Network Working Group                                              Z. Li
Internet-Draft                                       Huawei Technologies
Intended status: Informational                             July 26, 2019
Expires: January 27, 2020

                      Cross-Area Work in the IETF


   This document investigates the benefits of cross-area work in the
   IETF.  It is examines existing cross-area work and identifies other
   possibilities for work that spans more than one area.  The intention
   is to help community members who focus their work within a specific
   area to understand related work in other areas and to motivate
   efficient cooperation across different areas in the IETF.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 27, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

Li                      Expires January 27, 2020                [Page 1]

Internet-Draft            Cross-Area IETF Work                 July 2019

   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SRv6  . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  YANG Models . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Network Intelligence/Telemetry  . . . . . . . . . . . . . . .   6
     5.1.  Network Telemetry . . . . . . . . . . . . . . . . . . . .   6
     5.2.  Network Intelligence  . . . . . . . . . . . . . . . . . .   8
   6.  5G Transport  . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Cross-layer Work  . . . . . . . . . . . . . . . . . . . . . .   9
     7.1.  Path-Aware Networking . . . . . . . . . . . . . . . . . .   9
     7.2.  Application-aware IPv6 Networking . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   With the development of new network technologies such as cloud
   computing, 5G, IoT, etc., very many applications are carried over the
   network.  Each has different needs for network bandwidth, latency,
   jitter, and packet loss, etc.

   Work in the IETF is divided into Areas.  The demands of the new
   technologies motivates innovation and new architectures in multiple
   network layers, and resulting cross-area work is increasing in the
   IETF.  Existing protocol practice shows that people who focus on one
   specific area are sometimes not aware of related work in different
   areas.  Some cross-area work is not recognized until late in the
   lifecycle so that useful experiences cannot be shared early in the
   development.  Fixing problems that are identified late can become
   time consuming.

   This document investigates the benefits of cross-area work in the
   IETF.  It is examines existing cross-area work and identifies other
   possibilities for work that spans more than one area.  The intention

Li                      Expires January 27, 2020                [Page 2]

Internet-Draft            Cross-Area IETF Work                 July 2019

   is to help community members who focus their work within a specific
   area to understand related work in other areas and to motivate
   efficient cooperation across different areas in the IETF.

2.  Terminology

   SRv6: Segment Routing over IPv6

   MPLS: Multi-Protocol Label Switch

3.  SRv6

   Segment Routing is an important networking technology developed in
   the IETF.  SRv6 is the Segment Routing deployed on the IPv6 data
   plane[RFC8200] and SRv6 network programming
   [I-D.ietf-spring-srv6-network-programming] is introduced to support
   multiple services which have requirements on the SRv6 network.  The
   related areas and Working Groups for SRv6 are shown in Figure 1: the
   work can be categorized into Basics, Encapsulations, Protocols, YANG,
   Use cases, and Others.

        --------------------------- SRv6 ----------------------------
        |           |           |           |           |           |
        |           |           |           |           |           |
     +------+   +------+   +---------+   +-----+   +---------+   +------+
     |Basics|   |Encaps|   |Protocols|   |YANG |   |Use Cases|   |Others|
     +------+   +------+   +---------+   +-----+   +---------+   +------+
        |          |            |           |           |           |
RTG   SPRING     DETNET        LSR        YANG       DETNET         BFD
                   BIER       BESS                     TEAS       RTGWG
                               IDR                      SFC
                               PCE                     BIER

INT                6MAN

                   Figure 1: Related Areas/WGs for SRv6

   The major IETF areas for SRv6 work are the RTG area and the INT area.
   There is work in multiple working groups in the RTG area, and the
   major work in the INT area includes the new IPv6 encapsulation and
   the possible compression work on the IPv6 header.

