Interface to the Routing System (i2rs) E. Voit
Internet-Draft A. Clemm
Intended status: Informational A. Gonzalez Prieto
Expires: September 27, 2015 Cisco Systems
March 26, 2015
Requirements for Subscription to YANG Datastores
draft-ietf-i2rs-pub-sub-requirements-02
Abstract
This document provides requirements for a service that allows client
applications to subscribe to updates of a YANG datastore. Based on
criteria negotiated as part of a subscription, updates will be pushed
to targeted recipients. Such a capability eliminates the need for
periodic polling of YANG datastores by applications and fills a
functional gap in existing YANG transports (i.e. Netconf and
Restconf). Such a service can be summarized as a "pub/sub" service
for YANG datastore updates. Beyond a set of basic requirements for
the service, various refinements are addressed. These refinements
include: periodicity of object updates, filtering out of objects
underneath a requested a subtree, and delivery QoS guarantees.
Status of This Memo
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This Internet-Draft will expire on September 27, 2015.
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Business Drivers . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Pub/Sub in I2RS . . . . . . . . . . . . . . . . . . . . . 4
2.2. Pub/Sub variants on Network Elements . . . . . . . . . . 5
2.3. Existing Generalized Pub/Sub Implementations . . . . . . 6
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Assumptions for Subscriber Behavior . . . . . . . . . . . 8
4.2. Subscription Service Requirements . . . . . . . . . . . . 8
4.2.1. General . . . . . . . . . . . . . . . . . . . . . . . 8
4.2.2. Negotiation . . . . . . . . . . . . . . . . . . . . . 10
4.2.3. Update Distribution . . . . . . . . . . . . . . . . . 10
4.2.4. Transport . . . . . . . . . . . . . . . . . . . . . . 11
4.2.5. Security Requirements . . . . . . . . . . . . . . . . 11
4.2.6. Subscription QoS . . . . . . . . . . . . . . . . . . 12
4.2.7. Filtering . . . . . . . . . . . . . . . . . . . . . . 14
4.2.8. Assurance and Monitoring . . . . . . . . . . . . . . 14
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1. Normative References . . . . . . . . . . . . . . . . . . 15
6.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
YANG has gained acceptance as the data definition language of choice
for control and management related information. Applications that
interact with YANG datastores are extending beyond traditional
configuration of network elements. In many cases these applications
are aimed at service-assurance, which involves monitoring of
operational data and state. The existing YANG technology ecosystem
is proving insufficient for those applications due to:
o a reliance on RPC-style interactions where data is configured or
fetched on-demand by applications.
o change notifications which identify a node associated with the
config change, without the actual data updates
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Put simply, periodic fetching of data is not an adequate solution for
applications requiring frequent or prompt updates of remote object
state. Trying to impose a polling based solution to this problem
imposes load on networks, devices, and applications. Additionally,
polling solutions are brittle in the face of communication glitches,
and they have limitations in their ability to synchronize and
calibrate retrieval intervals across a network.
I2RS WG documents have expressed a need for more robust YANG object
subscriptions. Similar discussions are underway in NETMOD and
NETCONF. With the support of standards bodies such as OMG (DDS),
XMPP.org standard, generic Pub/Sub mechanisms to communicate data
updates have been defined and proven themselves in a wide variety of
deployments.
It is time to incorporate such generic object subscription mechanisms
as part of Network Elements, and allow these mechanisms to be applied
in the context of data that is conceptually contained in YANG
datastores. With such mechanisms, both controller and local Network
Element based applications can have access to a set of consistent
network information driven via push from peer Network Elements which
host authoritative information.
There are some valid IETF starting points and contexts for these
mechanisms. For example NETCONF Event Notifications [RFC5277]
provides a useful tool for an end-to-end solution. However RFC5277
does not follow the Pub/Sub paradigm, does not allow the explicit
deletion of subscriptions, and predates YANG. Predating YANG is an
issue, as monitoring and filtering based on YANG subtrees becomes
problematic . [RFC6470] defines configuration change notifications,
but doesn't provide the actual configuration change.
Because of this, the authors have put forward this requirements
document as well as [datastore-push]. We believe these provide a
context upon which to create new solution. It is intended that these
documents include requirements and provide technologies applicable
beyond I2RS.
