Asynchronous Management Protocol
draft-birrane-dtn-amp-00
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draft-birrane-dtn-amp-00
Delay-Tolerant Networking E. Birrane
Internet-Draft Johns Hopkins Applied Physics Laboratory
Intended status: Experimental August 17, 2015
Expires: February 18, 2016
Asynchronous Management Protocol
draft-birrane-dtn-amp-00
Abstract
This document describes an Asynchronous Management Protocol (AMP)
conformant with an Asynchronous Management Architecture (AMA). The
AMP provides monitoring and configuration services between managing
devices (Managers) and managed devices (Agents), some of which may
operate on the far side of high-delay or high-disruption links. The
AMP minimizes the number of transmitted bytes, operates without
sessions or (concurrent) two-way links, and functions autonomously
when there is no timely contact with a network operator. The AMP
accomplishes this without requiring mobile code and generally reduces
the processor, memory, and storage requirements of implementing
Managers and Agents.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF). Note that other groups may also distribute
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 18, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Technical Notes . . . . . . . . . . . . . . . . . . . . . 5
1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.1. Protocol Scope . . . . . . . . . . . . . . . . . . . 5
1.3.2. Specification Scope . . . . . . . . . . . . . . . . . 6
1.4. Requirements Language . . . . . . . . . . . . . . . . . . 6
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Data Model . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Basic Types . . . . . . . . . . . . . . . . . . . . . . . 7
3.1.1. Standard Numeric Types . . . . . . . . . . . . . . . 7
3.1.2. Self-Delimiting Numeric Value (SDNV) . . . . . . . . 8
3.1.3. Timestamp (TS) . . . . . . . . . . . . . . . . . . . 8
3.2. Compound Types . . . . . . . . . . . . . . . . . . . . . 9
3.2.1. String (STR) . . . . . . . . . . . . . . . . . . . . 9
3.2.2. Binary Large Object (BLOB) . . . . . . . . . . . . . 9
3.2.3. Data Collection (DC) . . . . . . . . . . . . . . . . 9
3.2.4. Typed Data Collection (TDC) . . . . . . . . . . . . . 10
3.3. Naming Structures . . . . . . . . . . . . . . . . . . . . 11
3.4. Special Types . . . . . . . . . . . . . . . . . . . . . . 15
3.4.1. MID Collections (MC) . . . . . . . . . . . . . . . . 16
3.4.2. Expressions (EXPR) . . . . . . . . . . . . . . . . . 16
3.4.3. Predicate (PRED) . . . . . . . . . . . . . . . . . . 16
3.4.4. Definition (DEF) . . . . . . . . . . . . . . . . . . 16
4. AMP Structures . . . . . . . . . . . . . . . . . . . . . . . 17
4.1. AMA Overview . . . . . . . . . . . . . . . . . . . . . . 17
4.2. Primitive Data . . . . . . . . . . . . . . . . . . . . . 18
4.2.1. Definition . . . . . . . . . . . . . . . . . . . . . 19
4.2.2. Processing . . . . . . . . . . . . . . . . . . . . . 19
4.3. Computed Data . . . . . . . . . . . . . . . . . . . . . . 19
4.3.1. Definition . . . . . . . . . . . . . . . . . . . . . 20
4.3.2. Processing . . . . . . . . . . . . . . . . . . . . . 21
4.4. Report . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.4.1. Definition . . . . . . . . . . . . . . . . . . . . . 21
4.4.2. Processing . . . . . . . . . . . . . . . . . . . . . 22
4.5. Control . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.5.1. Definition . . . . . . . . . . . . . . . . . . . . . 23
4.5.2. Processing . . . . . . . . . . . . . . . . . . . . . 24
4.6. Time-Based Rule (TRL) . . . . . . . . . . . . . . . . . . 24
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4.6.1. Definition . . . . . . . . . . . . . . . . . . . . . 25
4.6.2. Processing . . . . . . . . . . . . . . . . . . . . . 25
4.7. State-Based Rule (SRL) . . . . . . . . . . . . . . . . . 26
4.7.1. Definition . . . . . . . . . . . . . . . . . . . . . 26
4.7.2. Processing . . . . . . . . . . . . . . . . . . . . . 27
4.8. Macro . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.8.1. Definition . . . . . . . . . . . . . . . . . . . . . 28
4.8.2. Processing . . . . . . . . . . . . . . . . . . . . . 29
4.9. Literal . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.9.1. Definition . . . . . . . . . . . . . . . . . . . . . 30
4.9.2. Processing . . . . . . . . . . . . . . . . . . . . . 30
4.10. Operator . . . . . . . . . . . . . . . . . . . . . . . . 30
4.10.1. Definition . . . . . . . . . . . . . . . . . . . . . 31
4.10.2. Processing . . . . . . . . . . . . . . . . . . . . . 31
5. Data Type IDs and Enumerations . . . . . . . . . . . . . . . 31
6. Application Data Model Template . . . . . . . . . . . . . . . 33
6.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 33
6.2. Template . . . . . . . . . . . . . . . . . . . . . . . . 33
6.2.1. ADM Metadata . . . . . . . . . . . . . . . . . . . . 33
6.2.2. ADM Information Capture . . . . . . . . . . . . . . . 34
7. The Agent ADM . . . . . . . . . . . . . . . . . . . . . . . . 35
8. Functional Specification . . . . . . . . . . . . . . . . . . 36
8.1. Message Group Format . . . . . . . . . . . . . . . . . . 36
8.2. Message Format . . . . . . . . . . . . . . . . . . . . . 36
8.3. Register Agent (0x00) . . . . . . . . . . . . . . . . . . 38
8.4. Data Report (0x12) . . . . . . . . . . . . . . . . . . . 38
8.5. Perform Control (0x20) . . . . . . . . . . . . . . . . . 39
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39
10. Security Considerations . . . . . . . . . . . . . . . . . . . 39
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 40
11.1. Informative References . . . . . . . . . . . . . . . . . 40
11.2. Normative References . . . . . . . . . . . . . . . . . . 40
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction
This document specifies an Asynchronous Management Protocol (AMP)
that provides application-layer network management services over
links where propagation delays or link disruptions prevent timely
communications between a network operator and a managed device. The
AMP is conformant to the Asynchronous Management Architecture [AMA].
1.1. Overview
Network management protocols define the messages that implement
management functions amongst managed and managing devices in a
network. These functions include the definition, production, and
reporting of performance data, the application of administrative
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policy, and the configuration of behavior based on local time and
state measurements.
Networks whose communication links are frequently challenged by
physical or administrative effects may not provide the guarantee of
low-latency, duplex data communications necessary to support sessions
and other synchronous communication. For such networks, an
asynchronous management protocol is required which provides familiar
network management services in the absence of sessions and operator-
in-the-loop control.
AMP accomplishes the network management function using open-loop,
intelligent-push, asynchronous mechanisms that better scale as link
challenges scale. The protocol is designed to support several
desirable properties outlined in [AMA] and briefly listed below.
o Intelligent Push of Information - The intelligent push of
information eliminates the need for round-trip data exchange.
