Transaction ID Mechanism for NETCONF
draft-ietf-netconf-transaction-id-06
| Document | Type | Active Internet-Draft (netconf WG) | |
|---|---|---|---|
| Author | Jan Lindblad | ||
| Last updated | 2024-08-14 (Latest revision 2024-07-22) | ||
| Replaces | draft-lindblad-netconf-transaction-id | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Yang Validation | 3 errors, 28 warnings | ||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | In WG Last Call | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
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| Send notices to | (None) |
draft-ietf-netconf-transaction-id-06
NETCONF J. Lindblad
Internet-Draft Cisco Systems
Intended status: Standards Track 22 July 2024
Expires: 23 January 2025
Transaction ID Mechanism for NETCONF
draft-ietf-netconf-transaction-id-06
Abstract
NETCONF clients and servers often need to have a synchronized view of
the server's configuration data stores. The volume of configuration
data in a server may be very large, while data store changes
typically are small when observed at typical client resynchronization
intervals.
Rereading the entire data store and analyzing the response for
changes is inefficient for synchronization. This document specifies
a NETCONF extension that allows clients and servers to keep
synchronized with a much smaller data exchange and without any need
for servers to store information about the clients.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the Network Configuration
Working Group mailing list (netconf@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/netconf/.
Source for this draft and an issue tracker can be found at
https://github.com/netconf-wg/transaction-id.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 23 January 2025.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4
3. NETCONF Txid Extension . . . . . . . . . . . . . . . . . . . 5
3.1. Sample Use Cases . . . . . . . . . . . . . . . . . . . . 6
3.2. General Txid Principles . . . . . . . . . . . . . . . . . 7
3.3. Initial Configuration Retrieval . . . . . . . . . . . . . 7
3.4. Subsequent Configuration Retrieval . . . . . . . . . . . 9
3.5. Candidate Datastore Configuration Retrieval . . . . . . . 14
3.6. Conditional Transactions . . . . . . . . . . . . . . . . 14
3.6.1. Error Response on Out-of-Band Changes . . . . . . . . 16
3.6.2. Txid History Size Consideration . . . . . . . . . . . 17
3.7. Candidate Datastore Transactions . . . . . . . . . . . . 18
3.8. Dependencies within Transactions . . . . . . . . . . . . 20
3.9. Other NETCONF Operations . . . . . . . . . . . . . . . . 23
3.10. YANG-Push Subscriptions . . . . . . . . . . . . . . . . . 24
3.11. Comparing YANG Datastores . . . . . . . . . . . . . . . . 25
4. Txid Mechanisms . . . . . . . . . . . . . . . . . . . . . . . 27
4.1. The ETag Attribute txid Mechanism . . . . . . . . . . . . 27
4.2. The Last-Modified Attribute txid Mechanism . . . . . . . 28
4.3. Common features to both etag and last-modified txid
mechanisms . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.1. Candidate Datastore . . . . . . . . . . . . . . . . . 30
4.3.2. Namespaces and Attribute Placement . . . . . . . . . 30
5. Txid Mechanism Examples . . . . . . . . . . . . . . . . . . . 31
5.1. Initial Configuration Response . . . . . . . . . . . . . 31
5.1.1. With etag . . . . . . . . . . . . . . . . . . . . . . 31
5.1.2. With last-modified . . . . . . . . . . . . . . . . . 36
5.2. Configuration Response Pruning . . . . . . . . . . . . . 39
5.3. Configuration Change . . . . . . . . . . . . . . . . . . 43
5.4. Conditional Configuration Change . . . . . . . . . . . . 47
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5.5. Reading from the Candidate Datastore . . . . . . . . . . 50
5.6. Commit . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.7. YANG-Push . . . . . . . . . . . . . . . . . . . . . . . . 53
5.8. NMDA Compare . . . . . . . . . . . . . . . . . . . . . . 56
6. YANG Modules . . . . . . . . . . . . . . . . . . . . . . . . 58
6.1. Base module for txid in NETCONF . . . . . . . . . . . . . 58
6.2. Additional support for txid in YANG-Push . . . . . . . . 64
6.3. Additional support for txid in NMDA Compare . . . . . . . 66
7. Security Considerations . . . . . . . . . . . . . . . . . . . 67
7.1. NACM Access Control . . . . . . . . . . . . . . . . . . . 68
7.1.1. Hash-based Txid Algorithms . . . . . . . . . . . . . 68
7.2. Unchanged Configuration . . . . . . . . . . . . . . . . . 69
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 69
8.1. NETCONF Capability URN . . . . . . . . . . . . . . . . . 69
8.2. IETF XML Registry . . . . . . . . . . . . . . . . . . . . 69
8.3. YANG Module Names . . . . . . . . . . . . . . . . . . . . 70
9. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
9.1. Major changes in -06 since -05 . . . . . . . . . . . . . 70
9.2. Major changes in -05 since -04 . . . . . . . . . . . . . 70
9.3. Major changes in -04 since -03 . . . . . . . . . . . . . 70
9.4. Major changes in -03 since -02 . . . . . . . . . . . . . 71
9.5. Major changes in -02 since -01 . . . . . . . . . . . . . 71
9.6. Major changes in -01 since -00 . . . . . . . . . . . . . 71
9.7. Major changes in draft-ietf-netconf-transaction-id-00 since
-02 . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
9.8. Major changes in -02 since -01 . . . . . . . . . . . . . 73
9.9. Major changes in -01 since -00 . . . . . . . . . . . . . 73
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 74
10.1. Normative References . . . . . . . . . . . . . . . . . . 74
10.2. Informative References . . . . . . . . . . . . . . . . . 76
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 76
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 76
1. Introduction
When a NETCONF client [RFC6241] wishes to initiate a new
configuration transaction with a NETCONF server, a frequently
occurring use case is for the client to find out if the configuration
has changed since the client last communicated with that server.
Such changes could occur, for example, if another NETCONF client has
made changes, or another system or operator made changes through
other means than NETCONF (e.g., local configuration).
One way of detecting a change for a client would be to retrieve the
entire configuration from the server, then compare the result with a
previously stored copy at the client side. This approach is not
popular with most NETCONF users, however, since it would often be
very expensive in terms of communications and computation cost.
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Furthermore, even if the configuration is reported to be unchanged,
that will not guarantee that the configuration remains unchanged when
a client sends a subsequent change request, a few moments later.
In order to simplify the task of tracking changes, a NETCONF server
may implement a meta level transaction tag or timestamp for an entire
configuration datastore or YANG subtree, and offer clients a way to
read and compare this tag or timestamp. If the tag or timestamp is
unchanged, clients can avoid performing expensive operations. Such
tags and timestamps are referred to as a 'transaction id' (txid) in
this document.
Note that several server implementors have built proprietary and
mutually incompatible mechanisms for obtaining a transaction id from
a NETCONF server. This document solves the interoperability issue.
RESTCONF, [RFC8040], defines a mechanism for detecting changes in
configuration subtrees based on Entity-Tags (ETags) and Last-Modified
headers. An example is depicted in Appendix B.2.2 of [RFC8040]
In conjunction with this, RESTCONF provides a way to make
configuration changes conditional on the server configuration being
untouched by others. This mechanism leverages conditional requests
per Section 13 of [RFC9110].
This document defines similar mechanism for NETCONF, [RFC6241], for
config true data. It also ties this in with YANG-Push, [RFC8641],
and "Comparison of Network Management Datastore Architecture (NMDA)
Datastores", [RFC9144]. 'Config false' data (operational data,
state, and statistics) is left out of scope from this document.
This document does not change the RESTCONF protocol in any way, and
is carefully written to allow implementations to share much of the
code between NETCONF and RESTCONF. Note that the NETCONF txid
mechanism described in this document uses XML attributes, but the
RESTCONF mechanism relies on HTTP Headers instead, and use none of
the XML attributes described in this document, nor JSON Metadata (see
[RFC7952]).
2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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This document uses the terminology defined in [RFC6241], [RFC7950],
[RFC7952], [RFC8040], [RFC8641], and [RFC9144].
In addition, this document defines the following terms:
Versioned node: A node in the instantiated YANG data tree for which
the server maintains a transaction id (txid) value.
Transaction-id Mechanism: A protocol implementation that fulfills
the principles described in the first part, NETCONF Txid Extension
(Section 3), of this document.
Txid: Abbreviation of Transaction-id
C-txid: Client side transaction-id, i.e., a txid value maintained or
provided by a NETCONF client.
S-txid: Server side transaction-id, i.e., a txid value maintained or
sent by a NETCONF server.
Txid History: Temporally ordered list of txid values used by the
server. Allows the server to determine if a given txid occurred
more recently than another txid.
3. NETCONF Txid Extension
This document describes a NETCONF extension which modifies the
behavior of <get-config>, <get-data>, <edit-config>, <edit-data>,
<discard-changes>, <copy-config>, <delete-config>, and <commit>
operations such that clients are able to conditionally retrieve and
update the configuration in a NETCONF server.
For servers implementing YANG-Push [RFC8641], an extension for
conveying txid updates as part of subscription updates is also
defined. A similar extension is also defined for servers
implememnting "Comparison of NMDA Datastores" [RFC9144].
Several low level mechanisms could be defined to fulfill the
requirements for efficient client/server txid synchronization. This
document defines two such mechanisms, the 'etag txid' mechanism
(Section 4.1) and the 'last-modified txid' mechanism (Section 4.2).
However, additional txid mechanisms may be defined in the future.
Such mechanisms have to adhere to the principles defined in
Section 3.2.
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This document is divided into a two main parts; the first part
discusses the txid mechanism in an abstract, protocol-neutral way.
The second part, Txid Mechanisms (Section 4), then adds the protocol
layer, and provides concrete encoding examples.
3.1. Sample Use Cases
The common use cases for txid mecahnisms are briefly discussed in
this section.
Initial configuration retrieval: When a client initially connects to
a server, it may be interested to acquire a current view of (parts
of) the server's configuration. In order to be able to
efficiently detect changes later, it may also be interested to
store meta level txid information for subtrees of the
configuration.
Subsequent configuration retrieval: When a client needs to retrieve
again (parts of) the server's configuration, it may be interested
to leverage the txid metadata it has stored by requesting the
server to prune the response so that it does not repeat
configuration data that the client is already aware of.
Configuration update with txid return: When a client issues a
transaction towards a server, it may be interested to also learn
the new txid metadata that the server has stored for the updated
parts of the configuration.
Conditional configuration change: When a client issues a transaction
towards a server, it may specify txid metadata for the transaction
in order to allow the server to verify that the client is up to
date with any changes in the parts of the configuration that it is
concerned with. If the txid metadata in the server is different
than the client expected, the server rejects the transaction with
a specific error message.
