| I2RS working group | S. Hares |
| Internet-Draft | Huawei |
| Intended status: Informational | A. Dass |
| Expires: May 19, 2017 | Ericsson |
| November 15, 2016 |
RESTCONF Changes to Support I2RS Protocol
draft-hares-netconf-i2rs-restconf-00.txt
This document describes a RETCONF additions to support the Interface to Routing system (I2RS) protocol requirements for I2RS protocol version 1. The I2RS protocol is a re-use higher layer protocol which defines extensions to other protocols (NETCONF and RESTCONf) and extensions to the Yang Data Modeling language.
The I2RS protocol supports ephemeral state datastores as control plane datastores. Initial versions of this document contain descriptions of the ephemeral datastore. Future versions may move this description to NETMOD datastore description documents.
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This a proposal for yang additions to support the first version of the I2RS protocol.
The I2RS architecture [RFC7921] defines the I2RS interface "a programmatic interface for state transfer in and out of the Internet routing system". The I2RS protocol is a protocol designed to a higher level protocol comprised of a set of existing protocols which have been extended to work together to support a new interface to the routing system. The I2RS protocol is a "reuse" management protocol which creates new management protocols by reusing existing protocols and extending these protocols for new uses, and has been designed to be implemented in phases [RFC7921].
The first version of the I2RS protocol is comprised of extensions to existing features of NETCONF [RFC6241] and RESTCONF [I-D.ietf-netconf-restconf]. The data modeling language for the I2RS protocol will be Yang [RFC7950] with features and extensions proposed in this draft.
The structure of this document is:
This section reviews definitions from I2RS architecture [RFC7921] and NETCONF operational state definitions [I-D.nmdsdt-netmod-revised-datastores] before using these to construct a definition of the ephemeral data store.
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 I2RS architecture [RFC7921] defines the following terms:
An practical example for three states of the operator-applied policy may help the reader understand the concept. Consider the following three desired outcomes with their policy knob states:
Action: I2RS protocol software feature is installed, but the operator does not want the I2RS ephemarl datastore to take precedence (that is be used) on any variables in the applied configuration datastore. This policy set might be valid if I2RS is only suppose to monitor data on this node through newly defined parameters.
Action: This is the normal case for the I2RS Agent where the ephemeral control-plane datastore takes precedence over the intended configuration datastore and dynamic configuration datastores. The values from the I2RS ephemearl datastore are used rather than the intended configuration datastore and the dynamic configuration protocol datastore. When the ephemeral data is removed by the I2RS agent, the dyanmic configuration datastore and the intended configuration datastore state is restored, combined and passed to the routing protocols for application.
Action: This case can occur if the I2RS Client write to the ephemeral control plane data store is only suppose to take precedence until the next configuration cycle from a centralized system. Suppose the local configuration is get by the centralized system at 11:00pm each night. The I2RS Client writes temporary changes to the routing system via the I2RS agent ephemeral write. At 11:00pm, the local configuration update overwrite the ephemeral. The I2RS Agent notifies the I2RS Client which is tracking which of the ephemeral changes are being overwritten.
This oveview reviews the following:
The requirements for the I2RS protocol are defined in the following documents:
The Interface to the routing System (I2RS) creates a new capability for the routing systems, and with greater capaiblities come a greater need for security. The requirements for a secure environment for I2RS is described in [I-D.ietf-i2rs-security-environment-reqs].
The features the I2RS protocol requires are:
This protocol strawman utilizes the following existing proposed features for NETCONF and RESTCONF
The NETMOD Working Group has been working to create new definitions of datastores based on feedback from operators on desiring a split between operational state and configuration state.
This document takes [I-D.nmdsdt-netmod-revised-datastores] as the current status of the datastore discussion on configuration state, operational state, ephemeral state changes (via I2RS), and routing protocol state. The following things need to be carefully defined in this work:
[I-D.nmdsdt-netmod-revised-datastores] is making good progress, but these additional details need to be tied down.
This protocol strawman utilizes the following existing proposed features for NETCONF and RESTCONF
The NETMOD Working Group has been working to create new definitions of datastores based on feedback from operators on desiring a split between operational state and configuration state.
This document takes [I-D.nmdsdt-netmod-revised-datastores] as the current status of the datastore discussion on configuration state, operational state, ephemeral state changes (via I2RS), and routing protocol state. The following things need to be carefully defined in this work:
[I-D.nmdsdt-netmod-revised-datastores] is making good progress, but these additional details need to be tied down.
capability-name: ephemeral-datastore
This capability defines the RESTCONF protocol extensions for the ephemeral state. The ephemeral state has the features described in the previous section on NETCONF.