Li                      Expires January 27, 2020                [Page 3]

Internet-Draft            Cross-Area IETF Work                 July 2019

4.  YANG Models

   Data models written in the YANG modelling language [RFC6020] can be
   used for service and network management to provide a programmatic
   approach for representing (virtual) services or networks and for
   deriving configuration information that will be forwarded to network
   and service components that are used to build and deliver the

   YANG module developers have taken both top-down and bottom-up
   approaches to develop modules [RFC8199] and to establish a mapping
   between network technology and customer requirements on the top or
   abstracting common construct from various network technologies on the
   bottom.  There are many data models including configuration and
   service models that have been specified or are being specified by the
   IETF.  They cover many of the networking protocols and techniques.

   Figure 2 is from [I-D.wu-model-driven-management-virtualization]
   provides and provides an overview of various macro-functional blocks
   at different levels that articulate the various YANG data modules.
   In this figure, example models developed in the IETF are layered as
   Network Service Models, Network Resource Models, and Network Element
   Models.  The Network Element Models are further layered into
   Composition Models and Function Models.

Li                      Expires January 27, 2020                [Page 4]

Internet-Draft            Cross-Area IETF Work                 July 2019

   <<Network Service Models>>
| << Network Service Models>>                                             |
| +----------------+ +----------------+                                   |
| |      L3SM      | |     L2SM       |                                   |
| |  Service Model | |  Service Model |          .............            |
| +----------------+ +----------------+                                   |
+------------------------------------------------------------------------ +
  <<Network Resource Models>>
+------------------------------------------------------------------------ +
| << Network Resource Models >>                                           |
|      +------------+  +-------+  +----------------+   +------------+     |
|      |Network Topo|  | Tunnel|  |Path Computation|   |FM/PM/Alarm |     |
|      |   Models   |  | Models|  | API Models     |   | OAM  Models|...  |
|      +------------+  +-------+  +----------------+   +------------+     |
 <Network Element Models>>
|  <<Composition Models>>                                                 |
|      +-------------+ +---------------+ +----------------+               |
|      |Device Model | |Logical Network| |Network Instance|               |
|      |             | |Element Model  | |   Model        |    ...        |
|      +-------------+ +---------------+ +----------------+               |
| << Function Models>>                                                   |
|+---------++---------++---------++----------++---------++---------+      |
||         ||         ||         ||Common    ||         || OAM:    |      |
|| Routing ||Transport|| Policy  ||(interface||Multicast||         |      |
||(e.g.,BGP||(e.g.,   ||(e.g, ACL||multicast || (IGMP   ||FM,PM,   |      |
|| OSPF)   || MPLS)   ||  QoS)   || IP, ... )|| MLD,...)||Alarm    | ...  |
|+---------++---------++---------++----------++---------++---------+      |

               Figure 2: An overview of Layered YANG Modules

   A Network Service Model [RFC8309] is a kind of high level data model.
   It describes a service and the parameters of the service in a
   portable way that can be used uniformly and independent of the
   equipment and operating environment.  In the OPS area, the Layer
   Three Virtual Private Network Service Model (L3SM) [RFC8299] and the
   Layer Two Virtual Private Network Service Model (L2SM) [RFC8466]
   define L3VPN and L2VPN services that can be ordered by a customer
   from a network operator.  In the RTG area, the Virtual Network (VN)
   model[I-D.ietf-teas-actn-vn-yang] provides a YANG data model
   generally applicable to any mode of VN operation.

Li                      Expires January 27, 2020                [Page 5]

Internet-Draft            Cross-Area IETF Work                 July 2019

   The category of Network Resource Models includes topology modules and
   tunnel modules worked on in the RTG area, as well as the resource
   management tool models worked in both the RTG and OPS areas.

   A Network Element model is used to describe how a service can be
   implemented by activating and tweaking a set of functions (enabled in
   one or multiple devices, or hosted in cloud infrastructures) that are
   involved in the delivery of the service.  This includes various
   models for individual protocols specified in the RTG, OPS, TSV, and
   INT areas.

5.  Network Intelligence/Telemetry

   It is conceivable that an intent-driven autonomic network [RFC7575]
   is the logical next step for network evolution following Software
   Defined Network (SDN).  This approach aims to reduce (or even
   eliminate) human labor, make the most efficient usage of network
   resources, and provide better services more aligned with customer
   requirements.  Although it takes time to reach the ultimate goal, the
   journey has started nevertheless.