This is a necessary consequence of operating in an open-loop
system. AMP is designed to operate even in networks of solely
uni-directional links.
o Small Message Sizes - Smaller messages require smaller periods of
viable transmission for communication, incur less re-transmission
cost, and consume less resources when persistently stored en-route
in the network. AMP minimizes the size of a message whenever
practical, to include packing and unpacking binary data, variable-
length fields, and pre-configured data definitions.
o Fine-grained, Flexible Data Identification - Fine-grained
identification allows data in the system to be explicitly
addressed while flexible data identification allows users to
define their own customized, addressed data collections. In both
cases, the ability to define precisely the data required removes
the need to query and transmit large data sets only to filter/
downselect desired data at a receiving device.
o Stateless Operation - AMP does not rely on session establishment
or round-trip data exchange to perform network management
functions. Wherever possible, the AMP is designed to be
stateless. Where state is required, the AMP provides mechanisms
to support transactions and graceful degradation when nodes in the
network fail to synchronize on common definitions.
o Compatibility with Low-Latency Network Management Protocols - AMP
adopts an identifier approach compatible with the Managed
Information Base (MIB) format used by Internet management
protocols such as the Simple Network Management Protocol (SNMP),
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thus enabling management interfaces between challenged networks
and unchallenged networks (such as the Internet).
1.2. Technical Notes
o Multi-byte values presented in this specification are to be
transmitted in network-byte order.
o Bit-fields in this document are specified in Little-Endian format
with bit position 0 holding the least-significant bit (LSB). When
illustrated in this document, the LSB appears on the right.
o Illustrations of byte fields in this specification consist of the
name of the field, the type of the fields between []'s, and if the
field is optional, the text "(opt)". An example is shown in
Figure 1 below. In this illustration two fields (Field 1 and
Field 2) are shown, with Field 1 of Type 1 and Field 2 of Type 2.
Field 2 is also listed as being optional. Byte fields are shown
in order of receipt, from left-to-right. Therefore, when
transmitted on the wire, Field 1 will appear first, followed by
Field 2 (if present).
+----------+----------+
| Field 1 | Field 2 |
| [TYPE 1] | [TYPE 2] |
| | (opt) |
+----------+----------+
Figure 1: Byte Field Formatting Example
1.3. Scope
1.3.1. Protocol Scope
The AMP provides data monitoring, administration, and configuration
for applications operating above the data link layer of the OSI
networking model. While the AMP may be configured to support the
management of network layer protocols, it also uses these protocol
stacks to encapsulate and communicate its own messages.
It is assumed that the protocols used to carry AMP messages provide
addressing, confidentiality, integrity, security, fragmentation
support and other network/session layer functions. Therefore, these
items are not discussed in the scope of this document.
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1.3.2. Specification Scope
This document describes the format of the AMP messages exchanged
amongst managing and managed devices in a challenged network. This
document further describes the rationale behind key design decisions
to the extent that such a description informs the operational
deployment and configuration of an AMP implementation. This document
does not address specific data configurations of AMP-enabled devices,
nor does it discuss the interface between AMP and other management
protocols, such as SNMP.
1.4. Requirements Language
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 RFC 2119 [RFC2119].
2. Terminology
Note: The terms "Actor", "Agent", "Application Data Model", "Atomic
Data", "Computed Data", "Controls", "Macros", "Managers", and
"Reports" are exactly conformant with those definitions as provided
in [AMA]. Brief versions of these definitions are provided in this
document as an aid to the reader, but the AMA specification should be
read for a complete understanding of these concepts.
This section identifies those terms critical to understanding the
proper operation of the AMP. Whenever possible, these terms align in
both word selection and meaning with their analogs from other
management protocols and with the AMA.
o Actor - A software service running on either managed or managing
devices implementing an end-point in the AMP. Actors may
implement the "Manager" role, "Agent" role, or both.
o Agent Role - A role within the AMP, associated with a managed
device.
o Application Data Model (ADM) - The set of predefined data
definitions, reports, literals, operations, and controls given to
an AMP actor to manage a particular application or protocol. AMP
actors support multiple ADMs, one for each application/protocol
being managed.
o Atomic Data - Globally unique, managed data definitions whose
definition does not change based on the configuration of an AMP
Actor.
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o Computed Data - Data computed dynamically by an AMP Actor.
o Controls - Operations that may be undertaken by an AMP Actor to
change the behavior, configuration, or state of a protocol or
application managed by the AMP.
o Macros - A named, ordered collection of controls.
o Managed Item Definition (MID) - A parameterized structure used to
uniquely identify all data and control definitions within the AMP.
MIDs are a super-set of Object Identifiers (OIDs) and the
mechanism by which the AMP maintains data compatibility with other
management protocols.
o Manager - A role within the AMP associated with a managing device.
AMP managers also provide gateways to non-AMP management protocols
as part of conditioning the data returned from agents. Managers
interact with one or more agents located on the same device and/or
on remote devices in the network.
o Report - A named, ordered collection of data items gathered by one
or more AMP Agents and provided to one or more AMP Managers.
Reports may contain atomic data, computed data, and other reports.
Individual data within a report are not named; the report itself
is named to reduce the size of the report message.
3. Data Model
This section identifies the data types used to capture information
within the AMP. The data model consists of the description of basic
type definitions, compound type definitions, naming schemes, and type
enumerations.
3.1. Basic Types
Basic types are those that are not comprised of any other set of
types known to the AMP.
3.1.1. Standard Numeric Types
The AMP supports types for unsigned bytes, 32/64-bit signed and
unsigned integers, and 32/64-bit floating point values, as outlined
in Table 1.
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+------------+------------+-----------------------------------------+
| AMP ID | BitWidth | Description |
+------------+------------+-----------------------------------------+
| BYTE | 8 | unsigned byte value |
| | | |
| INT | 32 | Signed integer in 2's complement |
| | | |
| UINT | 32 | Unsigned integer in 2's complement |
| | | |
| VAST | 64 | Signed integer in 2's complement |
| | | |
| UVAST | 64 | Unsigned integer in 2's complement |
| | | |
| REAL32 | 32 | Single-precision, 32-bit floating point |
| | | value in IEEE-754 format. |
| | | |
| REAL64 | 64 | Double-precision, 64-bit floating point |
| | | value in IEEE-754 format. |
+------------+------------+-----------------------------------------+
Table 1: Standard Numeric Types
3.1.2. Self-Delimiting Numeric Value (SDNV)
The data type "SDNV" refers to a Self-Delimiting Numerical Value
(SDNV) described in [RFC6256]. SDNVs are used in the AMP to capture
any data items that are expected to be 8 bytes or less in total
length. AMP Actors MAY reject any value encoded in an SDNV that is
greater than 8 bytes in length.
One popular use of ADNVs in the AMP is to compress the representation
of 32/64-bit integer values. This simplifies the AMP by not having
to additionally support 8/16-bit versions of integers without
incurring significant transmission waste when encoding small numbers
into 32/64-bit representations.
3.1.3. Timestamp (TS)
Timestamps represent time within the AMP. For compatibility with a
variety of protocols, the use of UTC time is selected to represent
all time values in the AMP. However, timestamps in AMP may represent
either absolute or relative time based on the associated AMP Epoch.
AMP uses September 9th, 2012 as the timestamp epoch (UTC time
1348025776). Times less than this value MUST be considered as
relative times. Values greater than or equal to this epoch MUST be
considered as absolute times. In all cases, the AMP timestamp is
encoded as an SDNV to avoid the 32-bit 2038 UTC rollover problem.
