delay
Inter Arrival Jitter
Cumulative Packet Loss
Packet Loss in Fraction
CPU utilization in Fraction
Memory utilization in Fraction
The aggregation always results in the following statistics:
Mean End-to-End Delay
Min End-to-End Delay
Max End-to-End Delay
Mean Inter Arrival Jitter
Min Inter Arrival Jitter
Max Inter Arrival Jitter
Mean Cumulative Packet Loss
Min Cumulative Packet Loss
Max Cumulative Packet Loss
Mean Packet Loss in Fraction
Min Packet Loss in Fraction
Max Packet Loss in Fraction
Mean CPU utilization in Fraction
Min CPU utilization in Fraction
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Max CPU utilization in Fraction
Mean Memory utilization in Fraction
Min Memory utilization in Fraction
Max Memory utilization in Fraction
For this document following aggregation definitions are used:
Mean:
Mean is defined as the statistical average of a metric over the duration
of a communication session. For example if End-to-End delay metric of an
end device within a communication session is reported N times by the RDS,
then the Mean End-to-End Delay is the average End-to-End Delay metric over
N entries.
Min:
Min is defined as the statistical minimum of a metric over the duration
of a communication session. For example if End-to-End delay metric of an
end device within a communication session is reported N times by the RDS,
then the Min End-to-End Delay is the minimum of all N End-to-End Delay
metric entries in the table.
Max:
Max is defined as the statistical maximum of a metric over the duration
of a communication session. For example if End-to-End delay metric of an
end device within a communication session is reported N times by the RDS,
then the Max End-to-End Delay is the maximum of all N End-to-End Delay
metric entries in the table.
4.7 Keeping Historical Data and Storage
It is evident from the document that, RAQMON MIB data need to be managed
to optimize storage space. Enormous volume of data gathered in a
communication session could be optimized for storage space by performing
and storing only aggregated RAQMON metrics for history if required.
Such storage space optimization can be performed in following ways:
1. Store data in the MIB only at the end of a communication session
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(i.e. after receiving an END packet), the aggregated data could be stored
in RAQMON MIB as Mean, Max or Min entry and saved for historical purposes.
This will minimize storage space requirement, as instead of a column in a
table, only few scalars will be used to store a metric.
2. A time based algorithms that aggregate data over a specific period of
time within a communication session (i.e. thus requiring less entries) also
reduces storage space requirements. For example, if RDS sends data out every
10 seconds and RRC writes to the RAQMON MIB once every minute, for every 6
data points there will be one MIB entry.
3. Clearing up historical data periodically over a calendar time using
administration policy can perform further storage space optimization.
For example, an administrator could create a policy such that all historical
data get cleared up every 60 days. Such policies are interpreted by the
application, not by the RRC and usage of these policies left at the
application developer's discretion.
5. References
[RFC2819] Waldbusser, S., "Remote Network Monitoring Management
Information Base", STD 59, RFC 2819, May 2000
[RFC1890] H. Schulzrinne, "RTP Profile for Audio and Video Conferences
with Minimal Control" RFC 1890, January 1996.
[RFC1889] Henning Schulzrinne, S. Casner, R. Frederick, and V. Jacobson,
"RTP: A Transport Protocol for Real-Time Applications"
RFC 1889, January 1996.
[RFC1305] Mills, D., "Network Time Protocol Version 3", RFC 1305,
March 1992.
[RFC1034] Mockapetris, P., "Domain Names - Concepts and Facilities",
STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain Names - Implementation and
Specification", STD 13, RFC 1035, November 1987.
[RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791, September 1981.
[RFC1123] Braden, R., "Requirements for Internet Hosts - Application
and Support", STD 3, RFC 1123, October 1989.
[RFC1597] Rekhter, Y., Moskowitz, R., Karrenberg, D., and G. de Groot,
"Address Allocation for Private Internets", RFC 1597, March 1994.
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[RFC2679] G. Almes, S.kalidindi and M.Zekauskas, "A One-way Delay
Metric for IPPM", RFC 2679, September 1999
[RFC2680] G. Almes, S.Kalidindi and M.Zekauskas, "A One-way Packet
Loss Metric for IPPM", RFC 2680, September 1999
[RFC2681] G. Almes, S.kalidindi and M.Zekauskas, "A Round-Trip Delay
Metric for IPPM", RFC 2681, September 1999
[WALDBUSSER] Steven Waldbusser, "Application Performance Measurement MIB",
draft-ietf-rmonmib-apm-mib-04.txt, July 2001
[DIETZ] Russel Dietz, Robert Cole, "Transport Performance Metrics MIB",
draft-ietf-rmonmib-tpm-mib-03.txt, July 2001
[ISO10646] International Standards Organization, "ISO/IEC DIS 10646-1:1993
information technology -- universal multiple-octet coded
character set (UCS) -- part I: Architecture and basic
multilingual plane," 1993.
[UNICODE] The Unicode Consortium, The Unicode Standard New York,
New York:Addison-Wesley, 1991.