2. Business Drivers
For decades, information delivery of current network state has been
accomplished either by fetching from operations interfaces, or via
dedicated, customized networking protocols. With the growth of SDN,
imperative policy distribution, and YANG's ascent as a dominant
programmatic interface to network elements, this mixture of fetch
plus custom networking protocols is no longer sufficient. What is
needed is a push mechanism that is able to deliver objects and object
changes as they happen.
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These push distribution mechanisms will not replace existing
networking protocols. Instead they will supplement these protocols,
providing different response time, peering, scale, and security
characteristics.
At the same time, SNMP and MIBs are still widely deployed and the
defacto choice for many monitoring solutions. Those solutions do not
require support for configuration transactions and the need to
validate and maintain configuration consistency, hence there is less
pressure to abandon SNMP and MIBs. Arguably the biggest shortcoming
of SNMP for those applications concerns the need to rely on periodic
polling, because it introduces additional load on the network and
devices, is brittle in case polling cycles are missed, and is hard to
synchronize and calibrate across a network, making data obtained from
multiple devices less comparable. If applications need to apply
those same interaction patterns for YANG datastores, similar issues
can be expected. Migration to YANG datastores by applications that
do not have to worry about transactional integrity becomes a lot more
compelling if those issues are addressed.
2.1. Pub/Sub in I2RS
Various I2RS documents highlight the need to provide Pub/Sub
capabilities between network elements. From [i2rs-arch], there are
references throughout the document beginning in section 6.2. Some
specific examples include:
o section 7.6 provides high level pub/sub (notification) guidance
o section 6.4.2 identifies "subscribing to an information stream of
route changes receiving notifications about peers coming up or
going down"
o section 6.3 notes that when local config preempts I2RS, external
notification might be necessary
In addition [i2rs-usecase]has relevant requirements. A small subset
includes:
o L-Data-REQ-12: The I2RS interface should support user
subscriptions to data with the following parameters: push of data
synchronously or asynchronously via registered subscriptions...
o L-DATA-REQ-07: The I2RS interface (protocol and IMs) should allow
a subscribe to select portions of the data model.
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o PI-REQ01: monitor the available routes installed in the RIB of
each forwarding device, including near real time notification of
route installation and removal.
o BGP-REQ10: I2RS client should be able instruct the I2RS agent(s)
to notify the I2RS client when the BGP processes on an associated
routing system observe a route change to a specific set of IP
Prefixes and associated prefixes....The I2RS agent should be able
to notify the client via publish or subscribe mechanism.
o IGP-REQ-07: The I2RS interface (protocol and IMs) should support a
mechanism where the I2RS Clients can subscribe to the I2RS Agent's
notification of critical node IGP events.
o MPLS-LDP-REQ-03: The I2RS Agent notifications should allow an I2RS
client to subscribe to a stream of state changes regarding the LDP
sessions or LDP LSPs from the I2RS Agent.
o L-Data-REQ-01: I2rs must be able to collect large data set from
the network with high frequency and resolution with minimal impact
to the device's CPU and memory.
And [i2rs-traceability] has Pub/Sub requirements listed in
Section 7.4.3.
o I2RS Agents should support publishing I2RS trace log information
to that feed as described in [i2rs-arch]. Subscribers would then
receive a live stream of I2RS interactions in trace log format and
could flexibly choose to do a number of things with the log
messages
There are additional individual drafts such as [i2rs-pubsub-security]
documenting the Pub/Sub needs for: time delivery sensitivity, support
for multiple transport protocols, secure/authorized communications,
and support for a range specification of subscribed data delivery
content. So the list above should not be considered exhaustive.
2.2. Pub/Sub variants on Network Elements
This document is intended to cover requirements beyond I2RS. Looking
at history, there are many examples of switching and routing
protocols which have done explicit or implicit pub/sub in the past.