The ephemeral capabilities have the following dependencies:
The ephemeral-datastore capability is identified by the following capability string: (capability uri)
none
RESTCONF must be able to support the ephemeral datstore as a context with its rules as part of the "{+restconf}/data" subtree. The "edit collision" features in RESTCONF must be able to provide notification to I2RS read functions or to rpc functions. The "timestamp" with a last modified features must support the traceability function.
The "Entity Tag" could support saving a client-priority tuple as a opaque string, but it is important that that additions be made to restore client-priority so it can be compared with strimgs can be done to determine the comparison of two I2RS client-priorities.
The current operations in RESTCONF are: OPTIONS, HEAD, GET, POST, PUT, PATCH, and DELETE. This section describes the modification to these exiting operations.
The options methods should be augmented by the [RFC7895] information that will provide an indication of what ephemeral state exists in a data modules, or a data modules sub-modules or nodes.
The HEAD in retrieving the headers of a resources. It would be useful to changes these headers to indicate the datastore a node or submodule or module is in (ephemeral or normal), and allow filtering on ephemeral nodes or trees, submodules or module.
GET must be able to read from the URL and a context ("?context=ephemeral"). Similarly, it is important the Get be able to determine if the context=ephemeral.
POST must simply be able to create resources in ephemeral datastores ("context=ephemeral") and invoke operations defined in ephemeral data models.
PUT must be able to reference an ephemeral module, sub-module, and nodes ("?context=ephemeral").
Plain PATCH must be able to update or create child resources in an ephemeral context ("?context=ephemeral") The PATCH for the ephemeral state must be change to provide a merge or update of the original data only if the client's using the patch has a higher priority than an existing datastore's client, or if PATCH requests to create a new node, sub-module or module in the datastore.
The phrase "?context=ephemeral" following an element will specify the ephemeral data store when deleting an entry.
The query parameters (content, depth, fields, insert, point, start-time, stop-time, and with-defaults (report-all, trim, explicit, report-all-tagged) must support ephemeral context ("?context=ephemeral") described above.
The ephemeral database must support the ability to publish notifications as events and the I2RS clients being able to receiving notifications as Event stream. The event error stream processing should support the publication/subscription mechanisms for ephemeral state defined in [I-D.ietf-netconf-yang-push].
The ephemeral database must support in RESTCONF must also support passing error information regarding ephemeral data access over to RESTCONF equivalent of the and traceability client.
Note: This section probably goes with the definition of ephemeral state or as its own Draft
This section provides an overview of the ephemeral data store as a control plane datastore and discusses several concepts that implementers need to consider and provide feedback on. The concepts include basic ephemeral datastore concepts, I2RS caching of ephemeral data, issues for massive data flow, error handling (normal and reduced), use of IPFIX or Binary for carrying I2RS ephemeral data, and ephemeral state
This section augments [I-D.nmdsdt-netmod-revised-datastores] to begin to discuss how the ephemeral state comtrol-plane datastore might be implemented. The purpose of this section is to gather implementer wisdom on the ephemeral datastore into one place. This section discusses:
[I-D.ietf-i2rs-ephemeral-state] describes the requirements for I2RS ephemeral state.
This section augments [I-D.nmdsdt-netmod-revised-datastores] to begin to discuss how the ephemeral state comtrol-plane datastore might be implemented. This initial draft refines the general description so that early I2RS ephemeral state implementations may progress.
[I-D.nmdsdt-netmod-revised-datastores] architecture suggests that the applied configuration is the combination of intended datastore, the dynamic configuration protocols, and the control-plane datastores. As described above, there are policy knobs which allow the I2RS Agent to handle deciding what specific configuration variables is installed in protocols (E.g BGP) or protocol independent functions (RIB or Filters). In addition, the control-plane datastore may store the parameters need to provide publication of events, statistics, telementry within the ephemeral control-plane datastore.
The ephemeral data-store may have models which learn operational state and augment it by configuration. For example [I-D.ietf-i2rs-yang-l3-topology] uploads ospf and isis topology information from the routing system and allows configuration of additional links or nodes.
This new architecture is a multiple panes-of-glass model where the decision on what value is chosen is based on policy. The extension of this model is that it is possible for two or more of the control-plane datastores to be ephemeral. If this occurs, then the policy knobs must define the how the 2+ ephemeral datastores interact with each other and the configuration state.