   Network Intelligence and Telemetry are the cornerstone for the
   intent-driven autonomic network.

5.1.  Network Telemetry

   Network telemetry has emerged as a mainstream technical term to refer
   to the newer data collection and consumption techniques,
   distinguishing itself from the conventional techniques for network
   OAM.  Network Telemetry acquires network data remotely for network
   monitoring and operation.  It addresses the current network operation
   issues and enables smooth evolution toward intent-driven autonomous

   The Network Telemetry Framework [I-D.ietf-opsawg-ntf] provides a
   layered categorization for the telemetry technologies developed in
   the IETF across areas including OPS, TSV (IPPM working group), RTG
   (MPLS and NVO3 working groups), and INT (6MAN working group).  The
   categorization is shown in Figure 3.

Li                      Expires January 27, 2020                [Page 6]

Internet-Draft            Cross-Area IETF Work                 July 2019

       |              | Management    | Control        | Forwarding   |
       |              | Plane         | Plane          | Plane         |
       | data Config. | gRPC, NETCONF,| NETCONF/YANG   | NETCONF/YANG, |
       | & subscrib.  | YANG PUSH     |                | YANG FSM      |
       | data gen. &  | DNP,          | DNP,           | In-situ OAM,  |
       | processing   | YANG          | YANG           | PBT, IPFPM,   |
       |              |               |                | DNP           |
       | data         | gRPC, NETCONF | BMP, NETCONF   | IPFIX         |
       | export       | YANG PUSH     |                |               |

          Figure 3: Layer Category of Network Telemetry Framework

   The categories shown in Figure 3 are as follows:

   - Management Plane Telemetry: This refers to work on the push
   extensions for NETCONF [I-D.ietf-netconf-yang-push].  This work is
   on-going in the NETCONF working group in the OPS area.

   - Control Plane Telemetry: BGP is a very important protocol in the
   control plane.  The GROW working group in the OPS area is developing
   the BGP Monitoring Protocol (BMP) [RFC7854] to monitor BGP sessions
   and to provide a convenient interface for obtaining route views.

   - Data Plane Telemetry: In-situ Flow Information Telemetry (IFIT)
   [] is a new proposal that enumerates
   several key components and describes how they could be assembled to
   achieve a complete solution for on-path user traffic telemetry in
   carrier networks.  It includes two major modes that are described in
   further documents: Postcard mode in
   [] and Passport mode in
   [I-D.zhou-ippm-enhanced-alternate-marking] proposes a lightweight way
   to achieve most measurement requirements.  In general, the basic
   mechanism is discussed in the IPPM working group in the TSV area, and
   specific encapsulations are discussed in the working groups dedicated
   to the associated protocols including the 6MAN working group in the
   INT area for IPv6 and SRv6, and the MPLS and NVO3 working groups in
   the RTG area for MPLS and VXLAN.

Li                      Expires January 27, 2020                [Page 7]

Internet-Draft            Cross-Area IETF Work                 July 2019

5.2.  Network Intelligence

   Thanks to advances in computing and storage technologies, today's big
   data analytics gives network operators an unprecedented opportunity
   to gain network insights and move toward network autonomy.  Some
   operators have started to explore the application of Artificial
   Intelligence (AI) to make sense of network data.  Software tools can
   use the network data to detect and react to network faults,
   anomalies, and policy violations, as well as to predict future
   events.  In turn, the network policy can be updated for planning,
   intrusion prevention, optimization, and self-healing.

   This topic is relatively new and requires a central place for
   discussion.  The IRTF's Network Management Research Group (NMRG)
   recently discussed Network Intent []
   while [] presents intelligent network management
   scenarios based on reinforcement-learning approaches.

6.  5G Transport

   As work on the requirements, architecture, and protocols to support
   5G progress, cross-area work is gaining momentum to address major
   requirements for transport systems to underlie 5G.  This includes
   work on network slicing, deterministic latency/low latency, etc.