Subscribe to configuration changes with txid return: When a client
subscribes to configuration change updates through YANG-Push, it
may be interested to also learn the updated txid metadata for the
changed data trees.
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3.2. General Txid Principles
All servers implementing a txid mechanism MUST maintain a top level
server side txid (s-txid) metadata value for each configuration
datastore supported by the server. Txid mechanism implementations
MAY also maintain txid metadata values for nodes deeper in the YANG
data tree. The nodes for which the server maintains txids are
collectively referred to as the "Versioned Nodes".
Server implementations MAY use the YANG extension statement ietf-
netconf-txid:versioned-node to inform potential clients about which
YANG nodes the server maintains a txid value for. Another way to
discover (a partial) set of Versioned Nodes is for a client to
request the current configuration with txids. The returned
configuration will then have the Versioned Nodes decorated with their
txid values.
Regardless of whether a server declares the Versioned Nodes or not,
the set of Versioned Nodes in the server's YANG tree MUST remain
constant, except at system redefining events, such as software
upgrades or entitlement installations or removals.
The server returning txid values for the Versioned Nodes MUST ensure
that the txid values are changed every time there has been a
configuration change at or below the node associated with the txid
value. This means any update of a config true node will result in a
new txid value for all ancestor Versioned Nodes, up to and including
the datastore root itself.
This also means a server MUST update the txid value for any nodes
that change as a result of a configuration change, and their
ancestors, regardless of source, even if the changed nodes are not
explicitly part of the change payload. An example of this is
dependent data under YANG [RFC7950] "when" or "choice" statements.
A server MUST NOT change the txid value of a versioned node unless
the node itself or a child node of that node has been changed. The
server MUST NOT change any txid values due to changes in config false
data, or any kind of metadata that the server may maintain for YANG
data tree nodes.
3.3. Initial Configuration Retrieval
When a NETCONF server receives a <get-config> or <get-data> request
(Section 3.1.1 of [RFC8526]) containing requests for txid values, and
assuming no authorization or validation error is encountered, it
MUST, in the reply, return txid values for all Versioned Nodes below
the point requested by the client.
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The exact encoding varies by mechanism, but all txid mechanisms would
have a special "txid-request" txid value (e.g., "?") which is
guaranteed to never be used as a normal txid value. Clients MAY use
this special txid value associated with one or more nodes in the data
tree to indicate to the server that they are interested in txid
values below that point of the data tree.
Client Server
| |
| ------------------------------------------> |
| get-config (txid: ?) |
| acls |
| |
| <------------------------------------------ |
| data (txid: 5152) |
| acls (txid: 5152) |
| acl A1 (txid: 4711) |
| aces (txid: 4711) |
| ace R1 (txid: 4711) |
| matches ipv4 protocol 17 |
| actions forwarding accept |
| acl A2 (txid: 5152) |
| aces (txid: 5152) |
| ace R7 (txid: 4711) |
| matches ipv4 dscp 10 |
| actions forwarding accept |
| ace R8 (txid: 5152) |
| matches udp source-port port 22 |
| actions forwarding accept |
| ace R9 (txid: 5152) |
| matches tcp source-port port 22 |
| actions forwarding accept |
v v
Figure 1: Initial Configuration Retrieval. The client annotated
the get-config request itself with the txid request value, which
makes the server return all txid values in the entire datastore,
that also fall within the requested subtree filter. The most
recent change seems to have been an update to ace R8 and R9.
The call flow examples in this document use a 4-digit,
monotonously increasing integer as txid. This is convenient and
enhances readability of the examples, but does not necessarily
reflect a typical implementation.
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Txid values are opaque strings that uniquely identify a particular
configuration state. Servers are expected to know which txid values
it has used in the recent past, and in which order they were assigned
to configuration change transactions. This information is known as
the server's Txid History.
How many historical txid values to track is up to each server
implementor to decide, and a server MAY decide not to store any
historical txid values at all. The more txid values in the server's
Txid History, the more efficient the client synchronization may be,
as described in the coming sections. Servers may expose a
configuration parameter to control the history depth. Such control
depends on the local server capabilities. Refer to Section 3.6.2 for
more considerations about history size.
Some server implementors may decide to use a monotonically increasing
integer as the txid value or a timestamp. Doing so obviously makes
it very easy for the server to determine the sequence of historical
transaction ids.
Some server implementors may decide to use a completely different
txid value sequence, to the point that the sequence may appear
completely random to outside observers. Clients MUST NOT assume or
infer any semantic from txids. For example, clients must not assume
that servers use a txid value scheme that reveals information about
the temporal sequence of txid values.
3.4. Subsequent Configuration Retrieval
Clients MAY request the server to return txid values in the response
by adding one or more txid values received previously in <get-config>
or <get-data> requests. Txid values sent by a client are refered to
as c-txid.
When a client sends a c-txid value of a node that matches the
server's s-txid value for that Versioned Node, or matches a more
recent s-txid value in the server's Txid History, the server prunes
(i.e., does not return) that subtree from the response. Since the
client already knows the txid for that part of the data tree, or a
txid that occurred more recently, it is obviosuly already up to date
with that part of the configuration. Sending it again would be a
waste of time and energy.
Table 1 describes in detail how the client side (c-txid) and server
side txid (s-txid) values are determined and compared when the server
processes each data tree reply node from a get-config or get-data
request.
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Servers MUST process each of the config true nodes as follows:
+==========+===========================+============================+
| Case | Condition | Behavior |
+==========+===========================+============================+
| 1. NO | In its request, the | In this case, the server |
| CLIENT | client did not specify a | MUST return the current |
| TXID | c-txid value for the | node according to the |
| | current node, nor any | normal NETCONF |
| | ancestor of this node. | specifications. The |
| | | rules below do not apply |
| | | to the current node. Any |
| | | child nodes MUST also be |
| | | evaluated with respect to |
| | | these rules. |
+----------+---------------------------+----------------------------+
| 2. | The client did not | In this case, the current |
| CLIENT | specify a c-txid value | node MUST inherit the |
| ANCESTOR | for the current node, but | c-txid value of the |
| TXID | did specify a c-txid | closest ancestor node in |
| | value for one or more | the client's request that |
| | ancestors of this node. | has a c-txid value. |
| | | Processing of the current |
| | | node continues according |
| | | to the rules below. |
+----------+---------------------------+----------------------------+
| 3. | The node is not a | In this case, the current |
| SERVER | Versioned Node, i.e. the | node MUST inherit the |
| ANCESTOR | server does not maintain | server's s-txid value of |
| TXID | a s-txid value for this | the closest ancestor that |
| | node. | is a Versioned Node (has |
| | | a server side s-txid |
| | | value). The datastore |
| | | root is always a |
| | | Versioned Node. |
| | | Processing of the current |
| | | node continues according |
| | | to the rules below. |
+----------+---------------------------+----------------------------+
| 4. | The client specified | In this case the server |
| CLIENT | c-txid for the current | MUST return the node |
| TXID UP | node value is "up to | decorated with a special |
| TO DATE | date", i.e. it matches | "txid-match" txid value |
| | the server's s-txid | (e.g. "=") to the |
| | value, or matches a | matching node, pruning |
| | s-txid value from the | any value and child |
| | server's Txid History | nodes. |
| | that is more recent than | |
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| | the server's s-txid value | |
| | for this node. | |
+----------+---------------------------+----------------------------+
| 5. | The specified c-txid is | In this case the server |
| CLIENT | "outdated" or "unknown" | MUST return the current |
| TXID OUT | to the server, i.e. it | node according to the |
| OF DATE | does not match the | normal NETCONF |
| | server's s-txid value for | specifications. If the |
| | this node, nor does the | current node is a |
| | client c-txid value match | Versioned Node, it MUST |
| | any s-txid value in the | be decorated with the |
| | server's Txid History | s-txid value. Any child |
| | that is more recent than | nodes MUST also be |
| | the server's s-txid value | evaluated with respect to |
| | for this node. | these rules. |
+----------+---------------------------+----------------------------+
Table 1: The Txid rules for response pruning.
For list elements, pruning child nodes means that top-level key nodes
MUST be included in the response, and other child nodes MUST NOT be
included. For containers, child nodes MUST NOT be included.
Here follows a couple of examples of how the rules above are applied.
See the example above (Figure 1) for the most recent server
configuration state that the client is aware of, before this happens:
Client Server
| |
| ------------------------------------------> |
| get-config |
| acls (txid: 5152) |
| acl A1 (txid: 4711) |
| aces (txid: 4711) |
| acl A2 (txid: 5152) |
| aces (txid: 5152) |
| |
| <------------------------------------------ |
| data |
| acls (txid: =) |
v v
Figure 2: Response Pruning. Client sends get-config request with
known txid values. Server prunes response where the c-txid
matches expectations. In this case, the server had no changes,
and pruned the response at the earliest point offered by the
client.
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In this case, the server's txid-based pruning saved a substantial
amount of information that is already known by the client to be sent
to and processed by the client.
In the following example someone has made a change to the
configuration on the server. This server has chosen to implement a
Txid History with up to 5 entries. The 5 most recently used s-txid
values on this example server are currently: 4711, 5152, 5550, 6614,
7770 (most recent). Then a client sends this request:
Client Server
| |
| ------------------------------------------> |
| get-config |
| acls (txid: 5152) |
| acl A1 (txid: 4711) |
| acl A2 (txid: 5152) |
| |
| <------------------------------------------ |
| data |
| acls (txid: 6614) |
| acl A1 (txid: =) |
| acl A2 (txid: 6614) |
| aces (txid: 6614) |
| ace R7 (txid: =) |
| ace R8 (txid: =) |
| ace R9 (txid: 6614) |
| matches tcp source-port port 830 |
| actions forwarding accept |
v v
Figure 3: Out of band change detected. Client sends get-config
request with known txid values. Server provides updates only
where changes have happened.
In the example depicted in Figure 3, the server returns the acls
container because the client supplied c-txid value (5152) differs
from the s-txid value held by the server (6614), and 5152 is less
recent in the server's Txid History than 6614. The client is
apparently unaware of the latest config developments in this part of
the server config tree.
The server prunes list entry acl A1 is because it has the same s-txid
value as the c-txid supplied by the client (4711). The server
returns the list entry acl A2 because 5152 (specified by the client)
is less recent than 6614 (held by the server).
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The container aces under acl A2 is returned because 5152 is less
recent than 6614. The server prunes ace R7 because the c-txid for
this node is 5152 (from acl A2), and 5152 is more recent than the
closest ancestor Versioned Node (with txid 4711).
