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INFORMATIONAL
Network Working Group D. Harrington
Request for Comments: 5706 HuaweiSymantec USA
Category: Informational November 2009
Guidelines for Considering Operations and Management of
New Protocols and Protocol Extensions
Abstract
New protocols or protocol extensions are best designed with due
consideration of the functionality needed to operate and manage the
protocols. Retrofitting operations and management is sub-optimal.
The purpose of this document is to provide guidance to authors and
reviewers of documents that define new protocols or protocol
extensions regarding aspects of operations and management that should
be considered.
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (c) 2009 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
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
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not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
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Table of Contents
1. Introduction ....................................................4
1.1. Designing for Operations and Management ....................4
1.2. This Document ..............................................5
1.3. Motivation .................................................5
1.4. Background .................................................6
1.5. Available Management Technologies ..........................7
1.6. Terminology ................................................8
2. Operational Considerations - How Will the New Protocol
Fit into the Current Environment? ...............................8
2.1. Operations .................................................9
2.2. Installation and Initial Setup .............................9
2.3. Migration Path ............................................10
2.4. Requirements on Other Protocols and Functional
Components ................................................11
2.5. Impact on Network Operation ...............................11
2.6. Verifying Correct Operation ...............................12
3. Management Considerations - How Will the Protocol Be Managed? ..12
3.1. Interoperability ..........................................14
3.2. Management Information ....................................17
3.2.1. Information Model Design ...........................18
3.3. Fault Management ..........................................18
3.3.1. Liveness Detection and Monitoring ..................19
3.3.2. Fault Determination ................................19
3.3.3. Root Cause Analysis ................................20
3.3.4. Fault Isolation ....................................20
3.4. Configuration Management ..................................20
3.4.1. Verifying Correct Operation ........................22
3.5. Accounting Management .....................................22
3.6. Performance Management ....................................22
3.6.1. Monitoring the Protocol ............................23
3.6.2. Monitoring the Device ..............................24
3.6.3. Monitoring the Network .............................24
3.6.4. Monitoring the Service .............................25
3.7. Security Management .......................................25
4. Documentation Guidelines .......................................26
4.1. Recommended Discussions ...................................27
4.2. Null Manageability Considerations Sections ................27
4.3. Placement of Operations and Manageability
Considerations Sections ...................................28
5. Security Considerations ........................................28
6. Acknowledgements ...............................................28
7. Informative References .........................................29
Appendix A. Operations and Management Review Checklist ..........32
A.1. Operational Considerations ................................32
A.2. Management Considerations ................................34
A.3. Documentation .............................................35
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1. Introduction
Often when new protocols or protocol extensions are developed, not
enough consideration is given to how the protocol will be deployed,
operated, and managed. Retrofitting operations and management
mechanisms is often hard and architecturally unpleasant, and certain
protocol design choices may make deployment, operations, and
management particularly hard. This document provides guidelines to
help protocol designers and working groups consider the operations
and management functionality for their new IETF protocol or protocol
extension at an earlier phase.
1.1. Designing for Operations and Management
The operational environment and manageability of the protocol should
be considered from the start when new protocols are designed.
Most of the existing IETF management standards are focused on using
Structure of Management Information (SMI)-based data models (MIB
modules) to monitor and manage networking devices. As the Internet
has grown, IETF protocols have addressed a constantly growing set of
needs, such as web servers, collaboration services, and applications.
The number of IETF management technologies has been expanding and the
IETF management strategy has been changing to address the emerging
management requirements. The discussion of emerging sets of
management requirements has a long history in the IETF. The set of
management protocols you should use depends on what you are managing.
Protocol designers should consider which operations and management
needs are relevant to their protocol, document how those needs could
be addressed, and suggest (preferably standard) management protocols
and data models that could be used to address those needs. This is
similar to a working group (WG) that considers which security threats
are relevant to their protocol, documents how threats should be
mitigated, and then suggests appropriate standard protocols that
could mitigate the threats.
When a WG considers operation and management functionality for a
protocol, the document should contain enough information for readers
to understand how the protocol will be deployed and managed. The WG
should expect that considerations for operations and management may
need to be updated in the future, after further operational
experience has been gained.
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1.2. This Document
This document makes a distinction between "Operational
Considerations" and "Management Considerations", although the two are
closely related. The section on manageability is focused on
management technology, such as how to utilize management protocols
and how to design management data models. The operational
considerations apply to operating the protocol within a network, even
if there were no management protocol actively being used.
The purpose of this document is to provide guidance about what to
consider when thinking about the management and deployment of a new
protocol, and to provide guidance about documenting the
considerations. The following guidelines are designed to help
writers provide a reasonably consistent format for such
documentation. Separate manageability and operational considerations
sections are desirable in many cases, but their structure and
location is a decision that can be made from case to case.
This document does not impose a solution, imply that a formal data
model is needed, or imply that using a specific management protocol
is mandatory. If protocol designers conclude that the technology can
be managed solely by using proprietary command line interfaces (CLIs)
and that no structured or standardized data model needs to be in
place, this might be fine, but it is a decision that should be
explicit in a manageability discussion -- that this is how the
protocol will need to be operated and managed. Protocol designers
should avoid having manageability pushed for a later phase of the
development of the standard.
In discussing the importance of considering operations and
management, this document sets forth a list of guidelines and a
checklist of questions to consider (see Appendix A), which a protocol
designer or reviewer can use to evaluate whether the protocol and
documentation address common operations and management needs.
Operations and management are highly dependent on their environment,
so most guidelines are subjective rather than objective.
1.3. Motivation
For years the IETF community has used the IETF Standard Management
Framework, including the Simple Network Management Protocol
[RFC3410], the Structure of Management Information [RFC2578], and MIB
data models for managing new protocols. As the Internet has evolved,
operators have found the reliance on one protocol and one schema
language for managing all aspects of the Internet inadequate. The
IESG policy to require working groups to write a MIB module to
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provide manageability for new protocols is being replaced by a policy
that is more open to using a variety of management protocols and data
models designed to achieve different goals.
This document provides some initial guidelines for considering
operations and management in an IETF Management Framework that
consists of multiple protocols and multiple data-modeling languages,
with an eye toward being flexible while also striving for
interoperability.
Fully new protocols may require significant consideration of expected
operations and management, while extensions to existing, widely
deployed protocols may have established de facto operations and
management practices that are already well understood.