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The absolute time associated with a timestamp can be calculated by an
AMP Actor with the following pseudocode.
IF (timestamp < 1348025776) THEN
absolute_time = current_time + timestamp
ELSE
absolute_time = timestamp
3.2. Compound Types
3.2.1. String (STR)
The AMP supports the string type as an ordered collection of byte
values assumed terminated by a special NULL-terminator value of 0.
Within the AMP, the String type is almost always deprecated in favor
of the BLOB type (which asserts the data value first).
3.2.2. Binary Large Object (BLOB)
A Binary Large Object (BLOB) is an ordered collection of bytes
prefaced by the number of bytes making up the BLOB. The format of a
BLOB is illustrated in Figure 2. BLOBs are used in the AMP to
capture variable data sets that are too large to efficiently store in
an SDNV.
Binary Large Object Format
+---------+--------+--------+ +--------+
| # Bytes | BYTE 1 | BYTE 2 | ... | BYTE N |
| [SDNV] | [BYTE] | [BYTE] | | [BYTE] |
+---------+--------+--------+ +--------+
Figure 2: Binary Large Object Format
3.2.3. Data Collection (DC)
Often, multiple BLOBs must be communicated in the AMP. A Data
Collection (DC) is an ordered set of BLOBs, prefaced by the number of
BLOBs making up the collection. The format of a DC is illustrated in
Figure 3.
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Data Collection
+---------+--------+--------+ +--------+
| # BLOBs | BLOB 1 | BLOB 2 | ... | BLOB N |
| [SDNV] | [BLOB] | [BLOB] | | [BLOB] |
+---------+--------+--------+ +--------+
Figure 3: Data Collection Format
3.2.4. Typed Data Collection (TDC)
When Data Collections are used to convey parameters for AMP controls,
or otherwise used to capture the "return" values of controls, the
data SHOULD be annotated with the associated type for each data in
the collection. The Typed Data Collection (TDC) provides this
augmentation. A TDC is a regular DC with one additional BLOB added
to the collection to capture type information. This "Type BLOB"
stores the type of each other entry in the DC in a byte.
The TDC format is illustrated in Figure 4
Typed Data Collection
+---------+-----------+-------------+ +-------------+
| # BLOBs | TYPE BLOB | DATA BLOB 1 | ... | DATA BLOB N |
| [SDNV] | [BLOB] | [BLOB] | | [BLOB] |
+---------+-----------+-------------+ +-------------+
Figure 4: Typed Data Collection Format
For example, consider a Data Collection of 3 BLOBs, with BLOB 1
having type UINT, BLOB 2 having type VAST, and BLOB 3 having type
SDNV. The DC structure has no way of capturing this type
information. The corresponding TDC would have 4 BLOBs. BLOB 1 would
have length 3 and contain the enumerations for UINT, VAST, and SDNV -
each encoded in one byte. BLOBs 2, 3, and 4 would be the original
data. This example is illustrated in Figure 5.
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Typed Data Collection Example
DC TDC
+---------------------+ +--------------------------------+
| # BLOBs = {3} | | # BLOBs = {4} |
+---------------------+ +--------------------------------+
| BLOB 1 = {DATA1,...}|--------+ | TYPE BLOB = {UINT, VAST, SNDV} |
+---------------------+ | +--------------------------------+
| BLOB 2 = {DATA2,...}|-----+ +->| DATA BLOB 1 = {DATA1,...} |
+---------------------+ | +--------------------------------+
| BLOB 3 = {DATA3,...}|--+ +---->| DATA BLOB 2 = {DATA2,...} |
+---------------------+ | +--------------------------------+
+------->| DATA BLOB 3 = {DATA3,...} |
+--------------------------------+
Figure 5: Typed Data Collection Example
3.3. Naming Structures
Application, protocol, and user data defined and exchanged within the
AMP must be uniquely identifiable both within a network and (when AMP
is used in an overlay) across networks. This section describes the
"Managed Identifier" (MID) which is the single data structure used to
provide unique naming for all AMP data structures. The MID is a
variable-length structure that encapsulates all of the information
and annotation necessary to identify an AMP structure.
The MID consists of a "core" unique identifier and several useful
annotations to assist with filtering, access control, and
parameterization. The unique identifier at the core of a MID is
based on the Object Identifier (OID) and its Basic Encoding Rules
(BER) as identified in the ITU-T X.690 standard. The specifics of
the OID encoding are provided below.
The AMP uses the OID as its fundamental unit of identification to
allow its Agents and Managers to more easily interface with other
management schemes (such as SNMP) at management boundaries between
challenged and un-challenged networks.
The MID structure is comprised of up to four fields, as illustrated
in Figure 6.
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MID format
+--------+--------+--------+--------+
| Flags | Issuer | OID | Tag |
| [BYTE] | [SDNV] |[VARIED]| [SDNV] |
| | (opt) | | (opt) |
+--------+--------+--------+--------+
Figure 6: Managed Identifier Format
The MID fields are defined as follows.
Flags
Flags are used to describe the type of component identified
by the MID, identify which optional fields in the MID are
present, and the encoding used to capture the component's
OID. The layout of the flag byte is illustrated in Figure 7.
MID Flag Format
+-----+---+---+-----+------+
| OID |TAG|ISS| CAT | TYPE |
+-----+---+---+-----+------+
| 7 6 | 5 | 4 | 3 2 | 1 0 |
+-----+---+---+-----+------+
MSB LSB
Figure 7
MID Type (TYPE)
The type of the component encapsulated by the MID,
enumerated as data (0), control (1), literal (2), or
operator (3).
MID Category (CAT)
The category of the component encapsulated by the
MID, enumerated as atomic (0), computed (1), and
collection (2).
Issuer Present (ISS)
Whether the issuer field is present (1) or not (0)
for this MID. If this flag has a value of 1 then the
issuer field MUST be present in the MID. Otherwise,
the issuer field MUST NOT be present in the MID.
Tag Present (TAG)
Whether the tag field is present (1) or not (0) for
this MID. If this flag has a value of 1 then the tag
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field MUST be present in the MID. Otherwise, the tag
field MUST NOT be present.
OID Type (OID)
Whether the contained OID field represents an full
OID (0), a parameterized OID (1), a compressed full
OID (2), or a compressed, parameterized OID (3). OID
types are described below.
For example, a MID flag byte of 0x00 indicates an atomic data
value with no issuer or tag field encapsulating a full OID.
A MID flag byte of 0x94 indicates a computed data value with
an issuer field, but no tag field encapsulating a compressed
OID.
Issuer
This is a binary identifier representing a predetermined
issuer name. The AMP protocol does not parse or validate
this identifier, using it only as a distinguishing bit
pattern to assure MID uniqueness. This value, for example,
may come from a global registry of organizations, an issuing
node address, or some other network-unique marking.
OID
The core of a MID is its encapsulated OID. Aside from the
flag byte, this is the only other mandatory element within a
MID. The AMP defines four types of OID references: Full
OIDs, Parameterized OIDs, Compressed Full OIDs, and
Compressed Parameterized OIDs.
