Network Working Group A. Fessi
Internet-Draft G. Carle
Expires: September 6, 2007 University of Tuebingen
F. Dressler
University of Erlangen
J. Quittek
NEC
C. Kappler
H. Tschofenig
Siemens AG
March 5, 2007
NSLP for Metering Configuration Signaling
<draft-dressler-nsis-metering-nslp-05.txt>
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Copyright (C) The IETF Trust (2007).
Abstract
Monitoring, metering and accounting of packets are increasingly
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important functionality that needs to be provided in the Internet.
This document proposes the definition of a new NSIS Signaling Layer
Protocol (NSLP), named Metering NSLP (M-NSLP), which allows the
dynamic configuration of Metering Entities on the data path. An
accompanying document [I-D.fessi-nsis-m-nslp-framework] provides a
problem statement, describes scenarios where such a path-coupled
configuration of Metering Entities is useful, elaborates requirements
for a path-coupled protocol for the configuration of Metering
Entities and discusses the applicability of NSIS for this purpose.
This document defines a Metering NSLP protocol design and messages,
and describes the protocol operation.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Model of operation . . . . . . . . . . . . . . . . . . . . 7
3.2. Metering NSLP Messages . . . . . . . . . . . . . . . . . . 9
3.2.1. CONFIGURE . . . . . . . . . . . . . . . . . . . . . . 9
3.2.2. REFRESH . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.3. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . 9
3.2.4. RESPONSE . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.5. NOTIFY . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Design Decisions . . . . . . . . . . . . . . . . . . . . . . . 10
4.1. Soft State . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. Message Sequencing . . . . . . . . . . . . . . . . . . . . 10
4.3. Message Scoping . . . . . . . . . . . . . . . . . . . . . 10
4.4. Selection of MNEs . . . . . . . . . . . . . . . . . . . . 11
4.5. Coordination of Metering Tasks . . . . . . . . . . . . . . 11
4.6. Aggregation . . . . . . . . . . . . . . . . . . . . . . . 11
4.7. Reaction to Route Changes . . . . . . . . . . . . . . . . 11
4.8. Metering Configuration Information . . . . . . . . . . . . 12
4.9. Required State Information . . . . . . . . . . . . . . . . 12
5. Metering NSLP Messages and Objects . . . . . . . . . . . . . . 13
5.1. Metering NSLP Objects . . . . . . . . . . . . . . . . . . 13
5.1.1. The 'Session Identifier' Object (SID) . . . . . . . . 13
5.1.2. The 'Message Sequence Number' Object (MSN) . . . . . . 13
5.1.3. The 'Selection of Metering Entities' Object
(MNE_Selection) . . . . . . . . . . . . . . . . . . . 13
5.1.4. The 'Session Lifetime' Object (Session_LT) . . . . . . 14
5.1.5. The 'MNSLP Hop Count' Object (MNSLP_Hop_Count) . . . . 14
5.1.6. The 'Information Code' Object (INFO) . . . . . . . . . 14
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5.1.7. MSPEC Objects . . . . . . . . . . . . . . . . . . . . 15
5.2. Metering NSLP Messages . . . . . . . . . . . . . . . . . . 15
5.2.1. CONFIGURE . . . . . . . . . . . . . . . . . . . . . . 15
5.2.2. REFRESH . . . . . . . . . . . . . . . . . . . . . . . 15
5.2.3. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . 15
5.2.4. RESPONSE . . . . . . . . . . . . . . . . . . . . . . . 16
5.2.5. NOTIFY . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3. MSPEC Objects . . . . . . . . . . . . . . . . . . . . . . 16
5.3.1. IPFIX MSPEC Object . . . . . . . . . . . . . . . . . . 17
6. Processing Rules . . . . . . . . . . . . . . . . . . . . . . . 18
6.1. Session State Machine . . . . . . . . . . . . . . . . . . 18
6.2. Standard Message Processing Rules . . . . . . . . . . . . 21
6.2.1. Message Parsing . . . . . . . . . . . . . . . . . . . 21
6.2.2. Authentication and Authorization . . . . . . . . . . . 21
6.2.3. Message Sequencing . . . . . . . . . . . . . . . . . . 21
6.2.4. MNSLP Hop Counting . . . . . . . . . . . . . . . . . . 22
6.3. Message Processing Rules . . . . . . . . . . . . . . . . . 23
6.3.1. CONFIGURE . . . . . . . . . . . . . . . . . . . . . . 23
6.3.2. REFRESH . . . . . . . . . . . . . . . . . . . . . . . 24
6.3.3. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . 24
6.3.4. RESPONSE . . . . . . . . . . . . . . . . . . . . . . . 25
6.3.5. NOTIFY . . . . . . . . . . . . . . . . . . . . . . . . 25
6.4. Message Forwarding . . . . . . . . . . . . . . . . . . . . 26
6.5. Interaction with GIST . . . . . . . . . . . . . . . . . . 26
7. Examples of Operation . . . . . . . . . . . . . . . . . . . . 27
7.1. Example with MNE_Selection is ANY . . . . . . . . . . . . 27
7.2. Example with MNE_Selection is ALL . . . . . . . . . . . . 28
7.3. Example with MNE_Selection is FIRST_and_LAST . . . . . . . 29
7.4. Example with a Route Changes . . . . . . . . . . . . . . . 30
8. Bit-Level Formats and Error Messages . . . . . . . . . . . . . 30
8.1. Metering NSLP Messages . . . . . . . . . . . . . . . . . . 30
8.2. Metering NSLP Objects . . . . . . . . . . . . . . . . . . 31
8.2.1. MSN . . . . . . . . . . . . . . . . . . . . . . . . . 32
8.2.2. Session_LT . . . . . . . . . . . . . . . . . . . . . . 32
8.2.3. MNE_Selection . . . . . . . . . . . . . . . . . . . . 32
8.2.4. INFO . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.2.5. MSPEC Objects . . . . . . . . . . . . . . . . . . . . 33
9. Mapping onto M-NSLP Requirements . . . . . . . . . . . . . . . 34
10. Security considerations . . . . . . . . . . . . . . . . . . . 36
11. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 36
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 36
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13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36
13.1. Normative References . . . . . . . . . . . . . . . . . . . 36
13.2. Informative References . . . . . . . . . . . . . . . . . . 37
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38
Intellectual Property and Copyright Statements . . . . . . . . . . 41
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1. Introduction
Monitoring, metering and accounting of packets is an important
functionality in many networks today. Several working groups have
described mechanisms to collect and report usage data for resource
consumption in a network by a particular entity. For example, the
IPFIX WG defines a protocol for this purpose. The PSAMP WG defines a
standard to sample subsets of packets by statistical and other
methods. RADIUS (see [RFC2865] and [RFC2866]) and DIAMETER (see
[RFC3588] and [I-D.ietf-aaa-diameter-cc]) are also protocols which
provide information about consumed resources. The Meter MIB
[RFC2720] is a MIB for collecting flow information.
However, it is also necessary to configure and coordinate the
entities performing the metering. RADIUS, DIAMETER and SNMP are
candidates for this configuration. Nevertheless, these protocols
require some knowledge about the location of the appropriate Metering
Entities to configure them.