Suitable management approaches may vary for different areas, working
groups, and protocols in the IETF. This document does not prescribe
a fixed solution or format in dealing with operational and management
aspects of IETF protocols. However, these aspects should be
considered for any IETF protocol because we develop technologies and
protocols to be deployed and operated in the real-world Internet. It
is fine if a WG decides that its protocol does not need interoperable
management or no standardized data model, but this should be a
deliberate decision, not the result of omission. This document
provides some guidelines for those considerations.
1.4. Background
There have been a significant number of efforts, meetings, and
documents that are related to Internet operations and management.
Some of them are mentioned here to help protocol designers find
documentation of previous efforts. Hopefully, providing these
references will help the IETF avoid rehashing old discussions and
reinventing old solutions.
In 1988, the IAB published "IAB Recommendations for the Development
of Internet Network Management Standards" [RFC1052], which
recommended a solution that, where possible, deliberately separates
modeling languages, data models, and the protocols that carry data.
The goal is to allow standardized information and data models to be
used by different protocols.
In 2001, Operations and Management Area design teams were created to
document requirements related to the configuration of IP-based
networks. One output was "Requirements for Configuration Management
of IP-based Networks" [RFC3139].
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In 2003, the Internet Architecture Board (IAB) held a workshop on
Network Management [RFC3535] that discussed the strengths and
weaknesses of some IETF network management protocols and compared
them to operational needs, especially configuration.
One issue discussed was the user-unfriendliness of the binary format
of SNMP [RFC3410] and Common Open Policy Service (COPS) Usage for
Policy Provisioning (COPS-PR) [RFC3084], and it was recommended that
the IETF explore an XML-based Structure of Management Information and
an XML-based protocol for configuration.
Another conclusion was that the tools for event/alarm correlation and
for root cause analysis and logging are not sufficient and that there
is a need to support a human interface and a programmatic interface.
The IETF decided to standardize aspects of the de facto standard for
system-logging security and programmatic support.
In 2006, the IETF discussed whether the Management Framework should
be updated to accommodate multiple IETF schema languages for
describing the structure of management information and multiple IETF
standard protocols for performing management tasks. The IESG asked
that a document be written to discuss how protocol designers and
working groups should address management in this emerging multi-
protocol environment. This document and some planned companion
documents attempt to provide some guidelines for navigating the
rapidly shifting operating and management environments.
1.5. Available Management Technologies
The IETF has a number of standard management protocols available that
are suitable for different purposes. These include:
Simple Network Management Protocol - SNMP [RFC3410]
Syslog [RFC5424]
Remote Authentication Dial-In User Service - RADIUS [RFC2865]
DIAMETER [RFC3588]
Network Configuration Protocol - NETCONF [RFC4741]
IP Flow Information Export - IPFIX [RFC5101]
A planned supplement to this document will discuss these protocol
standards, discuss some standard information and data models for
specific functionality, and provide pointers to the documents that
define them.
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1.6. Terminology
This document deliberately does not use the (capitalized) keywords
described in RFC 2119 [RFC2119]. RFC 2119 states the keywords must
only be used where it is actually required for interoperation or to
limit behavior which has potential for causing harm (e.g., limiting
retransmissions). For example, they must not be used to try to
impose a particular method on implementers where the method is not
required for interoperability. This informational document is a set
of guidelines based on current practices of **some** protocol
designers and operators. This document is biased toward router
operations and management and some advice may not be directly
applicable to protocols with a different purpose, such as application
server protocols. This document **does not** describe
interoperability requirements, so the capitalized keywords from RFC
2119 do not apply here.
o CLI: Command Line Interface
o Data model: a mapping of the contents of an information model into
a form that is specific to a particular type of data store or
repository [RFC3444].
o Information model: an abstraction and representation of the
entities in a managed environment, their properties, attributes
and operations, and the way that they relate to each other. It is
independent of any specific repository, software usage, protocol,
or platform [RFC3444].
o New protocol: includes new protocols, protocol extensions, data
models, or other functionality being designed.
o Protocol designer: represents individuals and working groups
involved in the development of new protocols or extensions.
2. Operational Considerations - How Will the New Protocol Fit into the
Current Environment?
Designers of a new protocol should carefully consider the operational
aspects. To ensure that a protocol will be practical to deploy in
the real world, it is not enough to merely define it very precisely
in a well-written document. Operational aspects will have a serious
impact on the actual success of a protocol. Such aspects include bad
interactions with existing solutions, a difficult upgrade path,
difficulty of debugging problems, difficulty configuring from a
central database, or a complicated state diagram that operations
staff will find difficult to understand.
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BGP flap damping [RFC2439] is an example. It was designed to block
high-frequency route flaps; however, the design did not consider the
existence of BGP path exploration / slow convergence. In real
operations, path exploration caused false flap damping, resulting in
loss of reachability. As a result, many networks turned flap damping
off.
2.1. Operations
Protocol designers can analyze the operational environment and mode
of work in which the new protocol or extension will work. Such an
exercise need not be reflected directly by text in their document,
but could help in visualizing how to apply the protocol in the
Internet environments where it will be deployed.
A key question is how the protocol can operate "out of the box". If
implementers are free to select their own defaults, the protocol
needs to operate well with any choice of values. If there are
sensible defaults, these need to be stated.
There may be a need to support a human interface, e.g., for
troubleshooting, and a programmatic interface, e.g., for automated
monitoring and root cause analysis. The application programming
interfaces and the human interfaces might benefit from being similar
to ensure that the information exposed by these two interfaces is
consistent when presented to an operator. Identifying consistent
methods of determining information, such as what gets counted in a
specific counter, is relevant.
Protocol designers should consider what management operations are
expected to be performed as a result of the deployment of the
protocol -- such as whether write operations will be allowed on
routers and on hosts, or whether notifications for alarms or other
events will be expected.
2.2. Installation and Initial Setup
Anything that can be configured can be misconfigured. "Architectural
Principles of the Internet" [RFC1958], Section 3.8, states: "Avoid
options and parameters whenever possible. Any options and parameters
should be configured or negotiated dynamically rather than manually."
To simplify configuration, protocol designers should consider
specifying reasonable defaults, including default modes and
parameters. For example, it could be helpful or necessary to specify
default values for modes, timers, default state of logical control
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variables, default transports, and so on. Even if default values are
used, it must be possible to retrieve all the actual values or at
least an indication that known default values are being used.
Protocol designers should consider how to enable operators to
concentrate on the configuration of the network as a whole rather
than on individual devices. Of course, how one accomplishes this is
the hard part.