Full OID
This is a binary representation of the full OID
associated with the named value. The OID is encoded
using a modified form of the ASN.1 Basic Encoding
Rules (BER) for Object Identifiers (type value of
0x06). In the standard ASN.1 encoding, four octet
sets are defined: identifier octets, length octets,
contents octets, and end-of-contents octets. An AMP
Full OID does not use the identifier, length, or end-
of-contents octets. Instead, an AMP Full OID is
comprised of two fields: the length in bytes of the
encoded OID captured in an SDNV followed by the OID
contents octets. It should be noted that this
effectively encodes the "OID" as a Data Collection.
The Full OID format is illustrated in Figure 8.
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+----------+
| Full OID |
| [DC] |
+----++----+
||
||
_____________________/ \_________________________
/ \
+------------+---------+---------+ +---------+
| OID Length | Octet 1 | Octet 2 | ... | Octet N |
| [SDNV] | [BYTE] | [BYTE] | | [BYTE] |
+------------+---------+---------+ +---------+
Figure 8: Full OID Format
Parameterized OID
The parameterized OID is represented as the non-
parameterized portions of the OID followed by one or
more parameters. Parameterized OIDs are used to
templatize the specification of data items and
otherwise provide parameters to controls without
requiring potentially unmanageable growth of a Full
OID namespace. The format of a parameterized OID is
given in Figure 9.
+----------+------------+
| FULL OID | Parameters |
| [DC] | [DC] |
+----------+-----++-----+
||
||
__________________/ \_______________________
/ \
+----------+--------+--------+ +--------+
| # Params | Parm 1 | Parm 2 | | Parm N |
| [SDNV] | [BLOB] | [BLOB] | ... | [BLOB] |
+----------+--------+--------+ +--------+
Figure 9: Parameterized OID Format
Compressed OID
Since many related OIDs share a common and lengthy
hierarchy there is opportunity for significant
message size savings by defining a shorthand for
commonly-used portions of the OID tree. A partial
OID is a tuple consisting of a nickname for a pre-
defined portion of the OID tree (as an SDNV),
followed by a relative OID. Nicknames are defined in
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the formal Application Data Models of managed
applications and protocols. They must be managed to
ensure there is no collision in the nickname
namespace. The format of a compressed OID is given
in Figure 10.
+----------+--------------+
| Nickname | Relative OID |
| [SDNV] | [DC] |
+----------+--------------+
Figure 10: Compressed OID Format
Compressed Parameterized OID
A compressed, parameterized OID is similar to a
compressed OID. In this instance, the tuple
contained in this field is the nickname for the pre-
defined portion of the OID tree (as an SDNV) followed
by a parameterized OID whose hierarchy begins at the
place identified by the nickname. The format of a
compressed OID is given in Figure 11.
Compressed Parameterized OID Format
+----------+--------------+------------+
| Nickname | Relative OID | Parameters |
| [SDNV] | [DC] | [DC] |
+----------+--------------+------------+
Figure 11: Compressed Parameterized OID Format
Tag
A value used to disambiguate multiple MIDs with the same OID/
Issuer combination. The definition of the tag is left to the
discretion of the MID issuer. Proper name objects do not
require a tag as their OIDs are guaranteed to be globally
unique. Options for tag values include an issuer-known
version number or a hashing of the data associated with a
non-proper-name MIDs. The tag field MUST NOT be present for
the atomic category.
3.4. Special Types
In addition to the data types already mentioned, the following
special data types are also defined.
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3.4.1. MID Collections (MC)
A MID collection is comprised of a value identifying the number of
MIDs in the collection, followed by each MID, as illustrated in
Figure 12.
+--------+-------+ +-------+
| # MIDs | MID 1 | ... | MID N |
| [SDNV] | [MID] | | [MID] |
+--------+-------+ +-------+
Figure 12: MID Collection
3.4.2. Expressions (EXPR)
Expressions apply operations to data and literal values to generate
new data values. The expression type in AMP is a collection of MIDs
that represent a postfix notation stack of Data, Literal, and
Operation types. For example, the infix expression A * (B * C) is
represented as the sequence A B C * *. The format of an expression is
illustrated in Figure 13.
+------------+
| Expression |
| [MC] |
+------------+
Figure 13
Expression
An expression is represented in the AMP as a MID collection,
where each MID in the ordered collection represents the data,
literals, and operations that comprise the expression.
3.4.3. Predicate (PRED)
Predicates are expressions whose values are interpreted as a Boolean.
The value of zero MUST be considered "false" and all other values
MUST be considered "true". Similar to an expression, a predicate is
represented as a MID collection (MC).
3.4.4. Definition (DEF)
Several data structured within the AMP are defined as a named
collection of other named entities. For example, a Macro is a named
collection of Controls; a Report is a named collection of other data
items; a computed data definition is a named expression which, from
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above, is a collection of MIDs representing the postfix notation of
the calculating function.
The Definition (DEF) type captures instances where the AMP refers to
a named, typed collection of information. The format of a DEF is
illustrated in Figure 14.
+--------+----------+------------+
| Def ID | Def Type | Definition |
| [MID] | [BYTE] | [MC] |
+--------+----------+------------+
Figure 14: Definition Format
Def ID
The name of the item being defined. For example, the
identifier for the Macro, Report, or Computed Data Item.
Def Type
The enumeration representing the type for this definition.
Definition
The MC that captures the definition. This will be context-
sensitive based on the structure being defined.
4. AMP Structures
This section identifies the basic structures that comprise the data
items exchanged in the AMP, including the definition of these
structures based on the aforementioned data model and the behavior of
AMP Actors when interacting with these structures.
4.1. AMA Overview
The AMA defines a series of logical components that should be
included as part of an asynchronous management protocol. These
components are summarized from the AMA in the following table.
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+-------------+-----------------------------------------------------+
| Component | Summary Description |
+-------------+-----------------------------------------------------+
| Primitive | A typed, measured value whose definition does not |
| Data | change. |
| | |
| Computed | A value computed from primitive data and other |
| Data | computed data. |
| | |
| Report | Collection of primitive and/or computed data and/or |
| | other reports. |
| | |
| Control | Parameterized opcode for an action that can be |
| | taken by an Agent. |
| | |
| Rule | A pre-configured response to a pre-defined state on |
| | an Agent. |
| | |
| Macro | An ordered collection of controls. |
| | |
| Literal | A constant used when evaluated rules or computing |
| | data. |
| | |
| Operator | An opcode representing a mathematical function |
| | known to an Agent. |
+-------------+-----------------------------------------------------+
AMP Logical Components
The AMP implements these logical components in largely a one-to-one
fashion with the exception that the AMP defines two types of
autonomous rules: time-based and state-based. This section describes
the format of these data structures in the context of the
aforementioned AMP data types. NOTE: The expression of these
structures is only to describe how these structures appear in
messages exchanged between and amongst Agents and Managers in a
challenged network. Individual software applications may choose
their own most efficient internal representation of these structures.
4.2. Primitive Data
Primitive Data are pre-defined as part of ADMs for various
applications and protocols. These represent values that are directly
measured by firmware on Agents rather than computed as a function of
other data in the system.
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4.2.1. Definition
The representation of these data is simply their identifying MIDs.
The representation of a primitive data item is illustrated in
Figure 15.
+-------+
| ID |
| [MID] |
+-------+
Figure 15: Primitive Data Format
ID
This is the MID identifying the primitive data. Since
primitive data are always defined solely in the context of an
ADM, this MID MUST NOT have either an ISSUER field or a TAG
field. This ID MUST NOT encapsulate a parameterized OID.