In more complex network topologies and architectures, the appropriate
entities to meter the properties of a given data flow can be
discovered dynamically using path-coupled signaling. If more than
one Metering Entity is required, all of them can potentially be
configured and coordinated with a single message along the path.
Scenarios and requirements for Metering NSLP are described in
[I-D.fessi-nsis-m-nslp-framework].
This draft defines the Metering NSLP for configuration and
coordination of Metering Entities in a path-coupled fashion.
2. Terminology
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].
Furthermore, the terminology defined by GIST [I-D.ietf-nsis-ntlp]
applies to this draft.
Moreover, this document uses the following terms:
Metering Record
A Metering Record describes flow characteristics for a particular
flow. Examples of such data are packet counter and time
information.
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Monitoring Probe
A Monitoring Probe is an entity that examines data flows in order
to gather Metering Records.
Metering Entity
A Metering Entity is a node that is equipped with one or more
Monitoring Probes. A Metering Entity MAY process the Metering
Records, e.g. by aggregating them or by sampling them, before they
are exported elsewhere, typically to a Collector. A Metering
Entity MAY host other functions, for example, for processing of
NSIS signaling.
Collector
A Collector receives Metering Records from one or multiple
Metering Entities. These Metering Records can be aggregated
and/or correlated by the Collector. The Collector is typically
not co-located with a Metering Entity. Another protocol (e.g.
IPFIX) is needed to transport the Metering Records from the
Metering Entity to the Collector.
Metering Configuration State
A State used/kept by the Metering Manager to configure the
Monitoring Probe.
Metering Manager
A unit co-located with the Monitoring Probe that communicates with
M-NSLP processing. It holds Metering Configuration State which is
used to configure the Monitoring Probe.
Metering NSIS Entity (MNE)
A Metering Entity which supports the Metering NSLP.
Metering NSIS Initiator (MNI)
The first node in the sequence of MNEs that issues a configuration
message for a flow or aggregate.
Metering NSIS Responder (MNR)
The last node in the sequence of MNEs that receives a
configuration message for a flow or aggregate.
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Metering NSIS Forwarder (MNF)
A MNE that is neither MNI nor MNR.
3. Protocol Overview
The design for the Metering NSLP and the processing of M-NSLP
messages is in some aspects similar to QoS NSLP
[I-D.ietf-nsis-qos-nslp] and in other aspects to the NATFW NSLP
[I-D.ietf-nsis-nslp-natfw]. One of the main differences compared to
the QoS NSLP and the NATFW NSLP is that only a subset (in some cases
even only one) of the Metering Entities in the signaling path will
take part in the actual Metering. This fact has several consequences
on the signaling itself and therefore on the protocol design.
3.1. Model of operation
Figure 1 shows an example logical model of the operation of the
Metering NSLP and the associated metering mechanism in a MNE.
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+---------------+
| Local |
| Management |
+---------------+
^
V
+---------+ +----------+ +----------+
| Policy | | M-NSLP | | Metering |
| Control |<<>>|Processing|<<>>| Manager |
+---------+ +----------+ +----------+
. ^ | V
| ^ . V
| V . V
| V . V
+----------+ V
| GIST | V
.-.-.-.-.-|Processing|-.-.-v.-.-.-.-.-.-.-
. +----------+ V |
| v .
. v |
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
| v |
. v .
| +---------------------+ |
+----------+ | | +-----------+
<-.-| Input | | Monitoring | | Outgoing |-.->
| Packet | | | | Interface |
===>|Processing|===| Probe |====| |==>
+----------+ | | +-----------+
+---------------------+
<.-.-> = signaling flow
=====> = data flow (sender --> receiver)
<<<>>> = control and configuration operations
Figure 1: Metering-NSLP in Metering Entity
The Monitoring Probe collects metering data and processes them into
Metering Records, which can be sent to the Collector. The Monitoring
Probe is co-located with the Input Packet Processing and the Outgoing
Interface.
A M-NSLP message called CONFIGURE transports:
o Control information objects for the M-NSLP Processing, such as
message sequence numbers and whether the MNE should actually take
part in the metering process
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o Metering configuration information objects, also called MSPEC
objects, that describe the actual configuration information. The
MSPEC objects are interpreted by the Metering Manager and SHOULD
be opaque to the M-NSLP Processing.
o Policy information to authenticate and authorize the configuration
request
The M-NSLP Processing decides if the current MNE is addressed by this
configuring message. If yes, the MSPEC objects are extracted from
the M-NSLP message and passed to the Metering Manager, where they are
interpreted and used to install Metering Configuration State. The
Metering Manager uses this state to configure the Monitoring Probe.
The Policy Control determines whether the sender of the M-NSLP
message is authorized to configure the Monitoring Probe.
From the perspective of a single node, the request for configuration
of Metering Entities may result from processing a local management
request, or from processing an incoming M-NSLP message. The local
management may in turn be triggered by a local application, e.g. when
a video is requested from a video server, or by a physically separate
network node.
3.2. Metering NSLP Messages
The Metering NSLP messages are classified into 3 categories:
o request messages
o response messages
o asynchronous notifications
3.2.1. CONFIGURE
CONFIGURE is a M-NSLP request message. It is used to create Metering
Configuration State in a Metering Entity.
3.2.2. REFRESH
REFRESH is a M-NSLP request message. It is used:
o to extend the lifetime of an existing M-NSLP session.
o for terminating a session (with session lifetime zero).
o to detect route changes at the NSLP layer.
3.2.3. OPTIONS
OPTIONS is a M-NSLP request message. It is used to inquire the
metetering capabilities of MNEs along the signaling path.
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3.2.4. RESPONSE
The RESPONSE message is used to provide information about the result
of a previous M-NSLP request. This includes explicit confirmation of
the state manipulation signaled in the CONFIGURE/REFRESH message or
an error code.
3.2.5. NOTIFY
The NOTIFY message is an asynchronous notifications message used to
convey information to a MNE. It differs from RESPONSE messages in
that it is sent asynchronously and does not need to refer to any
particular state or previously received message. The information
conveyed by a NOTIFY message is typically related to error
conditions. An example would be a notification to the MNI about
state being torn down.
4. Design Decisions
4.1. Soft State
NSIS state is always soft state and needs to be refreshed. The
control information in CONFIGURE/REFRESH messages carry an object
that determines the lifetime of a M-NSLP session. The MNI suggests a
lifetime for the session that it is being signaled for. Each MNE
participating in the metering process MAY or MAY not accept the
suggested lifetime or MAY start the metering with a reduced lifetime,
depending on the local policies of the MNEs. This behavior is
similar to the calculation of session lifetime in the NATFW-NSLP
[I-D.ietf-nsis-nslp-natfw].
4.2. Message Sequencing
The order in which M-NSLP requests arrive influences the eventual
configuration state that will be stored at a MNE. Therefore the
M-NSLP supports the detection of message duplication and re-ordering
using a Message Sequence Number (MSN) object. More Details on
Message Sequencing are provided in Section 6.2.3
4.3. Message Scoping
Metering Entities at the edge of a signaling scope (for example, at
the edge of the administrative domain of an ISP) MUST be marked
accordingly. The Metering NSLP does not provide means by itself to
discover dynamically the border of the signaling scope.
When a MNE recognize that it is at the edge of the signaling scope,
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it MUST terminate the signaling and act as NSIS Responder (NR).
