NETCONF A. Gonzalez Prieto
Internet-Draft VMware
Intended status: Standards Track E. Voit
Expires: May 3, 2018 Cisco Systems
A. Clemm
Huawei
E. Nilsen-Nygaard
A. Tripathy
Cisco Systems
October 30, 2017
NETCONF Support for Event Notifications
draft-ietf-netconf-netconf-event-notifications-06
Abstract
This document provides a NETCONF binding for
[I-D.draft-ietf-netconf-subscribed-notifications]. Included are:
o Transport mappings for subscription RPCs, state change
notifications, and notification messages
o Functionality which must be supported with NETCONF
o Examples in appendices
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
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This Internet-Draft will expire on May 3, 2018.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Interleave Capability . . . . . . . . . . . . . . . . . . . . 3
4. Mandatory stream and datastore support . . . . . . . . . . . 3
5. Transport connectivity . . . . . . . . . . . . . . . . . . . 4
5.1. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 4
5.2. Configured Subscriptions . . . . . . . . . . . . . . . . 4
6. Notification Messages . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 6
A.1. Event Stream Discovery . . . . . . . . . . . . . . . . . 6
A.2. Dynamic Subscriptions . . . . . . . . . . . . . . . . . . 7
A.3. Configured Subscriptions . . . . . . . . . . . . . . . . 12
A.4. Subscription State Notifications . . . . . . . . . . . . 17
Appendix B. Changes between revisions . . . . . . . . . . . . . 19
B.1. v05 to v06 . . . . . . . . . . . . . . . . . . . . . . . 19
B.2. v03 to v04 . . . . . . . . . . . . . . . . . . . . . . . 19
B.3. v01 to v03 . . . . . . . . . . . . . . . . . . . . . . . 20
B.4. v00 to v01 . . . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
This document defines a binding for notification message delivery for
[I-D.draft-ietf-netconf-subscribed-notifications] transported over
the NETCONF protocol [RFC6241]. In addition, as
[I-D.ietf-netconf-yang-push] is itself built upon
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[I-D.draft-ietf-netconf-subscribed-notifications], this document
enables a NETCONF client to maintain a subset/extract of an actively
changing YANG datastore located on a NETCONF server.
This document is broken into two main parts. The first contains
normative requirements which are incremental to
[I-D.draft-ietf-netconf-subscribed-notifications] when NETCONF
transport is used. The second are examples and are included as
appendices.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The following terms are defined in
[I-D.draft-ietf-netconf-subscribed-notifications]: notification
message, stream, publisher, receiver, subscriber, subscription,
configured subscription.
3. Interleave Capability
To support multiple subscriptions on a single session, a NETCONF
publisher MUST support the :interleave capability as defined in
[RFC5277]. Such support MUST be indicated by the following
capability: "urn:ietf:params:netconf:capability:interleave:1.0".
Advertisement of this capability along with support
[I-D.draft-ietf-netconf-subscribed-notifications] will indicate that
a NETCONF publisher is able to receive, process, and respond to
NETCONF requests and
[I-D.draft-ietf-netconf-subscribed-notifications] subscription
operations on a session with active subscriptions.
4. Mandatory stream and datastore support
A NETCONF publisher supporting
[I-D.draft-ietf-netconf-subscribed-notifications] MUST support the
"NETCONF" event stream identified in that draft.
A NETCONF publisher supporting [I-D.ietf-netconf-yang-push] MUST
support the "running" datastore as defined by
[I.D.draft-ietf-netmod-revised-datastores].
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5. Transport connectivity
5.1. Dynamic Subscriptions
For dynamic subscriptions, if the NETCONF session involved with the
"establish-subscription" terminates, the subscription MUST be
deleted.
5.2. Configured Subscriptions
For a configured subscription, there is no guarantee a transport
session is currently in place with associated receiver(s). So where
a configured subscription has a receiver in the connecting state, but
no NETCONF transport exists to that receiver, the publisher MUST be
able to initiate a NETCONF transport session via NETCONF call home
[RFC8071], section 4.1 to that receiver. Until NETCONF connectivity
is established and a subscription-started state change notification
is successfully sent, that receiver MUST remain in its status of a
"connecting".
If the call home fails because the publisher receives receiver
credentials which are subsequently declined as part [RFC8071],
Section 4.1, step S5 authentication, then that receiver MUST be
assigned a "suspended" status.