The server also prunes acl R8 because the server and client txids
exactly match (5152). Finally, acl R9 is returned because of its
less recent c-txid value given by the client (5152, on the closest
ancestor acl A2) than the s-txid held on the server (6614).
In the example shown in Figure 4, the client specifies the c-txid for
a node that the server does not maintain a s-txid for, i.e., it is
not a Versioned Node.
Client Server
| |
| ------------------------------------------> |
| get-config |
| acls |
| acls A2 |
| aces |
| ace R7 |
| matches |
| ipv4 |
| dscp (txid: 4711) |
| |
| <------------------------------------------ |
| data |
| acls |
| acl A2 |
| aces |
| ace R7 |
| matches |
| ipv4 |
| dscp (txid: =) |
v v
Figure 4: Versioned Nodes. Server lookup of dscp txid gives
4711, as closest ancestor is ace R7 with txid 4711. Since the
server's and client's txid match, the etag value is '=', and the
leaf value is pruned.
Here, the server looks up the closest ancestor node that is a
Versioned Node. This particular server has chosen to keep a s-txid
for the list entry ace R7, but not for any of its children. Thus the
server finds the server side s-txid value to be 4711 (from ace R7),
which matches the client's c-txid value of 4711.
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Servers MUST NOT ever use the special txid values, txid-match, txid-
request, txid-unknown (e.g., "=", "?", or "!") as actual txid values.
3.5. Candidate Datastore Configuration Retrieval
When a client retrieves the configuration from the (or a) candidate
datastore, some of the configuration nodes may hold the same data as
the corresponding node in the running datastore. In such cases, the
server MUST return the same s-txid value for nodes in the candidate
datastore as in the running datastore.
If a node in the candidate datastore holds different data than in the
running datastore, the server has a choice of what to return:
* The server MAY return a txid-unknown value (e.g., "!"). This may
be convenient in servers that do not know a priori what txids will
be used in a future, possible commit of the canidate.
* If the txid-unknown value is not returned, the server MUST return
the s-txid value the node will have after commit, assuming the
client makes no further changes of the candidate datastore. If a
client makes further changes in the candidate datastore, the
s-txid value MAY change.
See the example in Candidate Datastore Transactions (Section 3.7).
3.6. Conditional Transactions
Conditional transactions are useful when a client is interested to
make a configuration change, being sure that relevant parts of the
server configuration have not changed since the client last inspected
it.
By supplying the latest c-txid values known to the client in its
change requests (<edit-config>, for example), it can request the
server to reject the transaction in case any relevant changes have
occurred at the server that the client is not yet aware of.
This allows a client to reliably compute and send configuration
changes to a server without either acquiring a global datastore lock
for a potentially extended period of time, or risk that a change from
another client disrupts the intent in the time window between a read
(<get-config>, for example) and write (<edit-config>, for example)
operation.
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Clients that are also interested to know the s-txid assigned to the
modified Versioned Nodes in the model immediately in the response
could set a flag in the <rpc> element to request the server to return
the new s-txid with the <ok> element.
Client Server
| |
| ------------------------------------------> |
| edit-config (request new txid in response) |
| config (txid: 5152) |
| acls (txid: 5152) |
| acl A1 (txid: 4711) |
| aces (txid: 4711) |
| ace R1 (txid: 4711) |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| |
| <------------------------------------------ |
| ok (txid: 7688) |
v v
Figure 5: Conditional transaction towards the Running datastore
successfully executed. As all the txid values specified by the
client matched those on the server, the transaction was
successfully executed.
After the above edit-config, the client might issues a get-config to
observe the change. It would look like this:
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Client Server
| |
| ------------------------------------------> |
| get-config |
| acls (txid: ?) |
| |
| <------------------------------------------ |
| data |
| acls (txid: 7688) |
| acl A1 (txid: 7688) |
| aces (txid: 7688) |
| ace R1 (txid: 7688) |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| acl A2 (txid: 6614) |
| aces (txid: 6614) |
| ace R7 (txid: 4711) |
| matches ipv4 dscp 10 |
| actions forwarding accept |
| ace R8 (txid: 5152) |
| matches udp source-port port 22 |
| actions forwarding accept |
| ace R9 (txid: 6614) |
| matches tcp source-port port 830 |
| actions forwarding accept |
v v
Figure 6: The txids are updated on all Versioned Nodes that were
modified themselves or have a child node that was modified.
When a client sends in a c-txid value of a node, the server MUST
consider it a match if the server's s-txid value is identical to the
client, or if the server's value is found earlier in the server's
Txid History than the value supplied by the client.
3.6.1. Error Response on Out-of-Band Changes
If the server rejects the transaction because one or more of the
configuration s-txid value(s) differs from the client's expectation,
the server MUST return at least one <rpc-error> with the following
values:
error-tag: operation-failed
error-type: protocol
error-severity: error
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Additionally, the error-info tag MUST contain an sx:structure
[RFC8791] containing relevant details about one of the mismatching
txids. A server MAY send multiple rpc-errors when multiple txid
mismatches are detected.
Client Server
| |
| ------------------------------------------> |
| edit-config |
| config |
| acls |
| acl A1 (txid: 4711) |
| aces (txid: 4711) |
| ace R1 (txid: 4711) |
| matches ipv4 dscp 20 |
| actions forwarding accept |
| |
| <------------------------------------------ |
| rpc-error |
| error-tag operation-failed |
| error-type protocol |
| error-severity error |
| error-info |
| mismatch-path /acls/acl[A1] |
| mismatch-etag-value 6912 |
v v
Figure 7: Conditional transaction that fails a txid check. The
client wishes to ensure there has been no changes to the
particular acl entry it edits, and therefore sends the c-txid it
knows for this part of the configuration. Since the s-txid has
changed (out of band), the server rejects the configuration
change request and reports an error with details about where the
mismatch was detected.
3.6.2. Txid History Size Consideration
It may be tempting for a client implementor to send a single c-txid
value for the tree being edited. In many cases, that would certainly
work just fine. This is a way for the client to request the server
to go ahead with the change as long as there has not been any changes
more recent in the subtree below the c-txid provided.
Here the client is sending the same change as in the example above
(Figure 5), but with only a single c-txid value that reflects the
latest txid the client is aware of anywhere in the configuration.
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Client Server
| |
| ------------------------------------------> |
| edit-config (request new txid in response) |
| config |
| acls |
| acl A1 (txid: 8602) |
| aces |
| ace R1 |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| |
| <------------------------------------------ |
| ok (txid: 9009) |
v v
Figure 8: Conditional transaction towards the Running datastore
successfully executed. As all the c-txid values specified by the
client were the same or more recent in the server's Txid History,
so the transaction was successfully executed.
This approach works well in the example above because the c-txid
value 8602 is inherited down in the child nodes, from acl A1 to aces,
ace R1, and onwards. The server compares the c-txid value 8602 with
the s-txid value in the data tree. The server finds that the values
do not match (e.g., s-txid 7688 for ace R1 is not equal to c-txid
8602), but finds that 8602 is a more recent txid than 7688 by looking
in the server's Txid History, and therefore accepts the transaction.
Clients relying on the server's Txid History being long enough, could
see their changes rejected if some of the s-txid have fallen out of
the server's Txid History (e.g., if the txid 7688 happened so long
ago that the it is no longer in the server's Txid History). Some
servers may have a Txid History size of zero. A client specifying a
single c-txid value for a change like the one above towards such a
server would not be able to get the transaction accepted.
3.7. Candidate Datastore Transactions
When using the (or a) Candidate datastore, the txid validation
happens at commit time, rather than at individual edit-config or
edit-data operations. Clients add their c-txid attributes to the
configuration payload the same way. In case a client specifies
different c-txid values for the same element in successive edit-
config or edit-data operations, the c-txid value specified last MUST
be used by the server at commit time.
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Client Server
| |
| ------------------------------------------> |
| edit-config (operation: merge) |
| config (txid: 5152) |
| acls (txid: 5152) |
| acl A1 (txid: 4711) |
| type ipv4 |
| |
| <------------------------------------------ |
| ok |
| |
| ------------------------------------------> |
| edit-config (operation: merge) |
| config |
| acls |
| acl A1 |
| aces (txid: 4711) |
| ace R1 (txid: 4711) |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| |
| <------------------------------------------ |
| ok |
| |
| ------------------------------------------> |
| get-config |
| config |
| acls |
| acl A1 |
| aces (txid: ?) |
| |
| <------------------------------------------ |
| config |
| acls |
| acl A1 |
| aces (txid: 7688 or !) |
| ace R1 (txid: 7688 or !) |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| ace R2 (txid: 2219) |
| matches ipv4 dscp 21 |
| actions forwarding accept |
| |
| ------------------------------------------> |
| commit (request new txid in response) |
| |
| <------------------------------------------ |
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| ok (txid: 7688) |
v v
Figure 9: Conditional transaction towards the Candidate datastore
successfully executed. As all the c-txid values specified by the
client matched those on the server at the time of the commit, the
transaction was successfully executed. If a client issues a get-
config towards the candidate datastore, the server may choose to
return the special txid-unknown value (e.g., "!") or the s-txid
value that would be used if the candidate was committed without
further changes (when that s-txid value is known in advance by
the server).
3.8. Dependencies within Transactions
YANG modules that contain 'when' statements referencing remote parts
of the model will cause the s-txid to change even in parts of the
data tree that were not modified directly.
Let's say there is an energy-example.yang module that defines a
mechanism for clients to request the server to measure the amount of
energy that is consumed by a given access control rule. The "energy-
example" module augments the access control module as follows:
module energy-example {
...
container energy {
leaf metering-enabled {
type boolean;
default false;
}
}
augment /acl:acls/acl:acl {
when /energy-example:energy/energy-example:metering-enabled;
leaf energy-tracing {
type boolean;
default false;
}
leaf energy-consumption {
config false;
type uint64;
units J;
}
}
}
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This means there is a system wide switch leaf metering-enabled in
energy-example which disables all energy measurements in the system
when set to false, and that there is a boolean leaf energy-tracing
that controls whether energy measurement is happening for each acl
rule individually.
In this example, we have an initial configuration like this:
Client Server
| |
| ------------------------------------------> |
| get-config |
| energy (txid: ?) |
| acls (txid: ?) |
| |
| <------------------------------------------ |
| data (txid: 7688) |
| energy metering-enabled true (txid: 4711) |
| acls (txid: 7688) |
| acl A1 (txid: 7688) |
| energy-tracing false |
| aces (txid: 7688) |
| ace R1 (txid: 7688) |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| acl A2 (txid: 6614) |
| energy-tracing true |
| aces (txid: 6614) |
| ace R7 (txid: 4711) |
| matches ipv4 dscp 10 |
| actions forwarding accept |
| ace R8 (txid: 5152) |
| matches udp source-port port 22 |
| actions forwarding accept |
| ace R9 (txid: 6614) |
| matches tcp source-port port 830 |
| actions forwarding accept |
v v
Figure 10: Initial configuration for the energy example. Note
the energy metering-enabled leaf at the top and energy-tracing
leafs under each acl.