4.4. Selection of MNEs
An interesting feature of the Metering NSLP is that only a subset of
MNEs on the data path might take part in the actual metering.
Metering Entities taking part in the metering process are determined
based, for example, on their type or position on the path.
When a CONFIGURE message is sent, each MNE on the data path needs to
determine whether it will take part in the metering process. For
this reason, the 'Selection of Metering Entities' object is included
in CONFIGURE messages.
4.5. Coordination of Metering Tasks
The M-NSLP allocates different metering tasks to different Metering
Entities on the signaling path depending on their position and
metering capabilities. A 'Correlation ID' is included in the MSPEC
and distributed to the Metering Entities during the configuration
process. This 'Correlation ID' can be forwarded to the Collector,
which can correlate Metering Records coming from different Metering
Entities and belonging to the same session/measurement.
4.6. Aggregation
The metering configuration SHOULD allow aggregation of Metering
Records belonging to the same user or application. The information
required for the aggregation must be specified in the MSPEC. Such
aggregation can be done in two ways.
o A Monitoring Probe separately collects and reports data for each
micro flow (e.g., given for all different combinations of port
numbers) contained in the macro flow that is signaled by the NTLP.
o A Monitoring Probe separately collects micro flows but reports all
flows in a single record.
4.7. Reaction to Route Changes
M-NSLP automatically adapts to re-routing events. State along the
old path times out automatically. When a new REFRESH message is
initiated by the MNI and hits a MNE that is a new on the signaling
path, the MNE sends a negative RESPONSE with error code "Unknown
Session" backwards to the MNI. The MNI MAY re-initiate the signaling
along the new path.
Since metering tasks are allocated dynamically to MNEs on the path,
when a MNE receives a CONFIGURE message for an existing session, old
state for this session MUST be torn down and a new session is created
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in order to avoid inconsistencies with an old configuration.
4.8. Metering Configuration Information
The actual configuration information for the Metering Entities is
carried within the MSPEC objects. MSPEC objects are interpreted by
the Metering Manager and SHOULD be opaque to M-NSLP Processing. Each
MSPEC object contains a meter configuration. A single CONFIGURE
message MAY contain multiple MSPEC objects describing different
metering tasks, which MAY be allocated to different MNEs.
The Metering NSLP does not provide its own format for encoding the
MSPEC objects. Instead, formats of existing protocols, such as IPFIX
[I-D.ietf-ipfix-protocol], Diameter [RFC3588], or NetFlow [RFC3954],
are re-used. The encoding of an MSPEC object depends on the metering
and reporting technology. For example, the MSPEC object used for the
configuration of an IPFIX device is encoded in IPFIX format.
Technology-specific encoding avoids the problems of mapping the
different semantics of information models for these technologies to
each other.
4.9. Required State Information
For each M-NSLP session, the required state information at each MNE
consists of:
NTLP state
NTLP state is required for each M-NSLP session at each MNE on the
signaling path, even if the MNE is not taking part in the metering
process, in order to avoid GIST re-discovering the MNE each time
when it refreshes its routing state [I-D.ietf-nsis-ntlp].
M-NSLP state
M-NSLP state is required for each M-NSLP session at each MNE on
the signaling path. Even if the MNE is not taking part in the
metering process a minimal session state is required, which
consists of the Session Identifier (SID) and the Session Lifetime
(Session_LT).
Assume MNEs located on the signaling path, which are not taking
part in the metering process, would not save M-NSLP state for this
M-NSLP session. Then when a MNE receives a REFRESH message with
an unknown Session ID, it would not be able to make the
difference:
* whether the MNE is new on the signaling path due to a route
change
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* or whether the MNE has been already on the signaling path but
is not taking part in the metering process.
Therefore, the MNE needs to keep M-NSLP state for this session in
order to be aware of it. Implementations of the M-NSLP MAY
include optimizations to reduce the amount of memory required if
the session is known but the MNE is not taking part in the
metering process.
Metering Configuration State (Optional)
Metering Configuration State is required for each M-NSLP only if
the MNE is taking part in the metering process. It includes the
MSPEC objects which describe the metering tasks that are allocated
to the MNE.
5. Metering NSLP Messages and Objects
5.1. Metering NSLP Objects
5.1.1. The 'Session Identifier' Object (SID)
SID is globally statistically unique identifier for a MNSLP session.
SID is not carried explicitly by MNSLP messages. It is rather
carried by GIST.
SID MUST be generated for each new MNSLP session by the MNI and
provided to GIST via the GIST API. All MNFs and the MNR receive the
SID via the GIST API and MUST NOT modify it.
Note that this is conform to the specification of GIST
[I-D.ietf-nsis-ntlp]: Section 3.5. (Signaling Sessions): "Signaling
applications provide the session identifier (SID) whenever they wish
to send a message, and GIST reports the SID when a message is
received."
5.1.2. The 'Message Sequence Number' Object (MSN)
MSN is used to detect duplicate and lost Metering NSLP messages. It
is also used to to mach an incoming RESPONSE message to the
appropriate request.
5.1.3. The 'Selection of Metering Entities' Object (MNE_Selection)
This object is required to determine which MNEs will actually take
part in the metering. The value of MNE_Selection can be one of the
following:
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o FIRST: the first MNE in the signaling path, i.e. the NI.
o LAST: the last MNE signaling in the signaling path, i.e. the NR
o 'FIRST_and_LAST': both the NI and the NR take part in the
signaling.
o ANY: any available MNE can perform the metering.
o ALL: Each MNE capable of executing this metering request MUST
perform it. "ALL" must be interpreted here as "as many as
possible".
o Enterprise-specific: Enterprises may wish to define their own
methods to decide which Metering Entities should perform the
metering. In this case, the parameter 'Selection of Metering
Entities' needs to be combined with an enterprise-specific
identifier. (See also
http://www.iana.org/assignments/enterprise-numbers) If enterprises
use their own defined methods for the MNE selection, some other
M-NSLP objects not defined in this document may be required to
take the decision which MNE will take part in the metering
process.
5.1.4. The 'Session Lifetime' Object (Session_LT)
This object carries the requested lifetime for a M-NSLP session in a
CONFIGURE / REFRESH message or the granted session lifetime in a
RESPONSE message, in milliseconds. When a M-NSLP session expires,
the Metering Manager MUST configure the Monitoring Probe to stop the
Metering.
A value of zero for the 'Session Lifetime' object leads to immediate
termination of the corresponding session.
5.1.5. The 'MNSLP Hop Count' Object (MNSLP_Hop_Count)
This object carries the number of previous MNEs on the signaling path
for this session. This object is a integer which starts by zero at
the MNI and MUST be incremented by one at each MNSLP hop on the
signaling path.
5.1.6. The 'Information Code' Object (INFO)
This object carries the response code, which may be an indication for
either a successful or failed request depending on the value of the
'response code' field (See Section 8.2.4 for more details).
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5.1.7. MSPEC Objects
The MSPEC objects describe the actual Configuration information.
They are interpreted in the Metering Manager and SHOULD be opaque to
M-NSLP Processing. MSPEC objects are described separately in
Section 5.3.
5.2. Metering NSLP Messages
This section defines which objects are carried in each Metering NSLP
message. The description is provided in Augmented Backus-Naur Form
(ABNF) specified in [RFC4234]. Message format at the bit-level is
provided in Section 8
The ABNF implies an order for the objects in a message. However, in
many (but not all) cases, object order makes no logical difference.