If the call home fails to establish for any other reason, the
publisher MAY leave the receiver in a "connecting" status, and retry
the call home at a future time. Alternatively, the publisher MAY
place the receiver into a "suspended" status after a predetermined
number of call home attempts.
NETCONF Transport session connectivity SHOULD be verified via
Section 4.1, step S7.
Failure of an active NETCONF session MUST reset the restart the call
home process, and return the receiver to "connecting".
6. Notification Messages
Notification messages transported over NETCONF will be identical in
format and content to those encoded using one-way operations defined
within [RFC5277], section 4.
7. Security Considerations
Notification messages (including state change notifications) are
never sent before the NETCONF capabilities exchange has completed.
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If a malicious or buggy NETCONF subscriber sends a number of
"establish-subscription" requests, then these subscriptions
accumulate and may use up system resources. In such a situation,
subscriptions MAY be terminated by terminating the suspect underlying
NETCONF sessions. The publisher MAY also suspend or terminate a
subset of the active subscriptions on the NETCONF session.
The NETCONF Authorization Control Model [RFC6536] SHOULD be used to
control and restrict authorization of subscription configuration.
8. Acknowledgments
We wish to acknowledge the helpful contributions, comments, and
suggestions that were received from: Andy Bierman, Yan Gang, Sharon
Chisholm, Hector Trevino, Peipei Guo, Susan Hares, Tim Jenkins,
Balazs Lengyel, Kent Watsen, and Guangying Zheng.
9. References
9.1. Normative References
[I-D.draft-ietf-netconf-subscribed-notifications]
Voit, E., Clemm, A., Gonzalez Prieto, A., Tripathy, A.,
and E. Nilsen-Nygaard, "Custom Subscription to Event
Streams", draft-ietf-netconf-subscribed-notifications-06
(work in progress), October 2017.
[I-D.ietf-netconf-yang-push]
Clemm, Alexander., Voit, Eric., Gonzalez Prieto, Alberto.,
Tripathy, A., Nilsen-Nygaard, E., Bierman, A., and B.
Lengyel, "YANG Datastore Subscription", October 2017,
.
[I.D.draft-ietf-netmod-revised-datastores]
Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,
and R. Wilton, "Network Management Datastore
Architecture", draft-ietf-netmod-revised-datastores-04
(work in progress), August 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, DOI 10.17487/RFC5277, July 2008,
.
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[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,
.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536,
DOI 10.17487/RFC6536, March 2012,
.
[RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
RFC 8071, DOI 10.17487/RFC8071, February 2017,
.
9.2. Informative References
[I.D.draft-ietf-netconf-notification-messages]
Voit, Eric., Clemm, Alexander., Bierman, A., and T.
Jenkins, "YANG Notification Headers and Bundles",
September 2017, .
Appendix A. Examples
A.1. Event Stream Discovery
As defined in [I-D.draft-ietf-netconf-subscribed-notifications] an
event stream exposes a continuous set of events available for
subscription. A NETCONF client can retrieve the list of available
event streams from a NETCONF publisher using the "get" operation
against the top-level container "/streams" defined in
[I-D.draft-ietf-netconf-subscribed-notifications]. Any reply will
include the stream identities supported on the NETCONF publisher
which may be available to that client.
The following example illustrates the retrieval of the list of
available event streams using the "get" operation.
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Figure 1: Get streams request
After such a request, the NETCONF publisher returns a list of event
streams available. In the example reply below, the list contains
just the NETCONF stream.
NETCONF
Figure 2: Get streams response
A.2. Dynamic Subscriptions
The dynamic subscription RPCs and interactions operation are defined
in [I-D.draft-ietf-netconf-subscribed-notifications] and enhanced in
[I-D.ietf-netconf-yang-push].
A.2.1. Establishing Dynamic Subscriptions
An example of establish-subscription interactions over NETCONF
transport for a sample subscription is described below:
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NETCONF
/ex:foo
Figure 3: establish-subscription over NETCONF
If the NETCONF publisher can satisfy the request, the publisher sends
a positive "subscription-result" element, and the subscription-id of
the accepted subscription.
ok
22
Figure 4: Successful establish-subscription
If the NETCONF publisher cannot satisfy the request, or subscriber
has no authorization to establish the subscription, the publisher
will send a negative "subscription-result" element. For instance:
stream-unavailable
Figure 5: Unsuccessful establish subscription
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To get an idea of the interaction model, the following figure shows
two separate establish subscriptions RPC being made. The first is
given subscription id 22, the second, id 23.