The low nibble of the MID flag byte for primitive data is
always 0x0.
4.2.2. Processing
Managers
o Store the MID for each known Primitive Data definition.
o Associate a data type to each known Primitive Data definition.
o Encode Primitive Data MIDs in Controls to Agents, as appropriate.
Agents
o Store the MID for each known Primitive Data definition.
o Associate a data type to each known Primitive Data definition.
o Calculate the value of a Primitive Data definition when required,
such as when generating a Report or evaluating an Expression.
4.3. Computed Data
Computed data are either as defined in an ADM or tactically by
operators in a particular network. Computed data differ from
Primitive Data in that they are completely described by other known
data in the system (either other Computed Data, or other Primitive
Data). For example, letting P# be a Primitive Data item and C# be a
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Computed Data item, the following are examples of Computed Data
definitions.
C1 = P1 * P2
C2 = C1 + P3
4.3.1. Definition
Computed data are defined by the triplet (TYPE, ID, EXPR) as
illustrated in Figure 16. Note that this format is identical to the
DEFINITION data type. As such, a computed data definition is
captured in a DEF.
+---------------+
| Computed Data |
| [DEF] |
+-------++------+
||
||
____________/ \_______________
/ \
+-------+--------+------------+
| ID | TYPE | Definition |
| [MID] | [BYTE] | [EXPR] |
+-------+--------+------------+
Figure 16: Computed Data Format
ID
This is the MID identifying the computed data. When a
computed data item is defined in an ADM this MID MUST NOT
have either an ISSUER field or a TAG field. When the
computed data is defined outside of an ADM, the MID MUST have
an ISSUE field and, optionally, a TAG field. This ID MUST
NOT encapsulate a parameterized OID. The low nibble of the
MID flag byte for computed data is always 0x4.
TYPE
This is the resultant type of the computed data, and acts as
a static cast for the result of the expression. Note, it is
possible to specify a type different then the resultant type
of an expression. For example, if an expression adds two
single-precision floating point numbers, the computed data
may have an integer type associated with it. This byte is
populated with the enumeration of the associated type and
MUST be defined as one of the numeric data types, as outlined
in Section 5.
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Definition
The computed data value is computed by an expression.
Notably, an EXPR is simply a MC with the restriction that the
MIDs represent a series of primitive data, computed data,
literals, and operations that form a postfix expression.
4.3.2. Processing
Managers
o Store the MID for each ADM-defined Computed Data definition.
o Send requests to Agents to add, list, describe, and remove custom
Computed Data definitions.
o Remember custom Computed Data definitions.
o Encode Computed Data MIDs in Controls to Agents, as appropriate.
Agents
o Store the MID for each ADM-defined Computed Data definition.
o Calculate the value of Computed Data when required, such as during
rule evaluation, calculating other Computed Data values, and
generating Reports.
o Add, Remove, List, and Describe custom Computed Data definitions.
4.4. Report
Reports capture information generated by Agents and transmitted to
Managers in the AMP. Since the AMP is an asynchronous protocol there
is no explicit association between the contents of a report and a
generating action by either a Manager or an Agent.
Note that reports in the AMP are NOT key-value pairs. The definition
of the report is assumed known by the Agent producing the report and
the Manager receiving the report. Similarly, when a report captured
the return of a control, the format of the return value is assumed
known to the Agent and Manager. This approach results in a
significant space saving when communicating reports in the network.
4.4.1. Definition
A report is a named, typed data collection. Each BLOB within the
typed data collection is referred to as a report entry. Reports are
generated in one of three scenarios: (1) when a report is explicitly
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requested, (2) when a rule determines that a report should be
generated, and (3) when a control runs and generates a return value
that is sent as a report.
When a report is generated by command or by rule, then the report is
given a unique identifier either by the ADM defining the report, or
by an operator defining a report as part of network configuration.
When a report is generated ad-hoc to capture the return value of a
control, the report identifier is the same as the identifier of the
control whose return value it captures.
The definition of a report is illustrated in Figure 17.
+-------+---------+
| ID | Entries |
| [MID] | [TDC] |
+-------+---++----+
||
||
___________________________/ \__________________________________
/ \
+-----------+-------------+---------+---------+ +---------+
| # Entries | Entry Types | Entry 1 | Entry 2 | | Entry N |
| [SDNV] | [BLOB] | [BLOB] | [BLOB] | ... | [BLOB] |
+-----------+-------------+---------+---------+ +---------+
Figure 17: Report Format
ID
This is the MID identifying the report. When a report is
defined in an ADM this MID MUST NOT have either an ISSUER
field or a TAG field. When the report is defined outside of
an ADM, the MID MUST have an ISSUE field and, optionally, a
TAG field. This ID MUST NOT encapsulate a parameterized OID.
The low nibble of the MID flag byte for computed data is
always 0x8.
Entries
This is the typed data collection containing all of the
report entries that comprise the report.
4.4.2. Processing
Managers
o Store the MID for each ADM-defined Report definition.
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o Send requests to Agents to add, list, describe, and remove custom
Report definitions.
o Remember custom Report definitions when processing reports
received by Agents.
o Encode Report MIDs in Controls to Agents, as appropriate.
Agents
o Store the MID for each ADM-defined Report definition.
o Populate Reports for transmission to Managers when appropriate,
such as when providing a result of running a control or when
directed to generate a report by a control or rule.
o Add, Remove, List, and Describe custom Report definitions.
o Agents SHOULD collect multiple Report entries into a single Report
for transmission to a Manager rather than sending multiple,
individual Reports to a Manager.
4.5. Control
A Control represents a pre-defined (possibly parameterized) opcode
that can be run on an Agent. Controls in the AMP are always defined
in the context of an ADM. There is no concept of an operator-defined
control, as controls represent the opcodes of actions taken directly
by the firmware. Since Controls are pre-configured in Agents and
Managers as part of ADM support, their representation is simply the
MID that identifies them, similar to Primitive Data.
One difference between the definition of Controls and Primitive Data
is that Controls may accept parameters. This is accomplished by
using a parameterized OID in the MID identifying the Control.
4.5.1. Definition
The format of a Control is illustrated in Figure 18.
+-------+
| ID |
| [MID] |
+-------+
Figure 18: Control Format
ID
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This is the MID identifying the Control. Since Controls are
always defined solely in the context of an ADM, this MID MUST
NOT have either an ISSUER field or a TAG field. The low
nibble of the MID flag byte for Controls is always 0x1.
4.5.2. Processing
Managers
o Store the MID for each ADM-defined Control definition.
o Store the number of parameters and each parameter type for
parameterized controls.
o Encode Control MIDs in other Controls to Agents, as appropriate.
Agents
o Store the MID for each ADM-defined Control definition.
o Implement Controls in firmware and run Controls with appropriate
parameters when necessary in the context of control messages and
autonomous rule execution.
o Communicate "return" values from Controls back to Managers in a
report where such return values are defined for a Control.
4.6. Time-Based Rule (TRL)
A Time-Based Rule (TRL) specifies that a particular action should be
taken by an Agent based on some time interval. A TRL specifies that
starting at a particular START time, and for every PERIOD seconds
thereafter, an ACTION should be run by the Agent until the ACTION has
been run for COUNT times. When the TRL is no longer valid it MAY BE
discarded by the Agent.
