draft-ietf-i2rs-ephemeral-state-00.txt   draft-ietf-i2rs-ephemeral-state-01.txt 
I2RS working group J. Haas I2RS working group J. Haas
Internet-Draft Juniper Internet-Draft Juniper
Intended status: Standards Track S. Hares Intended status: Standards Track S. Hares
Expires: December 25, 2015 Huawei Expires: February 29, 2016 Huawei
June 23, 2015 August 28, 2015
I2RS Ephemeral State Requirements I2RS Ephemeral State Requirements
draft-ietf-i2rs-ephemeral-state-00 draft-ietf-i2rs-ephemeral-state-01
Abstract Abstract
This document covers requests to the netmod and netconf Working This document covers requests to the netmod and netconf Working
Groups for functionality to support the ephemeral state requirements Groups for functionality to support the ephemeral state requirements
to implement the I2RS architecture. to implement the I2RS architecture.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 1, line 33 skipping to change at page 1, line 33
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 25, 2015. This Internet-Draft will expire on February 29, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Review of Requirements from I2RS architecture document . . . 3 2. Review of Requirements from I2RS architecture document . . . 3
3. Ephemeral State Requirements . . . . . . . . . . . . . . . . 4 3. Ephemeral State Requirements . . . . . . . . . . . . . . . . 4
3.1. Persistence . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Persistence . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Constraints . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Constraints . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . 4 3.3. Hierarchy . . . . . . . . . . . . . . . . . . . . . . . . 5
4. changes to YANG . . . . . . . . . . . . . . . . . . . . . . . 5 3.4. changes to YANG . . . . . . . . . . . . . . . . . . . . . 5
5. Changes to NETCONF . . . . . . . . . . . . . . . . . . . . . 5 3.5. Minimal sub-set of Changes . . . . . . . . . . . . . . . 5
6. Requirements regarding Identity, Secondary-Identity and 3.6. Requirements regarding Identity, Secondary-Identity and
Priority . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Priority . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Identity Requirements . . . . . . . . . . . . . . . . . . 6 3.6.1. Identity Requirements . . . . . . . . . . . . . . . . 5
6.2. Priority Requirements . . . . . . . . . . . . . . . . . . 6 3.6.2. Priority Requirements . . . . . . . . . . . . . . . . 5
6.3. Representing I2RS Attributes in ephemeral configuration 3.6.3. Transactions . . . . . . . . . . . . . . . . . . . . 6
state . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.6.4. Subscriptions to Changed State Requirements . . . . . 7
6.4. Semantics around storing and managing of priority and 4. Previously Considered Ideas . . . . . . . . . . . . . . . . . 8
client ID. . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. A Separate Ephemeral Datastore . . . . . . . . . . . . . 8
7. Subscriptions to Changed State Requirements . . . . . . . . . 9 4.2. Panes of Glass/Overlay . . . . . . . . . . . . . . . . . 8
8. Transactions . . . . . . . . . . . . . . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Previously Considered Ideas . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9.1. A Separate Ephemeral Datastore . . . . . . . . . . . . . 10 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
9.2. Panes of Glass/Overlay . . . . . . . . . . . . . . . . . 11 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10. Actions Required to Implement this Draft . . . . . . . . . . 11 8.1. Normative References: . . . . . . . . . . . . . . . . . . 10
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 8.2. Informative References . . . . . . . . . . . . . . . . . 10
12. Security Considerations . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
14.1. Normative References: . . . . . . . . . . . . . . . . . 12
14.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
The Interface to the Routing System (I2RS) Working Group is chartered The Interface to the Routing System (I2RS) Working Group is chartered
with providing architecture and mechanisms to inject into and with providing architecture and mechanisms to inject into and
retrieve information from the routing system. The I2RS Architecture retrieve information from the routing system. The I2RS Architecture
document [I-D.ietf-i2rs-architecture] abstractly documents a number document [I-D.ietf-i2rs-architecture] abstractly documents a number
of requirements for implementing the I2RS requirements. of requirements for implementing the I2RS requirements.
The I2RS Working Group has chosen to use the YANG data modeling The I2RS Working Group has chosen to use the YANG data modeling
language [RFC6020] as the basis to implement its mechanisms. language [RFC6020] as the basis to implement its mechanisms.