Note: The requirements for ephemeral state are in: [I-D.ietf-i2rs-ephemeral-state]).
This section provides a discussion so that implementers writing code for these datastores can discuss what needs to be standardized and what does not need to be standardized.
The ephemeral data store has the following general qualities:
The multiple control-plane datastore model [I-D.nmdsdt-netmod-revised-datastores] architecture allows multiple datastores which could allow an implementation of caching of ephemeral data in the I2RS Agent by having a main and a backup I2RS agent. Early implementations should at least support the single ephemeral data model, but MAY support the multiple datastore mode. It is important that these early implementations provide feedback for standardization on the following:
Large amounts of data can flow from the I2RS agent to the I2RS client, or from the I2RS client to the I2RS Agent. The I2RS client may set or query ephemeral configuration in the routing system via the I2RS agent and receive operational state, notifications, or logging from the I2RS Agent on behalf of the I2RS routing system. I2RS Clients can send large amount of ephemeral configuration data to the I2RS Agent. The writes may be done via NETCONF (<edit-config> or an rpc function), or via RESTCONF (PUT, PATCH, POST). Reads can be done via NETCONF <get-config> or RESTCONF GET or query.
The I2RS RIB Data Model [I-D.ietf-i2rs-rib-data-model] also supports the use of rpc to add/delete RIBs, add/delete/update routes, and add/delete nexthops. If the I2RS client does a small to medium number of writes to the I2RS ephemeral state in the I2RS Agent in a routing system, the full validation that NETCONF or RESTCONF does will be able to be done without any reduction in speed to the I2RS high-performance system. For example, if the I2RS RIB Data Model has adds a 1000 routes, the I2RS RIB use of rpc to add/delete/update routes should be able to provide a high-performance system. Alternatively the NETCONF <edit-config> could update these 1000 routes with a write, or the RESTCONF POST, PUT or PATCH should be able to add the 1000 routes.
If a large number of ephemeral routes or filters are written (updates or new) by the I2RS Client to the ephemeral state in the I2RS agent, one of the key issues for a high performance interface is the time it takes to validate routes. Due to this concern, the I2RS architecture was design to allow less than the full NETCONF or RESTCONF validation. The concept is that the I2RS routes would be validated within the I2RS client and sent via a 99.999% reliable connection. In this scenario, the I2RS Agent would trust the validation that the I2RS Client did, and the communication of the route additions via the network connection.
An experiment regarding this has been done with the ODL code base update of ephemeral routes, but additional experimentation needs to be done prior to finalizing this design. Section 3.4.2 reviews how this process might be done, but many open issues exist in implementing this "low-validation" interface. Without additional experimentation and prototype code, this type of "low-validation",
This section reviews I2RS normal error handling and error handling for rpc with no validation checks.
An I2RS agent validates an I2RS client's information by examining the following:
Can the I2RS protocol allow for reduced error checking? The need for speed in the I2RS protocol insertions in to the I2RS RIB suggest that it is worth experimenting for reduced validation in order to obtain high levels of throughput. If NETCONF or RESTCONf streams pre-checked routes to the datastore, what happens? Implementation experience is needed to determine the feasibility of this approach.
This feature may require a operator-applied policy knob swith a "no validation" feature
Due to the potentially large data flow the traffic measurment statistics generate, these statistics are best handled by publication techniques within NETCONF or a separate protocol such as IPFIX. In the future version of the I2RS protocol may desire to support a data stream outbound from the I2RS Agent to an I2RS client via the IPFIX protocol.
The binary encoding of JSON or XML encodnig in RESTCONF or NETCONF may provide a better throughput. Research needs to be done on what is the appropriate binary encoding.
I2RS ephemeral state may operate in places where there is a DDoS attacks where the network devices are attacked. Is one attack plane the ability to remove all tracing if the I2RS reboots an attack vector?
This is a protocol strawman - nothing is going to IANA.
The security requirements for the I2RS protocol are covered in [I-D.ietf-i2rs-protocol-security-requirements]. The security environment the I2RS protocol is covered in [I-D.ietf-i2rs-security-environment-reqs]. Any person implementing or deploying the I2RS protocol should consider both security requirements.