It is desirable to discuss the background of chosen default values,
or perhaps why a range of values makes sense. In many cases, as
technology changes, the values in an RFC might make less and less
sense. It is very useful to understand whether defaults are based on
best current practice and are expected to change as technologies
advance or whether they have a more universal value that should not
be changed lightly. For example, the default interface speed might
be expected to change over time due to increased speeds in the
network, and cryptographical algorithms might be expected to change
over time as older algorithms are "broken".
It is extremely important to set a sensible default value for all
parameters.
The default value should stay on the conservative side rather than on
the "optimizing performance" side (example: the initial RTT and
RTTvar values of a TCP connection).
For those parameters that are speed-dependent, instead of using a
constant, try to set the default value as a function of the link
speed or some other relevant factors. This would help reduce the
chance of problems caused by technology advancement.
2.3. Migration Path
If the new protocol is a new version of an existing one, or if it is
replacing another technology, the protocol designer should consider
how deployments should transition to the new protocol. This should
include coexistence with previously deployed protocols and/or
previous versions of the same protocol, incompatibilities between
versions, translation between versions, and side effects that might
occur. Are older protocols or versions disabled or do they coexist
in the network with the new protocol?
Many protocols benefit from being incrementally deployable --
operators may deploy aspects of a protocol before deploying the
protocol fully.
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2.4. Requirements on Other Protocols and Functional Components
Protocol designers should consider the requirements that the new
protocol might put on other protocols and functional components and
should also document the requirements from other protocols and
functional elements that have been considered in designing the new
protocol.
These considerations should generally remain illustrative to avoid
creating restrictions or dependencies, or potentially impacting the
behavior of existing protocols, or restricting the extensibility of
other protocols, or assuming other protocols will not be extended in
certain ways. If restrictions or dependencies exist, they should be
stated.
For example, the design of the Resource ReSerVation Protocol (RSVP)
[RFC2205] required each router to look at the RSVP PATH message and,
if the router understood RSVP, add its own address to the message to
enable automatic tunneling through non-RSVP routers. But in reality,
routers cannot look at an otherwise normal IP packet and potentially
take it off the fast path! The initial designers overlooked that a
new "deep packet inspection" requirement was being put on the
functional components of a router. The "router alert" option
([RFC2113], [RFC2711]) was finally developed to solve this problem
for RSVP and other protocols that require the router to take some
packets off the fast-forwarding path. Yet, router alert has its own
problems in impacting router performance.
2.5. Impact on Network Operation
The introduction of a new protocol or extensions to an existing
protocol may have an impact on the operation of existing networks.
Protocol designers should outline such impacts (which may be
positive), including scaling concerns and interactions with other
protocols. For example, a new protocol that doubles the number of
active, reachable addresses in use within a network might need to be
considered in the light of the impact on the scalability of the
interior gateway protocols operating within the network.
A protocol could send active monitoring packets on the wire. If we
don't pay attention, we might get very good accuracy, but could send
too many active monitoring packets.
The protocol designer should consider the potential impact on the
behavior of other protocols in the network and on the traffic levels
and traffic patterns that might change, including specific types of
traffic, such as multicast. Also, consider the need to install new
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components that are added to the network as a result of changes in
the configuration, such as servers performing auto-configuration
operations.
The protocol designer should consider also the impact on
infrastructure applications like DNS [RFC1034], the registries, or
the size of routing tables. For example, Simple Mail Transfer
Protocol (SMTP) [RFC5321] servers use a reverse DNS lookup to filter
out incoming connection requests. When Berkeley installed a new spam
filter, their mail server stopped functioning because of overload of
the DNS cache resolver.
The impact on performance may also be noted -- increased delay or
jitter in real-time traffic applications, or increased response time
in client-server applications when encryption or filtering are
applied.
It is important to minimize the impact caused by configuration
changes. Given configuration A and configuration B, it should be
possible to generate the operations necessary to get from A to B with
minimal state changes and effects on network and systems.
2.6. Verifying Correct Operation
The protocol designer should consider techniques for testing the
effect that the protocol has had on the network by sending data
through the network and observing its behavior (aka active
monitoring). Protocol designers should consider how the correct end-
to-end operation of the new protocol in the network can be tested
actively and passively, and how the correct data or forwarding plane
function of each network element can be verified to be working
properly with the new protocol. Which metrics are of interest?
Having simple protocol status and health indicators on network
devices is a recommended means to check correct operation.
3. Management Considerations - How Will the Protocol Be Managed?
The considerations of manageability should start from identifying the
entities to be managed, as well as how the managed protocol is
supposed to be installed, configured, and monitored.
Considerations for management should include a discussion of what
needs to be managed, and how to achieve various management tasks.
Where are the managers and what type of management interfaces and
protocols will they need? The "write a MIB module" approach to
considering management often focuses on monitoring a protocol
endpoint on a single device. A MIB module document typically only
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considers monitoring properties observable at one end, while the
document does not really cover managing the *protocol* (the
coordination of multiple ends), and does not even come near managing
the *service* (which includes a lot of stuff that is very far away
from the box). This is exactly what operators hate -- you need to be
able to manage both ends. As [RFC3535] says, "MIB modules can often
be characterized as a list of ingredients without a recipe".
The management model should take into account factors such as:
o What type of management entities will be involved (agents, network
management systems)?
o What is the possible architecture (client-server, manager-agent,
poll-driven or event-driven, auto-configuration, two levels or
hierarchical)?
o What are the management operations (initial configuration, dynamic
configuration, alarm and exception reporting, logging, performance
monitoring, performance reporting, debugging)?
o How are these operations performed (locally, remotely, atomic
operation, scripts)? Are they performed immediately or are they
time scheduled or event triggered?
Protocol designers should consider how the new protocol will be
managed in different deployment scales. It might be sensible to use
a local management interface to manage the new protocol on a single
device, but in a large network, remote management using a centralized
server and/or using distributed management functionality might make
more sense. Auto-configuration and default parameters might be
possible for some new protocols.
Management needs to be considered not only from the perspective of a
device, but also from the perspective of network and service
management. A service might be network and operational functionality
derived from the implementation and deployment of a new protocol.
Often an individual network element is not aware of the service being
delivered.
WGs should consider how to configure multiple related/co-operating
devices and how to back off if one of those configurations fails or
causes trouble. NETCONF [RFC4741] addresses this in a generic manner
by allowing an operator to lock the configuration on multiple
devices, perform the configuration settings/changes, check that they
are OK (undo if not), and then unlock the devices.