Additionally, the I2RS Working group has chosen to use the NETCONF Additionally, the I2RS Working group has chosen to use the NETCONF
[RFC6241] and its similar but lighter-weight relative RESTCONF [RFC6241] and its similar but lighter-weight relative RESTCONF
[I-D.bierman-netconf-restconf] as the protocols for carrying I2RS. [I-D.ietf-netconf-restconf] as the protocols for carrying I2RS.
While YANG, NETCONF and RESTCONF are a good starting basis for I2RS, While YANG, NETCONF and RESTCONF are a good starting basis for I2RS,
there are some things needed from each of them in order for I2RS to there are some things needed from each of them in order for I2RS to
be implemented. be implemented.
2. Review of Requirements from I2RS architecture document 2. Review of Requirements from I2RS architecture document
The following are ten requirements that [I-D.ietf-i2rs-architecture] The following are ten requirements that [I-D.ietf-i2rs-architecture]
contains which are important high level requirements: contains which are important high level requirements:
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10. The I2RS protocol MUST support the use of a secure transport. 10. The I2RS protocol MUST support the use of a secure transport.
However, certain functions such as notifications MAY use a non- However, certain functions such as notifications MAY use a non-
secure transport. Each model or service (notification, logging) secure transport. Each model or service (notification, logging)
must define within the model or service the valid uses of a non- must define within the model or service the valid uses of a non-
secure transport. secure transport.
3. Ephemeral State Requirements 3. Ephemeral State Requirements
3.1. Persistence 3.1. Persistence
I2RS requires ephemeral state; i.e. state that does not persist Ephemeral-REQ-01: I2RS requires ephemeral state; i.e. state that does
across reboots. If state must be restored, it should be done solely not persist across reboots. If state must be restored, it should be
by replay actions from the I2RS client via the I2RS agent. done solely by replay actions from the I2RS client via the I2RS
agent.
While at first glance this may seem equivalent to the writable- While at first glance this may seem equivalent to the writable-
running datastore in NETCONF, running-config can be copied to a running datastore in NETCONF, running-config can be copied to a
persistant data store, like startup config. I2RS ephemeral state persistant data store, like startup config. I2RS ephemeral state
MUST NOT be persisted. MUST NOT be persisted.
3.2. Constraints 3.2. Constraints
Ephemeral state MAY refer to non-ephemeral state for purposes of Ephemeral-REQ-02: Non-ephemeral state MUST NOT refer to ephemeral
implementing constraints. The designer of ephemeral state modules state for constraint purposes; it SHALL be considered a validation
are advised that such constraints may impact the speed of processing error if it does.
ephemeral state commits and should avoid them when speed is
essential.
Non-ephemeral state MUST NOT refer to ephemeral state for constraint
purposes; it SHALL be considered a validation error if it does.
3.3. Hierarchy
Similar to configuration state (config true, see [RFC6020], section
7.19.1), ephemeral state is not permitted to be configured underneath
nodes that are "config false" (state data).
Configuration of ephemeral state underneath "config true" is
permitted. This permits augmentation of configuration state with
ephemeral nodes.
Configuration of "config true" state underneath ephemeral state MUST
NOT be done.
State data, "config false", is permitted underneath ephemeral state.
This state data is part of the ephemeral module and should become
inaccessible if the ephemeral module reboots.
4. changes to YANG Ephemeral-REQ-03: Ephemeral state must be able to utilized temporary
operational state which (MPLS LSP-ID or a BGP IN-RIB) as a
constraints.
The YANG "config" keyword ([RFC6020], section 7.19.1) is extended to Ephemeral-REQ-04> Ephemeral state MAY refer to non-ephemeral state
support the keyword "ephemeral" in addition to "true" and "false". for purposes of implementing constraints. The designer of ephemeral
"config ephemeral" declares the nodes underneath to be ephemeral state modules are advised that such constraints may impact the speed
configuration. of processing ephemeral state commits and should avoid them when
speed is essential.
5. Changes to NETCONF 3.3. Hierarchy
A capability is registered declaring that the server supports Ephemeral-REQ-05: The ability to add on an object (or a hierarchy of
ephemeral configuration. E.g.: objects) that have the property of being ephemeral. An object needs
to be able to have (both) the property of being writable and the
property of the data being ephemeral (or non-ephemeral).