An implementation should create messages with the objects in the
order shown here, but accept the objects in any order, except for
MSPEC object(s) which always appear last in the message, and whose
mutual order matters.
All M-NSLP messages start with a common header 'HEADER' which is
defined in Section 8
Note that the Session ID (SID) is not explicitly mentioned in this
notation, since it is provided in GIST.
5.2.1. CONFIGURE
The format of a CONFIGURE message is as follows:
CONFIGURE = HEADER MSN Session_LT MNE_Selection [MNSLP_Hop_Count]
<1>*MSPEC
(According to [RFC4234] '<1>*MSPEC' means 'one or more MSPEC
objects')
5.2.2. REFRESH
The format of a REFRESH message is as follows:
REFRESH = HEADER MSN Session_LT
5.2.3. OPTIONS
The format of a OPTIONS message is as follows:
OPTIONS = HEADER MSN
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5.2.4. RESPONSE
The format of a RESPONSE message is as follows:
RESPONSE = HEADER MSN INFO Session_LT <0>*MSPEC
(According to [RFC4234] '<0>*MSPEC' means 'zero or more MSPEC
objects')
The MSN MUST be the same as in the corresponding M-NSLP request in
order to match a RESPONSE message to the appropriate request
Session_LT carries the granted session lifetime, which might be lower
than the session lifetime requested by the MNI.
NO MSPEC object MUST be included if INFO indicates a successful
confirmation of the request. The MSPEC objects are required only to
report a failure in case the MSPEC objects list in the CONFIGURE
message, or a sub-set of it, can not be processed.
5.2.5. NOTIFY
The format of a NOTIFY message is as follow:
NOTIFY = HEADER INFO
The INFO indicates the reason for the notification.
5.3. MSPEC Objects
As mentioned above, the MSPEC objects describe the actual
configuration information. They are interpreted in the Metering
Manager and SHOULD be opaque to M-NSLP Processing. Each MSPEC object
contains a meter configuration. The MRI provides additional
information to the MSPEC object on the flows/packets to be metered.
The combination of the MRI and an MSPEC object contains a complete
description of a requested metering task. A single CONFIGURE message
may contain multiple MSPEC objects describing different metering
tasks.
There is no common format or semantics for encoding metering tasks
within an MSPEC object. The encoding of an MSPEC object depends on
the requested metering and reporting technology, such as IPFIX,
Diameter, or NetFlow.
There are different types of MSPEC objects depending on the metering
and reporting technology. For example, there are IPFIX MSPEC
objects, Diamter MSPEC objects, etc. The object type, which is
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provided in the object header as described in Section 8.2, implicits
the requested metering and reporting technology.
Independently of the encoding, each MSPEC object MUST, in combination
with the MRI, contain sufficient information for configuring an MNE
to peform a metering task. Specifications of MSPEC objects MUST
ensure that they provide sufficient means for configuring the MNE as
described in sections 4.1.2 and 4.2.2 of
[I-D.fessi-nsis-m-nslp-framework].
Below the MSPEC object for IPFIX metering tasks is specified. MSPEC
objects for other meters may be defined in further standards
documents. Proprietary MSPEC objects MAY be also used.
5.3.1. IPFIX MSPEC Object
The IPFIX MSPEC object uses structure, semantics and encoding of
IPFIX Messages as defined in [I-D.ietf-ipfix-protocol] and
[I-D.ietf-ipfix-info]. An IPFIX MSPEC object consists of a single
IPFIX Message that contains three Sets, a Template Set, an Option
Template Set, and a Data Set. Each set contains a single record only.
Fields of the header of the contained IPFIX Message are filled with
values according to section 3.1 of [I-D.ietf-ipfix-protocol] except
for fields "Export Time" and "Observation Domain ID" which must be
both set to 0x00000000.
The Template Record in the Template Set defines the requested
reporting. Except for the Template ID in the Template Record Header,
the MNE MUST use exactly this Template Record for reporting metering
results. The MNE also MUST use the Template ID received in the
Template record for its metering reports. But if there is a
collision caused by two different MSPEC objects (potentially from
different NSIS sessions) that would violate the uniqueness of
Template IDs as specified in section 3.4.1 of
[I-D.ietf-ipfix-protocol], then the MNE MUST solve this conflict by
modifying Template IDs. In order to keep the probability of such a
collision low, the Template ID SHOULD be a randomly generated number.
The Option Template Record in the Option Template Set describes the
format of the single Data Record in the Data Set. To the Template ID
the same rules apply as for the Template Record. The Scope Field
Count is always 0.
The Data Record in the Data Set contains the requested metering
configuration. It is structured according to the Option Template
Record in the Option Template Set. It MUST contain the following
Information Elements that are specified in [I-D.ietf-ipfix-info].
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flowKeyIndicator
This Information Element identifies which of the reported Flow
properties are Flow Keys.
collectorIPv4Address or collectorIPv6Address, respectively
The IPv4 or IPv6 address, respectively, to which metering results
are requested to be reported.
collectorProtocolVersion
The version of the IPFIX protocol to be used.
collectorTransportProtocol and collectorTransportPort
The transport protocol and transport port number to be used for
reporting metering results
The Data record MAY contain further Information Elements for
specifying the metering task, for example, the flowIdleTimeout.
If flow properties to be measured are specified in the Data record,
they serve as filter. Only Flows that match the values of all these
Information Element MUST be reported by the MNE. If multiple values
are contained for the same property, i.e. it multiple Information
Elements with the same Information Element identifier are contained,
then it is sufficient if one of these values is matched by a Flow.
6. Processing Rules
6.1. Session State Machine
The hereby presented state machine of a M-NSLP session outlines the
operation of the M-NSLP. It has three main states:
'closed':
At this state, the MNE does not keep any state for the session.
'pending':
At this state a CONFIGURE message has been received. The
'pending' state consists of 2 sub-states
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pending.forward
The MNE is not taking part in the metering process. Instead,
it is just expecting a confirmation to know that the session is
active and some other MNEs will be metering.
pending.participating
The MNE is actively taking part in the metering process. The
MNE has been configured. However, the configuration has not
been activated yet, i.e. metering function has not been
started.
'metering':
At this state the configuration request has been successfully
confirmed with an appropriate RESPONSE message. The 'metering'
state consists also of 2 sub-states.
metering.forward
The MNE is not actively taking part in the metering process.
Instead, it is informed that the session is active and there
are some other MNEs along the signaling path for this session
that took over the metering process.
metering.participating
The MNE is actively taking part in the metering process The MNE
is metering according to a metering configuration received by a
CONFIGURE message.
A session is uniquely identified by the SID. All sessions start in
state 'closed'. Transitions between states are caused by events:
CONF:
This transition is triggered by a CONFIGURE message that is
received and processed successfully by the MNE and that identifies
a new session.
CONF-O:
This transition is triggered by a CONFIGURE message that is
received and processed successfully by the MNE and that identifies
an existing session in state 'pending' or 'metering'. This
transition leads always to the state 'closed' in order to avoid
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inconsistencies with old configurations. Furthermore, this
transition MUST be immediately followed by a 'CONF' transition,
i.e. after the old session is torn down, a new session is created.