In addition, new policy notification mechanisms which operate on
Switches and Routers are being specified now. A very small subset of
these includes:
o Routing Adjacencies in MPLS VPNs [RFC6513]
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o OSPF Route Flooding [RFC2328]
o Multicast topology establishment protocols (IGMP, PIM, etc.)
o Audio-Video Bridging streams needing guaranteed latency
[AVB-latency] (802.1Q-2011 Clause 35)
o Secure Automation and Continuous Monitoring (SACM)
[sacm-requirements]
o "Peer Mount" subscriptions for configuration verification between
peers[draft-voit-netmod]
Worthy of note in the list above is the wide variety of broadcast,
multicast, and unicast transports used. In addition some transports
are at L3, and some at L2. Therefore if we are going to attempt a
generic Pub/Sub mechanism, it will need to be structured so that it
may support alternative transports. Looking at the nearer term based
on current I2RS requirements, NETCONF should be our transport
starting point as it supports connection oriented/Unicast
communication. But we need to be prepared to decouple where viable
to support Multicast and Broadcast distribution as well.
2.3. Existing Generalized Pub/Sub Implementations
TIBCO, RSS, CORBA, and other technologies all show precursor Pub/Sub
technologies. However there are new needs described in Section 4
below which these technologies do not serve. We need a technology.
There are at least two widely deployed generalized pub/sub
implementations which come close to current needs: XMPP[XEP-0060] and
DDS[OMG-DDS]. Both serve as proof-points that a highly scalable
distributed datastore implementation connecting millions of edge
devices is possible.
Because of these proof points, we can be comfortable that the
underlying technologies can enable reusable generalized YANG object
distribution. Analysis will need to fully dimension the speed and
scale of such object distribution for various subtree sizes and
transport types.
3. Terminology
A Subscriber makes requests for set(s) of YANG object data. The
Subscriber is the owner of the Subscription.
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A Publisher is responsible for distributing subscribed YANG object
data per the terms of a Subscription. In general, a Publisher is the
owner of the YANG datastore that is subjected to the Subscription.
A Receiver is the target where a Publisher pushes updates. In
general, the Receiver and Subscriber will be the same entity. A
Subscription Service provides Subscriptions to Subscribers of YANG
data.
A Subscription Service interacts with the Publisher of the YANG data
as needed to provide the data per the terms of the Subscription.
A Subscription Request for one or more YANG subtrees (including
single leafs) made by the Subscriber of a Publisher and targeted to a
Receiver. A Subscription may include constraints which dictate how
often or under what conditions YANG information updates might be
sent.
A Subscription is a contract between a Subscription Service and a
Subscriber that stipulates the data to be pushed and the associated
terms.
A YANG datastore is a conceptual datastore that contains hierarchical
data defined in YANG data models. It is what is referred in existing
RFCs as "NETCONF datastore". However, as the same datastore is no
longer tied to NETCONF as a specific transport, the term "YANG
datastore" is deemed more appropriate.
An Update provides object changes which have occurred within
subscribed YANG subtree(s). An Update must include the current
status of (data) node instances which according to any filtering are
reportably different from the previously provided state. An Update
may include a bundled set of ordered/sequential changes for a given
object which have been made since the last update.
A Filter contains evaluation criteria which are evaluated against
YANG object(s) within a Subscription. There are two types of
Filters: Subtree Filters which identify selected objects/nodes
published under a target data node, and object Property Filters where
an object should only be published if it has propert(ies) meeting
specified Filter criteria. For "on-change" notifications, passing
through the Filter requires that a subscribed object is now different
that from the previous Push, AND at least one of the YANG objects
being evaluated has changed since the last Update.
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4. Requirements
Many of the requirements within this section have been morphed from
OMG's DDS and XMPP.org's requirements specifications.
4.1. Assumptions for Subscriber Behavior
This document provides requirements for the Subscription Service. It
does not define all the requirements for the Subscriber/Receiver.
However In order to frame the desired behavior of the Subscription
Service, it is important to specify key input constraints.
4.2. Subscription Service Requirements
This document provides requirements for the Subscription Service. It
does not define all the requirements for the Subscriber/Receiver.
However In order to frame the desired behavior of the Subscription
Service, it is important to specify key input constraints.
A Subscriber should avoid attempting to establish multiple
Subscriptions pertaining to the same information, i.e. referring to
the same datastore YANG subtrees.
A Subscriber may provide Subscription QoS criteria to the
Subscription Service such that if the Subscription Service is unable
to meet those criteria, the Subscription should not be established.
When a Subscriber needs to restart, it is acceptable for the
Subscriber to have to resubscribe. There is no requirement for the
life span of the Subscription to extend beyond the life span of the
Subscriber.