Examples of TRLs include:
Starting 2 hours from receipt, produce Report R1 every 10 hours
ending after 20 times.
Starting at the given absolute time, run Macro M1 every 24 hours
ending after 365 times.
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4.6.1. Definition
The format of a TRL is illustrated in Figure 19.
+-------+-------+--------+--------+--------+
| ID | START | PERIOD | COUNT | ACTION |
| [MID] | [TS] | [SDNV] | [SDNV] | [MC] |
+-------+-------+--------+--------+--------+
Figure 19: Time-Based Rule Format
ID
This is the MID identifying the TRL. When a report is
defined in an ADM this MID MUST NOT have either an ISSUER
field or a TAG field. When the report is defined outside of
an ADM, the MID MUST have an ISSUE field and, optionally, a
TAG field. This ID MUST NOT encapsulate a parameterized OID.
The low nibble of the MID flag byte for computed data is
always 0x5.
START
The time at which the TRL should start to be evaluated. This
will mark the first running of the action associated with the
TRL.
PERIOD
The number of seconds to wait between running the action
associated with the TRL.
COUNT
The number of times the TRL action will be run. The special
value of 0 indicates the TRL should continue running the
action indefinitely.
ACTION
The Macro representing the collection of controls to run as
part of the action. This is captured as a MC data type with
the constraint that every MID within the MC represent a
control or another Macro.
4.6.2. Processing
Managers
o Send requests to Agents to add, list, describe, and remove custom
TRL definitions.
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o Remember custom TRL definitions when processing reports received
by Agents.
o Encode TRL MIDs in Controls to Agents, as appropriate.
Agents
o Run the actions associated with TRLs in accordance with their
start time and period.
o Add, Remove, List, and Describe custom TRL definitions.
4.7. State-Based Rule (SRL)
A State-Based Rule (SRL) specifies that a particular action should be
taken by an Agent based on some evaluation of the internal state of
the Agent. A SRL specifies that starting at a particular START time,
and for every PERIOD seconds thereafter, an ACTION should be run by
the Agent if some CONDITION evaluates to true, until the CONDITION
has been evaluated COUNT times. When the SRL is no longer valid it
MAY BE discarded by the Agent.
Examples of SRLs include:
Starting 2 hours from receipt, whenever Computed Data C1 > 10,
produce Report R1 no more than 20 times.
Starting at the given absolute time, whenever C2 + (P1 * C3) !=
C4, run Macro M1 no more than 36 times.
4.7.1. Definition
The format of a SRL is illustrated in Figure 20.
+-------+-------+-----------+--------+--------+
| ID | START | CONDITION | COUNT | ACTION |
| [MID] | [TS] | [PRED] | [SDNV] | [MC] |
+-------+-------+-----------+--------+--------+
Figure 20: State-Based Rule Format
ID
This is the MID identifying the SRL. When a report is
defined in an ADM this MID MUST NOT have either an ISSUER
field or a TAG field. When the report is defined outside of
an ADM, the MID MUST have an ISSUE field and, optionally, a
TAG field. This ID MUST NOT encapsulate a parameterized OID.
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The low nibble of the MID flag byte for computed data is
always 0x5.
START
The time at which the SRL condition should start to be
evaluated. This will mark the first evaluation of the
condition associated with the SRL.
CONDITION
The predicate capturing the internal Agent state evaluation
which, if true, results in the SRL running the associated
action. The predicate is an EXPR which evaluates to "false"
if the expression result is 0 and evaluates to "true" in any
other case. An expression, itself, is simply a MC
representing a series of Primitive Data, Computed Data,
Literal, and/or Operator MIDs that are ordered to create a
valid postfix expression.
COUNT
The number of times the SRL condition will be run. The
special value of 0 indicates the SRL should continue
evaluating the condition indefinitely.
ACTION
The Macro representing the collection of controls to run as
part of the action. This is captured as a MC data type with
the constraint that every MID within the MC represent a
control or another Macro.
4.7.2. Processing
Managers
o Send requests to Agents to add, list, describe, and remove custom
SRL definitions.
o Remember custom SRL definitions when processing reports received
by Agents.
o Encode SRL MIDs in Controls to Agents, as appropriate.
Agents
o Run the actions associated with SRLs in accordance with their
start time and evaluation of their predicate.
o Add, Remove, List, and Describe custom SRL definitions.
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4.8. Macro
Macros in the AMP are simply ordered collections of MIDs (an MC) that
describe Controls or other Macros. When run by an Agent, each MID in
the MC is run in order. Similar to a Computed Data definition, a
Macro is a named collection of MIDs and is represented by a DEF
structure.
While the MIDs representing any given control may be parameterized,
the MID associated with a Macro MAY NOT be parameterized.
4.8.1. Definition
The format of a Macro is illustrated in Figure 21.
+-------+
| Macro |
| [DEF] |
+---++--+
||
||
____________/ \_______________
/ \
+-------+--------+------------+
| ID | TYPE | Definition |
| [MID] | [BYTE] | [MC] |
+-------+--------+------------+
Figure 21: Macro Format
ID
This is the MID identifying the Macro. When a Macro item is
defined in an ADM this MID MUST NOT have either an ISSUER
field or a TAG field. When the computed data is defined
outside of an ADM, the MID MUST have an ISSUE field and,
optionally, a TAG field. This ID MUST NOT encapsulate a
parameterized OID. The low nibble of the MID flag byte for
Macro is always 0x9.
TYPE
The data type for a Macro is always the special type for
Macro as defined in Section 5. Macros do not have a specific
return type otherwise.
Definition
This is the ordered collection of MIDs that identify the
Controls and other Macros that should be run as part of
running this Macro.
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4.8.2. Processing
Managers
o Store the MID for each ADM-defined Macro definition.
o Send requests to Agents to add, list, describe, and remove custom
Macro definitions.
o Encode Macro MIDs in Controls to Agents, as appropriate.
Agents
o Store the MID for each ADM-defined Macro definition.
o Remember custom Macro definitions and run Macros when appropriate,
such as when responding to a run-macro command or when executing
the action of a TRL or SRL.
o Add, Remove, List, and Describe custom Macro definitions.
4.9. Literal
Literals in the AMP represent constants either as defined in an ADM
or as specified by a user. Examples of constants that could be
defined in an ADM include common mathematical values such as PI or
well-known Epochs such as the UNIX Epoch. Examples of constants that
could be user-defined as part of expressions include simple numerical
values, such as 5 in the expression (A > 5). In both cases, Literals
MUST ALWAYS be defined in an ADM, with user-definable Literal values
being provided through the MID parameterization mechanism as follows.
The ADM definition of a Literal MUST include the type of the Literal
value. Since ADM definitions are preconfigured on Agents and
Managers in an AMA the type information for a given Literal is
therefore known by all Actors in the system.
If the MID identifying the Literal encapsulates a non-parameterized
OID, then the value is given in the ADM and Agents and Managers can
lookup this value in their set of pre-configured data.
If the MID identifying the Literal encapsulates a parameterized OID,
then the parameters to the OID define the value of the Literal.
Users wishing to create a new Literal will create a MID with whatever
parameters are necessary to create the value. The documentation of
the ADM defining the Literal MUST describe how parameters result in
the calculation of the Literal value.
