Subject: [netmod] "00" Notification for draft-voit-netmod-peer-mount-requirements

From: "Eric Voit (evoit)" <[email-masked]>
Date: Thu, 25 Sep 2014 22:38:08 +0000

We have been developing SDN applications which require quick, iterative access to objects representing network and device abstractions.  These objects include ones authoritatively owned by a local system, as well as ones provided from remote datastores.  Two such applications we have prototyped are “Cloud Policer” and “DDoS Thresholding”.  (See links below for more on these apps.)

The good news is that we found YANG models and syntax to be a nice fit for these applications.   However we have been trying to cover several missing elements:

Missing Element #1: Developer Simplicity
We wanted applications to access remote objects from a single datastore, without having to have the applications peer directly with remote devices.  We also wanted clients and applications to access datastores in the same way independent of whether the applications were hosted on a Network Element or Controller.

Missing Element #2: Who owns an Object?
Applications can't tell which Network Element across a set of devices is the authoritative owner of a particular replicated object.  Since replicated data gets out of synch, resolution / convergence is a problem.

Missing Element #3: Maintaining caches of remote information
Applications need timely access to remote information, which can necessitate the introduction cache infrastructure.  Netconf provides little support to facilitate this.  For example, notifications are not a good match to subscribe to push-updates.  

To solve these problems, we need technology solutions which work equally well for both Controllers and Network Elements.  These solutions must expose local datastores which provide authoritative, consolidated views of distributed network objects.  This must be done in a way which allows the applications to sit anywhere in the network, on various abstractions, while maintaining domain consistency. And this must be done while maximizing application developer simplicity.  

This draft is intended to start aggregating requirements in this space.  The draft is not complete, so it would be great to hear from others who are interested in helping so that we end up with a more comprehensive context.

Solutions do exist which can solve a subset of these requirements.  One particular technology we have built is known as “peer mount”.  Peer mount gives the ability to reference YANG information into a local datastore from remote datastores.  This provides client applications with local access to information which might be transparently federated across multiple systems and datastores.  It also retains clear object ownership to minimize synchronization and inter-system dependency issues.   There are already implementations of this technology, for example, in Open Daylight.  However, we believe requirements and use cases for this technology apply equally well to network devices.  

Please let us know if either the requirements or technology specifications are problem you are interested in exploring.

Thanks!
Eric, Alex, Prabhakara, Ambika, Shashi

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Thursday, September 25, 2014 8:41 AM
To: Prabhakara Yellai (pyellai); Shashi Kumar Bansal (shabansa); Ambika Prasad Tripathy (ambtripa); Alexander Clemm (alex); Eric Voit (evoit); Ambika Prasad Tripathy (ambtripa); Alexander Clemm (alex); Prabhakara Yellai (pyellai); Eric Voit (evoit); Shashi Kumar Bansal (shabansa)
Subject: New Version Notification for draft-voit-netmod-peer-mount-requirements-00.txt

A new version of I-D, draft-voit-netmod-peer-mount-requirements-00.txt
has been successfully submitted by Eric Voit and posted to the IETF repository.

Name:                  draft-voit-netmod-peer-mount-requirements
Revision:              00
Title:                     Requirements for Peer Mounting of YANG subtrees from Remote Datastores
Document date: 2014-09-25
Group:                  Individual Submission
Pages:                  22
URL:            http://www.ietf.org/internet-drafts/draft-voit-netmod-peer-mount-requirements-00.txt
Status:         https://datatracker.ietf.org/doc/draft-voit-netmod-peer-mount-requirements/
Htmlized:       http://tools.ietf.org/html/draft-voit-netmod-peer-mount-requirements-00

Abstract:
   Network integrated applications want simple ways to access YANG
   objects and subtrees which might be distributed across network.
   Performance requirements may dictate that it is unaffordable for a
   subset of these applications to go through existing centralized
   management brokers.  For such applications, development complexity
   must be minimized.  Specific aspects of complexity developers want to
   ignore include:

   o  whether authoritative information is actually sourced from remote
      datastores (as well as how to get to those datastores),

   o  whether such information has been locally cached or not,

   o  whether there are zero, one, or more controllers asserting
      ownership of information, and

   o  whether there are interactions with other applications
      concurrently running elsewhere

   The solution requirements described in this document detail what is
   needed to support application access to authoritative network YANG
   objects from controllers (star) or peering network devices (mesh) in
   such a way to meet these goals.

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