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.

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   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

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.

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

   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].

   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.

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.

   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

   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.

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

   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

   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.

   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.

   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

   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)

   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?

   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?

   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?

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.

   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

   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

   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?

   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?

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.

   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.

   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.

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.

   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.

   [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.

   [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>.

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.

       *  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?

* 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?

   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