TBD
| [I-D.ietf-i2rs-ephemeral-state] | Haas, J. and S. Hares, "I2RS Ephemeral State Requirements", Internet-Draft draft-ietf-i2rs-ephemeral-state-22, November 2016. |
| [I-D.ietf-i2rs-protocol-security-requirements] | Hares, S., Migault, D. and J. Halpern, "I2RS Security Related Requirements", Internet-Draft draft-ietf-i2rs-protocol-security-requirements-17, September 2016. |
| [I-D.ietf-i2rs-rib-data-model] | Wang, L., Ananthakrishnan, H., Chen, M., amit.dass@ericsson.com, a., Kini, S. and N. Bahadur, "A YANG Data Model for Routing Information Base (RIB)", Internet-Draft draft-ietf-i2rs-rib-data-model-06, July 2016. |
| [I-D.ietf-i2rs-rib-info-model] | Bahadur, N., Kini, S. and J. Medved, "Routing Information Base Info Model", Internet-Draft draft-ietf-i2rs-rib-info-model-09, July 2016. |
| [I-D.ietf-i2rs-security-environment-reqs] | Migault, D., Halpern, J. and S. Hares, "I2RS Environment Security Requirements", Internet-Draft draft-ietf-i2rs-security-environment-reqs-01, April 2016. |
| [I-D.ietf-i2rs-yang-l3-topology] | Clemm, A., Medved, J., Varga, R., Tkacik, T., Liu, X., Bryskin, I., Guo, A., Ananthakrishnan, H., Bahadur, N. and V. Beeram, "A YANG Data Model for Layer 3 Topologies", Internet-Draft draft-ietf-i2rs-yang-l3-topology-04, September 2016. |
| [I-D.ietf-netconf-call-home] | Watsen, K., "NETCONF Call Home and RESTCONF Call Home", Internet-Draft draft-ietf-netconf-call-home-17, December 2015. |
| [I-D.ietf-netconf-keystore] | Watsen, K. and G. Wu, "Keystore Model", Internet-Draft draft-ietf-netconf-keystore-00, October 2016. |
| [I-D.ietf-netconf-netconf-event-notifications] | Prieto, A., Clemm, A., Voit, E., Nilsen-Nygaard, E., Tripathy, A., Chisholm, S. and H. Trevino, "NETCONF Support for Event Notifications", Internet-Draft draft-ietf-netconf-netconf-event-notifications-01, October 2016. |
| [I-D.ietf-netconf-restconf] | Bierman, A., Bjorklund, M. and K. Watsen, "RESTCONF Protocol", Internet-Draft draft-ietf-netconf-restconf-18, October 2016. |
| [I-D.ietf-netconf-rfc5277bis] | Clemm, A., Prieto, A., Voit, E., Nilsen-Nygaard, E., Tripathy, A., Chisholm, S. and H. Trevino, "Subscribing to Event Notifications", Internet-Draft draft-ietf-netconf-rfc5277bis-01, October 2016. |
| [I-D.ietf-netconf-tls-client-server] | Watsen, K., "TLS Client and Server Models", Internet-Draft draft-ietf-netconf-tls-client-server-01, November 2016. |
| [I-D.ietf-netconf-yang-patch] | Bierman, A., Bjorklund, M. and K. Watsen, "YANG Patch Media Type", Internet-Draft draft-ietf-netconf-yang-patch-13, November 2016. |
| [I-D.ietf-netconf-yang-push] | Clemm, A., Voit, E., Prieto, A., Tripathy, A., Nilsen-Nygaard, E., Bierman, A. and B. Lengyel, "Subscribing to YANG datastore push updates", Internet-Draft draft-ietf-netconf-yang-push-04, October 2016. |
| [I-D.ietf-netconf-zerotouch] | Watsen, K. and M. Abrahamsson, "Zero Touch Provisioning for NETCONF or RESTCONF based Management", Internet-Draft draft-ietf-netconf-zerotouch-11, October 2016. |
| [I-D.ietf-netmod-schema-mount] | Bjorklund, M. and L. Lhotka, "YANG Schema Mount", Internet-Draft draft-ietf-netmod-schema-mount-03, October 2016. |
| [I-D.ietf-netmod-syslog-model] | Wildes, C. and K. Koushik, "A YANG Data Model for Syslog Configuration", Internet-Draft draft-ietf-netmod-syslog-model-11, November 2016. |
| [I-D.nmdsdt-netmod-revised-datastores] | Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K. and R. Wilton, "A Revised Conceptual Model for YANG Datastores", Internet-Draft draft-nmdsdt-netmod-revised-datastores-00, October 2016. |