:ephemeral-config 3.4. changes to YANG
urn:ietf:params:netconf:capability:ephemeral-config:1.0
<get-config> will normally return "config ephemeral" nodes as it is a Ephemeral-REQ-06: Yang MUST have a way to indicate in a data model
form of configuration. It is further extended to add a new that nodes have the following properties: ephemeral, writable/not-
parameter, "filter-ephemeral". This parameter accepts the following writable, status/configuration.
arguments:
o none (default): No filtering of persistent or ephemeral state is 3.5. Minimal sub-set of Changes
done.
o ephemeral-only: Only nodes representing ephemeral state are Ephemeral-REQ-07: The minimal set is ...
returned.
o exclude-ephemeral: Only persistent configuration is returned. Potential set:
<get> is similarly extended to support "filter-ephemeral". 3.6. Requirements regarding Identity, Secondary-Identity and Priority
When a <copy-config> is done, regardless of datastore, nodes that are 3.6.1. Identity Requirements
"config ephemeral" are excluded from the target output.
6. Requirements regarding Identity, Secondary-Identity and Priority Ephemeral-REQ-08:Clients shall have identities, and secondary
identities.
6.1. Identity Requirements Explanation
I2RS requires clients to have an identity. This identity will be I2RS requires clients to have an identity. This identity will be
used by the Agent authentication mechanism over the appropriate used by the Agent authentication mechanism over the appropriate
protocol. protocol.
I2RS also permits clients to have a secondary identity which may be The Secondary identities can be carried as part of RPC or meta-data.
used for troubleshooting. This secondary identity is an opaque The primary purpose of the secondary identity is for traceability
value. [I-D.ietf-i2rs-traceability] provides an example of how the information which logs (who modifies certain nodes). This secondary
secondary identity can be used for traceability. identity is an opaque value. [I-D.ietf-i2rs-traceability] provides
an example of how the secondary identity can be used for
The secondary identity is carried in the configuration operation traceability.
using a new parameter to <edit-config>. E.g.:
<rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<i2rs:irs-secondary-identity>user1</i2rs>
<target>
<running/>
</target>
<config>
<top xmlns="http://example.com/schema/1.2/config">
<interface>
<name>Ethernet0/0</name>
<mtu>1500</mtu>
</interface>
</top>
</config>
</edit-config>
</rpc>
"config ephemeral" nodes that are created or altered as part of the
config operation will carry the secondary-identity as read-only
metadata.
6.2. Priority Requirements 3.6.2. Priority Requirements
To support Multi-Headed Control, I2RS requires that there be a To support Multi-Headed Control, I2RS requires that there be a
decidable means of arbitrating the correct state of data when decidable means of arbitrating the correct state of data when
multiple clients attempt to manipulate the same piece of data. This multiple clients attempt to manipulate the same piece of data. This
is done via a priority mechanism with the highest priority winning. is done via a priority mechanism with the highest priority winning.
This priority is per-client. This priority is per-client.
This further implies that priority is an attribute that is stored in Ephemeral-REQ-09: The data nodes MAY store I2RS client identity and
the NETCONF Access Control Model [RFC6536] as part of the group. not the effective priority at the time the data node is stored. The
E.g.: I2RS Client MUST have one priority at a time. The priority MAY be
dynamically changed by AAA, but the exact actions are part of the
protocol definition as long as Collisions are handled as described in
Ephemeral-REQ-10, Ephemeral-REQ-11, and Ephemeral-REQ-12.
+--rw nacm Ephemeral-REQ-10: When a collision occurs as two clients are trying
+--rw enable-nacm? boolean to write the same data node, this collision is considered an error
+--rw read-default? action-type and priorities were created to give a deterministic result. When
+--rw write-default? action-type there is a collision, a notification MUST BE sent to the original
+--rw exec-default? action-type client to give the original client a chance to deal with the issues
+--rw enable-external-groups? boolean surrounding the collision. The original client may need to fix their
+--ro denied-operations yang:zero-based-counter32 state.