+------------+ +-----------+
| Subscriber | | Publisher |
+------------+ +-----------+
| |
| Capability Exchange |
|<---------------------------->|
| |
| |
| Establish Subscription |
|----------------------------->|
| RPC Reply: OK, id = 22 |
|<-----------------------------|
| |
| notification message (for 22)|
|<-----------------------------|
| |
| |
| Establish Subscription |
|----------------------------->|
| RPC Reply: OK, id = 23 |
|<-----------------------------|
| |
| |
| notification message (for 22)|
|<-----------------------------|
| notification message (for 23)|
|<-----------------------------|
| |
Figure 6: Multiple subscription establishments over a single NETCONF
session
In the example above, it is important to note that the subscription
ids of 22 and 23 are not included in the notification messages of
[I-D.draft-ietf-netconf-subscribed-notifications]. However because
[I-D.ietf-netconf-yang-push] has defined its own notifications,
subscription identifiers are available within those notification
messages. With the availability of
[I.D.draft-ietf-netconf-notification-messages], all notification
messages will be able to transport a subscription identifier.
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A.2.2. Modifying Dynamic Subscriptions
The following demonstrates modifying a dynamic subscription.
Consider a subscription from [I-D.ietf-netconf-yang-push]. An
established may have a new filter applied. The desired modification
is the application of a new filter.
/interfaces-state/interface/oper-status
22
Figure 7: Subscription modification
If the NETCONF publisher can satisfy the request, the publisher sends
a positive "subscription-result". This response is like that to an
establish-subscription request, but without the subscription
identifier.
ok
Figure 8: Successful modify-subscription
If the NETCONF publisher cannot satisfy the request, the publisher
sends a negative "subscription-result" element. Its contents and
semantics match those from an establish-subscription request.
To get an idea of the interaction model, the following figure shows a
successful RPC modification request to subscription with an
identifier of 22.
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+------------+ +-----------+
| Subscriber | | Publisher |
+------------+ +-----------+
| |
| notification message |
|<-----------------------------|
| |
| Modify Subscription |
|----------------------------->|
| RPC Reply: OK |
|<-----------------------------|
| |
| notification message |
|<-----------------------------|
| |
Figure 9: Interaction model for successful subscription modification
A.2.3. Deleting Dynamic Subscriptions
The following demonstrates deleting a subscription.
22
Figure 10: Delete subscription
If the NETCONF publisher can satisfy the request, the publisher sends
an OK element. For example:
Figure 11: Successful delete subscription
If the NETCONF publisher cannot satisfy the request, the publisher
sends an error-rpc element indicating the modification didn't work.
One way this could happen is if an existing valid subscription
identifier was given, but that subscription was created on a
different NETCONF transport session:
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application
invalid-value
error
sn:identifier
no-such-subscription
Figure 12: Unsuccessful delete subscription
A.3. Configured Subscriptions
Configured subscriptions may be established, modified, and deleted
using configuration operations against the top-level subtree of
[I-D.draft-ietf-netconf-subscribed-notifications] or
[I-D.ietf-netconf-yang-push].
In this section, we present examples of how to manage the
configuration subscriptions using a NETCONF client. Key differences
from dynamic subscriptions over NETCONF is that subscription
lifetimes are decoupled from NETCONF sessions.
A.3.1. Creating Configured Subscriptions
For subscription creation, a NETCONF client may send:
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encode-xml
NETCONF
1.2.3.4
1234
Figure 13: Create a configured subscription
If the request is accepted, the publisher would reply:
Figure 14: Response to a successful configuration subscription
establishment
If the request is not accepted because the publisher cannot serve it,
no configuration is changed. In this case the publisher may reply:
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application
resource-denied
error
Temporarily the publisher cannot serve this
subscription due to the current workload.
Figure 15: Response to a failed configured subscription establishment
After a subscription has been created, NETCONF connectivity to each
receiver's IP address and port will be established if it does not
already exist. This will be accomplished via [RFC8071].
To get an idea of the interaction model, the following figure shows a
successful configuration based creation of a subscription.
+----------+ +-----------+ +---------+
|Config Ops| | Publisher | | 1.2.3.4 |
+----------+ +-----------+ +---------+
| | |
| Capability Exchange | |
|<-------------------------->| |
| | |
| | |
| Edit-config | |
|--------------------------->| |
| RPC Reply: OK | |
|<---------------------------| |
| | Call Home |
| |<-------------->|
| | |
| | Subscription |
| | Started |
| |--------------->|
| | |
| | notification |
| | message |
| |--------------->|
Figure 16: Interaction model for configured subscription
establishment
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A.3.2. Modifying Configured Subscriptions
Configured subscriptions can be modified using configuration
operations against the top-level subtree subscription-config.