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4.9.1. Definition
The format of a Literal is illustrated in Figure 22.
+-------+
| ID |
| [MID] |
+-------+
Figure 22: Control Format
ID
This is the MID identifying the Literal. When a Literal item
is defined in an ADM this MID MUST NOT have either an ISSUER
field or a TAG field. When the Literal is defined outside of
an ADM, the MID MUST have an ISSUE field and, optionally, a
TAG field. This ID MUST NOT encapsulate a parameterized OID.
The low nibble of the MID flag byte for a literal is always
0x2.
4.9.2. Processing
Managers
o Store the MID for each ADM-defined Literal definition.
o Encode Literal MIDs in Controls to Agents, as appropriate.
Agents
o Store the MID for each ADM-defined Literal definition.
o Calculate the value of Literals where appropriate, such as when
generating a Report or when evaluating an Expression.
4.10. Operator
Operators in the AMP are always defined in the context of an ADM.
There is no concept of a user-defined operator, as operators
represent mathematical functions implemented by the firmware on an
Agent. Since Operators are pre-configured in Agents and Managers as
part of ADM support, their representation is simply the MID that
identifies them, similar to Primitive Data and Controls.
The ADM definition of an Operator MUST specify how many parameters
are expected. For example, the unary NOT Operator ("!") would accept
one parameter. The binary PLUS Operator ("+") would accept two
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parameters. A custom function to calculate the average of the last
10 samples of a data item would accept 10 parameters.
4.10.1. Definition
Operators are always evaluated in the context of an Expression. The
format of an Operator is illustrated in Figure 23.
+-------+
| ID |
| [MID] |
+-------+
Figure 23: Operator Format
ID
This is the MID identifying the Operator. Since Operators
are always defined solely in the context of an ADM, this MID
MUST NOT have either an ISSUER field or a TAG field. The low
nibble of the MID flag byte for Operators is always 0x3.
4.10.2. Processing
Managers
o Store the MID for each ADM-defined Operator definition.
o Encode Operator MIDs in Controls to Agents, as appropriate.
Agents
o Store the MID for each ADM-defined Operator definition.
o Store the number of parameters expected for each Operator.
o Calculate the value of applying an Operator to a given set of
parameters, such as when evaluating an Expression.
5. Data Type IDs and Enumerations
This section lists the data type IDs and enumerations for the data
types outlined in this section. IDs are the text abbreviations used
in this specification and in ADMs to identify data types.
Enumerations associate data types with an unsigned integer value.
These enumerations MUST be used whenever a data type is represented
as a numerical representation, such as the case with the TYPE BLOB of
a TDC.
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+----------------------------------+--------+-------------+---------+
| Data Type | ID | Enumeration | Numeric |
+----------------------------------+--------+-------------+---------+
| BYTE | BYTE | 0 | No |
| | | | |
| Signed 32-bit Integer | INT | 1 | Yes |
| | | | |
| Unsigned 32-bit Integer | UINT | 2 | Yes |
| | | | |
| Signed 64-bit Integer | VAST | 3 | Yes |
| | | | |
| Unsigned 64-bit Integer | UVAST | 4 | Yes |
| | | | |
| Single-Precision Floating Point | REAL32 | 5 | Yes |
| | | | |
| Double-Precision Floating Point | REAL64 | 6 | Yes |
| | | | |
| Character String | STR | 7 | No |
| | | | |
| Binary Large Object | BLOB | 8 | No |
| | | | |
| Self-Delineating Numerical Value | SDNV | 9 | No |
| | | | |
| Timestamp | TS | 10 | No |
| | | | |
| Data Collection | DC | 11 | No |
| | | | |
| Managed Identifier | MID | 12 | No |
| | | | |
| Managed Identifier Collection | MC | 13 | No |
| | | | |
| Expression | EXPR | 14 | No |
| | | | |
| Definition | DEF | 15 | No |
| | | | |
| Time-Based Rule | TRL | 16 | No |
| | | | |
| State-Based Rule | SRL | 17 | No |
| | | | |
| Typed Data Collection | TDC | 18 | No |
| | | | |
| Report | RPT | 19 | No |
| | | | |
| Macro | MACRO | 20 | No |
| | | | |
| Unknown Type | UNK | 21 | No |
+----------------------------------+--------+-------------+---------+
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AMP Data Type IDs and Enumerations
6. Application Data Model Template
6.1. Overview
An application data model (ADM) specifies the set of AMP components
associated with a particular application/protocol. The purpose of
the ADM is to provide a guaranteed interface for the management of an
application or protocol over AMP that is independent of the nuances
of its software implementation. In this respect, the ADM is
conceptually similar to the Managed Information Base (MIB) used by
SNMP, but contains additional information relating to command opcodes
and more expressive syntax for automated behavior.
Currently, the ADM is an organizing document and not used to
automatically generate software. As such, the ADM template lists the
kind of information that must be present in an ADM definition but
does not address mechanisms for automating implementations.
Each ADM specifies the globally unique identifiers and descriptions
for all data, controls, literals, and operators associated with the
application or protocol managed by the ADM. Any implementation
claiming compliance with a given ADM must compute all identified
data, perform identified controls, and understand identified literals
and operators.
6.2. Template
ADM definitions specify the metadata, data, controls, literals, and
operators associated with a managed application or protocol.
6.2.1. ADM Metadata
ADM metadata consist of the items necessary to uniquely identify the
ADM itself. The required metadata items include the following.
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+-------------+--------+-------------------------------------+------+
| Item | Type | Description | Req. |
+-------------+--------+-------------------------------------+------+
| Name | STR | The human-readable name of the ADM. | Y |
| | | | |
| Version | STR | Version of the ADM encoded as a | Y |
| | | string. | |
| | | | |
| OID | OID | ADMs provide an ordered list of | N |
| Nickname N | | nicknames that can be used by other | |
| | | MIDs in the ADM definition to | |
| | | defined compressed OIDs. There can | |
| | | an arbitrary number of nicknames | |
| | | defined for an ADM. | |
+-------------+--------+-------------------------------------+------+
Table 2: ADM Terminology
6.2.2. ADM Information Capture
The ADM Data Section consist of all components in the "data" category
associated with the managed application or protocol. The information
that must be provided for each of these items is as follows.
Name
Every component in an ADM MUST be given a human-readable,
consistent name that uniquely identifies the component in the
context of the application or protocol. These names will be used
by human-computer interfaces for manipulating components.
MID
The managed identifier that describes this data item. MIDs in
components identified by an ADM MUST NOT contain an issuer or a
tag value. In cases where a partial OID is specified, the ADM OID
prefix is presumed as the base. In cases where the OID is
parameterized, the parameter values are not included in the MID
definition in the ADM as parameters are provided at runtime by
implementations.
OID
A human-readable version of the OID encapsulated in the MID for
the component (e.g., 1.2.3.4). When a nickname is used to
represent an compressed OID, the nickname enumeration is included
in this field enclosed by square brackets. For example, if OID
nickname 0 refers to the OID prefix 1.2.3.4.5, then the OID
1.2.3.4.5.6 may be listed more compactly as [0].6
Description
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Every component in an ADM MUST be given a human-readable,
consistent description that provides a potential user with a
compact, effective summary of the component.