At this point, a client updates metering-enabled to false. This
causes the when-expression on energy-tracing to turn false, removing
the leaf entirely. This counts as a configuration change, and the
s-txid must be updated appropriately.
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Client Server
| |
| ------------------------------------------> |
| edit-config (request new txid in response) |
| config |
| energy metering-enabled false |
| |
| <------------------------------------------ |
| ok (txid: 9118) |
v v
Figure 11: Transaction changing a single leaf. This leaf is the
target of a when-statement, however, which means other leafs
elsewhere may be indirectly modified by this change. Such
indirect changes will also result in s-txid changes.
After the transaction above, the new configuration state has the
energy-tracing leafs removed. Every such removal or (re)introduction
of a node counts as a configuration change from a txid perspective,
regardless of whether the change has any net configuration change
effect in the server.
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Client Server
| |
| ------------------------------------------> |
| get-config |
| energy (txid: ?) |
| acls (txid: ?) |
| |
| <------------------------------------------ |
| data (txid: 9118) |
| energy metering-enabled false (txid: 9118) |
| acls (txid: 9118) |
| acl A1 (txid: 9118) |
| aces (txid: 7688) |
| ace R1 (txid: 7688) |
| matches ipv4 protocol 6 |
| actions forwarding accept |
| acl A2 (txid: 9118) |
| aces (txid: 6614) |
| ace R7 (txid: 4711) |
| matches ipv4 dscp 10 |
| actions forwarding accept |
| ace R8 (txid: 5152) |
| matches udp source-port port 22 |
| actions forwarding accept |
| ace R9 (txid: 6614) |
| matches tcp source-port port 830 |
| actions forwarding accept |
v v
Figure 12: The txid for the energy subtree has changed since that
was the target of the edit-config. The txids of the ACLs have
also changed since the energy-tracing leafs are now removed by
the now false when- expression. Both acl A1 and acl A2 have
their txids updated, even though energy-tracing was already false
for acl A1.
3.9. Other NETCONF Operations
<discard-changes>: The <discard-changes> operation resets the
candidate datastore to the contents of the running datastore. The
server MUST ensure the txid values in the candidate datastore get
the same txid values as in the running datastore when this
operation runs.
<copy-config>: The <copy-config>` operation can be used to copy
contents between datastores. The server MUST ensure the txid
values are retained and changed as if the data being copied had
been sent in through an edit-config operation.
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<delete-config>: The server MUST ensure the datastore txid value is
changed, unless it was already empty.
<commit>: At commit, with regards to the txid values, the server
MUST treat the contents of the candidate datastore as if any txid
value provided by the client when updating the candidate was
provided in a single edit-config towards the running datastore.
If the transaction is rejected due to txid value mismatch, an rpc-
error as described in section Conditional Transactions
(Section 3.6) MUST be sent.
3.10. YANG-Push Subscriptions
A client issuing a YANG-Push establish-subscription or modify-
subscription request towards a server that supports ietf-netconf-
txid-yang-push.yang MAY request that the server provides updated txid
values in YANG-Push on-change subscription updates.
This functionality pertains only to on-change updates. This RPC may
also be invoked over RESTCONF or other protocols, and might therefore
be encoded in JSON.
To request txid values (e.g. etag), the client adds a flag in the
request (e.g., with-etag). The server then returns the txid (e.g.,
etag) value in the yang-patch payload (e.g., as etag-value).
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Client Server
| |
| ------------------------------------------> |
| rpc |
| establish-subscription |
| datastore running |
| datastore-xpath-filter /acls |
| on-change |
| with-etag true |
| |
| <------------------------------------------ |
| ok |
| |
| <------------------------------------------ |
| notification |
| eventTime 2022-04-04T06:00:24.16Z |
| push-change-update |
| id 89 |
| datastore-changes |
| yang-patch |
| patch-id 0 |
| edit |
| edit-id edit1 |
| operation delete |
| target /acls/acl[A1] |
| edit |
| edit-id edit2 |
| operation merge |
| target /acls/acl[A2]/ace[R7] |
| value |
| matches ipv4 dscp 10 |
| actions forwarding accept |
| etag-value 8008 |
| |
v v
Figure 13: A client requests a YANG-Push subscription for a given
path with txid value included. When the server delivers a push-
change-update notification, the txid value pertaining to the
entire patch is included.
3.11. Comparing YANG Datastores
A client issuing an NMDA Datastore compare request towards a server
that supports ietf-netconf-txid-nmda-compare.yang MAY request that
the server provides updated txid values in the compare reply.
Besides NETCONF, this RPC may also be invoked over RESTCONF or other
protocols, and might therefore be encoded in JSON.
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To request txid values (e.g. etag), the client adds a flag in the
request (e.g. with-etag). The server then returns the txid (e.g.
etag) value in the yang-patch payload (e.g. as etag-value).
The txid value returned by the server MUST be the txid value
pertaining to the target node in the source or target datastores that
is the most recent. If one of the datastores being compared is not a
configuration datastore, the txid in the configuration datastore MUST
be used. If none of the datastores being compared are a
configuration datastore, then txid values MUST NOT be returned at
all.
The txid to return is the one that pertains to the target node, or in
the case of delete, the closest surviving ancestor of the target
node.
Client Server
| |
| ------------------------------------------> |
| rpc |
| compare |
| source ds:running |
| target ds:operational |
| with-etag true |
| |
| <------------------------------------------ |
| differences |
| yang-patch |
| patch-id 0 |
| edit |
| edit-id edit1 |
| operation delete |
| target /acls/acl[A1] |
| etag-value 8008 |
| edit |
| edit-id edit2 |
| operation merge |
| target /acls/acl[A2]/ace[R7] |
| value |
| matches ipv4 dscp 10 |
| actions forwarding accept |
| etag-value 8008 |
| |
v v
Figure 14: A client requests a NMDA Datastore compare for a given
path with txid values included. When the server delivers the
reply, the txid is included for each edit.
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4. Txid Mechanisms
This document defines two txid mechanisms:
* The etag attribute txid mechanism (Section 4.1)
* The last-modified attribute txid mechanism (Section 4.2)
Servers implementing this specification MUST support the etag
attribute txid mechanism and MAY support the last-modified attribute
txid mechanism.
Section NETCONF Txid Extension (Section 3) describes the logic that
governs all txid mechanisms. This section describes the mapping from
the generic logic to specific mechanism and encoding.
If a client uses more than one txid mechanism, such as both etag and
last-modified in a particular message to a server, or patricular
commit, the result is undefined.
4.1. The ETag Attribute txid Mechanism
The etag txid mechanism described in this section is centered around
a meta data XML attribute called "etag". The etag attribute is
defined in the namespace "urn:ietf:params:xml:ns:netconf:txid:1.0".
The etag attribute is added to XML elements in the NETCONF payload in
order to indicate the txid value for the YANG node represented by the
element.
NETCONF servers that support this extension MUST announce the
capability "urn:ietf:params:netconf:capability:txid:etag:1.0".
The etag attribute values are opaque strings chosen freely. They
MUST consist of ASCII printable characters (VCHAR), except that the
etag string MUST NOT contain space, backslash or double quotes. The
point of these restrictions is to make it easy to reuse
implementations that adhere to section 2.3.1 in [RFC7232]. The
probability SHOULD be made very low that an etag value that has been
used historically by a server is used again by that server if the
configuration is different.
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It is RECOMMENDED that the same etag txid values are used across all
management interfaces (i.e. NETCONF, RESTCONF and any other the
server might implement), if it implements more than one. It is
RECOMMENDED that the etag txid has an encoding specific suffix,
especially when it is not encoded in XML. E.g. a response encoded in
JSON might append "+json" at the end of the etag value. This is in
line with the language in [RFC7232] and traditions in the HTTP world
at large.
The detailed rules for when to update the etag value are described in
Section 3.2. These rules are chosen to be consistent with the ETag
mechanism in RESTCONF, specifically Sections 3.4.1.2, 3.4.1.3 and
3.5.2 of [RFC8040].
4.2. The Last-Modified Attribute txid Mechanism
The last-modified txid mechanism described in this section is
centered around a meta data XML attribute called "last-modified".
The last-modified attribute is defined in the namespace
"urn:ietf:params:xml:ns:netconf:txid:1.0". The last-modified
attribute is added to XML elements in the NETCONF payload in order to
indicate the txid value for the YANG node represented by the element.
NETCONF servers that support this extension MUST announce the feature
last-modified defined in ietf-netconf-txid.yang.
The last-modified attribute values are yang:date-and-time values as
defined in ietf-yang-types.yang, [RFC6991].
"2022-04-01T12:34:56.123456Z" is an example of what this time stamp
format looks like. It is RECOMMENDED that the time stamps provided
by the server closely match the real world clock. Servers MUST
ensure the timestamps provided are monotonously increasing for as
long as the server's operation is maintained.
It is RECOMMENDED that server implementors choose the number of
digits of precision used for the fractional second timestamps high
enough so that there is no risk that multiple transactions on the
server would get the same timestamp.
It is RECOMMENDED that the same last-modified txid values are used
across all management interfaces (i.e. NETCONF and any other the
server might implement), except RESTCONF.
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RESTCONF, as defined in [RFC8040], is using a different format for
the time stamps which is limited to one second resolution. Server
implementors that support the Last-Modified txid mechanism over both
RESTCONF and other management protocols are RECOMMENDED to use Last-
Modified timestamps that match the point in time referenced over
RESTCONF, with the fractional seconds part added.
The detailed rules for when to update the last-modified value are
described in Section 3.2. These rules are chosen to be consistent
with the Last-Modified mechanism in RESTCONF, [RFC8040], specifically
sections 3.4.1.1, 3.4.1.3 and 3.5.1.
4.3. Common features to both etag and last-modified txid mechanisms
Clients MAY add etag or last-modified attributes to zero or more
individual elements in the get-config or get-data filter, in which
case they pertain to the subtree(s) rooted at the element(s) with the
attributes.
Clients MAY also add such attributes directly to the get-config or
get-data tags (e.g. if there is no filter), in which case it pertains
to the txid value of the datastore root.