REFR:
This transition is triggered by a REFRESH message that identifies
an existing session in state 'pending' or 'metering'.
RESP-P:
This transition is triggered by a positive RESPONSE message that
indicates that a metering configuration request or a refreshing
request can be activated. This transaction always leads to state
'metering'.
RESP-N:
This transition is triggered by a negative RESPONSE message. This
transaction always leads to state 'closed'.
T-OUT-1:
This transition is triggered by a timeout of a session in state
'pending'. The time interval for this timeout is typically large
enough in order to tolerate network failures, network congestion
and slow MNEs along the signaling path. This transition always
leads to state 'closed'.
T-OUT-2:
This transition is triggered by a timeout of a session in state
'metering'. The time interval for this timeout is defined by the
MNSLP session lifetime. This transition always leads to state
'closed'.
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REFR +----+
| v
+----------+
| session |
| closed |<---------------+
+----------+ |
| ^ |
| | CONF-O | CONF-O
CONF | | RESP-N | RESP-N
v | T-OUT-1 | T-OUT-2
+----------+ +----------+
| pending | RESP-P | metering |
| |---------->| |
+----------+ +----------+
| ^ | ^
REFR | | REFR | |
+----+ RESP-P +----+
Figure 2: M-NSLP Session State Machine
6.2. Standard Message Processing Rules
6.2.1. Message Parsing
When a M-NSLP message is received, the MNE first checks the message
format. In case of a malformed message or a mandatory object is
missing, the MNE MUST NOT propagate the message any further. If the
message has been a request the MNE MUST construct an RESPONSE message
indicating the error condition and send it back to towards the MNI.
If it has been a response, the message is discarded silently.
If a message contains an object of an unrecognized type, then the
behavior depends on the object type value.
6.2.2. Authentication and Authorization
When a M-NSLP message is received, the MNE MUST determine whether the
sender of the request is authenticated and authorized before any
state changing actions are performed.
6.2.3. Message Sequencing
Message sequencing in the Metering NSLP is identical to message
sequencing in the NATFW NSLP.
In more details:
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M-NSLP messages need to carry an identifier so that all MNEs along
the path can distinguish messages sent at different points in time.
Messages can be lost along the path or duplicated. So all MNEs
should be able to identify either old messages that have been
received before (duplicated), or the case that messages have been
lost before (loss). This requires every Metering message to carry a
message sequence number (MSN), see also Section 5.1.2.
The MSN MUST be set by the NI and MUST NOT be set or modified by any
other MNE. The initial value for the MSN MUST be generated randomly
and MUST be unique only within the session for which it is used. The
NI MUST increment the MSN by one for every message sent. Once the
MSN has reached the maximum value, the next value it takes is zero.
All MNEs MUST use the algorithm defined in [RFC1982] to detect MSN
wrap-arounds.
NSIS forwarders and the responder store the MSN from the initial
CONFIGURE packet which creates the session as the start value for the
session. NFs and NRs MUST include the received MSN value in the
corresponding RESPONSE message that they generate.
When receiving a request message, a MNE uses the MSN given in the
message to determine whether the state being requested is different
to the state already installed. If the received MSN value is equal
to or lower than the stored MSN value, this can indicate a duplicated
or replayed message. In this case, the message MUST NOT have any
impact the state of the MNE or the MNSLP session. However, the
message MUST be forwarded towards the next MNSLP hop, since one or
more of the MNEs on the rest of the signaling path may have not
received this message yet.
If the received MSN value is greater than the already stored MSN
value, the MNE MUST update its stored state accordingly, if permitted
by all security checks, and stores the updated MSN value accordingly.
6.2.4. MNSLP Hop Counting
Depending on the application scenario for the MNSLP, MNEs may need to
know their position on the signaling path. In this case, a MNE needs
to make the difference between:
o the number of IP hops between the MNI and itself
o the number of GIST hops between the MNI and itself
o the number of MNSLP hops between the MNI and itself
The GIST-hop-count and IP-TTL can be provided by the GIST API as
described in [I-D.ietf-nsis-ntlp] (Section B.1 and Section B.2).
The MNI MAY introduce an 'MNSLP Hop Count' object in the CONFIGURE
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message. In cases it does, it MUST set the 'MNSLP Hop Count' to
zero.
If a 'MNSLP Hop Count' object is included in a CONFIGURE message,
MNFs and MNRs MUST increment the 'MNSLP Hop Count' by one before the
message is forwarded to the next MNSLP hop.
6.3. Message Processing Rules
6.3.1. CONFIGURE
When a MNE receives a CONFIGURE message, and after successful message
parsing and authentication/authorization are performed, the MNE
performs a lookup in its M-NSLP session table. If the session
already exists, the state for this session MUST be torn down and a
new session MUST be created in order to avoid inconsistencies with
earlier configurations due to the dynamic allocation of the MSPEC
objects to the MNEs.
Now, regardless of whether the session is new or has been renewed,
the MNE needs to figure out if it will take part in the metering
process based on the MNE_Selection object, the MSPEC objects list and
the capabilities of the MNE.
6.3.1.1. MNE_Selection is ALL
o If the MNE is capable of metering the objects in the MSPEC objects
list, then the MNE is taking part in the metering process. The
MNE MUST change the current session state to
'pending.participating'.
o If the MNE is NOT capable of metering the objects in the MSPEC
objects list, then the MNE is NOT taking part in the metering
process. The MNE MUST change the current session state to
'pending.forward'
6.3.1.2. MNE_Selection is FIRST_and_LAST
If MNE_Selection is FIRST_and_LAST and the MNE is the first or the
last on the signaling path:
o If the MNE is capable of metering the objects in the MSPEC objects
list, then the MNE is taking part in the metering process. The
MNE MUST change the current session state to
'pending.participating'.
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o If MSPEC objects can not be metered, i.e. the MNE is the first or
the last on the signaling path but is not capable to measure the
objects given in the MSPEC objects list, the MNE generates a
negative RESPONSE message with the appropriate INFO object. The
MNE changes the current session state to 'closed'.
o EDITORIAL NOTE: The case FIRST_and_LAST is different from the
cases ALL and ANY here.
If MNE_Selection is FIRST_and_LAST and the MNE is NOT the first NOR
the last on the signaling path, the MNE MUST change the current
session state to 'pending.forward'.
6.3.1.3. MNE_Selection is ANY
In case MNE_Selection is 'ANY', the MNE inspects the MSPEC objects
list and removes those objects that it is capable to meter and adds
them to its local MSPEC objects list for this session. This local
MSPEC objects list represents the list of metering tasks allocated to
this MNE for this session.
o After inspecting the MSPEC objects list in the CONFIGURE message,
if the local MSPEC objects list is empty, i.e. the MNE is not able
to meter any of the given objects in the MSPEC objects list, the
MNE MUST change the current session state to 'pending.forward'.
o If the local MSPEC objects list is NOT empty, i.e. the MNE has
been allocated some metering tasks from the MSPEC objects list,
the MNE MUST change the current session state to
'pending.participating'. The local MSPEC objects is stored in the
Metering Configuration State in order to use when the
configuration will be activated.