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Techniques for debugging protocol interactions in a network must be
part of the network-management discussion. Implementation source
code should be debugged before ever being added to a network, so
asserts and memory dumps do not normally belong in management data
models. However, debugging on-the-wire interactions is a protocol
issue: while the messages can be seen by sniffing, it is enormously
helpful if a protocol specification supports features that make
debugging of network interactions and behaviors easier. There could
be alerts issued when messages are received or when there are state
transitions in the protocol state machine. However, the state
machine is often not part of the on-the-wire protocol; the state
machine explains how the protocol works so that an implementer can
decide, in an implementation-specific manner, how to react to a
received event.
In a client/server protocol, it may be more important to instrument
the server end of a protocol than the client end, since the
performance of the server might impact more nodes than the
performance of a specific client.
3.1. Interoperability
Just as when deploying protocols that will inter-connect devices,
management interoperability should be considered -- whether across
devices from different vendors, across models from the same vendor,
or across different releases of the same product. Management
interoperability refers to allowing information sharing and
operations between multiple devices and multiple management
applications, often from different vendors. Interoperability allows
for the use of third-party applications and the outsourcing of
management services.
Some product designers and protocol designers assume that if a device
can be managed individually using a command line interface or a web
page interface, that such a solution is enough. But when equipment
from multiple vendors is combined into a large network, scalability
of management may become a problem. It may be important to have
consistency in the management interfaces so network-wide operational
processes can be automated. For example, a single switch might be
easily managed using an interactive web interface when installed in a
single-office small business, but when, say, a fast-food company
installs similar switches from multiple vendors in hundreds or
thousands of individual branches and wants to automate monitoring
them from a central location, monitoring vendor- and model-specific
web pages would be difficult to automate.
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The primary goal is the ability to roll out new useful functions and
services in a way in which they can be managed in a scalable manner,
where one understands the network impact (as part of the total cost
of operations) of that service.
Getting everybody to agree on a single syntax and an associated
protocol to do all management has proven to be difficult. So
management systems tend to speak whatever the boxes support, whether
or not the IETF likes this. The IETF is moving from support for one
schema language for modeling the structure of management information
(Structure of Management Information Version 2 (SMIv2) [RFC2578]) and
one simple network management protocol (Simple Network Management
Protocol (SNMP) [RFC3410]) towards support for additional schema
languages and additional management protocols suited to different
purposes. Other Standard Development Organizations (e.g., the
Distributed Management Task Force - DMTF, the Tele-Management Forum -
TMF) also define schemas and protocols for management and these may
be more suitable than IETF schemas and protocols in some cases. Some
of the alternatives being considered include:
o XML Schema Definition [W3C.REC-xmlschema-0-20010502]
and
o NETCONF Configuration Protocol [RFC4741]
o the IP Flow Information Export (IPFIX) Protocol [RFC5101]) for
usage accounting
o the syslog protocol [RFC5424] for logging
Interoperability needs to be considered on the syntactic level and
the semantic level. While it can be irritating and time-consuming,
application designers, including operators who write their own
scripts, can make their processing conditional to accommodate
syntactic differences across vendors, models, or releases of product.
Semantic differences are much harder to deal with on the manager side
-- once you have the data, its meaning is a function of the managed
entity.
Information models are helpful to try to focus interoperability on
the semantic level -- they establish standards for what information
should be gathered and how gathered information might be used,
regardless of which management interface carries the data or which
vendor produces the product. The use of an information model might
help improve the ability of operators to correlate messages in
different protocols where the data overlaps, such as a syslog message
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and an SNMP notification about the same event. An information model
might identify which error conditions should be counted separately
and which error conditions can be counted together in a single
counter. Then, whether the counter is gathered via SNMP, a CLI
command, or a syslog message, the counter will have the same meaning.
Protocol designers should consider which information might be useful
for managing the new protocol or protocol extensions.
IM --> conceptual/abstract model
| for designers and operators
+----------+---------+
| | |
DM DM DM --> concrete/detailed model
for implementers
Information Models and Data Models
Figure 1
Protocol designers may decide an information model or data model
would be appropriate for managing the new protocol or protocol
extensions.
"On the Difference between Information Models and Data Models"
[RFC3444] can be helpful in determining what information to consider
regarding information models (IMs), as compared to data models (DMs).
Information models should come from the protocol WGs and include
lists of events, counters, and configuration parameters that are
relevant. There are a number of information models contained in
protocol WG RFCs. Some examples:
o [RFC3060] - Policy Core Information Model version 1
o [RFC3290] - An Informal Management Model for Diffserv Routers
o [RFC3460] - Policy Core Information Model Extensions
o [RFC3585] - IPsec Configuration Policy Information Model
o [RFC3644] - Policy Quality of Service Information Model
o [RFC3670] - Information Model for Describing Network Device QoS
Datapath Mechanisms
o [RFC3805] - Printer MIB v2 (contains both an IM and a DM)
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Management protocol standards and management data model standards
often contain compliance clauses to ensure interoperability.
Manageability considerations should include discussion of which level
of compliance is expected to be supported for interoperability.
3.2. Management Information
Languages used to describe an information model can influence the
nature of the model. Using a particular data-modeling language, such
as the SMIv2, influences the model to use certain types of
structures, such as two-dimensional tables. This document recommends
using English text (the official language for IETF specifications) to
describe an information model. A sample data model could be
developed to demonstrate the information model.
A management information model should include a discussion of what is
manageable, which aspects of the protocol need to be configured, what
types of operations are allowed, what protocol-specific events might
occur, which events can be counted, and for which events an operator
should be notified.
Operators find it important to be able to make a clear distinction
between configuration data, operational state, and statistics. They
need to determine which parameters were administratively configured
and which parameters have changed since configuration as the result
of mechanisms such as routing protocols or network management
protocols. It is important to be able to separately fetch current
configuration information, initial configuration information,
operational state information, and statistics from devices; to be
able to compare current state to initial state; and to compare
information between devices. So when deciding what information
should exist, do not conflate multiple information elements into a
single element.
What is typically difficult to work through are relationships between
abstract objects. Ideally, an information model would describe the
relationships between the objects and concepts in the information
model.
Is there always just one instance of this object or can there be
multiple instances? Does this object relate to exactly one other
object or may it relate to multiple? When is it possible to change a
relationship?
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Do objects (such as rows in tables) share fate? For example, if a
row in table A must exist before a related row in table B can be
created, what happens to the row in table B if the related row in
table A is deleted? Does the existence of relationships between
objects have an impact on fate sharing?