[IEEE802.1D] Information technology-Telecommunications and information
exchange between systems--Local and metropolitan area networks-
Common Specification a--Media access control (MAC) bridges:
15802-3: 1998 (ISO/IEC) [ANSI/IEEE Std 802.1D, 1998 Edition]
[RFC1349] P. Almquist, "Type of Service in the Internet Protocol Suite",
RFC 1349, July 1992
[RFC1812] F. Baker, "Requirements for IP Version 4 Routers" RFC1812,
June 1995
[RFC2474] K. Nicholas, S. Blake, F. Baker and D. Black, "Definition of the
Differentiated Services Field (DS Field) in the IPv4 and IPv6
Headers", RFC2474, December 1998
[RFC2475] S. Blake, D. Black, M. Carlson, E.Davies, Z.Wang and W.Weiss,
"An Architecture for Differentiated Services" RFC2475,
December 1998
[SIDDIQUI1] A. Siddiqui, D.Romascanu, E. Golovinsky, and R. Smith,
"Real-time Application Quality of Service Monitoring (RAQMON)
MIB", Internet-Draft, draft-siddiqui-rmonmib-raqmon-mib-01.txt,
February 2002
[SIDDIQUI2] A. Siddiqui, S. Waldbusser, D.Romascanu, and E. Golovinsky,
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"Protocol Data Units for Real-time Application Quality of Service
Monitoring (RAQMON)", Internet-Draft, draft-siddiqui-raqmon-pdu-
00.txt, October 2002
[SIDDIQUI3] A. Siddiqui, D.Romascanu, E. Golovinsky, and R. Smith,
"Real-time Application Quality of Service Monitoring (RAQMON)
MIB", Internet-Draft, draft-siddiqui-rmonmib-raqmon-mib-02.txt,
October 2002
6. Intellectual Property
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
7. Security Considerations
There are a number of management objects defined in this MIB
that have a MAX-ACCESS clause of read-write and/or read-create.
Such objects may be considered sensitive or vulnerable in some
network environments. The support for SET operations in a
non-secure environment without proper protection can have a
negative effect on network operations.
It is thus important to control even GET access to these objects
and possibly to even encrypt the values of these object when
sending them over the network via SNMP. Not all versions of
SNMP provide features for such a secure environment.
SNMPv1 by itself is not a secure environment. Even if the
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network itself is secure (for example by using IPSec), even then,
there is no control as to who on the secure network is allowed
to access and GET/SET (read/change/create/delete) the objects in
this MIB.
It is RECOMMENDED that the implementers consider the security
features as provided by the SNMPv3 framework. Specifically, the
use of the User-based Security Model [RFC2274] and the
View-based Access Control Model [RFC2275] is RECOMMENDED.
It is then a customer/user responsibility to ensure that the SNMP
entity giving access to an instance of this MIB, is properly
configured to give access to the objects only to those
principals (users) that have legitimate rights to indeed GET or
SET (change/create/delete) them.
It is also imperative that the RAQMON framework be able to provide the
following protection mechanisms:
1. Authentication - the RRC should be able to verify that a RAQMON
report was originated by whom ever claims to have sent it.
2. Privacy - RAQMON information include identification of the parties
participating in a communication session. RAQMON framework should be
able to provide protection from eavsdropping, to prevent an
un-authorized third party from gathering potentially sensitive
information. This can be achieved by using various payload encryption
technologies like DES, 3-DES, AES
3. Protection from denial of service attacks directed at the RRC -
RDSs send RAQMON reports as a side effect of an external event (for
example, a phone call is being received). An attacker can try and
overwhelm the RRC (or the network) by initiating a large number of
events (i.e., calls) for the purpose of swamping the RRC with too many
RAQMON PDUs.
To prevent DoS attacks against RRC, the RDS will send the first report
for a session only after the session has been in progress for the TBD
reporting interval. Sessions shorter than that will not be reported.
4. NAT and Firewall Friendly Design: Presence for IP addresses,
TCP/UDP ports information in RAQMON PDUs may be NAT un-friendly. In
such a scenario, where NAT Friendliness is a requirement, the RDS may
opt to not to provide IP Addresses in RAQMON PDU. Another way to avoid
this problem is by using NAT Aware Application Layer Gateways (ALGs)
to fill out IP Addresses in RAQMON PDUs.
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8. IANA Considerations
This memo introduces 2 new ports for IANA registration. This
specification registers port 5YYYY as specified in Section 4.5.1
and Port 5XXX as specified in section 4.5.2.2. at
http://www.iana.org/numbers.html
9. Authors' Addresses
Anwar A. Siddiqui
Avaya Labs
307 Middletown Lincroft Road
Lincroft, New Jersey 07738
USA
Tel: +1 732 852-3200
Fax: +1 732 817-5922
E-mail: anwars@avaya.com
Dan Romascanu
Avaya Inc.
Atidim Technology Park, Bldg. #3
Tel Aviv, 61131
Israel
Tel: +972-3-645-8414
Email: dromasca@avaya.com
Eugene Golovinsky
BMC Software Inc.
2101 CityWest Blvd.
Houston, Texas 77042
USA
Tel: +1 713 918-1816
Email: eugene_golovinsky@bmc.com
A. Full Copyright Statement
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
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developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
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English.
The limited permissions granted above are perpetual and will not be
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This document and the information contained herein is provided on an
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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