Clients might wish to send a txid value that is guaranteed to never
match a server constructed txid. With both the etag and last-
modified txid mechanisms, such a txid-request value is "?".
Clients MAY add etag or last-modified attributes to the payload of
edit-config or edit-data requests, in which case they indicate the
client's txid value of that element.
Clients MAY request servers that also implement YANG-Push to return
configuration change subsription updates with etag or last-modified
txid attributes. The client requests this service by adding a with-
etag or with-last-modified flag with the value 'true' to the
subscription request or yang-push configuration. The server MUST
then return such txids on the YANG Patch edit tag and to the child
elements of the value tag. The txid attribute on the edit tag
reflects the txid associated with the changes encoded in this edit
section, as well as parent nodes. Later edit sections in the same
push-update or push-change-update may still supercede the txid value
for some or all of the nodes in the current edit section.
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Servers returning txid values in get-config, edit-config, get-data,
edit-data and commit operations MUST do so by adding etag and/or
last-modified txid attributes to the data and ok tags. When servers
prune output due to a matching txid value, the server MUST add a
txid-match attribute to the pruned element, and MUST set the
attribute value to "=", and MUST NOT send any element value.
Servers returning a txid mismatch error MUST return an rpc-error as
defined in section Conditional Transactions (Section 3.6) with an
error-info tag containing a txid-value-mismatch-error-info structure.
4.3.1. Candidate Datastore
When servers return txid values in get-config and get-data operations
towards the candidate datastore, the txid values returned MUST adhere
to the following rules:
* If the versioned node holds the same data as in the running
datastore, the same txid value as the versioned node in running
MUST be used.
* If the versioned node is different in the candidate store than in
the running datastore, the server has a choice of what to return.
The server MAY return the special "txid-unknown" value "!". If
the txid-unknown value is not returned, the server MUST return the
txid value the versioned node will have if the client decides to
commit the candidate datastore without further updates.
4.3.2. Namespaces and Attribute Placement
The txid attributes are valid on the following NETCONF tags, where
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0" [RFC4741]
[RFC6241], xmlns:ncds="urn:ietf:params:xml:ns:yang:ietf-netconf-nmda"
[RFC8526], xmlns:sn="urn:ietf:params:xml:ns:yang:ietf-subscribed-
notifications" [RFC8639], xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-
yang-push" [RFC8641] [RFC8072]:
In client messages sent to a server:
* /nc:rpc/nc:get-config
* /nc:rpc/nc:get-config/nc:filter//*
* /nc:rpc/ncds:get-data
* /nc:rpc/ncds:get-data/ncds:subtree-filter//*
* /nc:rpc/ncds:get-data/ncds:xpath-filter//*
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* /nc:rpc/nc:edit-config/nc:config
* /nc:rpc/nc:edit-config/nc:config//*
* /nc:rpc/ncds:edit-data/ncds:config
* /nc:rpc/ncds:edit-data/ncds:config//*
In server messages sent to a client:
* /nc:rpc-reply/nc:data
* /nc:rpc-reply/nc:data//*
* /nc:rpc-reply/ncds:data
* /nc:rpc-reply/ncds:data//*
* /nc:rpc-reply/nc:ok
* /yp:push-update/yp:datastore-contents/yp:yang-patch/ yp:edit
* /yp:push-update/yp:datastore-contents/yp:yang-patch/ yp:edit/
yp:value//*
* /yp:push-change-update/yp:datastore-contents/yp:yang-patch/
yp:edit
* /yp:push-change-update/yp:datastore-contents/yp:yang-patch/
yp:edit/yp:value//*
5. Txid Mechanism Examples
5.1. Initial Configuration Response
5.1.1. With etag
NOTE: In the etag examples below, we have chosen to use a txid value
consisting of "nc" followed by a monotonously increasing integer.
This is convenient for the reader trying to make sense of the
examples, but is not an implementation requirement. An etag would
often be implemented as a "random" string of characters.
To retrieve etag attributes across the entire NETCONF server
configuration, a client might send:
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<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="1"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<get-config txid:etag="?"/>
</rpc>
The server's reply might then be:
<rpc-reply message-id="1"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data txid:etag="nc5152">
<acls xmlns=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc5152">
<acl txid:etag="nc4711">
<name>A1</name>
<aces txid:etag="nc4711">
<ace txid:etag="nc4711">
<name>R1</name>
<matches>
<ipv4>
<protocol>17</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
<acl txid:etag="nc5152">
<name>A2</name>
<aces txid:etag="nc5152">
<ace txid:etag="nc4711">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
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</actions>
</ace>
<ace txid:etag="nc5152">
<name>R8</name>
<matches>
<udp>
<source-port>
<port>22</port>
</source-port>
</udp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc5152">
<name>R9</name>
<matches>
<tcp>
<source-port>
<port>22</port>
</source-port>
</tcp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"
txid:etag="nc3072">
<groups txid:etag="nc3072">
<group txid:etag="nc3072">
<name>admin</name>
<user-name>sakura</user-name>
<user-name>joe</user-name>
</group>
</groups>
</nacm>
</data>
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</rpc>
To retrieve etag attributes for a specific ACL using an xpath filter,
a client might send:
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="2"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<get-config>
<source>
<running/>
</source>
<filter type="xpath"
xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list"
select="/acl:acls/acl:acl[acl:name='A1']"
txid:etag="?"/>
</get-config>
</rpc>
To retrieve etag attributes for "acls", but not for "nacm", a client
might send:
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="3"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<get-config>
<source>
<running/>
</source>
<filter>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="?"/>
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"/>
</filter>
</get-config>
</rpc>
If the server considers "acls", "acl", "aces" and "acl" to be
Versioned Nodes, the server's response to the request above might
look like:
<rpc-reply message-id="3"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls xmlns=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc5152">
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<acl txid:etag="nc4711">
<name>A1</name>
<aces txid:etag="nc4711">
<ace txid:etag="nc4711">
<name>R1</name>
<matches>
<ipv4>
<protocol>17</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
<acl txid:etag="nc5152">
<name>A2</name>
<aces txid:etag="nc5152">
<ace txid:etag="nc4711">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc5152">
<name>R8</name>
<matches>
<udp>
<source-port>
<port>22</port>
</source-port>
</udp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
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acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc5152">
<name>R9</name>
<matches>
<tcp>
<source-port>
<port>22</port>
</source-port>
</tcp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"/>
<groups>
<group>
<name>admin</name>
<user-name>sakura</user-name>
<user-name>joe</user-name>
</group>
</groups>
</nacm>
</data>
</rpc>
5.1.2. With last-modified
To retrieve last-modified attributes for "acls", but not for "nacm",
a client might send:
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<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="4"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<get-config>
<source>
<running/>
</source>
<filter>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:last-modified="?"/>
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"/>
</filter>
</get-config>
</rpc>
If the server considers "acls", "acl", "aces" and "acl" to be
Versioned Nodes, the server's response to the request above might
look like:
<rpc-reply message-id="4"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:last-modified="2022-04-01T12:34:56.789012Z">
<acl txid:last-modified="2022-03-20T16:20:11.333444Z">
<name>A1</name>
<aces txid:last-modified="2022-03-20T16:20:11.333444Z">
<ace txid:last-modified="2022-03-20T16:20:11.333444Z">
<name>R1</name>
<matches>
<ipv4>
<protocol>17</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
<acl txid:last-modified="2022-04-01T12:34:56.789012Z">
<name>A2</name>
<aces txid:last-modified="2022-04-01T12:34:56.789012Z">
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<ace txid:last-modified="2022-03-20T16:20:11.333444Z">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:last-modified="2022-04-01T12:34:56.789012Z">
<name>R8</name>
<matches>
<udp>
<source-port>
<port>22</port>
</source-port>
</udp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:last-modified="2022-04-01T12:34:56.789012Z">
<name>R9</name>
<matches>
<tcp>
<source-port>
<port>22</port>
</source-port>
</tcp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
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</acls>
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"/>
<groups>
<group>
<name>admin</name>
<user-name>sakura</user-name>
<user-name>joe</user-name>
</group>
</groups>
</nacm>
</data>
</rpc>
5.2. Configuration Response Pruning
A NETCONF client that already knows some txid values MAY request that
the configuration retrieval request is pruned with respect to the
client's prior knowledge.
To retrieve only changes for "acls" that do not have the last known
etag txid value, a client might send:
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="6"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<get-config>
<source>
<running/>
</source>
<filter>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc5152">
<acl txid:etag="nc4711">
<name>A1</name>
<aces txid:etag="nc4711"/>
</acl>
<acl txid:etag="nc5152">
<name>A2</name>
<aces txid:etag="nc5152"/>
</acl>
</filter>
</get-config>
</rpc>
Assuming the NETCONF server configuration is the same as in the
previous rpc-reply example, the server's response to request above
might look like:
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<rpc-reply message-id="6"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="="/>
</data>
</rpc>
Or, if a configuration change has taken place under /acls since the
client was last updated, the server's response may look like:
<rpc-reply message-id="6"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc6614">
<acl txid:etag="=">
<name>A1</name>
</acl>
<acl txid:etag="nc6614">
<name>A2</name>
<aces txid:etag="nc6614">
<ace txid:etag="nc4711">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc5152">
<name>R8</name>
<matches>
<ipv4>
<source-port>
<port>22</port>
</source-port>
</ipv4>
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</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc6614">
<name>R9</name>
<matches>
<ipv4>
<source-port>
<port>830</port>
</source-port>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc>
In case the client provides a txid value for a non-versioned node,
the server needs to treat the node as having the same txid value as
the closest ancestor that does have a txid value.
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<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="7"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<get-config>
<source>
<running/>
</source>
<filter>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list">
<acl>
<name>A2</name>
<aces>
<ace>
<name>R7</name>
<matches>
<ipv4>
<dscp txid:etag="nc4711"/>
</ipv4>
</matches>
</ace>
</aces>
</acl>
</acls>
</filter>
</get-config>
</rpc>
If a txid value is specified for a leaf, and the txid value matches
(i.e. is identical to the server's txid value, or found earlier in
the server's Txid History), the leaf value is pruned.