3.2.1. Information Model Design
This document recommends keeping the information model as simple as
possible by applying the following criteria:
1. Start with a small set of essential objects and add only as
further objects are needed.
2. Require that objects be essential for management.
3. Consider evidence of current use and/or utility.
4. Limit the total number of objects.
5. Exclude objects that are simply derivable from others in this or
other information models.
6. Avoid causing critical sections to be heavily instrumented. A
guideline is one counter per critical section per layer.
3.3. Fault Management
The protocol designer should document the basic faults and health
indicators that need to be instrumented for the new protocol, as well
as the alarms and events that must be propagated to management
applications or exposed through a data model.
The protocol designer should consider how fault information will be
propagated. Will it be done using asynchronous notifications or
polling of health indicators?
If notifications are used to alert operators to certain conditions,
then the protocol designer should discuss mechanisms to throttle
notifications to prevent congestion and duplications of event
notifications. Will there be a hierarchy of faults, and will the
fault reporting be done by each fault in the hierarchy, or will only
the lowest fault be reported and the higher levels be suppressed?
Should there be aggregated status indicators based on concatenation
of propagated faults from a given domain or device?
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SNMP notifications and syslog messages can alert an operator when an
aspect of the new protocol fails or encounters an error or failure
condition, and SNMP is frequently used as a heartbeat monitor.
Should the event reporting provide guaranteed accurate delivery of
the event information within a given (high) margin of confidence?
Can we poll the latest events in the box?
3.3.1. Liveness Detection and Monitoring
Protocol designers should always build in basic testing features
(e.g., ICMP echo, UDP/TCP echo service, NULL RPCs (remote procedure
calls)) that can be used to test for liveness, with an option to
enable and disable them.
Mechanisms for monitoring the liveness of the protocol and for
detecting faults in protocol connectivity are usually built into
protocols. In some cases, mechanisms already exist within other
protocols responsible for maintaining lower-layer connectivity (e.g.,
ICMP echo), but often new procedures are required to detect failures
and to report rapidly, allowing remedial action to be taken.
These liveness monitoring mechanisms do not typically require
additional management capabilities. However, when a system detects a
fault, there is often a requirement to coordinate recovery action
through management applications or at least to record the fact in an
event log.
3.3.2. Fault Determination
It can be helpful to describe how faults can be pinpointed using
management information. For example, counters might record instances
of error conditions. Some faults might be able to be pinpointed by
comparing the outputs of one device and the inputs of another device,
looking for anomalies. Protocol designers should consider what
counters should count. If a single counter provided by vendor A
counts three types of error conditions, while the corresponding
counter provided by vendor B counts seven types of error conditions,
these counters cannot be compared effectively -- they are not
interoperable counters.
How do you distinguish between faulty messages and good messages?
Would some threshold-based mechanisms, such as Remote Monitoring
(RMON) events/alarms or the EVENT-MIB, be usable to help determine
error conditions? Are SNMP notifications for all events needed, or
are there some "standard" notifications that could be used? Or can
relevant counters be polled as needed?
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3.3.3. Root Cause Analysis
Root cause analysis is about working out where in the network the
fault is. For example, if end-to-end data delivery is failing
(reported by a notification), root cause analysis can help find the
failed link or node in the end-to-end path.
3.3.4. Fault Isolation
It might be useful to isolate or quarantine faults, such as isolating
a device that emits malformed messages that are necessary to
coordinate connections properly. This might be able to be done by
configuring next-hop devices to drop the faulty messages to prevent
them from entering the rest of the network.
3.4. Configuration Management
A protocol designer should document the basic configuration
parameters that need to be instrumented for a new protocol, as well
as default values and modes of operation.
What information should be maintained across reboots of the device,
or restarts of the management system?
"Requirements for Configuration Management of IP-based Networks"
[RFC3139] discusses requirements for configuration management,
including discussion of different levels of management, high-level
policies, network-wide configuration data, and device-local
configuration. Network configuration is not just multi-device push
or pull. It is knowing that the configurations being pushed are
semantically compatible. Is the circuit between them configured
compatibly on both ends? Is the IS-IS metric the same? ... Now
answer those questions for 1,000 devices.
A number of efforts have existed in the IETF to develop policy-based
configuration management. "Terminology for Policy-Based Management"
[RFC3198] was written to standardize the terminology across these
efforts.
Implementations should not arbitrarily modify configuration data. In
some cases (such as access control lists (ACLs)), the order of data
items is significant and comprises part of the configured data. If a
protocol designer defines mechanisms for configuration, it would be
desirable to standardize the order of elements for consistency of
configuration and of reporting across vendors and across releases
from vendors.
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There are two parts to this:
1. A Network Management System (NMS) could optimize ACLs for
performance reasons.
2. Unless the device/NMS systems has correct rules / a lot of
experience, reordering ACLs can lead to a huge security issue.
Network-wide configurations may be stored in central master databases
and transformed into formats that can be pushed to devices, either by
generating sequences of CLI commands or complete configuration files
that are pushed to devices. There is no common database schema for
network configuration, although the models used by various operators
are probably very similar. Many operators consider it desirable to
extract, document, and standardize the common parts of these network-
wide configuration database schemas. A protocol designer should
consider how to standardize the common parts of configuring the new
protocol, while recognizing that vendors may also have proprietary
aspects of their configurations.
It is important to enable operators to concentrate on the
configuration of the network as a whole, rather than individual
devices. Support for configuration transactions across a number of
devices could significantly simplify network configuration
management. The ability to distribute configurations to multiple
devices, or to modify candidate configurations on multiple devices,
and then activate them in a near-simultaneous manner might help.
Protocol designers can consider how it would make sense for their
protocol to be configured across multiple devices. Configuration
templates might also be helpful.
Consensus of the 2002 IAB Workshop [RFC3535] was that textual
configuration files should be able to contain international
characters. Human-readable strings should utilize UTF-8, and
protocol elements should be in case-insensitive ASCII.
A mechanism to dump and restore configurations is a primitive
operation needed by operators. Standards for pulling and pushing
configurations from/to devices are desirable.
Given configuration A and configuration B, it should be possible to
generate the operations necessary to get from A to B with minimal
state changes and effects on network and systems. It is important to
minimize the impact caused by configuration changes.
A protocol designer should consider the configurable items that exist
for the control of function via the protocol elements described in
the protocol specification. For example, sometimes the protocol
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requires that timers can be configured by the operator to ensure
specific policy-based behavior by the implementation. These timers
should have default values suggested in the protocol specification
and may not need to be otherwise configurable.