6.3.2. REFRESH
When a MNE receives a REFRESH message, and after successful message
parsing and authentication/authorization are performed, the MNE
performs a lookup in its M-NSLP session table.
o If the Session ID is not known, the MNE constructs a negative
RESPONSE message with the appropriate error code and sends it
upstream towards the MNI.
o If the Session ID is found, the MNE remembers the requested
lifetime in the REFRESH message and waits for a confirmation with
a RESPONSE message. The current session state remains the same.
6.3.3. OPTIONS
tbd.
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6.3.4. RESPONSE
When a MNE receives a RESPONSE message and after successful message
parsing and authentication/authorization are performed, the remaining
processing of the RESPONSE message depends on whether it is a
negative RESPONSE or a positive RESPONSE. If it is a negative
RESPONSE with the appropriate INFO object:
o The MNE MUST change the current state for this session to
'closed'.
o The MNE MAY keep state information for this session for
optimization purposes, since the the MNI may re-initiate the
signaling with different parameters soon.
o The MNE MUST forward the message upstream towards the MNI as
described in Section 6.4.
When the MNI receives this message it MAY take the appropriate action
based on the content of the INFO object.
If the RESPONSE message is a positive RESONSE, the processing of the
message depends on the type of the corresponding M-NSLP request:
RESPONSE to a CONFIGURE message
The pending configuration can be activated. If the session is
currently in state 'pending.participating' the MNE MUST change the
session state to 'metering.participating', and the Monitoring
Probe MUST be configured to start the metering.
If the session is in state 'pending.forward' the MNE MUST change
the session state to 'metering.forward'. No configuration action
with the Monitoring Probe is taken.
RESPONSE to a REFRESH message
All existing timeouts for this session are reset. The session
lifetime is extended with the lifetime given in the RESPONSE
message. Note that this can be different from the session
lifetime given in the previous REFRESH message.
In both cases, the MNE updates the session lifetime. If the session
lifetime is zero, this implies that the session state is changed
immediately to 'closed'.
6.3.5. NOTIFY
tbd.
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6.4. Message Forwarding
CONFIGURE / REFRESH
After a M-NSLP request is successfully processed as described in
Section 6.3 (no error has been generated), then the session can be
either in state 'pending' or 'metering'. Now, MNE needs to decide
whether to forward the M-NSLP request towards the MNR or to
construct a positive RESPONSE message. M-NSLP requests MUST be
forwarded downstream except if:
* the M-NSLP request has reached the MNR
* the 'scoping' flag is set and the signaling scope has been
reached.
* all the involved MNEs in the metering process for this session
have been reached.
The latter case can occur with a CONFIGURE request if
MNE_Selection is 'ANY' and the MSPEC objects list has become
empty, i.e. an appropriate MNE has been already found for each
object in the MSPEC objects list and all the metering tasks have
been allocated to some Metering Entities.
EDITORIAL NOTE: it has to verified whether this is the only case.
In this case, the MNE MUST act as a MNR for this session from now
on. All the remaining requests MUST NOT be forwarded any further.
RESPONSE / NOTIFY
M-NSLP response messages and asynchronous notifications are
forwarded upstream, i.e. the reverse direction of the data flow,
until they reach the MNI.
6.5. Interaction with GIST
M-NSLP request messages (CONFIGURE or REFRESH) are initiated by the
MNI and forwarded downstream, i.e. in the same direction as the data
flow, towards the MNR, using the GIST API.
M-NSLP response messages can be initiated by the MNR or by any MNF on
the signaling path and forwarded upstream, i.e. in the reverse
direction as the data flow, towards the MNI, using the GIST API.
M-NSLP asynchronous notifications can be initiated by any MNE on the
signaling path and forwarded upstream, i.e. in the reverse direction
as the data flow, towards the MNI, using the GIST API.
All M-NSLP signaling is transported using GIST C-mode.
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EDITORIAL NOTE: it should be verified whether D-mode might be also an
option for initial configuration messages. However, authentication/
authorization issues need to be considered.
7. Examples of Operation
7.1. Example with MNE_Selection is ANY
The MNI constructs a CONFIGURE message with the required MSPEC
objects, and sends it towards the MNR. Assume 2 MSPEC objects are
included, for example, MSPEC1 for 'counting bytes', and MSPEC2 for
'reporting the usage of the wireless link'. Assume further that MNI
itself can perform MSPEC1 while and MNF2 can perform MSPEC2, for
example, because it is an access router managing a range of WLAN
networks. MNR can be, for example, the WLAN access point.
The CONFIGURE message is interpreted by the MNEs along the data path.
MNI removes MSPEC1 from the MSPEC objects list, changes its session
state from 'closed' to 'pending.participating' and forwards the
CONFIGURE message to MNF1.
MNF1 receives the CONFIGURE message with only MSPEC2 in the MSPEC
objects list. However, MNF1 does not have the capabilities to meter
and report the usage of the wireless link. MNF1 changes its session
state from 'closed' to 'pending.forward' and forwards the CONFIGURE
message to MNF2.
MNF2 interprets the CONFIGURE, removes MSPEC2 from the MSPEC objects
list. Furthermore, it notices that the MSPEC object lists is now
empty. Therefore, MNF2 replies with a positive RESPONSE message and
becomes Responder for this session. Subsequent signaling for this
session is stopped at MNF2 as shown in Figure 4. MNF2 starts the
metering, changes the session state to 'metering.participating',
constructs a positive RESPONSE message and sends it to MN1.
MNF1 receives the RESPONSE message and changes the session state to
'metering.forward'.
MNI receives the RESPONSE message, starts the metering and changes
the session state to 'metering.participating'.
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+---+ CONFIGURE +--- + CONFIGURE +-- -+ +---+
| |------------>| |------------>| | | |
|MNI| |MNF1| |MNF2| |MNR|
| |<------------| |<------------| | | |
+---+ RESPONSE +--- + RESPONSE +----+ +---+
Figure 3: CONFIGURE-RESPONSE Message Flow with MNE_Selection 'ANY'
+---+ REFRESH +---+ REFRESH +---+ +---+
| |------------>| |------------>| | | |
|MNI| |MNF| |MNF| |MNR|
| |<------------| |<------------| | | |
+---+ RESPONSE +---+ RESPONSE +---+ +---+
Figure 4: REFRESH-RESPONSE Message Flow with MNE_Selection 'ANY'
7.2. Example with MNE_Selection is ALL
The MNI constructs a CONFIGURE message with the required MSPEC
objects, and sends it towards the MNR. The message is interpreted by
each MNEs on the data path. Each MNE changes its state for this
session to 'pending.participating' or 'pending.forward' depending on
whether they are taking part of the metering process.
The MNR replies with a positive RESPONSE message. The RESPONSE
message is interpreted by each MNE. Each MNE changes the session
state to 'metering.participating' or 'metering.forward' depending on
whether they are taking part of the metering process.
+---+ CONFIGURE +---+ CONFIGURE +---+ CONFIGURE +---+
| |------------>| |------------>| |------------>| |
|MNI| |MNF| |MNF| |MNR|
| |<------------| |<------------| |<------------| |
+---+ RESPONSE +---+ RESPONSE +---+ RESPONSE +---+
Figure 5: CONFIGURE-RESPONSE Message Flow with MNE_Selection 'ALL'
Similarly, a REFRESH message is initiated by MNI, travels towards the
MNR where a RESPONSE is issued and sent back.