   1.  Network Slicing

   Transport network slicing involves work in the IETF RTG area and the
   INT area.  In the TEAS working group in the RTG area,
   [I-D.ietf-teas-enhanced-vpn] specifies a framework for using
   existing, modified, and potentially new networking technologies as
   components to provide Enhanced Virtual Private Network (VPN+)
   services to satisfy the network slicing requirement.  SR is an
   important transport technologies for network slicing and the SPRING
   working group is also involved.

   The DMM WG in the INT area focuses on the mobility work involved in
   supporting end-to-end network slicing.  When considering RAN slicing
   and Mobile Core slicing, other SDOs (such as 3GPP and the BBF) are
   also ntvolved, interacting with each other and with the IETF via

   2.  Deterministic latency/Low latency

   The main relevant WG is Detnet which belongs to the RTG area.  The
   technologies developed in the TSV area and the ART area can also
   provide the latency service.

Li                      Expires January 27, 2020                [Page 8]

Internet-Draft            Cross-Area IETF Work                 July 2019

7.  Cross-layer Work

   Layering is an important network design principle.  Cross-layer work
   often gives rise to cross-area work.

   As ideas around network services are progressing cross-layer work is
   as an important research are such as path-aware networking in the
   IRTF's Path Aware Networking Research Group (PANRG), and application-
   aware IPv6 networking proposed by

7.1.  Path-Aware Networking

   Work on the path-aware network is being done in the PANRG.  The
   Internet architecture assumes a division between the end-to-end
   functionality of the transport layer and the properties of the path
   between endpoints.  Increased diversity in access networks, and
   ubiquitous mobile connectivity, have made this architecture's
   assumptions about paths less tenable.  Multipath protocols taking
   advantage of this mobile connectivity begin to show us a way forward:
   if endpoints cannot control the path, at least they can determine the
   properties of the path by choosing among paths available to them.
   The PANRG aims to support research in bringing path awareness to
   transport and application layer protocols, and to bring research in
   this space to the attention of the Internet engineering and protocol
   design community.

   The group's scope overlaps with existing IETF and IRTF efforts (and
   also with some past efforts).  Of the existing overlaps, the group
   collaborates with working groups and research groups chartered to
   work on multipath transport protocols (MPTCP, QUIC, TSVWG),
   congestion control in multiply-connected environments (ICCRG), and
   alternate routing architectures (e.g., PCE and LISP).  The charter is
   also related to the questions discussed in a number of past BoF
   sessions, e.g.  SPUD, PLUS, and BANANA.

7.2.  Application-aware IPv6 Networking

   [] proposes possible work on
   application-aware IPv6 networking (APN6).  As the Internet continues
   to develop, the decoupling of applications from network transport
   causes the operation actions on service provider networks to be
   pipelined which becomes the bottleneck of network service deployment.
   Moreover, a multitude of applications with varying needs for network
   bandwidth, latency, jitter, and packet loss are being carried over
   the IP network.  However it is hard for the network to learn the
   applications' service requirements which make it difficult for an
   operator to provide truly fine-grain traffic operations for the

Li                      Expires January 27, 2020                [Page 9]

Internet-Draft            Cross-Area IETF Work                 July 2019

   applications and to guarantee their SLA requirements.  APN6 aims to
   make use of an IPv6 extensions header to convey the application
   related information including its requirements along with the packet
   to tell the network how to adjust the network resources to facilitate
   the deployment of services.

   The scope of the work overlaps with existing IETF and IRTF efforts
   including, but not limited to, multiple working groups in RTG area,
   the 6MAN working group in the INT area, and the IRTF's ICNRG and

8.  IANA Considerations

   This document makes no request of IANA.

9.  Security Considerations

   Security is a fundamental part of all work done at the IETF.  At the
   least this requires security considerations to be part of every RFC
   published, and attention should also be given to privacy
   requirements.  This work is usually supported by reviews from
   security experts on the Security Directorate and is a good example of
   cross-area work.  Furthermore, when major new technologies are being
   developed within the IETF it is possible to ask for security advisors
   to be appointed for working groups.  And from time to time, new work
   needs to be spun up in the SEC area to support demands from new

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

10.2.  Informative References

              Brockners, F., Bhandari, S., Pignataro, C., Gredler, H.,
              Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov,
              P., Chang, R.,, d., and J. Lemon,
              "Data Fields for In-situ OAM", draft-ietf-ippm-ioam-
              data-06 (work in progress), July 2019.