A Subscriber must be able to infer when a Subscription Service is no
longer active and when no more updates are being sent.
A Subscriber may check with a Subscription Service to validate the
existence and monitored subtrees of a Subscription.
A Subscriber must be able to periodically lease and re-lease a
Subscription from a Subscription Service.
4.2.1. General
A Subscription Service must support the ability to create, renew,
timeout, and terminate a Subscription.
A Subscription Service must be able to support and independently
track one or more Subscription Requests by the same Subscriber.
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A Subscription Service must be able to support an add/change/delete
of one or more YANG subtrees as part of the same Subscription
Request.
A Subscription Service must support Subscriptions against operational
datastores, configuration datastores, or both.
A Subscription Service must be able support a Subtree Filter so that
subscribed updates under a target node might publish only operational
data, only configuration data, or both.
A Subscription may include filters as defined within a Subscription
Request, the Subscription Service must publish only data nodes that
meet the filter criteria.
A Subscription Service must support the ability to subscribe to
periodic updates. The subscription period must be configurable as
part of the subscription request.
A Subscription Service should support the ability to subscribe to
updates "on-change", i.e. whenever values of subscribed data objects
change.
For "on-change" updates, the Subscription Service must support a
dampening period that needs to pass before the first or subsequent
"on-change" updates are sent. The dampening period should be
configurable as part of the subscription request.
A Subscription Service must allow Subscriptions to be monitored.
Specifically, a Subscription Service must at a minimum maintain
information about which Subscriptions are being serviced, the terms
of those subscriptions (e.g. what data is being subscribed,
associated filters, update policy - on change, periodic), and the
overall status of the Subscription - e.g. active or suspended.
A Subscription Service should be able to interpret Subscription QoS
parameters, and only establish a Subscription if it is possible to
meet the QoS needs of the provided QoS parameters.
A Subscription Service must support terminating of a Subscription
when requested by the Subscriber.
A Subscription Service should support the ability to suspend and to
resume a Subscription on request of a client.
A Subscription Service may at its discretion revoke or suspend an
existing subscription. Reasons may include transitory resource
limitation, credential expiry, failure to reconfirm a subscription,
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loss of connectivity with the Receiver, operator CLI, and/or others.
When this occurs, the Subscription Service must notify the Subscriber
and update subscription status.
A Subscription Service may offer the ability to modify a subscription
filter. If such an ability is offered, the service must provide
subscribers with an indication at what point the modified
subscription goes into effect.
4.2.2. Negotiation
A Subscription Service must be able to negotiate the following terms
of a Subscription:
o The policy: i.e. whether updates are on-change of periodic
o The interval, for periodic publication policy
o The dampening period, for on-change update policy
o Any filters associated with a subtree subscription
A Subscription Service should be able to negotiate QoS criteria for a
Subscription. Examples of Subscription QoS criteria may include
reliability of the Subscription Service, reaction time between a
monitored YANG subtree/object change and a corresponding notification
push, and the Subscription Service's ability to support certain
levels of object liveliness.
In cases where a Subscription Request cannot be fulfilled, the
Subscription Service must include in its decline a set of criteria
that would have been acceptable when the Subscription Request was
made. For example, if periodic updates were requested with too short
update intervals for the specified data set, the minimum acceptable
interval period should be included. If on-change updates were
requested with a dampening period, the minimum acceptable dampening
period should be included, or an indication whether only periodic
updates are supported along with the minimum acceptable interval
period for the data set being subscribed to.
4.2.3. Update Distribution
For "on-change" updates, the Subscription Service must only send
deltas to the object data for which a change occurred. [Otherwise
the subscriber will not know what has actually undergone change.]
The updates for each object needs to include an indication whether it
was removed, added, or changed.
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When a Subscription Service is not able to send updates per its
subscription contract, the Subscription must notify subscribers and
put the subscription into a state of indicating the Subscription was
suspended by the service. When able to resume service, subscribers
need to be notified as well. If unable to resume service, the
Subscription Service may terminate the subscription and notify
Subscribers accordingly.
When a Subscription with "on-change" updates is suspended and then
resumed, the first update should include updates of any changes that
occurred while the Subscription was suspended, with the current
value. The Subscription Service must provide a clear indication when
this capability is not supported (because in this case a client
application may have to synchronize state separately).