Type
For components that evaluate to a data value, the data type for
that value must be represented.
# Parameters
For components with a parameterized OID, the ADM MUST provide the
expected number of parameters. A value of 0 indicates that the
OID has no parameters and MUST NOT be used for any MID which has a
parameterized OID. When omitted, the number of parameters is
considered 0.
Parameter N Name
Each parameter of a parameterized component must be given a name.
Parameter N Description
Each parameter of a parameterized component must be given a
summary that describes how the parameter will be used by the
application or protocol.
Parameter N Type
Each parameter of a parameterized component must be given a type
that describes the structure capturing the parameter value.
Notably, while parameters in the OID form something similar to a
function prototype, there is no sense of function call or stack
and therefore all parameters should be considered as pass-by-
value.
7. The Agent ADM
The full set of Primitive Data, Computed Data, Reports, Controls,
Rules, Macros, Literals, and Operators that can be understood by an
AMP Agent have been separated into an AMP Agent ADM. Just as the AMP
uses ADMs to manage applications and protocols, the ADM model is also
used to implement the functionality of the Agent. As such, the AMP
message specification is limited to three basic communications:
- Adding an Agent to the list of managed devices known to a
Manager.
- Sending a Macro of one or more Controls to an Agent.
- Receiving a Report of one or more Report Entries from an Agent.
as outlined in Section 8.
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The entire management of a network can be performed using these three
messages and the configurations from associated ADMs.
8. Functional Specification
This section describes the format of the messages that comprise the
AMP protocol. When discussing the format/types of data that comprise
message fields, the following conventions are used.
8.1. Message Group Format
Individual messages within the AMP are combined into a single group
for communication with another AMP Actor. Messages within a group
MUST be received and applied as an atomic unit. The format of a
message group is illustrated in Figure 24. These message groups are
assumed communicated amongst Agents and Managers as the payloads of
encapsulating protocols which MAY provide additional security and
data integrity features.
+--------+-----------+-----------+ +-----------+
| # Msgs | Timestamp | Message 1 | ... | Message N |
| [SDNV] | [TS] | [VAR] | | [VAR] |
+--------+-----------+-----------+ +-----------+
Figure 24: AMP Message Group Format
# Msgs
The number of messages that are together in this message
group.
Timestamp
The creation time for this messaging group. This timestamp
MUST be an absolute time. Individual messages may have their
own creation timestamps based on their type, but the group
timestamp also serves as the default creation timestamp for
every message in the group.
Message N
The Nth message in the group.
8.2. Message Format
Each message identified in the AMP specification adheres to a common
message format, illustrated in Figure 25, consisting of a message
header, a message body, and an optional trailer.
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+--------+-------+---------+
| Header | Body | Trailer |
| [BYTE] | [VAR] | [VAR] |
| | | (opt.) |
+--------+-------+---------+
Figure 25: AMP Message Format
Header
The message header byte is shown in Figure 26. The header
identifies a message context and opcode as well as flags that
control whether a report should be generated on message
success (Ack) and whether a report should be generated on
message failure (Nack).
+--------+----+---+---------+-------+
|ACL Used|Nack|Ack| Context |Opcode |
+--------+----+---+---------+-------+
| 7 | 6 | 5 | 4 3 | 2 1 0 |
+--------+----+---+---------+-------+
MSB LSB
Figure 26: AMP Common Message Header
Opcode
The opcode field identifies the opcode of the
message, within the associated message context.
ACK Flag
The ACK flag describes whether successful application
of the message must generate an acknowledgement back
to the message sender. If this flag is set (1) then
the receiving actor MUST generate a report
communicating this status. Otherwise, the actor MAY
generate such a report based on other criteria.
NACK Flag
The NACK flag describes whether a failure applying
the message must generate an error notice back to the
message sender. If this flag is set (1) then the
receiving Actor MUST generate a report communicating
this status. Otherwise, the Actor MAY generate such
a report based on other criteria.
ACL Used Flag
The ACL used flag indicates whether the message has a
trailer associated with it that specifies the list of
AMP actors that may participate in the Actions or
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definitions associated with the message. This area
is still under development.
Body
The message body contains the information associated with the
given message.
Trailer
An OPTIONAL access control list (ACL) may be appended as a
trailer to a message. When present, the ACL for a message
identifiers the agents and managers that can be affected by
the definitions and actions contained within the message.
The explicit impact of an ACL is described in the context of
each message below. When an ACL trailer is not present, the
message results may be visible to any AMP Actor in the
network, pursuant to other security protocol implementations.
8.3. Register Agent (0x00)
The Register Agent message is used to inform a AMP manager of the
presence of another agent in the network.
+----------+
| Agent ID |
| [SDNV] |
+----------+
Figure 27: Register Agent Message Body
Agent ID
The Agent ID MUST represent the unique address of the Agent
in whatever protocol is used to communicate with the Agent.
8.4. Data Report (0x12)
Data reports include a listing of one or more data items collected
from a managed device. These reports may include atomic data,
computed data, or any report definition known to the generating
device. Each message is a concatenation of ID/Data definitions with
the overall message length assumed to be captured in the underlying
transport container.
+------+----------+-------+-------+ +-------+
| Time | Num Rpts | RPT 1 | RPT 2 | | RPT N |
| [TS] | [SDNV] | [RPT] | [RPT] | ... | [RPT] |
+------+----------+-------+-------+ +-------+
Figure 28: Data Report Message Body
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Time
The time at which the report was generated by the AMP Actor.
Num Rpts
The number of reports in the data report message.
RPT N
The Nth report.
8.5. Perform Control (0x20)
The perform control method causes the receiving AMP Actor to apply
one or more pre-configured controls provided in the form of a Macro.
+-------+-----------+
| Start | Controls |
| [TS] | [MC] |
+-------+-----------+
Figure 29: Perform Control Message Body
Start
The time at which the Macro should be run.
Controls
The collection of controls (Macro) to be run by the AMP
Actor. The MID identifying a control will contain the
parameters for the control (if any) through the use of a
parameterized OID captured within the MIDs in the MC.
9. IANA Considerations
At this time, this protocol has no fields registered by IANA.
10. Security Considerations
Security within the AMP exists in two layers: transport layer
security and access control.
Transport-layer security addresses the questions of authentication,
integrity, and confidentiality associated with the transport of
messages between and amongst Managers and Agents. This security is
applied before any particular Actor in the system receives data and,
therefore, is outside of the scope of this document.
Finer grain application security is done via ACLs provided in the AMP
message headers.
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11. References
11.1. Informative References
[AMA] Birrane, E., "Asynchronous Management Architecture",
draft-birrane-dtn-ama-00 (work in progress), August 2015.
[I-D.irtf-dtnrg-dtnmp]
Birrane, E. and V. Ramachandran, "Delay Tolerant Network
Management Protocol", draft-irtf-dtnrg-dtnmp-01 (work in
progress), December 2014.
11.2. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6256] Eddy, W. and E. Davies, "Using Self-Delimiting Numeric
Values in Protocols", RFC 6256, DOI 10.17487/RFC6256, May
2011, <http://www.rfc-editor.org/info/rfc6256>.
Author's Address
Edward J. Birrane
Johns Hopkins Applied Physics Laboratory
Email: Edward.Birrane@jhuapl.edu
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