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Network Working Group                                    M. Jethanandani
Internet-Draft                                         Ciena Corporation
Intended status: Standards Track                        October 27, 2014
Expires: April 30, 2015

                    NETCONF and persistent responses


   This document outlines a solution for NETCONF operations that might
   be initiated with a single request but require multiple responses to
   be received, with an ability to terminate the operation at any time.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on April 30, 2015.

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1.  Introduction

   NETCONF [RFC6241] protocol is being positioned as a replacement for
   Command Line Interface (CLI) and Simple Network Management Protocol
   (SNMP).  It is therefore expected that NETCONF will provide all the
   capabilities that CLI and SNMP offer today and more.

   One of the operations that CLI offers today is the ability to issue
   an operation that might result in multiple responses being returned,
   till such time that a terminaing condition is encountered or when the
   operation is cancelled.  An example of such an operation is when the
   ping or a traceroute command is issued.  In the former case, the
   operation can continue sending responses back till it is cancelled,
   while in the latter case there is usually a terminating condition
   that stops the responses.  NETCONF protocol as defined today sends a
   single Remote Procedure Call (RPC) request and expects a single reply
   to that request.  The "persistent" operation defined above expects
   multiple responses for a single request, till such time a terminating
   condition is encountered.

   This problem should not be confused with "bulk responses" where one
   might be dealing with fragments of the same response.  It is not
   enough to have the server collect all the possible responses before
   responding because in some cases there may not be a response,
   indicating a failure and it will hold up the NETCONF session till a
   response is received.

   Section 2 suggest at least one solution to this problem.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in Key words for use in
   RFCs to Indicate Requirement Levels [RFC2119].

1.1.  Terminology

             | Acronym | Meaning                            |
             | CLI     | Command Line Interface             |
             |         |                                    |
             | RPC     | Remote Procedure Call              |
             |         |                                    |
             | SNMP    | Simple Network Management Protocol |

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2.  Solution

   The proper solution should address the requirement of multiple
   responses, fragmented responses and an ability to terminate the
   request without terminating the NETCONF session.  This can be best
   achieved at the messaging layer in NETCONF, where a single request
   can result in multiple responses being received and way to associate
   the multiple responses with the original request.

   One of the suggested solutions would look like this.  A request goes
   out with the operation to perform.

   <rpc message-id="101" link-id="201" xmlns="...">


   And a reply can come back with either a <rpc-reply> as it happens
   today or a series of "linked replies" which would look like this.

   <rpc-reply message-id="101" next-message-id="102" link-id="201"


   <rpc-reply message-id="102" next-message-id="103" link-id="201"


   with the last reply looking like this.

   <rpc-reply message-id="101" message-id="103" link-id="201"


   When the client wants to terminate the task, it issues an <rpc-
   cancel> to terminate the condition.  Note, NETCONF currently does not
   support this particular operation.

   <rpc-cancel link-id="201">


   And a reply comes back acknowledging that the task was terminated.


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3.  IANA Considerations

4.  Security Considerations

5.  Acknowledgements

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)", RFC
              6241, June 2011.

6.2.  Informative References

   [RFC6243]  Bierman, A. and B. Lengyel, "With-defaults Capability for
              NETCONF", RFC 6243, June 2011.

Author's Address

   Mahesh Jethanandani
   Ciena Corporation
   3939 North 1st Street
   San Jose, CA  95134

   Phone: 408.904.2160
   Fax:   408.436.5582
   Email: mjethanandani@gmail.com

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