3.4.1. Verifying Correct Operation
An important function that should be provided is guidance on how to
verify the correct operation of a protocol. A protocol designer
could suggest techniques for testing the impact of the protocol on
the network before it is deployed as well as techniques for testing
the effect that the protocol has had on the network after being
deployed.
Protocol designers should consider how to test the correct end-to-end
operation of the service or network, how to verify the correct
functioning of the protocol, and whether that is verified by testing
the service function and/or by testing the forwarding function of
each network element. This may be achieved through status and
statistical information gathered from devices.
3.5. Accounting Management
A protocol designer should consider whether it would be appropriate
to collect usage information related to this protocol and, if so,
what usage information would be appropriate to collect.
"Introduction to Accounting Management" [RFC2975] discusses a number
of factors relevant to monitoring usage of protocols for purposes of
capacity and trend analysis, cost allocation, auditing, and billing.
The document also discusses how some existing protocols can be used
for these purposes. These factors should be considered when
designing a protocol whose usage might need to be monitored or when
recommending a protocol to do usage accounting.
3.6. Performance Management
From a manageability point of view, it is important to determine how
well a network deploying the protocol or technology defined in the
document is doing. In order to do this, the network operators need
to consider information that would be useful to determine the
performance characteristics of a deployed system using the target
protocol.
The IETF, via the Benchmarking Methodology WG (BMWG), has defined
recommendations for the measurement of the performance
characteristics of various internetworking technologies in a
laboratory environment, including the systems or services that are
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built from these technologies. Each benchmarking recommendation
describes the class of equipment, system, or service being addressed;
discusses the performance characteristics that are pertinent to that
class; clearly identifies a set of metrics that aid in the
description of those characteristics; specifies the methodologies
required to collect said metrics; and lastly, presents the
requirements for the common, unambiguous reporting of benchmarking
results. Search for "benchmark" in the RFC search tool.
Performance metrics may be useful in multiple environments and for
different protocols. The IETF, via the IP Performance Monitoring
(IPPM) WG, has developed a set of standard metrics that can be
applied to the quality, performance, and reliability of Internet data
delivery services. These metrics are designed such that they can be
performed by network operators, end users, or independent testing
groups. The existing metrics might be applicable to the new
protocol. Search for "metric" in the RFC search tool. In some
cases, new metrics need to be defined. It would be useful if the
protocol documentation identified the need for such new metrics. For
performance monitoring, it is often important to report the time
spent in a state, rather than reporting the current state. Snapshots
are of less value for performance monitoring.
There are several parts to performance management to be considered:
protocol monitoring, device monitoring (the impact of the new
protocol / service activation on the device), network monitoring, and
service monitoring (the impact of service activation on the network).
3.6.1. Monitoring the Protocol
Certain properties of protocols are useful to monitor. The number of
protocol packets received, the number of packets sent, and the number
of packets dropped are usually very helpful to operators.
Packet drops should be reflected in counter variable(s) somewhere
that can be inspected -- both from the security point of view and
from the troubleshooting point of view.
Counter definitions should be unambiguous about what is included in
the count and what is not included in the count.
Consider the expected behaviors for counters -- what is a reasonable
maximum value for expected usage? Should they stop counting at the
maximum value and retain the maximum value, or should they rollover?
How can users determine if a rollover has occurred, and how can users
determine if more than one rollover has occurred?
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Consider whether multiple management applications will share a
counter; if so, then no one management application should be allowed
to reset the value to zero since this will impact other applications.
Could events, such as hot-swapping a blade in a chassis, cause
discontinuities in counter? Does this make any difference in
evaluating the performance of a protocol?
The protocol document should make clear the limitations implicit
within the protocol and the behavior when limits are exceeded. This
should be considered in a data-modeling-independent manner -- what
makes managed-protocol sense, not what makes management-protocol-
sense. If constraints are not managed-protocol-dependent, then it
should be left for the management-protocol data modelers to decide.
For example, VLAN identifiers have a range of 1..4095 because of the
VLAN standards. A MIB implementing a VLAN table should be able to
support 4096 entries because the content being modeled requires it.
3.6.2. Monitoring the Device
Consider whether device performance will be affected by the number of
protocol entities being instantiated on the device. Designers of an
information model should include information, accessible at runtime,
about the maximum number of instances an implementation can support,
the current number of instances, and the expected behavior when the
current instances exceed the capacity of the implementation or the
capacity of the device.
Designers of an information model should model information,
accessible at runtime, about the maximum number of protocol entity
instances an implementation can support on a device, the current
number of instances, and the expected behavior when the current
instances exceed the capacity of the device.
3.6.3. Monitoring the Network
Consider whether network performance will be affected by the number
of protocol entities being deployed.
Consider the capability of determining the operational activity, such
as the number of messages in and the messages out, the number of
received messages rejected due to format problems, and the expected
behaviors when a malformed message is received.
What are the principal performance factors that need to be looked at
when measuring the operational performance of the network built using
the protocol? Is it important to measure setup times? End-to-end
connectivity? Hop-to-hop connectivity? Network throughput?
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3.6.4. Monitoring the Service
What are the principal performance factors that need to be looked at
when measuring the performance of a service using the protocol? Is
it important to measure application-specific throughput? Client-
server associations? End-to-end application quality? Service
interruptions? User experience?
3.7. Security Management
Protocol designers should consider how to monitor and manage security
aspects and vulnerabilities of the new protocol.
There will be security considerations related to the new protocol.
To make it possible for operators to be aware of security-related
events, it is recommended that system logs should record events, such
as failed logins, but the logs must be secured.
Should a system automatically notify operators of every event
occurrence, or should an operator-defined threshold control when a
notification is sent to an operator?
Should certain statistics be collected about the operation of the new
protocol that might be useful for detecting attacks, such as the
receipt of malformed messages, messages out of order, or messages
with invalid timestamps? If such statistics are collected, is it
important to count them separately for each sender to help identify
the source of attacks?
Manageability considerations that are security-oriented might include
discussion of the security implications when no monitoring is in
place, the regulatory implications of absence of audit-trail or logs
in enterprises, exceeding the capacity of logs, and security
exposures present in chosen/recommended management mechanisms.
Consider security threats that may be introduced by management
operations. For example, Control and Provisioning of Wireless Access
Points (CAPWAP) breaks the structure of monolithic Access Points
(APs) into Access Controllers and Wireless Termination Points (WTPs).
