Internet DRAFT - draft-sanchez-ops-ip-config-management-reqmnts
draft-sanchez-ops-ip-config-management-reqmnts
Internet Draft Luis Sanchez, BBN
draft-sanchez-ops-ip-config-management-reqmnts-00.txt Keith McCloghrie, Cisco
Expires in January 14, 2001 Jon Saperia, JDS Consultant
July 14, 2000
Requirements for Configuration Management of IP-based networks
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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Abstract
This document is the output of a design team chartered with the
identification of a global set of configuration management
requirements for IP-based networks.
Sanchez, McCloghrie, Saperia [page 1]
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Table of Contents
1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1 Motivation, Scope and Goals of this document . . . . . . . 2
1.2 Requirements Terminology . . . . . . . . . . . . . . . . . 3
1.3 Audience . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Definition of Technical Terms. . . . . . . . . . . . . . . 3
2.0 Statement of the Problem . . . . . . . . . . . . . . . . . . 4
3.0 Requirements for an IP-based Configuration Management System . 7
4.0 Security Considerations . . . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1.0 Introduction
1.1 Motivation, Scope and Goals of this document
Over the past several months, a number of IETF working groups have
introduced new technologies which offer integrated and
differentiated services. To support these new technologies,
working group members found that they had new requirements for
configuration of these technologies. One of these new requirements
was for the provisioning (configuration) of behavior at the
network level.
An example of this type of configuration would be instructing all
routers in a network to provide 'gold' service to a particular set
of customers. Depending on the specific network equipment and
definition of 'gold' service, this configuration request might
translate to different configuration parameters on different
vendors equipment and many individual configuration commands at
the router. This higher level of configuration management has come
to commonly be known as policy based management.
Working groups associated with these new technologies believed
that the existing SNMP based management framework, while adequate
for fault, configuration management at the individual instance
(e.g., interface) level, performance and other management
functions commonly associated with it, was not able to meet these
new needs. As a result they began working on new solutions and
approaches.
COPS [COPS] for RSVP [RSVP] provides routers with the opportunity
to ask their Policy Server for an admit/reject decision for a
particular RSVP session. This model allows routers to outsource
their resource allocation decisions to some other entity. However,
this model does not work with DiffServ [DSARCH] where there is no
signalling protocol. Therefore, the policies that affect resource
allocation decisions must be provisioned to the routers. It became
evident that there was a need for coordinating both RSVP-based and
DiffServ-based policies to provide end2end QoS. Working groups
began to extend and leverage approaches such as COPS for RSVP to
support Diffserv policies. This gave birth to COPS-PR [COPS-PR].
These extensions caused concern that the IETF was about to develop
a set of fragmented solutions which were locally optimized for
specific technologies and not well integrated in the existing
Internet Management Framework. The concern prompted some of the
Area Directors associated with the Operations and Management,
Transport and General areas, and some IAB members to organize a
two day meeting in mid September 1999. The primary purpose of the
meeting was to examine the requirements for configuration
management and evaluate the COPS/PIB and SNMP/MIB approaches in
light of these requirements.
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At the end of the two day meeting there was no consensus on
several issues and as a result a number of 'design teams' were
created. This document is the output of the design team chartered
with the identification of a global set of configuration
management requirements. This document has benefited from feedback
received during the Configuration Management BOF that took place
on November 11, 1999 during the 46th IETF in Washington DC,
USA. The document has also benefited from comments sent to the
confmgt@ops.ietf.org mailing list.
1.2 Requirements Terminology
Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT"
and "MAY" that appear in this document are to be interpreted as
described in RFC 2119 [Bra97].
1.3 Audience
The target audience for this document includes system designers,
implementers of network configuration and management technology
and others interested in gaining a general background
understanding of the issues related to configuration management in
general, and in the Internet in particular along with associated
requirements. This document assumes that the reader is familiar
with the Internet Protocol, related networking technology, and
general network management terms and concepts.
1.4 Definition of Terms
Device-Local Configuration
Configuration data that is specific to a particular network
device. This is the finest level of granularity for configuring
network devices.
Network-Wide Configuration
Configuration data that is not specific to any particular network
device and from which multiple device-local configurations can
be derived. Network-wide configuration provides a level of
abstraction above device-local configurations.
Configuration Data Translator
A function that transforms Configuration Management Data
(high-level policies) or Network-wide configuration data
(middle-level policies) into device local configurations
(low-level policies) based on the generic capabilities of network
devices. This function can be performed either by devices
themselves or by some intermediate entity.