+--ro denied-data-writes yang:zero-based-counter32
+--ro denied-notifications yang:zero-based-counter32 Ephemeral-REQ-11: The requirement to support multi-headed control is
+--rw groups required for collisions and the priority resolution of collisions.
| +--rw group [name] Multi-headed control is not tied to ephemeral state. I2RS is not
| +--rw name group-name-type mandating how AAA supports priority. Mechanisms which prevent
| +--rw user-name* user-name-type collisions of two clients trying the same node of data are the focus.
| +--rw i2rs:i2rs-priority i2rs-priority-type
Ephemeral-REQ-12: If two clients have the same priority, the
architecture says the first one wins. The I2RS protocol has this
requirement to prevent was the oscillation between clients. If one
uses the last wins scenario, you may oscillate. That was our
opinion, but a design which prevents oscillation is the key point.
Hints for Implementation
Ephemeral configuration state nodes that are created or altered by Ephemeral configuration state nodes that are created or altered by
users that match a rule carrying i2rs-priority will have those nodes users that match a rule carrying i2rs-priority will have those nodes
annotated with metadata. Additionally, during commit processing, if annotated with metadata. Additionally, during commit processing, if
nodes are found where i2rs-priority is already present, and the nodes are found where i2rs-priority is already present, and the
priority is better than the transaction's user's priority for that priority is better than the transaction's user's priority for that
node, the commit SHALL fail. An appropriate error should be returned node, the commit should fail. An appropriate error should be
to the user stating the nodes where the user had insufficient returned to the user stating the nodes where the user had
priority to override the state. insufficient priority to override the state.
6.3. Representing I2RS Attributes in ephemeral configuration state
I2RS attributes may be modeled as meta-data,
[I-D.ietf-netmod-yang-metadata]. This meta-data MUST be read-only;
operations attempting to alter it MUST be silently ignored. An I2RS
module will be defined to document this meta data. An example of its
use:
<foo xmlns:i2rs="https://ietf.example.com/i2rs"
i2rs:i2rs-secondary-identity="user1" i2rs:i2rs-priority="47">
...
</foo>
6.4. Semantics around storing and managing of priority and client ID.
The semantics and desired behavior around the storing and managing of
priority and client ID have the following properties:
1. First - the priority mechanism is intended to handle "error cases
of colliding writes" in a predictable way that results in a
consistent mechanism. It is true that the same mechanism could
be used if they were not considered "errors", but it is important
to minimize the need and impact of the priority mechanism
2. Second, if there is a priority conflict where both clients
(Client_A and Client_B) share the same priority, the client that
wrote first wins. This is to avoid network oscillation if two
clients are "fighting" over writing the same state. When there
are multiple clients and the time arrival of the messages may not
be predictable (network transit differences, which socket is
read, software differences), basing state on last arrival time
doesn't give consistent and predictable behavior. That gives
behavior ont the following time-line
1. Time_1: Client_A writes X=N with priority 10
2. Time_2: Client_B attempts to write X=K with priority 10 and
is rejected
3. Time_3: Client_A writes X=P with priority 10 and succeeds
For the I2RS Agent to properly handle these actions, it is
necessary to know that X is owned by Client_A. Priority alone is
not sufficient because the basis for rejecting Client_B's write
but accepting Client_A's write is that Client_A is the owner.
Thus it is necessary to store the Client Identity with the nodes
that it owns. This could be in an I2RS-specific overlay that is
only used by the I2RS agent and only contains the nodes that have
been written by I2RS.
3. Third, a question has come up regarding what the behavior of
priority is if a client's priority changes and whether priority
needs to be stored with each node when that node is written. In
my "keep-it-simple" perspective, priority is associated with a
Client and is only used on a conflict. This would mean that
priority is not stored with a node when that node is written.