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<rpc-reply message-id="7"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list">
<acl>
<name>A2</name>
<aces>
<ace>
<name>R7</name>
<matches>
<ipv4>
<dscp txid:etag="="/>
</ipv4>
</matches>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc-reply>
5.3. Configuration Change
A client that wishes to update the ace R1 protocol to tcp might send:
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<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="8">
<edit-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:ietf-netconf-txid=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid">
<target>
<running/>
</target>
<test-option>test-then-set</test-option>
<ietf-netconf-txid:with-etag>true</ietf-netconf-txid:with-etag>
<config>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc5152">
<acl txid:etag="nc4711">
<name>A1</name>
<aces txid:etag="nc4711">
<ace txid:etag="nc4711">
<matches>
<ipv4>
<protocol>6</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</config>
</edit-config>
</rpc>
The server would update the protocol leaf in the running datastore,
and return an rpc-reply as follows:
<rpc-reply message-id="8"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<ok txid:etag="nc7688"/>
</rpc-reply>
A subsequent get-config request for "acls", with txid:etag="?" might
then return:
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<rpc-reply message-id="9"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc7688">
<acl txid:etag="nc7688">
<name>A1</name>
<aces txid:etag="nc7688">
<ace txid:etag="nc7688">
<name>R1</name>
<matches>
<ipv4>
<protocol>6</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
<acl txid:etag="nc6614">
<name>A2</name>
<aces txid:etag="nc6614">
<ace txid:etag="nc4711">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc5152">
<name>R8</name>
<matches>
<udp>
<source-port>
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<port>22</port>
</source-port>
</udp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc6614">
<name>R9</name>
<matches>
<tcp>
<source-port>
<port>830</port>
</source-port>
</tcp>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc>
In case the server at this point received a configuration change from
another source, such as a CLI operator, removing ace R8 and R9 in acl
A2, a subsequent get-config request for acls, with txid:etag="?"
might then return:
<rpc-reply message-id="9"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="cli2222">
<acl txid:etag="nc7688">
<name>A1</name>
<aces txid:etag="nc7688">
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<ace txid:etag="nc7688">
<name>R1</name>
<matches>
<ipv4>
<protocol>6</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
<acl txid:etag="cli2222">
<name>A2</name>
<aces txid:etag="cli2222">
<ace txid:etag="nc4711">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc>
5.4. Conditional Configuration Change
If a client wishes to delete acl A1 if and only if its configuration
has not been altered since this client last synchronized its
configuration with the server, at which point it received the etag
"nc7688" for acl A1, regardless of any possible changes to other
acls, it might send:
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<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="10"
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0"
xmlns:ietf-netconf-txid=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid">
<edit-config>
<target>
<running/>
</target>
<test-option>test-then-set</test-option>
<ietf-netconf-txid:with-etag>true</ietf-netconf-txid:with-etag>
<config>
<acls xmlns=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
<acl nc:operation="delete"
txid:etag="nc7688">
<name>A1</name>
</acl>
</acls>
</config>
</edit-config>
</rpc>
If acl A1 now has the etag txid value "nc7688", as expected by the
client, the transaction goes through, and the server responds
something like:
<rpc-reply message-id="10"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<ok txid:etag="nc8008"/>
</rpc-reply>
A subsequent get-config request for acls, with txid:etag="?" might
then return:
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<rpc-reply message-id="11"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc8008">
<acl txid:etag="cli2222">
<name>A2</name>
<aces txid:etag="cli2222">
<ace txid:etag="nc4711">
<name>R7</name>
<matches>
<ipv4>
<dscp>10</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc>
In case acl A1 did not have the expected etag txid value "nc7688"
when the server processed this request, nor was the client's txid
value found later in the server's Txid History, then the server
rejects the transaction, and might send:
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<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list"
xmlns:ietf-netconf-txid=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid"
message-id="11">
<rpc-error>
<error-type>protocol</error-type>
<error-tag>operation-failed</error-tag>
<error-severity>error</error-severity>
<error-info>
<ietf-netconf-txid:txid-value-mismatch-error-info>
<ietf-netconf-txid:mismatch-path>
/acl:acls/acl:acl[acl:name="A1"]
</ietf-netconf-txid:mismatch-path>
<ietf-netconf-txid:mismatch-etag-value>
cli6912
</ietf-netconf-txid:mismatch-etag-value>
</ietf-netconf-txid:txid-value-mismatch-error-info>
</error-info>
</rpc-error>
</rpc-reply>
5.5. Reading from the Candidate Datastore
Let's assume that a get-config towards the running datastore
currently contains the following data and txid values:
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<rpc-reply message-id="12"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list"
txid:etag="nc4711">
<acl txid:etag="nc4711">
<name>A1</name>
<aces txid:etag="nc4711">
<ace txid:etag="nc4711">
<name>R1</name>
<matches>
<ipv4>
<protocol>17</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc2219">
<name>R2</name>
<matches>
<ipv4>
<dscp>21</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc-reply>
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A client issues discard-changes (to make the candidate datastore
equal to the running datastore), and issues an edit-config to change
the R1 protocol from udp (17) to tcp (6), and then executes a get-
config with the txid-request attribute "?" set on the acl A1, the
server might respond:
<rpc-reply message-id="13"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<data>
<acls
xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list">
<acl txid:etag="!">
<name>A1</name>
<aces txid:etag="!">
<ace txid:etag="!">
<name>R1</name>
<matches>
<ipv4>
<protocol>6</protocol>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
<ace txid:etag="nc2219">
<name>R2</name>
<matches>
<ipv4>
<dscp>21</dscp>
</ipv4>
</matches>
<actions>
<forwarding xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
acl:accept
<forwarding>
</actions>
</ace>
</aces>
</acl>
</acls>
</data>
</rpc-reply>
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Here, the txid-unknown value "!" is sent by the server. This
particular server implementation does not know beforehand which txid
value would be used for this versioned node after commit. It will be
a value different from the current corresponding txid value in the
running datastore.
In case the server is able to predict the txid value that would be
used for the versioned node after commit, it could respond with that
value instead. Let's say the server knows the txid would be "7688"
if the candidate datastore was committed without further changes,
then it would respond with that value in each place where the example
shows "!" above.
5.6. Commit
The client MAY request that the new etag txid value is returned as an
attribute on the ok response for a successful commit. The client
requests this by adding with-etag to the commit operation.
For example, a client might send:
<rpc message-id="14"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
xmlns:ietf-netconf-txid=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid"
<commit>
<ietf-netconf-txid:with-etag>true</ietf-netconf-txid:with-etag>
</commit>
</rpc>
Assuming the server accepted the transaction, it might respond:
<rpc-reply message-id="14"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
xmlns:txid="urn:ietf:params:xml:ns:netconf:txid:1.0">
<ok txid:etag="nc8008"/>
</rpc-reply>
5.7. YANG-Push
A client MAY request that the updates for one or more YANG-Push
subscriptions are annotated with the txid values. The request might
look like this:
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<netconf:rpc message-id="16"
xmlns:netconf="urn:ietf:params:xml:ns:netconf:base:1.0">
<establish-subscription
xmlns=
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push"
xmlns:ietf-netconf-txid-yp=
"urn:ietf:params:xml:ns:yang:ietf-txid-yang-push">
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:running
</yp:datastore>
<yp:datastore-xpath-filter
xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
/acl:acls
</yp:datastore-xpath-filter>
<yp:on-change/>
<ietf-netconf-txid-yp:with-etag>
true
</ietf-netconf-txid-yp:with-etag>
</establish-subscription>
</netconf:rpc>
A server might send a subscription update like this:
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<notification
xmlns="urn:ietf:params:xml:ns:netconf:notification:1.0"
xmlns:ietf-netconf-txid-yp=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid-yang-push">
<eventTime>2022-04-04T06:00:24.16Z</eventTime>
<push-change-update
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-push">
<id>89</id>
<datastore-changes>
<yang-patch>
<patch-id>0</patch-id>
<edit>
<edit-id>edit1</edit-id>
<operation>delete</operation>
<target xmlns:acl=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
/acl:acls
</target>
<value>
<acl xmlns=
"urn:ietf:params:xml:ns:yang:ietf-access-control-list">
<name>A1</name>
</acl>
</value>
</edit>
<ietf-netconf-txid-yp:etag-value>
nc8008
</ietf-netconf-txid-yp:etag-value>
</yang-patch>
</datastore-changes>
</push-change-update>
</notification>
In case a client wishes to modify a previous subscription request in
order to no longer receive YANG-Push subscription updates, the
request might look like this:
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<rpc message-id="17"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<modify-subscription
xmlns=
"urn:ietf:params:xml:ns:yang:ietf-subscribed-notifications"
xmlns:yp="urn:ietf:params:xml:ns:yang:ietf-yang-push"
xmlns:ietf-netconf-txid-yp=
"urn:ietf:params:xml:ns:yang:ietf-txid-yang-push">
<id>1011</id>
<yp:datastore
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
ds:running
</yp:datastore>
<ietf-netconf-txid-yp:with-etag>
false
</ietf-netconf-txid-yp:with-etag>
</modify-subscription>
</rpc>
5.8. NMDA Compare
The following example is taken from section 5 of [RFC9144]. It
compares the difference between the operational and intended
datastores for a subtree under "interfaces".
In this version of the example, the client requests that txid values,
in this case etag-values, are annotated to the result.
<rpc message-id="101"
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<compare xmlns="urn:ietf:params:xml:ns:yang:ietf-nmda-compare"
xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores"
xmlns:ietf-netconf-txid-nmda-compare=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid-nmda-compare">
<source>ds:operational</source>
<target>ds:intended</target>
<report-origin/>
<ietf-netconf-txid-nmda-compare:with-etag>
true
</ietf-netconf-txid-nmda-compare:with-etag>
<xpath-filter
xmlns:if="urn:ietf:params:xml:ns:yang:ietf-interfaces">
/if:interfaces
</xpath-filter>
</compare>
</rpc>
RPC reply when a difference is detected:
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<rpc-reply
xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"
message-id="101">
<differences
xmlns="urn:ietf:params:xml:ns:yang:ietf-nmda-compare"
xmlns:or="urn:ietf:params:xml:ns:yang:ietf-origin"
xmlns:ietf-netconf-txid-nmda-compare=
"urn:ietf:params:xml:ns:yang:ietf-netconf-txid-nmda-compare">
<yang-patch>
<patch-id>interface status</patch-id>
<comment>
diff between operational (source) and intended (target),
with txid values taken from intended.