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+---+ REFRESH +---+ REFRESH +---+ REFRESH +---+
| |------------>| |------------>| |------------>| |
|MNI| |MNF| |MNF| |MNR|
| |<------------| |<------------| |<------------| |
+---+ RESPONSE +---+ RESPONSE +---+ RESPONSE +---+
Figure 6: REFRESH-RESPONSE Message Flow with MNE_Selection 'ALL'
7.3. Example with MNE_Selection is FIRST_and_LAST
The MNI constructs a CONFIGURE message with the required MSPEC
objects, and sends it towards the MNR. The message is interpreted by
each MNEs on the data path. Each MNE changes its state for this
session to 'pending.forward' except MNI itself and MNR, which perform
a transition to the state 'pending.participating'.
The MNR replies with a positive RESPONSE message. The RESPONSE
message is interpreted by each MNE. Each MNE changes the session
state to 'metering.forward' except MNR and MNI, which perform a
transition to the state 'metering.participating'.
+---+ CONFIGURE +---+ CONFIGURE +---+ CONFIGURE +---+
| |------------>| |------------>| |------------>| |
|MNI| |MNF| |MNF| |MNR|
| |<------------| |<------------| |<------------| |
+---+ RESPONSE +---+ RESPONSE +---+ RESPONSE +---+
Figure 7: CONFIGURE-RESPONSE Message Flow with MNE_Selection
'FIRST_and_LAST'
Similarly, a REFRESH message is initiated by MNI, travels towards the
MNR where a RESPONSE is issued and sent back.
+---+ REFRESH +---+ REFRESH +---+ REFRESH +---+
| |------------>| |------------>| |------------>| |
|MNI| |MNF| |MNF| |MNR|
| |<------------| |<------------| |<------------| |
+---+ RESPONSE +---+ RESPONSE +---+ RESPONSE +---+
Figure 8: REFRESH-RESPONSE Message Flow with MNE_Selection
'FIRST_and_LAST'
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7.4. Example with a Route Changes
Assume a topology as in Figure 9:
+-------+ +-------+ +-------+ +-------+
| MNI |----| MNF1 |-----| MNF2 |----| MNR1 |
+-------+ +-------+ | +-------+ +-------+
|
| +-------+ +-------+ +-----+
+---| MNF3 |----| MNR2 |----|host |
+-------+ +-------+ +-----+
Figure 9: Example with a Route Change'
After a route change MNF2 and MNR1 are not on the signaling path
anymore. MNF3 is new on the signaling path and receives a REFRESH
message with an unknown Session ID. It sends a negative RESPONSE
with error code "Unknown Session".
MNI receives the negative RESPONSE and re-initiates the signaling
with a CONFIGURE message with the same Session ID.
When the MNE receives a CONFIGURE message with the same Session ID it
re-starts the configuration process: the session is considered as a
new session.
8. Bit-Level Formats and Error Messages
8.1. Metering NSLP Messages
All Metering NSLP messages start with a common header 'HEADER'. The
Metering NSLP common header is similar to the QoS NSLP header. Note
that it is not the same as the GIST Common Header.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type | Message Flags | Generic Flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: M-NSLP Message Common Header
The fields in the common header are as follows:
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Message Type: 8 bits
1 = CONFIGURE
2 = RESPONSE
3 = NOTIFY
Message-specific flags: 8 bits
These flags are defined as part of the specification of individual
messages.
Generic flags: 16 bits
There exists currently one generic flag, the Scoping bit (S). The
use of the S-bit is described with each message that makes use of
it.
The set of appropriate flags depends on the particular message
being processed. Any bit not defined as a flag for a particular
message MUST be set to zero on sending and MUST be ignored on
receiving.
8.2. Metering NSLP Objects
The Metering NSLP uses the Type-Length-Value (TLV) object format
defined by GIST [I-D.ietf-nsis-ntlp]. Every object consists of one
or more 32-bit words with a one-word header. For convenience the
standard object header is shown here:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|B|r|r| Type |r|r|r|r| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: M-NSLP Object Common Header
The value for the Type field comes from Metering NSLP object type
space, the various objects are presented in subsequent sections. The
Length field is given in units of 32 bit words and measures the
length of the Value component of the TLV object (i.e., it does not
include the standard header).
The bits marked 'A' and 'B' are extensibility flags, and used to
signal the desired treatment for objects whose treatment has not been
defined in the protocol specification (i.e., whose Type field is
unknown at the receiver).
EDITORIAL NOTE: include text here for the explanation of the meaning
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of the A and B bits.
8.2.1. MSN
Type: MNSLP_MSN
Length: 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Message Sequence Number Object
8.2.2. Session_LT
Type: MNSLP_Session_LT
Length: 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Session Lifetime Object
8.2.3. MNE_Selection
Type: MNSLP_MNE_Selection
Length: 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Selection of Metering Entities |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Selection of Metering Entities Object
Possible values are:
1 = ALL
2 = ANY
3 = FIRST
4 = LAST
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5 = FIRST_and_LAST
greater than 1024 : Enterprise Specific
EDITORIAL NOTE: it still needs to be defined in the case Enterprise
Specific, how MNSLP_SelectionMNEs is encoded.
8.2.4. INFO
This object carries the response code, which may be indications for
either a successful request or failed request depending on the value
of the 'response code' field.
Note that the format of this object is similar the INFO object for
the NATFW NSLP.
Type: MNSLP_INFO
Length: 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Resv. | Class | Response Code | Object Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: Information Code Object
The field 'Resv.' is reserved for future extensions and MUST be set
to zero when generating such an object and MUST be ignored when
receiving. The 'Object Type' field contains the type of the object
causing the error. The value of 'Object Type' is set to 0, if no
object is concerned. The 4 bit class field contains the severity
class. The following classes are defined:
o 0x1: Informational (NOTIFY only)
o 0x2: Success
o 0x3: Protocol error
o 0x4: Transient failure
o 0x5: Permanent failure
o 0x6: Signaling session failures
EDITORIAL NOTE: Response Codes need to be defined here.
8.2.5. MSPEC Objects
Type:
Different types are possible.
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* MNSLP_IPFIX_MSPEC
* MNSLP_DIAMETER_MSPEC
* MNSLP_NETFLOW9
Note that this list is extensible.
Length: Variable.
9. Mapping onto M-NSLP Requirements
EDITORIAL NOTE: This section needs to be updated.
With the design described above, the requirements from
[I-D.fessi-nsis-m-nslp-framework] are at this point satisfied as
follows:
Extensibility:
The actual configuration information is encapsulated in the MSPEC.
The MSPEC is designed such as it is interpreted by the Metering
Manager and can be opaque to the M-NSLP processing. Furthermore,
the MSPEC can be easily extended. Therefore, from the point of
view of the configuration information, this requirement is
fulfilled. Note however, that the Metering NSLP in its current
design might show some lack of extensibility. For example,
considering the selection of the MNEs, it might be useful for
future application of the Metering NSLP to have the option "ANY
N", where N is greater than one.
Interoperability:
Again, whether different metering solutions can interwork depends
on how the MSPEC is designed. In QoS NSLP, the QSpec template
design [I-D.ietf-nsis-qspec] aims at similar extensibility and
interoperability. It needs to be studied whether or not the
solutions chosen by the QSpec can also be applied to the MSPEC.