Instead, the Client Identity is stored with the node and the
Client's priority is looked up in a client table that the I2RS
Agent can access. That client table could be populated via
configuration, via a AAA protocol, via NACM, etc. The sematic
implications are as follows:
1. Time_1: Client_A writes X=N with priority 10
2. Time_2: Client_A's priority is changed (UNUSUAL) to priority
6
3. Time_3: Client_B writes X=K with priority 8 (succeeds since 8
> 6)
4. Time_4: Client_A attempts to write X=N with priority 6 (fails
b/c 8 > > 6)
5. Time_5: Client_B's priority is changed (UNUSUAL) to priority
7
6. Time_6 Client_B writes X=P with priority 7 and succeeds (same
> owner, no priority check)
The alternate approach would have store the priority with which a 3.6.3. Transactions
node was written. That is more like a priority lock that could
only be changed by a client with higher priority or by the same
client, regardless of priority. This approach would require
storing a priority per node and the semantic implications would
be as follows:
1. Time_1:Client_A writes X=N with priority 10 Ephemeral-REQ-13: Section 7.9 of the [I-D.ietf-i2rs-architecture]
states the I2RS architecture does not include multi-message atomicity
and roll-back mechanisms, but suggests an I2RS client may indicates
one of the following error handling techniques for a given message
sent to the I2RS client:
2. Time_2:Client_A's priority is changed (UNUSUAL) to priority 6 1. Perform all or none: All operations succeed or none of them will
be applied. This useful when there are mutual dependencies.
3. Time_3: Client_B attempts to write X=K with priority 8 and 2. Perform until error: Operations are applied in order, and when
fails (10 > 8) error occurs the processing stops. This is useful when
dependencies exist between multiple-message operations, and order
is important.
4. Time_4: Client_A writes X=N with priority 6 and succeeds 3. Perform all storing errors: Perform all actions storing error
(same owner, no priority check) indications for errors. This method can be used when there are
no dependencies between operations, and the client wants to sort
it out.
5. Time_5: Client_B's priority is changed (UNUSUAL) to priority I2RS-REQ-XX: None of these three error handling for multi-message
7 cases SHOULD cause errors into be insert the I2RS ephemeral data-
store.
6. Time_6 Client_B writes X=P with priority 7 and succeeds (7 > Discussion of Current NETCONF/RESTCONF versus
6)
The behavior for these two models is different at Time_3 and RESTCONF does an atomic action within a http session, and NETCONF has
Time_4. atomic actions within a commit. These features may be used to
perform these features.
The initial preference was that the priority is not stored with the I2RS processing is dependent on the I2RS model. The I2RS model must
node, but if it necessary to store it with the node additional consider the dependencies within multiple operations work within a
discussion may be needed with the I2RS WG. model.
7. Subscriptions to Changed State Requirements 3.6.4. Subscriptions to Changed State Requirements
I2RS clients require the ability to monitor changes to ephemeral I2RS clients require the ability to monitor changes to ephemeral
state. While subscriptions are well defined for receiving state. While subscriptions are well defined for receiving
notifications, the need to create a notification set for all notifications, the need to create a notification set for all
ephemeral configuration state may be overly burdensome to the user. ephemeral configuration state may be overly burdensome to the user.
There is thus a need for a general subscription mechanism that can There is thus a need for a general subscription mechanism that can
provide notification of changed state, with sufficient information to provide notification of changed state, with sufficient information to
permit the client to retrieve the impacted nodes. This should be permit the client to retrieve the impacted nodes. This should be
doable without requiring the notifications to be created as part of doable without requiring the notifications to be created as part of
every single I2RS module. every single I2RS module.
8. Transactions The following requirements from the
[I-D.ietf-i2rs-pub-sub-requirements] apply to ephemeral state:
Section 7.9 of the [I-D.ietf-i2rs-architecture] states the I2RS o PubSub-REQ-1: The I2RS interface SHOULD support user subscriptions
architecture does not include multi-message atomicity and rollback to data with the following parameters: push of data synchronously
mechanisms, but suggests an I2RS client may inidicate one of the or asynchronously via registered subscriptions.
following error handling techniques for a given message sent to the
I2RS client:
1. Perform all or none: All operations succeed or none of them will o PubSSub-REQ-2: Real time for notifications SHOULD BEdefined
be applied. This useful when there are mutual dependencies. defined by the data models.
2. Perform until error: Operations are applied in order, and when o PubSub-REQ-3: Security of the pub/sub data stream SHOULD be able
error occurs the processing stops. This is useful when to be model dependent.
dependencies exist between multiple-message operations, and order
is important.
3. Perform all storing errors: Perform all actions storing error o PubSub-REQ-4: The Pub/Sub mechanism SHOULD allow subscription to
indications for errors. This method can be used when there are critical Node Events. Examples of critical node events are BGP
no dependencies between operations, and the client wants to sort peers down or ISIS protocol overload bits.
it out.
