Internet DRAFT - draft-ietf-netmod-opstate-reqs
draft-ietf-netmod-opstate-reqs
NETMOD Working Group K. Watsen
Internet-Draft Juniper Networks
Intended status: Informational T. Nadeau
Expires: July 25, 2016 Brocade Networks
January 22, 2016
Terminology and Requirements for Enhanced Handling of Operational State
draft-ietf-netmod-opstate-reqs-04
Abstract
This document primarily regards the difference between the intended
configuration and the applied configuration of a device and how
intended and applied configuration relate to the operational state of
a device. This document defines requirements for the applied
configuration's data model and its values, as well as for enabling a
client to know when a configuration has been fully applied or not,
how to access operational state, and how to relate intended
configuration nodes to applied configuration and derived state nodes.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This document primarily regards the difference between the intended
configuration and the applied configuration of a device and how
intended and applied configuration relate to the operational state of
a device. This document defines requirements for the applied
configuration's data model and its values, as well as for enabling a
client to know when a configuration has been fully applied or not,
how to access operational state, and how to relate intended
configuration nodes to applied configuration and derived state nodes.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The term "client" is used throughout this document to refer to what
is many times known as the "application" or "network management
system". This definition is intended to be consistent with the term
"client" defined in [RFC6241], Section 1.1, but independent of any
association to a particular protocol.
The term "server" is used throughout this document to refer to what
is many times known as the "device", "system", or "network element".
This definition is intended to be consistent with the term "server"
defined in [RFC6241], Section 1.1, but independent of any association
to a particular protocol.
This document defines the following terms:
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Applied Configuration: This data represents the configuration state
that the server is actually in. That is, the configuration state
which is currently being used by server components (e.g., control
plane daemons, operating system kernels, line cards). With
respect to NETCONF architecture, the applied configuration
resides in the "system software component" box listed on page 15
of [RFC6244]
NOTE: The server's ability to report applied configuration
accurately may be limited in some cases, such as when the
configuration goes through an intermediate layer without an
ability to inspect the lower layer.
Asynchronous Configuration Operation: A configuration request to
update the running configuration of a server that is applied
asynchronously with respect to the client request. The server
MUST update its intended configuration before replying to the
client indicating whether the request will be processed. This
reply to the client only indicates whether there are any errors
in the original request. The server's applied configuration
state is updated after the configuration change has been fully
effected to all impacted components in the server.
Derived State: This data represents information which is generated
as part of the server's own interactions. For example, derived
state may consist of the results of protocol interactions (the
negotiated duplex state of an Ethernet link), statistics (such as
message queue depth), or counters (such as packet input or output
bytes).
Intended Configuration: This data represents the configuration state
that the network operator intends the server to be in, and that
has been accepted by the server as valid configuration. With
respect to NETCONF architecture, the intended configuration is
captured by the "config database" box listed on page 15 of
[RFC6244]
Operational State: Operational State is the current state of the
system as known to the various components of the system (e.g.,
control plane daemons, operating system kernels, line cards).
The operational state includes both applied configuration and
derived state.
Synchronous Configuration Operation: A configuration request to
update the running configuration of a server that is applied
synchronously with respect to the client request (i.e. a blocking
call). The server MUST fully attempt to apply the configuration
change to all impacted components in the server, updating both
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the server's intended and applied configuration, before replying
to the client. The reply to the client indicates whether there
are any errors in the request or errors from applying the
configuration change.
3. Requirements
1. Ability to interact with both intended and applied configuration
A. The ability to ask the operational components of a server
(e.g., line cards) for the configuration that they are
currently using. This is the applied configuration.
B. Applied configuration is read-only
C. The data model for the applied configuration is the same as
the data model for the intended configuration (same leaves)
D. When a configuration change for any intended configuration
node has been successfully applied to the server (e.g. not
failed, nor deferred due to absent hardware) then the
existence and value of the corresponding applied
configuration node must match the intended configuration
node.
2. Support for both synchronous and asynchronous configuration
operations
A. A server MUST support only synchronous configuration
operations, or only asynchronous configuration operations, or
both synchronous and asynchronous configuration operations on
a client-specified per-operation basis.
B. Servers that support asynchronous configuration operations
MUST provide a mechanism to notify the client when a request
has completed processing. The notification MUST indicate
whether the intended config is now fully applied or if there
were any errors from applying the configuration change.
C. Servers that support asynchronous configuration operations
SHOULD also provide a verify operation that a client can
request from the server to return information regarding the
difference between the intended and applied configurations.
D. The configuration protocol MUST specify how configuration
errors are handled. Errors SHOULD be handled by semantics
similar to NETCONF's error-options for the <edit-config>
operation (stop-on-error, continue-on-error, rollback-on-
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error), as described in Section 7.2 in [RFC6241], but
extended to incorporate both the intended and applied
configurations. Support for "rollback on error" semantics
SHOULD be provided.
3. Separation of the applied configuration and derived state aspects
of operational state; ability to retrieve them independently and
together
A. Be able to retrieve only the applied configuration aspects of
operational state
B. Be able to retrieve only the derived state aspects of
operational state
C. Be able to retrieve both the applied configuration and
derived state aspects of operational state together
4. Ability to relate configuration with its corresponding
operational state
A. Ability to relate intended config nodes to corresponding
applied config nodes
B. Ability to relate intended config nodes to associated derived
state nodes
C. The relationships need to be programmatically consumable
5. Backwards compatibility
A. It MUST be possible to upgrade a server to one that supports
the solution without breaking existing/legacy clients.
B. It MUST be possible for a client that has been coded to
support the solution to interoperate appropriately with
existing/legacy servers.
4. Security Considerations
It is understood that the intended and applied configurations will
differ while synchronization is in progress. During the
synchronization process, the server will be in an inconsistent state
from the client's perspective. Implementations need to take care to
ensure that this process minimizes gaps in the application of
security policy (e.g., replacing a firewall policy in a single step).
Implementations additionally need to ensure that any gaps in security
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policies are not dependent on external input that an attacker might
be able to control or prevent access to.
5. IANA Considerations
None
6. Acknowledgements
The authors would like to thank the following for contributing to
this document (in alphabetic order): Acee Lindem, Andy Bierman, Anees
Shaikh, Benoit Claise, Carl Moberg, Dan Romascanu, Dean Bogdanovic,
Gert Grammel, Jason Sterne, Jonathan Hansford, Juergen Schoenwaelder,
Lou Berger, Mahesh Jethanandani, Martin Bjorklund, Phil Shafer, Randy
Presuhn, Rob Shakir, Robert Wilton.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
7.2. Informative References
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC6244] Shafer, P., "An Architecture for Network Management Using
NETCONF and YANG", RFC 6244, DOI 10.17487/RFC6244, June
2011, <http://www.rfc-editor.org/info/rfc6244>.
Authors' Addresses
Kent Watsen
Juniper Networks
EMail: kwatsen@juniper.net
Thomas Nadeau
Brocade Networks
EMail: tnadeau@lucidvision.com
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