</comment>
<edit>
<edit-id>1</edit-id>
<operation>replace</operation>
<target>/ietf-interfaces:interface=eth0/enabled</target>
<value>
<if:enabled>false</if:enabled>
</value>
<source-value>
<if:enabled or:origin="or:learned">true</if:enabled>
</source-value>
<ietf-netconf-txid-nmda-compare:etag-value>
4004
</ietf-netconf-txid-nmda-compare:etag-value>
</edit>
<edit>
<edit-id>2</edit-id>
<operation>create</operation>
<target>/ietf-interfaces:interface=eth0/description</target>
<value>
<if:description>ip interface</if:description>
</value>
<ietf-netconf-txid-nmda-compare:etag-value>
8008
</ietf-netconf-txid-nmda-compare:etag-value>
</edit>
</yang-patch>
</differences>
</rpc-reply>
The same response in RESTCONF (using JSON format):
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HTTP/1.1 200 OK
Date: Thu, 24 Jan 2019 20:56:30 GMT
Server: example-server
Content-Type: application/yang-data+json
{ "ietf-nmda-compare:output" : {
"differences" : {
"ietf-yang-patch:yang-patch" : {
"patch-id" : "interface status",
"comment" : "diff between intended (source) and operational",
"edit" : [
{
"edit-id" : "1",
"operation" : "replace",
"target" : "/ietf-interfaces:interface=eth0/enabled",
"value" : {
"ietf-interfaces:interface/enabled" : "false"
},
"source-value" : {
"ietf-interfaces:interface/enabled" : "true",
"@ietf-interfaces:interface/enabled" : {
"ietf-origin:origin" : "ietf-origin:learned"
}
},
"ietf-netconf-txid-nmda-compare:etag-value": "4004"
},
{
"edit-id" : "2",
"operation" : "create",
"target" : "/ietf-interfaces:interface=eth0/description",
"value" : {
"ietf-interface:interface/description" : "ip interface"
},
"ietf-netconf-txid-nmda-compare:etag-value": "8008"
}
]
}
}
}
}
6. YANG Modules
6.1. Base module for txid in NETCONF
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<CODE BEGINS> file "ietf-netconf-txid@2023-03-01.yang"
module ietf-netconf-txid {
yang-version 1.1;
namespace
'urn:ietf:params:xml:ns:yang:ietf-netconf-txid';
prefix ietf-netconf-txid;
import ietf-netconf {
prefix nc;
}
import ietf-netconf-nmda {
prefix ncds;
}
import ietf-yang-structure-ext {
prefix sx;
}
import ietf-yang-types {
prefix yang;
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <netconf@ietf.org>
Author: Jan Lindblad
<mailto:jlindbla@cisco.com>";
description
"NETCONF Transaction ID aware operations for NMDA.
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
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for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
";
revision 2023-03-01 {
description
"Initial revision";
reference
"RFC XXXX: Xxxxxxxxx";
}
feature last-modified {
description "Servers implementing this module MUST support the
etag txid mechanism. Servers MAY also support the
last-modified txid mechanism. Support is shown by announcing
this feature.";
}
extension versioned-node {
description "This statement is used by servers to declare that a
the server is maintaining a Txid for the YANG node with this
statement. Which YANG nodes are versioned nodes may be useful
information for clients (especially during development).
Servers are not required to use this statement to declare
which nodes are versioned nodes.
Example of use:
container interfaces {
ietf-netconf-txid:versioned-node;
...
}
";
}
typedef etag-t {
type string {
pattern ".* .*" {
modifier invert-match;
}
pattern '.*".*' {
modifier invert-match;
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}
pattern ".*\\.*" {
modifier invert-match;
}
}
description
"Unique Entity-tag txid value representing a specific
transaction. Could be any string that does not contain
spaces, double quotes or backslash.
The txid values '?', '!' and '=' have special meaning:
'?' This txid value is used by clients and is
guaranteed not to match any txid on the server.
'!' This txid value used by servers to indicate
the node in the candidate datastore has changed
relative to the running datastore, but not yet received
a new txid value on the server.
'=' This txid value used by servers to indicate
that contents has been pruned due to txid match
between client and server.
";
}
typedef last-modified-t {
type union {
type yang:date-and-time;
type enumeration {
enum ? {
description "Txid value used by clients that is
guaranteed not to match any txid on the server.";
}
enum ! {
description "Txid value used by servers to indicate
the node in the candidate datastore has changed
relative to the running datastore, but not yet received
a new txid value on the server.";
}
enum = {
description "Txid value used by servers to indicate
that contents has been pruned due to txid match
between client and server.";
}
}
}
description
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"Last-modified txid value representing a specific transaction.
The txid values '?', '!' and '=' have special meaning.";
}
grouping txid-grouping {
leaf with-etag {
type boolean;
description
"Indicates whether the client requests the server to include
a txid:etag txid attribute when the configuration has
changed.";
}
leaf with-last-modified {
if-feature last-modified;
type boolean;
description
"Indicates whether the client requests the server to include
a txid:last-modified attribute when the configuration has
changed.";
}
description
"Grouping for txid mechanisms, to be augmented into
rpcs that modify configuration data stores.";
}
grouping txid-value-grouping {
leaf etag-value {
type etag-t;
description
"Indicates server's txid value for a YANG node.";
}
leaf last-modified-value {
if-feature last-modified;
type last-modified-t;
description
"Indicates server's txid value for a YANG node.";
}
description
"Grouping for txid mechanisms, to be augmented into
output of rpcs that return txid metadata for configuration
data stores.";
}
augment /nc:edit-config/nc:input {
uses txid-grouping;
description
"Injects the txid mechanisms into the
edit-config operation";
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}
augment /nc:commit/nc:input {
uses txid-grouping;
description
"Injects the txid mechanisms into the
commit operation";
}
augment /ncds:edit-data/ncds:input {
uses txid-grouping;
description
"Injects the txid mechanisms into the
edit-data operation";
}
sx:structure txid-value-mismatch-error-info {
container txid-value-mismatch-error-info {
description
"This error is returned by a NETCONF server when a client
sends a configuration change request, with the additonal
condition that the server aborts the transaction if the
server's configuration has changed from what the client
expects, and the configuration is found not to actually
not match the client's expectation.";
leaf mismatch-path {
type instance-identifier;
description
"Indicates the YANG path to the element with a mismatching
etag txid value.";
}
leaf mismatch-etag-value {
type etag-t;
description
"Indicates server's txid value of the etag
attribute for one mismatching element.";
}
leaf mismatch-last-modified-value {
if-feature last-modified;
type last-modified-t;
description
"Indicates server's txid value of the last-modified
attribute for one mismatching element.";
}
}
}
}
<CODE ENDS>
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6.2. Additional support for txid in YANG-Push
<CODE BEGINS> file "ietf-netconf-txid-yang-push@2022-04-01.yang"
module ietf-netconf-txid-yang-push {
yang-version 1.1;
namespace
'urn:ietf:params:xml:ns:yang:ietf-netconf-txid-yang-push';
prefix ietf-netconf-txid-yp;
import ietf-subscribed-notifications {
prefix sn;
reference
"RFC 8639: Subscription to YANG Notifications";
}
import ietf-yang-push {
prefix yp;
reference
"RFC 8641: Subscriptions to YANG Datastores";
}
import ietf-netconf-txid {
prefix ietf-netconf-txid;
reference
"RFC XXXX: Xxxxxxxxx";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <netconf@ietf.org>
Author: Jan Lindblad
<mailto:jlindbla@cisco.com>";
description
"NETCONF Transaction ID aware operations for YANG Push.
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
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(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
";
revision 2022-04-01 {
description
"Initial revision";
reference
"RFC XXXX: Xxxxxxxxx";
}
augment "/sn:establish-subscription/sn:input" {
description
"This augmentation adds additional subscription parameters
that apply specifically to datastore updates to RPC input.";
uses ietf-netconf-txid:txid-grouping;
}
augment "/sn:modify-subscription/sn:input" {
description
"This augmentation adds additional subscription parameters
specific to datastore updates.";
uses ietf-netconf-txid:txid-grouping;
}
augment "/sn:subscriptions/sn:subscription" {
description
"This augmentation adds additional subscription parameters
specific to datastore updates.";
uses ietf-netconf-txid:txid-grouping;
}
augment "/yp:push-change-update/yp:datastore-changes/" +
"yp:yang-patch" {
description
"This augmentation makes it possible for servers to return
txid-values.";
uses ietf-netconf-txid:txid-value-grouping;
}
}
<CODE ENDS>
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6.3. Additional support for txid in NMDA Compare
<CODE BEGINS> file "ietf-netconf-txid-nmda-compare@2023-05-01.yang"
module ietf-netconf-txid-nmda-compare {
yang-version 1.1;
namespace
'urn:ietf:params:xml:ns:yang:ietf-netconf-txid-nmda-compare';
prefix ietf-netconf-txid-nmda-compare;
import ietf-nmda-compare {
prefix cmp;
reference
"RFC 9144: Comparison of Network Management Datastore
Architecture (NMDA) Datastores";
}
import ietf-netconf-txid {
prefix ietf-netconf-txid;
reference
"RFC XXXX: Xxxxxxxxx";
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <netconf@ietf.org>
Author: Jan Lindblad
<mailto:jlindbla@cisco.com>";
description
"NETCONF Transaction ID aware operations for NMDA Compare.
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Revised BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
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The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
";
revision 2023-05-01 {
description
"Initial revision";
reference
"RFC XXXX: Xxxxxxxxx";
}
augment "/cmp:compare/cmp:input" {
description
"This augmentation makes it possible for clients to request
txids to be returned.";
uses ietf-netconf-txid:txid-grouping;
}
augment "/cmp:compare/cmp:output/cmp:compare-response/" +
"cmp:differences/cmp:differences/cmp:yang-patch/cmp:edit" {
description
"This augmentation makes it possible for servers to return
txid-values.";
container most-recent {
description "The txid value returned by the server MUST be the
txid value pertaining to the target node in the source or
target datastores that is the most recent.";
uses ietf-netconf-txid:txid-value-grouping;
}
}
}
<CODE ENDS>
7. Security Considerations
The YANG modules specified in this document define YANG types,
groupings, structures and additional RPC parameters for data that is
designed to be accessed via network management protocols such as
NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is
the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
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The Network Configuration Access Control Model (NACM) [RFC8341]
provides the means to restrict access for particular NETCONF or
RESTCONF users to a preconfigured subset of all available NETCONF or
RESTCONF protocol operations and content.
In the YANG modules published with this document, there is no
configuration, state data, new RPCs or notifications. This document
defines additional XML attributes and headers, however, that merit
consideration from a security perspective.
7.1. NACM Access Control
NACM, [RFC8341], access control processing happens as usual,
independently of any txid handling, if supported by the server and
enabled by the NACM configuration.
It should be pointed out however, that when txid information is added
to a reply, it may occasionally be possible for a client to deduce
that a configuration change has happened in some part of the
configuration to which it has no access rights.
For example, a client may notice that the root node txid has changed
while none of the subtrees it has access to have changed, and thereby
conclude that someone else has made a change to some part of the
configuration that is not acessible by the client.