For example, the subscription established in the previous section
could be modified as follows, here a adding a second receiver:
1922
1.2.3.5
1234
Figure 17: Modify configured subscription
If the request is accepted, the publisher would reply:
Figure 18: A successful configured subscription modification
And the previous interaction model would be extended as follows.
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+----------+ +-----------+ +---------+ +---------+
|Config Ops| | Publisher | | 1.2.3.4 | | 1.2.3.5 |
+----------+ +-----------+ +---------+ +---------+
| | | |
| | | |
| | notification | |
| | message | |
| |--------------->| |
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Call Home | |
| |<--------------------------->|
| | Subscription | |
| | Started | |
| |---------------------------->|
| | | |
| | notification | |
| | message | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 19: Interaction model for configured subscription modification
Note in the above that in the specific example above, modifying a
configured subscription actually resulted in subscription-started
notification. If the edit of the configuration had also added a
filter, a separate modify-subscription would have gone to the
original receiver.
A.3.3. Deleting Configured Subscriptions
Configured subscriptions can be deleted using configuration
operations against the top-level subtree subscription-config.
Deleting the subscription above would result in the following flow
impacting all receivers.
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+----------+ +-----------+ +---------+ +---------+
|Config Ops| | Publisher | | 1.2.3.4 | | 1.2.3.5 |
+----------+ +-----------+ +---------+ +---------+
| | | |
| | notification | |
| | message | |
| |--------------->| |
| |---------------------------->|
| | | |
| Edit-config | | |
|--------------------------->| | |
| RPC Reply: OK | | |
|<---------------------------| | |
| | Subscription | |
| | Terminated | |
| |--------------->| |
| |---------------------------->|
| | | |
Figure 20: Interaction model for configured subscription deletion
A.4. Subscription State Notifications
A publisher will send subscription state notifications according to
the definitions within
[I-D.draft-ietf-netconf-subscribed-notifications]).
A.4.1. subscription-started and subscription-modified
A subscription-started over NETCONF encoded in XML would look like:
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2007-09-01T10:00:00Z
39
encode-xml
NETCONF
/ex:foo
Figure 21: subscription-started subscription state notification
The subscription-modified is identical, with just the word "started"
being replaced by "modified".
A.4.2. subscription-completed, subscription-resumed, and replay-
complete
A subscription-completed would look like:
2007-09-01T10:00:00Z
39
Figure 22: subscription-completed notification in XML
The subscription-resumed and replay-complete are virtually identical,
with "subscription-completed" simply being replaced by "subscription-
resumed" and "replay-complete" in both encodings.
A.4.3. subscription-terminated and subscription-suspended
A subscription-terminated would look like:
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2007-09-01T10:00:00Z
39
unsupportable-volume
Figure 23: subscription-terminated subscription state notification
The subscription-suspended is virtually identical, with
"subscription-terminated" simply being replaced by "subscription-
suspended".
Appendix B. Changes between revisions
(To be removed by RFC editor prior to publication)
B.1. v05 to v06
o Moved examples to appendices
o All examples rewritten based on namespace learnings
o Normative text consolidated in front
o Removed all mention of JSON
o Call home process detailed
o Note: this is a major revision attempting to cover those comments
received from two week review.
B.2. v03 to v04
o Added additional detail to "configured subscriptions"
o Added interleave capability
o Adjusted terminology to that in draft-ietf-netconf-subscribed-
notifications
o Corrected namespaces in examples
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B.3. v01 to v03
o Text simplifications throughout
o v02 had no meaningful changes
B.4. v00 to v01
o Added Call Home in solution for configured subscriptions.
o Clarified support for multiple subscription on a single session.
No need to support multiple create-subscription.
o Added mapping between terminology in yang-push and [RFC6241] (the
one followed in this document).
o Editorial improvements.
Authors' Addresses
Alberto Gonzalez Prieto
VMware
Email: agonzalezpri@vmware.com
Eric Voit
Cisco Systems
Email: evoit@cisco.com
Alexander Clemm
Huawei
Email: ludwig@clemm.org
Einar Nilsen-Nygaard
Cisco Systems
Email: einarnn@cisco.com
Ambika Prasad Tripathy
Cisco Systems
Email: ambtripa@cisco.com
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