By using a management interface, internal information that was
previously not accessible is now exposed over the network and to
management applications and may become a source of potential security
threats.
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The granularity of access control needed on management interfaces
needs to match operational needs. Typical requirements are a role-
based access control model and the principle of least privilege,
where a user can be given only the minimum access necessary to
perform a required task.
Some operators wish to do consistency checks of access control lists
across devices. Protocol designers should consider information
models to promote comparisons across devices and across vendors to
permit checking the consistency of security configurations.
Protocol designers should consider how to provide a secure transport,
authentication, identity, and access control that integrates well
with existing key and credential management infrastructure. It is a
good idea to start with defining the threat model for the protocol,
and from that deducing what is required.
Protocol designers should consider how access control lists are
maintained and updated.
Standard SNMP notifications or syslog messages [RFC5424] might
already exist, or can be defined, to alert operators to the
conditions identified in the security considerations for the new
protocol. For example, you can log all the commands entered by the
operator using syslog (giving you some degree of audit trail), or you
can see who has logged on/off using the Secure SHell Protocol (SSH)
and from where; failed SSH logins can be logged using syslog, etc.
An analysis of existing counters might help operators recognize the
conditions identified in the security considerations for the new
protocol before they can impact the network.
Different management protocols use different assumptions about
message security and data-access controls. A protocol designer that
recommends using different protocols should consider how security
will be applied in a balanced manner across multiple management
interfaces. SNMP authority levels and policy are data-oriented,
while CLI authority levels and policy are usually command-oriented
(i.e., task-oriented). Depending on the management function,
sometimes data-oriented or task-oriented approaches make more sense.
Protocol designers should consider both data-oriented and task-
oriented authority levels and policy.
4. Documentation Guidelines
This document is focused on what a protocol designer should think
about and how those considerations might be documented.
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This document does not describe interoperability requirements but
rather describes practices that are useful to follow when dealing
with manageability aspects in IETF documents, so the capitalized
keywords from [RFC2119] do not apply here. Any occurrence of words
like 'must' or 'should' needs to be interpreted only in the context
of their natural, English-language meaning.
4.1. Recommended Discussions
A Manageability Considerations section should include discussion of
the management and operations topics raised in this document, and
when one or more of these topics is not relevant, it would be useful
to contain a simple statement explaining why the topic is not
relevant for the new protocol. Of course, additional relevant topics
should be included as well.
Existing protocols and data models can provide the management
functions identified in the previous section. Protocol designers
should consider how using existing protocols and data models might
impact network operations.
4.2. Null Manageability Considerations Sections
A protocol designer may seriously consider the manageability
requirements of a new protocol and determine that no management
functionality is needed by the new protocol. It would be helpful to
those who may update or write extensions to the protocol in the
future or to those deploying the new protocol to know the thinking of
the working group regarding the manageability of the protocol at the
time of its design.
If there are no new manageability or deployment considerations, it is
recommended that a Manageability Considerations section contain a
simple statement such as, "There are no new manageability
requirements introduced by this document," and a brief explanation of
why that is the case. The presence of such a Manageability
Considerations section would indicate to the reader that due
consideration has been given to manageability and operations.
In the case where the new protocol is an extension and the base
protocol discusses all the relevant operational and manageability
considerations, it would be helpful to point out the considerations
section in the base document.
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4.3. Placement of Operations and Manageability Considerations Sections
If a protocol designer develops a Manageability Considerations
section for a new protocol, it is recommended that the section be
placed immediately before the Security Considerations section.
Reviewers interested in such sections could find it easily, and this
placement could simplify the development of tools to detect the
presence of such a section.
5. Security Considerations
This document is informational and provides guidelines for
considering manageability and operations. It introduces no new
security concerns.
The provision of a management portal to a network device provides a
doorway through which an attack on the device may be launched.
Making the protocol under development be manageable through a
management protocol creates a vulnerability to a new source of
attacks. Only management protocols with adequate security apparatus,
such as authentication, message integrity checking, and
authorization, should be used.
A standard description of the manageable knobs and whistles on a
protocol makes it easier for an attacker to understand what they may
try to control and how to tweak it.
A well-designed protocol is usually more stable and secure. A
protocol that can be managed and inspected offers the operator a
better chance of spotting and quarantining any attacks. Conversely,
making a protocol easy to inspect is a risk if the wrong person
inspects it.
If security events cause logs and/or notifications/alerts, a
concerted attack might be able to be mounted by causing an excess of
these events. In other words, the security-management mechanisms
could constitute a security vulnerability. The management of
security aspects is important (see Section 3.7).
6. Acknowledgements
This document started from an earlier document edited by Adrian
Farrel, which itself was based on work exploring the need for
Manageability Considerations sections in all Internet-Drafts produced
within the Routing Area of the IETF. That earlier work was produced
by Avri Doria, Loa Andersson, and Adrian Farrel, with valuable
feedback provided by Pekka Savola and Bert Wijnen.
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Some of the discussion about designing for manageability came from
private discussions between Dan Romascanu, Bert Wijnen, Juergen
Schoenwaelder, Andy Bierman, and David Harrington.
Thanks to reviewers who helped fashion this document, including
Harald Alvestrand, Ron Bonica, Brian Carpenter, Benoit Claise, Adrian
Farrel, David Kessens, Dan Romascanu, Pekka Savola, Juergen
Schoenwaelder, Bert Wijnen, Ralf Wolter, and Lixia Zhang.
7. Informative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC1052] Cerf, V., "IAB recommendations for the development of
Internet network management standards", RFC 1052,
April 1988.
[RFC1958] Carpenter, B., "Architectural Principles of the Internet",
RFC 1958, June 1996.
[RFC2113] Katz, D., "IP Router Alert Option", RFC 2113,
February 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2439] Villamizar, C., Chandra, R., and R. Govindan, "BGP Route
Flap Damping", RFC 2439, November 1998.
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999.
[RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option",
RFC 2711, October 1999.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000.
[RFC2975] Aboba, B., Arkko, J., and D. Harrington, "Introduction to
Accounting Management", RFC 2975, October 2000.
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[RFC3060] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen,
"Policy Core Information Model -- Version 1
Specification", RFC 3060, February 2001.
[RFC3084] Chan, K., Seligson, J., Durham, D., Gai, S., McCloghrie,
K., Herzog, S., Reichmeyer, F., Yavatkar, R., and A.