Flexible metering models:
As above, this is an issue of MSPEC design.
Distinguishing flows
The aggregation feature detailed in this requirement can be
realized as described in Section 4.6.
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Flexible data collection:
Another issue that can be fixed in the MSPEC.
Location of Metering Entities:
MNEs, including MNI and MNR can be located anywhere on the data
path.
Access parameters of the Collector Information:
Access parameters of the Collector Information on how to deliver
flow records to the Collector is coded in the MSPEC.
Configuration of Metering Entities:
The protocol can configure Metering Entities that are MNEs, or
that are controlled by MNEs.
Selection of Metering Entities:
As described in Section 4.4, a MNE should be able to decide to
pull out of the metering process. This is realized by the
'Selection of Metering Entities' object.
Metering Configuration State installation and removal:
By means of the CONFIGURE message, the protocol can install and
remove Metering Configuration State.
Initiation and maintenance of metering tasks:
Triggers and correlation identifier are transported in the MSPEC.
Reaction to Route Changes:
The protocol detects route changes by a REFRESH or a refreshing
CONFIGURE message and installs state along the new route, as
described in Section 4.7.
Scoping of configuration:
The M-NSLP needs to provide sufficient means for flexible scoping
signaling messages.
Requirements not mentioned in this list are not yet addressed.
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10. Security considerations
The process of configuring entities to start and stop metering and to
transmit collected resource records to a third party introduces
security challenges.
An extensive analysis of security issues related to the Metering NSLP
is presented in Section 7 of [I-D.fessi-nsis-m-nslp-framework].
Based on this section, future versions of the M-NSLP protocol
specification will elaborate the required security mechanisms for the
M-NSLP.
11. Open Issues
Open issues for the Metering NSLP are discussed here:
https://www.ri.uni-tuebingen.de/cgi-bin/roundup.cgi/mnslp/
12. Acknowledgements
The authors would like to thank Robert Hancock, Martin Stiemerling
and Andreas Klenk for their valuable input.
Furthermore, the authors would like to thank Angie So. By providing
the first running prototype of the Metering NSLP, she gave us a
helpful feedback for the protocol specification.
13. References
13.1. Normative References
[I-D.ietf-nsis-ntlp]
Schulzrinne, H. and R. Hancock, "GIST: General Internet
Signalling Transport", draft-ietf-nsis-ntlp-12 (work in
progress), March 2007.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
[RFC1982] Elz, R. and R. Bush, "Serial Number Arithmetic", RFC 1982,
Fessi, et al. draft-dressler-nsis-metering-nslp-05.txt [Page 36]
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August 1996.
13.2. Informative References
[RFC2720] Brownlee, N., "Traffic Flow Measurement: Meter MIB",
RFC 2720, October 1999.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC2866] Rigney, C., "RADIUS Accounting", RFC 2866, June 2000.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[RFC3954] Claise, B., "Cisco Systems NetFlow Services Export Version
9", RFC 3954, October 2004.
[RFC4080] Hancock, R., Karagiannis, G., Loughney, J., and S. Van den
Bosch, "Next Steps in Signaling (NSIS): Framework",
RFC 4080, June 2005.
[I-D.ietf-ipfix-protocol]
Claise, B., "Specification of the IPFIX Protocol for the
Exchange", draft-ietf-ipfix-protocol-24 (work in
progress), November 2006.
[I-D.ietf-ipfix-info]
Quittek, J., "Information Model for IP Flow Information
Export", draft-ietf-ipfix-info-15 (work in progress),
February 2007.
[I-D.ietf-psamp-sample-tech]
Zseby, T., "Sampling and Filtering Techniques for IP
Packet Selection", draft-ietf-psamp-sample-tech-07 (work
in progress), July 2005.
[I-D.ietf-psamp-mib]
Dietz, T. and B. Claise, "Definitions of Managed Objects
for Packet Sampling", draft-ietf-psamp-mib-06 (work in
progress), June 2006.
[I-D.ietf-psamp-info]
Dietz, T., "Information Model for Packet Sampling
Exports", draft-ietf-psamp-info-05 (work in progress),
October 2006.
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[I-D.dressler-ipfix-aggregation]
Dressler, F., "IPFIX Aggregation",
draft-dressler-ipfix-aggregation-03 (work in progress),
June 2006.
[RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander,
"Requirements for IP Flow Information Export (IPFIX)",
RFC 3917, October 2004.
[I-D.ietf-nsis-qos-nslp]
Manner, J., "NSLP for Quality-of-Service Signaling",
draft-ietf-nsis-qos-nslp-12 (work in progress),
October 2006.
[I-D.ietf-nsis-fw]
Hancock, R., "Next Steps in Signaling: Framework",
draft-ietf-nsis-fw-07 (work in progress), December 2004.
[I-D.ietf-nsis-nslp-natfw]
Stiemerling, M., "NAT/Firewall NSIS Signaling Layer
Protocol (NSLP)", draft-ietf-nsis-nslp-natfw-13 (work in
progress), October 2006.
[I-D.ietf-nsis-qspec]
Ash, J., "QoS NSLP QSPEC Template",
draft-ietf-nsis-qspec-15 (work in progress),
February 2007.
[I-D.fessi-nsis-m-nslp-framework]
Fessi, A., "Framework for Metering NSLP",
draft-fessi-nsis-m-nslp-framework-03 (work in progress),
June 2006.
[I-D.ietf-aaa-diameter-cc]
Mattila, L., Koskinen, J., Stura, M., Loughney, J., and H.
Hakala, "Diameter Credit-control Application",
draft-ietf-aaa-diameter-cc-06 (work in progress),
August 2004.
[3GPP.32.240]
3GPP, "Telecommunication management; Charging management;
Charging architecture and principles", 3GPP TS 32.240
6.0.0, September 2004.
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Authors' Addresses
Ali Fessi
University of Tuebingen
Wilhelm-Schickard-Institute for Computer Science
Sand 13
Tuebingen 72072
Germany
Phone: +49 7071 29-70576
Email: fessi@informatik.uni-tuebingen.de
URI: http://net.informatik.uni-tuebingen.de/
Georg Carle
University of Tuebingen
Wilhelm-Schickard-Institute for Computer Science
Sand 13
Tuebingen 72072
Germany
Phone: +49 7071 29-70505
Email: carle@informatik.uni-tuebingen.de
URI: http://net.informatik.uni-tuebingen.de/
Falko Dressler
University of Erlangen
Department of Computer Science 7
Martensstr. 3
Erlangen 91058
Germany
Phone: +49 9131 85-27914
Email: dressler@informatik.uni-erlangen.de
URI: http://www7.informatik.uni-erlangen.de/
Juergen Quittek
NEC
Kurfuersten-Anlage 36
Heidelberg 69115
Germany
Phone: +49 6221 90511-15
Email: quittek@netlab.nec.de
URI: http://www.netlab.nec.de/
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Cornelia Kappler
Siemens AG
Siemensdamm 62
Berlin 13627
Germany
Phone: +49 30 386-32894
Email: cornelia.kappler@siemens.com
Hannes Tschofenig
Siemens AG
Otto-Hahn-Ring 6
Munich, Bayern 81739
Germany
Email: Hannes.Tschofenig@siemens.com
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