None of these three cases insert known errors into the I2RS ephemeral o PubSub-REQ-5:I2RS telemetry data for certain protocols (E.g. BGP)
datastore. will require a hierarchy of filters or XPATHs. The I2RS protocol
design MUST balance security against the throughput of the
telemetry data.
RESTCONF does an atomic action within a http session, and NETCONF has o PubSub-REQ-6: I2RS Filters SHOULD be able to be dynamic.
atomic actions within a commit. These features may be used to
perform these features.
I2RS processing is dependent on the I2RS model. The I2RS model must o Pub-Sub-REQ-7: I2rs protocol MUST be able to allow I2RS agent to
consider the dependencies within multiple operations work within a set limits on the data models it will support for pub/sub and
model. within data models to support knobs for maximum frequency or
resolution of pub/sub data.
9. Previously Considered Ideas 4. Previously Considered Ideas
9.1. A Separate Ephemeral Datastore 4.1. A Separate Ephemeral Datastore
The primary advantage of a fully separate datastore is that the The primary advantage of a fully separate datastore is that the
semantics of its contents are always clearly ephemeral. It also semantics of its contents are always clearly ephemeral. It also
provides strong segregation of I2RS configuration and operational provides strong segregation of I2RS configuration and operational
state from the rest of the system within the network element. state from the rest of the system within the network element.
The most obvious disadvantage of such a fully separate datastore is The most obvious disadvantage of such a fully separate datastore is
that interaction with the network element's operational or that interaction with the network element's operational or
configuration state becomes significantly more difficult. As an configuration state becomes significantly more difficult. As an
example, a BGP I2RS use case would be the dynamic instantiation of a example, a BGP I2RS use case would be the dynamic instantiation of a
skipping to change at page 11, line 13 skipping to change at page 8, line 48
groupings from an IETF-standardized BGP module in such an I2RS groupings from an IETF-standardized BGP module in such an I2RS
ephemeral datastore's modules, one cannot currently reference state ephemeral datastore's modules, one cannot currently reference state
from one datastore to anothe from one datastore to anothe
For example, XPath queries are done in the context document of the For example, XPath queries are done in the context document of the
datastore in question and thus it is impossible for an I2RS model to datastore in question and thus it is impossible for an I2RS model to
fulfil a "must" or "when" requirement in the BGP module in the fulfil a "must" or "when" requirement in the BGP module in the
standard data stores. To implement such a mechanism would require standard data stores. To implement such a mechanism would require
appropriate semantics for XPath. appropriate semantics for XPath.
9.2. Panes of Glass/Overlay 4.2. Panes of Glass/Overlay
I2RS ephemeral configuration state is generally expected to be I2RS ephemeral configuration state is generally expected to be
disjoint from persistent configuration. In some cases, extending disjoint from persistent configuration. In some cases, extending
persistent configuration with ephemeral attributes is expected to be persistent configuration with ephemeral attributes is expected to be
useful. A case that is considered potentially useful but problematic useful. A case that is considered potentially useful but problematic
was explored was the ability to "overlay" persistent configuration was explored was the ability to "overlay" persistent configuration
with ephemeral configuration. with ephemeral configuration.
In this overlay scenario, persistent configuration that was not In this overlay scenario, persistent configuration that was not
shadowed by ephemeral configuration could be "read through". shadowed by ephemeral configuration could be "read through".
There were two perceived disadvantages to this mechanism: There were two perceived disadvantages to this mechanism:
The general complexity with managing the overlay mechanism itself. The general complexity with managing the overlay mechanism itself.
Consistency issues with validation should the ephemeral state be Consistency issues with validation should the ephemeral state be
lost, perhaps on reboot. In such a case, the previously shadowed lost, perhaps on reboot. In such a case, the previously shadowed
persistent state may no longer validate. persistent state may no longer validate.
10. Actions Required to Implement this Draft 5. IANA Considerations
o Draft for adding "config ephemeral" to YANG.
o Draft defining NETCONF changes including capability, RPC operation
changes and support of secondary identity, RPC changes to support
priority.
o I2RS draft to define meta-data for priority and secondary-
identity.
11. IANA Considerations
TBD. There are no IANA requirements for this document.
12. Security Considerations 6. Security Considerations
TBD. The security requirements for the I2RS protocol are covered in
[I-D.hares-i2rs-auth-trans] document.