Smith, "COPS Usage for Policy Provisioning (COPS-PR)",
RFC 3084, March 2001.
[RFC3139] Sanchez, L., McCloghrie, K., and J. Saperia, "Requirements
for Configuration Management of IP-based Networks",
RFC 3139, June 2001.
[RFC3198] Westerinen, A., Schnizlein, J., Strassner, J., Scherling,
M., Quinn, B., Herzog, S., Huynh, A., Carlson, M., Perry,
J., and S. Waldbusser, "Terminology for Policy-Based
Management", RFC 3198, November 2001.
[RFC3290] Bernet, Y., Blake, S., Grossman, D., and A. Smith, "An
Informal Management Model for Diffserv Routers", RFC 3290,
May 2002.
[RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart,
"Introduction and Applicability Statements for Internet-
Standard Management Framework", RFC 3410, December 2002.
[RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between
Information Models and Data Models", RFC 3444,
January 2003.
[RFC3460] Moore, B., "Policy Core Information Model (PCIM)
Extensions", RFC 3460, January 2003.
[RFC3535] Schoenwaelder, J., "Overview of the 2002 IAB Network
Management Workshop", RFC 3535, May 2003.
[RFC3585] Jason, J., Rafalow, L., and E. Vyncke, "IPsec
Configuration Policy Information Model", RFC 3585,
August 2003.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[RFC3644] Snir, Y., Ramberg, Y., Strassner, J., Cohen, R., and B.
Moore, "Policy Quality of Service (QoS) Information
Model", RFC 3644, November 2003.
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[RFC3670] Moore, B., Durham, D., Strassner, J., Westerinen, A., and
W. Weiss, "Information Model for Describing Network Device
QoS Datapath Mechanisms", RFC 3670, January 2004.
[RFC3805] Bergman, R., Lewis, H., and I. McDonald, "Printer MIB v2",
RFC 3805, June 2004.
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.
[RFC5101] Claise, B., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, January 2008.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.
[W3C.REC-xmlschema-0-20010502]
Fallside, D., "XML Schema Part 0: Primer", World Wide Web
Consortium FirstEdition REC-xmlschema-0-20010502,
May 2001,
<http://www.w3.org/TR/2001/REC-xmlschema-0-20010502>.
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Appendix A. Operations and Management Review Checklist
This appendix provides a quick checklist of issues that protocol
designers should expect operations and management expert reviewers to
look for when reviewing a document being proposed for consideration
as a protocol standard.
A.1. Operational Considerations
1. Has deployment been discussed? See Section 2.1.
* Does the document include a description of how this protocol
or technology is going to be deployed and managed?
* Is the proposed specification deployable? If not, how could
it be improved?
* Does the solution scale well from the operational and
management perspective? Does the proposed approach have any
scaling issues that could affect usability for large-scale
operation?
* Are there any coexistence issues?
2. Has installation and initial setup been discussed? See
Section 2.2.
* Is the solution sufficiently configurable?
* Are configuration parameters clearly identified?
* Are configuration parameters normalized?
* Does each configuration parameter have a reasonable default
value?
* Will configuration be pushed to a device by a configuration
manager, or pulled by a device from a configuration server?
* How will the devices and managers find and authenticate each
other?
3. Has the migration path been discussed? See Section 2.3.
* Are there any backward compatibility issues?
4. Have the Requirements on other protocols and functional
components been discussed? See Section 2.4.
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* What protocol operations are expected to be performed relative
to the new protocol or technology, and what protocols and data
models are expected to be in place or recommended to ensure
for interoperable management?
5. Has the impact on network operation been discussed? See
Section 2.5.
* Will the new protocol significantly increase traffic load on
existing networks?
* Will the proposed management for the new protocol
significantly increase traffic load on existing networks?
* How will the new protocol impact the behavior of other
protocols in the network? Will it impact performance (e.g.,
jitter) of certain types of applications running in the same
network?
* Does the new protocol need supporting services (e.g., DNS or
Authentication, Authorization, and Accounting - AAA) added to
an existing network?
6. Have suggestions for verifying correct operation been discussed?
See Section 2.6.
* How can one test end-to-end connectivity and throughput?
* Which metrics are of interest?
* Will testing have an impact on the protocol or the network?
7. Has management interoperability been discussed? See Section 3.1.
* Is a standard protocol needed for interoperable management?
* Is a standard information or data model needed to make
properties comparable across devices from different vendors?
8. Are there fault or threshold conditions that should be reported?
See Section 3.3.
* Does specific management information have time utility?
* Should the information be reported by notifications? Polling?
Event-driven polling?
* Is notification throttling discussed?
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* Is there support for saving state that could be used for root
cause analysis?
9. Is configuration discussed? See Section 3.4.
* Are configuration defaults and default modes of operation
considered?
* Is there discussion of what information should be preserved
across reboots of the device or the management system? Can
devices realistically preserve this information through hard
reboots where physical configuration might change (e.g., cards
might be swapped while a chassis is powered down)?
A.2. Management Considerations
Do you anticipate any manageability issues with the specification?
1. Is management interoperability discussed? See Section 3.1.
* Will it use centralized or distributed management?
* Will it require remote and/or local management applications?
* Are textual or graphical user interfaces required?
* Is textual or binary format for management information
preferred?
2. Is management information discussed? See Section 3.2.
* What is the minimal set of management (configuration, faults,
performance monitoring) objects that need to be instrumented
in order to manage the new protocol?
3. Is fault management discussed? See Section 3.3.
* Is Liveness Detection and Monitoring discussed?
* Does the solution have failure modes that are difficult to
diagnose or correct? Are faults and alarms reported and
logged?
4. Is configuration management discussed? See Section 3.4.
* Is protocol state information exposed to the user? How? Are
significant state transitions logged?
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5. Is accounting management discussed? See Section 3.5.
6. Is performance management discussed? See Section 3.6.
* Does the protocol have an impact on network traffic and
network devices? Can performance be measured?
* Is protocol performance information exposed to the user?
7. Is security management discussed? See Section 3.7.
* Does the specification discuss how to manage aspects of
security, such as access controls, managing key distribution,
etc.
A.3. Documentation
Is an operational considerations and/or manageability section part of
the document?
Does the proposed protocol have a significant operational impact on
the Internet?
Is there proof of implementation and/or operational experience?
Author's Address
David Harrington
HuaweiSymantec USA
20245 Stevens Creek Blvd
Cupertino, CA 95014
USA
Phone: +1 603 436 8634
EMail: ietfdbh@comcast.net
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