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2.0 Statement of the Problem
Configuring large networks is becoming an increasingly difficult
task. The problem intensifies as networks increase their size, not
only in terms of number of devices, but also with a greater
variety of devices, with each device having increasing
functionality and complexity. That is, networks are getting more
complex in multiple dimensions simultaneously (number of devices,
time scales for configuration, etc.) making the task of
configuring these more complex.
In the past, configuring a network device has been a three step
process. The network operator, engineer or entity responsible for
the network created a model of the network and its expected
behavior. Next, this (model + expected behavior) was formalized
and recorded in the form of high-level policies. Finally, these
policies were then translated into device-local configurations and
provisioned into each network device for enforcement.
Any high-level policy changes (changes in the network topology
and/or its expected behavior) needed to be translated and
provisioned to all network devices affected by the change. Figure
1 depicts this model and shows how high-level policies for a
network could be translated into four device-local
configurations. In this model, network operators or engineers
functioned as configuration data translators; they translated the
high-level policies to device-local configuration data.
A configuration data translator could take the topology
independent behavior description such as high-level policies
(first input source) combine it with topology information (second
input source) as well as status/performance/monitoring information
(third input source) to derive device-local configurations. Note
that there could be several configuration data translators
operating in tandem on a set of devices. However, there could be
only one configuration data translator operating at a particular
device at any given instance.
Sanchez, McCloghrie, Saperia [page 5]
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Configuration Management
Data (High-level Policies)
|
|
|
|
Network V Network
Topology -----> Configuration <---- Status/performance
Information Data Translator(s) Information
|
|
|
|
-------------------------------------------------
| | | |
Device Device Device Device
Local Local Local Local
Conf(1) Conf(2) Conf(3) Conf(4)
Figure 1. Current model for configuring network devices.
Historically, network operators and engineers used protocols and
mechanisms such as SNMP and CLI applications to provision or
configure network devices. In their current versions, these
mechanisms have proven to be difficult to use because of their
low-level of granularity and their device-specific nature. This
problem is worse when provisioning multiple network devices
requiring large amounts of configuration data.
It is evident that network administrators and existing
configuration management software can not keep up with the growth
in complexity of networks and that an efficient, integrated
configuration management solution is needed. Several IETF Working
Groups working on this problem converged into adding a layer of
abstraction to the traditional configuration management process
described in figure 1. Figure 2 depicts this process after the
layer of abstraction is added. As in the previous figure, first
the network operator, engineer or entity responsible for the
network creates a model of the network and its expected
behavior. This is formalized and recorded in the form of
high-level policies.
These policies are combined with topology information as well as
status/performance information to generate network-wide
configuration data. These middle level-policies are simpler to
manage and represent behaviors shared by multiple network devices.
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Configuration Management
Data (High-level Policies)
|
|
|
|
Network V Network
Topology -----> Network-Wide <---- Status/performance
Information Configuration Information
Data
|
|
|
|
V
Configuration
Data Translator(s)
|
|
|
|
-------------------------------------------------
| | | |
Device Device Device Device
Local Local Local Local
Conf(1) Conf(2) Conf(3) Conf(4)
Figure 2. Propose model for configuring network devices.
Device local configurations are generated by automated
configuration data translators and are supplied to each network
device for enforcement. Note how this model only describes the
function of the configuration data translators and it does not
dictate its functional location. This is to say that translators
may reside outside of the devices (as it was the case in figure 1
since they were humans) or may be possibly collocated with each
device.
As in the previous model, any high-level policy changes (changes
in the network topology and/or its expected behavior) needs to be
propagated to all network devices affected by the change. However,
in the configuration model depicted in figure 2 network operators
and engineers can specify the behavior of the network in a
simplified manner reducing the amount of device specific knowledge
needed.
One should keep in mind that in some cases per instance device
local configuration is needed in network devices. An integrated
solution MUST allow room for this. Also, the introduction of
automated configuration data translators assumes that all
information needed to make an error free conversion of
network-wide configuration data into device-local configuration
data is available. In the event that such data is not available
the solution MUST detect this and act accordingly.