13. Acknowledgements 7. Acknowledgements
This document is an attempt to distill lengthy conversations on the This document is an attempt to distill lengthy conversations on the
I2RS mailing list for an architecture that was for a long period of I2RS mailing list for an architecture that was for a long period of
time a moving target. Some individuals in particular warrant time a moving target. Some individuals in particular warrant
specific mention for their extensive help in providing the basis for specific mention for their extensive help in providing the basis for
this document: this document:
o Alia Atlas o Alia Atlas
o Andy Bierman o Andy Bierman
skipping to change at page 12, line 32 skipping to change at page 10, line 4
o Dean Bogdanavich o Dean Bogdanavich
o Rex Fernando o Rex Fernando
o Joel Halpern o Joel Halpern
o Thomas Nadeau o Thomas Nadeau
o Juergen Schoenwaelder o Juergen Schoenwaelder
o Kent Watsen o Kent Watsen
14. References 8. References
14.1. Normative References: 8.1. Normative References:
[I-D.hares-i2rs-auth-trans]
Hares, S., Migault, D., and J. Halpern, "I2RS Security
Related Requirements", draft-hares-i2rs-auth-trans-05
(work in progress), August 2015.
[I-D.ietf-i2rs-architecture] [I-D.ietf-i2rs-architecture]
Atlas, A., Halpern, J., Hares, S., Ward, D., and T. Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
Nadeau, "An Architecture for the Interface to the Routing Nadeau, "An Architecture for the Interface to the Routing
System", draft-ietf-i2rs-architecture-09 (work in System", draft-ietf-i2rs-architecture-09 (work in
progress), March 2015. progress), March 2015.
[I-D.ietf-i2rs-pub-sub-requirements]
Voit, E., Clemm, A., and A. Prieto, "Requirements for
Subscription to YANG Datastores", draft-ietf-i2rs-pub-sub-
requirements-02 (work in progress), March 2015.
[I-D.ietf-i2rs-rib-info-model] [I-D.ietf-i2rs-rib-info-model]
Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing
Information Base Info Model", draft-ietf-i2rs-rib-info- Information Base Info Model", draft-ietf-i2rs-rib-info-
model-06 (work in progress), March 2015. model-06 (work in progress), March 2015.
[I-D.ietf-i2rs-traceability] [I-D.ietf-i2rs-traceability]
Clarke, J., Salgueiro, G., and C. Pignataro, "Interface to Clarke, J., Salgueiro, G., and C. Pignataro, "Interface to
the Routing System (I2RS) Traceability: Framework and the Routing System (I2RS) Traceability: Framework and
Information Model", draft-ietf-i2rs-traceability-03 (work Information Model", draft-ietf-i2rs-traceability-03 (work
in progress), May 2015. in progress), May 2015.
[I-D.ietf-netmod-yang-metadata] [I-D.ietf-netmod-yang-metadata]
Lhotka, L., "Defining and Using Metadata with YANG", Lhotka, L., "Defining and Using Metadata with YANG",
draft-ietf-netmod-yang-metadata-01 (work in progress), draft-ietf-netmod-yang-metadata-01 (work in progress),
June 2015. June 2015.
14.2. Informative References 8.2. Informative References
[I-D.bierman-netconf-restconf] [I-D.ietf-netconf-restconf]
Bierman, A., Bjorklund, M., Watsen, K., and R. Fernando, Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
"RESTCONF Protocol", draft-bierman-netconf-restconf-04 Protocol", draft-ietf-netconf-restconf-07 (work in
(work in progress), February 2014. progress), July 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
Network Configuration Protocol (NETCONF)", RFC 6020, the Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010. DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
Bierman, "Network Configuration Protocol (NETCONF)", RFC and A. Bierman, Ed., "Network Configuration Protocol
6241, June 2011. (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536, March Protocol (NETCONF) Access Control Model", RFC 6536,
2012. DOI 10.17487/RFC6536, March 2012,
<http://www.rfc-editor.org/info/rfc6536>.
Authors' Addresses Authors' Addresses
Jeff Haas Jeff Haas
Juniper Juniper
Email: jhaas@juniper.net Email: jhaas@juniper.net
Susan Hares Susan Hares
Huawei Huawei
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