7.1.1. Hash-based Txid Algorithms
Servers that implement NACM and choose to implement a hash-based txid
algorithm over the configuration may reveal to a client that the
configuration of a subtree that the client has no access to is the
same as it was at an earlier point in time.
For example, a client with partial access to the configuration might
observe that the root node txid was 1234. After a few configuration
changes by other parties, the client may again observe that the root
node txid is 1234. It may then deduce that the configuration is the
same as earlier, even in the parts of the configuration it has no
access to.
In some use cases, this behavior may be considered a feature, since
it allows a security client to verify that the configuration is the
same as expected, without transmitting or storing the actual
configuration.
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7.2. Unchanged Configuration
It will also be possible for clients to deduce that a configuration
change has not happened during some period, by simply observing that
the root node (or other subtree) txid remains unchanged. This is
true regardless of NACM being deployed or choice of txid algorithm.
Again, there may be use cases where this behavior may be considered a
feature, since it allows a security client to verify that the
configuration is the same as expected, without transmitting or
storing the actual configuration.
8. IANA Considerations
8.1. NETCONF Capability URN
This document requets IANA to register the following capability
identifier URN in the 'Network Configuration Protocol (NETCONF)
Capability URNs' registry:
Capability: :txid
Capability Identifier: urn:ietf:params:netconf:capability:txid:1.0
Reference: RFC XXXX
8.2. IETF XML Registry
This document request IANA to register four XML namespace URIs in the
the "ns" subregistry within the "IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:netconf:txid:1.0
Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces.
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-txid
Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces.
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-txid-yang-push
Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces.
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-txid-nmda-compare
Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces.
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8.3. YANG Module Names
This document requests IANA to register three module names in the
"YANG Module Names" subregistry [RFC6020] within the "YANG
Parameters" registry.
name: ietf-netconf-txid
prefix: ietf-netconf-txid
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-txid
maintained by IANA? N
RFC: XXXX
name: ietf-netconf-txid-yp
prefix: ietf-netconf-txid-yp
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-txid-yang-push
maintained by IANA? N
RFC: XXXX
name: ietf-netconf-txid-nmda-compare
prefix: ietf-netconf-txid-nmda-compare
namespace:
urn:ietf:params:xml:ns:yang:ietf-netconf-txid-nmda-compare
maintained by IANA? N
RFC: XXXX
9. Changes
9.1. Major changes in -06 since -05
* Many language, style, spelling and formatting improvements thanks
to reviews by Reshad Rahman and Med Boucadair
* Clarified Txid History Size Consideration example
9.2. Major changes in -05 since -04
* Corrected namespace for reference to elements in ietf-yang-push
9.3. Major changes in -04 since -03
* Updated security considerations.
* Added several normative RFC references.
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9.4. Major changes in -03 since -02
* Updated language slightly regarding format of etag values, and
some recommendations for implementors that support etags in
multiple management protocols (NETCONF, RESTCONF, ...) and
encodings (XML, JSON, ...).
* Added missing normative RFC references.
* Corrected the YANG-push namespace reference.
9.5. Major changes in -02 since -01
* Added optional to implement Txid History concept in order to make
the algorithm both more efficient and less verbose. Servers may
still choose a Txid History size of zero, which makes the server
behavior the same as in earlier versions of this document.
Implementations that use txids consisting of a monotonically
increasing integer or timestamp will be able to determine the
sequnce of transactions in the history directly, making this
trivially simple to implement.
* Added extension statement versioned-node, which servers may use to
declare which YANG tree nodes are Versioned Nodes. This is
entirely optional, however, but possibly useful to client
developers.
* Renamed YANG feature ietf-netconf-txid:txid-last-modified to ietf-
netconf-txid:last-modified in order to reduce redundant mentions
of "txid".
9.6. Major changes in -01 since -00
* Changed YANG-push txid mechanism to use a simple leaf rather than
an attribute to convey txid information. This is preferable since
YANG-push content may be requested using other protocols than
NETCONF and other encodings than XML. By removing the need for
XML attributes in this context, the mechanism becomes
significantly more portable.
* Added a section and YANG module augmenting the RFC9144 NMDA
datastore compare operation to allow request and reply with txid
information. This too is done with augments of plain leafs for
maximum portability.
* Added note clarifying that the txid attributes used in the XML
encoding are never used in JSON (since RESTCONF uses HTTP headers
instead).
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* Added note clarifying that pruning happens when client and server
txids _match_, since the server sending information to the client
only makes sense when the information on the client is out of
date.
* Added note clarifying that this entire document is about config
true data only.
* Rephrased slightly when referring to the candidate datastore to
keep making sense in the event that private candidate datastores
become a reality in the future.
* Added a note early on to more clearly lay out the structure of
this document, with a first part about the generic mechanism part,
and a second part about the two specific txid mechanisms.
* Corrected acl data model examples to conform to their YANG module.
9.7. Major changes in draft-ietf-netconf-transaction-id-00 since -02
* Changed the logic around how txids are handled in the candidate
datastore, both when reading (get-config, get-data) and writing
(edit-config, edit-data). Introduced a special "txid-unknown"
value "!".
* Changed the logic of copy-config to be similar to edit-config.
* Clarified how txid values interact with when-dependencies together
with default values.
* Added content to security considerations.
* Added a high-level example for YANG-Push subscriptions with txid.
* Updated language about error-info sent at txid mismatch in an
edit-config: error-info with mismatch details MUST be sent when
mismatch detected, and that the server can choose one of the txid
mismatch occurrences if there is more than one.
* Some rewording and minor additions for clarification, based on
mailing list feedback.
* Divided RFC references into normative and informative.
* Corrected a logic error in the second figure (figure 6) in the
"Conditional Transactions" section
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9.8. Major changes in -02 since -01
* A last-modified txid mechanism has been added (back). This
mechanism aligns well with the Last-Modified mechanism defined in
RESTCONF [RFC8040], but is not a carbon copy.
* YANG-Push functionality has been added. This allows YANG-Push
users to receive txid updates as part of the configuration
updates. This functionality comes in a separate YANG module, to
allow implementors to cleanly keep all this functionality out.
* Changed name of "versioned elements". They are now called
"Versioned Nodes".
* Clarified txid behavior for transactions toward the Candidate
datastore, and some not so common situations, such as when a
client specifies a txid for a non-versioned node, and when there
are when-statement dependencies across subtrees.
* Examples provided for the abstract mechanism level with simple
message flow diagrams.
* More examples on protocol level, and with ietf-interfaces as
example target module replaced with ietf-access-control to reduce
confusion.
* Explicit list of XPaths to clearly state where etag or last-
modified attributes may be added by clients and servers.
* Document introduction restructured to remove duplication between
sections and to allow multiple (etag and last-modified) txid
mechanisms.
* Moved the actual YANG module code into proper module files that
are included in the source document. These modules can be
compiled as proper modules without any extraction tools.
9.9. Major changes in -01 since -00
* Updated the text on numerous points in order to answer questions
that appeared on the mailing list.
* Changed the document structure into a general transaction id part
and one etag specific part.
* Renamed entag attribute to etag, prefix to txid, namespace to
urn:ietf:params:xml:ns:yang:ietf-netconf-txid.
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* Set capability string to
urn:ietf:params:netconf:capability:txid:1.0
* Changed YANG module name, namespace and prefix to match names
above.
* Harmonized/slightly adjusted etag value space with RFC 7232 and
RFC 8040.
* Removed all text discussing etag values provided by the client
(although this is still an interesting idea, if you ask the
author)
* Clarified the etag attribute mechanism, especially when it comes
to matching against non-versioned elements, its cascading upwards
in the tree and secondary effects from when- and choice-
statements.
* Added a mechanism for returning the server assigned etag value in
get-config and get-data.
* Added section describing how the NETCONF discard-changes, copy-
config, delete-config and commit operations work with respect to
etags.
* Added IANA Considerations section.
* Removed all comments about open questions.
10. References
10.1. 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,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC4741] Enns, R., Ed., "NETCONF Configuration Protocol", RFC 4741,
DOI 10.17487/RFC4741, December 2006,
<https://www.rfc-editor.org/rfc/rfc4741>.
[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,
<https://www.rfc-editor.org/rfc/rfc6241>.
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[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/rfc/rfc6242>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/rfc/rfc6991>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/rfc/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/rfc/rfc8040>.
[RFC8072] Bierman, A., Bjorklund, M., and K. Watsen, "YANG Patch
Media Type", RFC 8072, DOI 10.17487/RFC8072, February
2017, <https://www.rfc-editor.org/rfc/rfc8072>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/rfc/rfc8341>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.
[RFC8526] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "NETCONF Extensions to Support the Network
Management Datastore Architecture", RFC 8526,
DOI 10.17487/RFC8526, March 2019,
<https://www.rfc-editor.org/rfc/rfc8526>.
[RFC8639] Voit, E., Clemm, A., Gonzalez Prieto, A., Nilsen-Nygaard,
E., and A. Tripathy, "Subscription to YANG Notifications",
RFC 8639, DOI 10.17487/RFC8639, September 2019,
<https://www.rfc-editor.org/rfc/rfc8639>.
[RFC8641] Clemm, A. and E. Voit, "Subscription to YANG Notifications
for Datastore Updates", RFC 8641, DOI 10.17487/RFC8641,
September 2019, <https://www.rfc-editor.org/rfc/rfc8641>.
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[RFC8791] Bierman, A., Björklund, M., and K. Watsen, "YANG Data
Structure Extensions", RFC 8791, DOI 10.17487/RFC8791,
June 2020, <https://www.rfc-editor.org/rfc/rfc8791>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>.
[RFC9144] Clemm, A., Qu, Y., Tantsura, J., and A. Bierman,
"Comparison of Network Management Datastore Architecture
(NMDA) Datastores", RFC 9144, DOI 10.17487/RFC9144,
December 2021, <https://www.rfc-editor.org/rfc/rfc9144>.
10.2. Informative References
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/rfc/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/rfc/rfc6020>.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
DOI 10.17487/RFC7232, June 2014,
<https://www.rfc-editor.org/rfc/rfc7232>.
[RFC7952] Lhotka, L., "Defining and Using Metadata with YANG",
RFC 7952, DOI 10.17487/RFC7952, August 2016,
<https://www.rfc-editor.org/rfc/rfc7952>.
Acknowledgments
The author wishes to thank Benoît Claise for making this work happen,
and the following individuals, who all provided helpful comments and
reviews: Per Andersson, James Cumming, Kent Watsen, Andy Bierman,
Robert Wilton, Qiufang Ma, Jason Sterne, Robert Varga, Reshad Rahman
and Med Boucadair.
Author's Address
Jan Lindblad
Cisco Systems
Email: jlindbla@cisco.com
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