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3.0 Requirements for an IP-based Configuration Management System
The IETF currently agrees upon the following requirements for
configuration management. An integrated configuration management
solution MUST:
1) provide means by which the behavior of the network can be
specified at a level of abstraction (network-wide
configuration) higher than a set of configuration information
specific to individual devices,
2) be capable of translating network-wide configurations into
device-local configuration. The identification of the relevant
subset of the network-wide policies to be down-loaded is
according to the capabilities of each device,
3) be able to interpret device-local configuration, status and
monitoring information within the context of network-wide
configurations,
4) be capable of provisioning (e.g., adding, modifying, deleting,
dumping, restoring) complete or partial configuration data to
network devices simultaneously or in a synchronized fashion as
necessary,
5) provide means by which network devices can send feedback
information (configuration data confirmation, network status
and monitoring information, specific events, etc.) to the
management system,
6) be capable of provisioning complete or partial configuration
data to network devices dynamically as a result of network
specific or network-wide events,
7) provide efficient and reliable means compared to current
versions of today's mechanisms (CLI, SNMP) to provision large
amounts of configuration data,
8) provide secure means to provision configuration data. The
system must provide support for access control, authentication,
integrity-checking, replay- protection and/or privacy security
services. The minimum level of granularity for access control
and authentication is host based. The system SHOULD support
user/role based access control and authentication for users in
different roles with different access privileges,
9) provide expiration time and effective time capabilities to
configuration data. It is required that some configuration data
items be set to expire, and other items be set to never expire,
10) provide error detection (including data-specific errors) and
failure recovery mechanisms (including prevention of
inappropriately partial configurations when needed) for the
provisioning of configuration data,
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11) eliminate the potential for mis-configuration occurring through
concurrent shared write access to the device's configuration
data,
12) provide facilities (with host and user-based authentication
granularity) to help in tracing back configuration changes,
13) allow for the use of redundant components, both network
elements and configuration application platforms, and for the
configuration of redundant network elements.
14) be flexible and extensible to accommodate future
needs. Configuration management data models are not fixed for
all time and are subject to evolution like any other management
data model. It is therefore necessary to anticipate that
changes will be needed, but it is not possible to anticipate
what those changes might be. Such changes could be to the
configuration data model, supporting message types, data types,
etc., and to provide mechanisms that can deal with these
changes effectively without causing inter-operability problems
or having to replace/update large amounts of fielded networking
devices,
15) leverage knowledge of the existing SNMP management
infrastructure. The system MUST leverage knowledge of and
experience with MIBs and SMI.
Security Considerations
This document reflects the current requirements that the IETF
believes configuration management systems MUST have to properly
support IP-based networks. The authors believes that a
configuration management system MUST provide mechanisms by which
one can ascertain the integrity and authenticity of the
configuration data at all times. In some cases the privacy of the
data is important therefore configuration management system MUST
provide facilities to support this services as required not only
while the data is stored but also during provisioning or
reception. Requirements eight and twelve capture the required
security services.
Acknowledgments
The authors thank Juergen Schoenwaelder for his contributions to
this document. The authors also thank Walter Weiss and Andrew
Smith for providing feedback to early versions of this
document. Finally, the authors thank the IESG for motivating and
supporting this work.
References
[Bra97] Bradner, S., "Key Words for use in RFCs to indicate
Requirement Levels", RFC2119, March 1997.
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[COPS] Boyle, J., Cohen, R., Durham, D., Herzog, S., Rajan, R.,
and A. Sastry, "The COPS (Common Open Policy Service) Protocol",
draft-ietf-rap-cops-07.txt, work-in-progress, August 1999.
[RSVP] Braden, R. ed. et al., "Resource ReSerVation Protocol
(RSVP) Version 1 - Functional Specification", RFC 2205, September
1997.
[COPS-RSVP] Boyle, J., Cohen, R., Durham, D., Herzog, S., Rajan,
R., and A. Sastry, "COPS usage for RSVP",
draft-ietf-rap-cops-rsvp-05.txt, work-in-progress, June 1999.
[COPS-PROV] Reichmeyer, F., Herzog, S., Chan, K., Durham, D.,
Yavatkar, R., Gai, S., McCloghrie, K., and A. Smith, "COPS Usage
for Policy Provisioning", draft-ietf-rap-pr-00.txt,
work-in-progress, June 1999.
Disclaimer
The views and specification here are those of the authors and are
not necessarily those of their employers. The authors and their
employers specifically disclaim responsibility for any problems
arising from correct or incorrect implementation or use of this
specification.
Copyright (C) The Internet Society (November 1997). All
Rights Reserved.
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Sanchez, McCloghrie, Saperia [page 10]
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Author Information
Keith McCloghrie Jon Saperia
Cisco Systems, Inc. JDS Consulting, Inc.
170 West Tasman Drive 174 Chapman Street
San Jose, CA 95134-1706 Watertown, MA 02472
USA USA
Email: kzm@cisco.com Email: saperia@mediaone.net
Phone: +1 (408) 526-5260 Telephone: +1 (617) 744-1079
Luis A. Sanchez
BBN Technologies
10 Moulton Street
Cambridge, MA 02138
USA
Email: lsanchez@bbn.com
Telephone: +1 (617) 873-3351
Sanchez, McCloghrie, Saperia [page 10]