Multiple objects being pushed to a Subscriber, perhaps from different
Subscriptions, should be bundled together into a single Update.
The sending of an Update must not be delayed beyond the Push Latency
of any enclosed object changes.
The sending of an Update must not be delayed beyond the dampening
period of any enclosed object changes.
The sending of an Update must not occur before the dampening period
expires for any enclosed object changes.
A Subscription Service may, as an option, support a persistence/
replay capability.
4.2.4. Transport
A Subscription Service should support different transports.
A Subscription Service should support different encodings of payload.
It must be possible for Receivers to associate the update with a
specific Subscription.
In the case of connection-oriented transport, when a transport
connection drops, the associated Subscription should be terminated.
It is up the Subscriber to request a new Subscription.
4.2.5. Security Requirements
As part of the Subscription establishment, there must be mutual
authentication between the Subscriber and the Subscription Service.
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When there are multiple Subscribers, it should be possible to provide
cryptographic authentication in such a way that no Subscriber can
pose as the original Subscription Service.
Versioning must be supported.
A Subscription could be used to attempt to retrieve information that
a client has not authorized access to. Therefore it is important
that data pushed based on Subscriptions is authorized in the same way
that regular data retrieval operations are. Data being pushed to a
client must be filtered accordingly, just like if the data were being
retrieved on-demand. For Unicast transports, the NETCONF
Authorization Control Model applies.
Additions or changes within a subscribed subtree structure must be
validated against authorization methods before Subscription Updates
including new subtree information are pushed.
A loss of authenticated access to subtree or node SHOULD be
communicated to the Subscriber
Subscription requests, including requests to create, terminate,
suspend, and resume Subscriptions must be properly authorized.
When the Subscriber and Receiver are different, the Receiver must be
able to terminate any Subscription to it where objects are being
delivered over a Unicast transport.
A Subscription Service should decline a Subscription Request if it
would deplete its resources. It is preferable to decline a
Subscription when originally requested, rather than having to
terminate it prematurely later.
4.2.6. Subscription QoS
A Subscription Service should be able to negotiate the following
Subscription QoS parameters with a Subscriber: Dampening,
Reliability, Deadline, Bundling.
4.2.6.1. Liveliness
A Subscription Service must be able to respond to requests to verify
the Liveliness of a subscription.
A Subscription Service must be able to report the currently monitored
Nodes of a Subscription.
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4.2.6.2. Dampening
A Subscription Service must be able to negotiate the minimum time
separation since the previous update before transmitting a subsequent
update for Subscription. (Note: this is intended to confine the
visibility of volatility into something digestible by the receiver.)
4.2.6.3. Reliability
A Subscription Service may send Updates over Best Effort and Reliable
transports.
4.2.6.4. Coherence
Every update to a subscribed object must be sent to the Receiver in
sequential order.
4.2.6.5. Presentation
The Subscription Service should have the ability to bundle a set of
discrete object notifications into a single publishable update for a
Subscription. A bundle may include information on different Data
Nodes and/or multiple updates about a single Data Node.
For any bundled updates, the Subscription Service must provide
information for a Receiver to reconstruct the order and timing of
updates.
4.2.6.6. Deadline
The Subscription Service must be able to push updates at a regular
cadence that corresponds with Subscriber specified start and end
timestamps. (Note: the regular cadence can drive one, a discrete
quantity, or an unbounded set of periodic updates.)
4.2.6.7. Push Latency
The Subscription Service should be able to delay Updates on object
push for a configurable period per Subscriber.
It must be possible for an administrative entity to determine the
Push latency between object change in a monitored subtree and the
Subscription Service Push of the update transmission.
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4.2.7. Filtering
If no filtering criteria are provided, or if filtering criteria are
met, updates for a subscribed object must be pushed, subject to the
QoS limits established for the subscription.
It must be possible for the Subscription Service to receive Filter(s)
from a Subscriber and apply them to corresponding object(s) within a
Subscription.
It must be possible to attach one or more Subtree and/or Property
Filters to a subscription. Mandatory Property Filter types include:
o For character based object properties, filter values which are
exactly equal to a provided string, not equal to the string, or
containing a string.
o For numeric based object properties, filter values which are =,
!=, <, <=, >, >= a provided number.
It should be possible for Property Filtering criteria to evaluate
more than one property of a particular subscribed object as well as
apply multiple filters against a single property.
It should be possible to establish query match criteria on additional
objects to be used in conjunction with Property Filtering criteria on
a subscribed object. (For example: if A has changed AND B=1, then
Push A.) (Note: Query match capability may be done on objects within
the datastore even if those objects are not included within the
subscription. This of course assumes the subscriber has read access
to those objects.)
4.2.8. Assurance and Monitoring
It must be possible to fetch the state of a single subscription from
a Subscription Service.
It must be possible to fetch the state of all subscriptions of a
particular Subscriber.
It must be possible to fetch a list and status of all Subscription
Requests over a period of time. If there us a failure, some failure
reasons might include:
o Improper security credentials provided to access the target node
o Target node referenced does not exist
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o Subscription type requested is not available upon the target node
o Out of resources, or resources not available
o Incomplete negotiations with the Subscriber.
5. Acknowledgements
We wish to acknowledge the helpful contributions, comments, and
suggestions that were received from Ambika Tripathy and Prabhakara
Yellai as well as the helpfulness of related end-to-end system
context from [i2rs-pubsub-security] from Nancy Cam Winget, Ken Beck,
and David McGrew.
6. References
6.1. Normative References
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, July 2008.
[RFC6470] Bierman, A., "Network Configuration Protocol (NETCONF)
Base Notifications", RFC 6470, February 2012.
[RFC6513] Rosen, E. and R. Aggarwal, "Multicast in MPLS/BGP IP
VPNs", RFC 6513, February 2012.
6.2. Informative References
[AVB-latency]
Jeffree, T., "802.1Qav - Forwarding and Queuing
Enhancements for Time-Sensitive Streams", December 2009,
<http://www.ieee802.org/1/pages/802.1av.html>.
[OMG-DDS] "Data Distribution Service for Real-time Systems, version
1.2", January 2007, <http://www.omg.org/spec/DDS/1.2/>.
[XEP-0060]
Millard, P., "XEP-0060: Publish-Subscribe", July 2010,
<XEP-0060: Publish-Subscribe>.
[datastore-push]
Clemm, A., Gonzalez Prieto, A., and E. Voit, "Subscribing
to datastore push updates", October 2014,
<https://tools.ietf.org/html/draft-netmod-clemm-datastore-
push-00>.
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[draft-voit-netmod]
Voit, E., "Requirements for Peer Mounting of YANG subtrees
from Remote Datastores", October 2014,
<https://tools.ietf.org/html/draft-voit-netmod-peer-mount-
requirements-01>.
[i2rs-arch]
Atlas, A., "An Architecture for the Interface to the
Routing System", December 2014,
<https://tools.ietf.org/html/draft-ietf-i2rs-architecture-
06>.
[i2rs-pubsub-security]
Beck, K., Cam Winget, N., and D. McGrew, "Using the
Publish-Subscribe Model in the Interface to the Routing
System", July 2013, <https://tools.ietf.org/html/draft-
camwinget-i2rs-pubsub-sec-00>.
[i2rs-traceability]
Clarke, J., Salgueiro, G., and C. Pignataro, "Interface to
the Routing System (I2RS) Traceability: Framework and
Information Model", December 2014,
<https://datatracker.ietf.org/doc/draft-ietf-i2rs-
traceability/>.
[i2rs-usecase]
Hares, S. and M. Chen, "Summary of I2RS Use Case
Requirements", October 2014,
<https://datatracker.ietf.org/doc/draft-ietf-i2rs-usecase-
reqs-summary/>.
[sacm-requirements]
Cam Winget, N., "Secure Automation and Continuous
Monitoring (SACM) Requirements", October 2014,
<https://tools.ietf.org/html/draft-ietf-sacm-requirements-
02>.
Authors' Addresses
Eric Voit
Cisco Systems
Email: evoit@cisco.com
Voit, et al. Expires September 27, 2015 [Page 16]
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Alexander Clemm
Cisco Systems
Email: alex@cisco.com
Alberto Gonzalez Prieto
Cisco Systems
Email: albertgo@cisco.com