Li                      Expires January 27, 2020               [Page 10]

Internet-Draft            Cross-Area IETF Work                 July 2019

              Clemm, A. and E. Voit, "Subscription to YANG Datastores",
              draft-ietf-netconf-yang-push-25 (work in progress), May

              Song, H., Qin, F., Martinez-Julia, P., Ciavaglia, L., and
              A. Wang, "Network Telemetry Framework", draft-ietf-opsawg-
              ntf-01 (work in progress), June 2019.

              Filsfils, C., Camarillo, P., Leddy, J.,
    , d., Matsushima, S., and Z. Li, "SRv6
              Network Programming", draft-ietf-spring-srv6-network-
              programming-01 (work in progress), July 2019.

              Lee, Y., Dhody, D., Ceccarelli, D., Bryskin, I., and B.
              Yoon, "A Yang Data Model for VN Operation", draft-ietf-
              teas-actn-vn-yang-06 (work in progress), July 2019.

              Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
              Framework for Enhanced Virtual Private Networks (VPN+)
              Service", draft-ietf-teas-enhanced-vpn-02 (work in
              progress), July 2019.

              Kim, M., Han, Y., and Y. Hong, "Intelligent Reinforcement-
              learning-based Network Management", draft-kim-nmrg-rl-05
              (work in progress), July 2019.

              Li, Z., Peng, S., Xie, C., and L. Cong, "Application-aware
              IPv6 Networking", draft-li-6man-app-aware-ipv6-network-00
              (work in progress), July 2019.

              Li, C., Cheng, Y., Strassner, J., Havel, O., LIU, W.,
              Martinez-Julia, P., Nobre, J., and D. Lopez, "Intent
              Classification", draft-li-nmrg-intent-classification-01
              (work in progress), July 2019.

              Song, H., Zhou, T., Li, Z., Shin, J., and K. Lee,
              "Postcard-based On-Path Flow Data Telemetry", draft-song-
              ippm-postcard-based-telemetry-04 (work in progress), June

Li                      Expires January 27, 2020               [Page 11]

Internet-Draft            Cross-Area IETF Work                 July 2019

              Song, H., Li, Z., Zhou, T., Qin, F., Shin, J., and J. Jin,
              "In-situ Flow Information Telemetry Framework", draft-
              song-opsawg-ifit-framework-03 (work in progress), July

              Wu, Q., Boucadair, M., Jacquenet, C., Contreras, L.,
              Lopez, D., Xie, C., Cheng, W., and Y. Lee, "A Framework
              for Automating Service and Network Management with YANG",
              draft-wu-model-driven-management-virtualization-05 (work
              in progress), July 2019.

              Zhou, T., Fioccola, G., Li, Z., Lee, S., Cociglio, M., and
              Z. Li, "Enhanced Alternate Marking Method", draft-zhou-
              ippm-enhanced-alternate-marking-03 (work in progress),
              July 2019.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,

   [RFC7575]  Behringer, M., Pritikin, M., Bjarnason, S., Clemm, A.,
              Carpenter, B., Jiang, S., and L. Ciavaglia, "Autonomic
              Networking: Definitions and Design Goals", RFC 7575,
              DOI 10.17487/RFC7575, June 2015,

   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854,
              DOI 10.17487/RFC7854, June 2016,

   [RFC8199]  Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module
              Classification", RFC 8199, DOI 10.17487/RFC8199, July
              2017, <>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,

   [RFC8299]  Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki,
              "YANG Data Model for L3VPN Service Delivery", RFC 8299,
              DOI 10.17487/RFC8299, January 2018,

Li                      Expires January 27, 2020               [Page 12]

Internet-Draft            Cross-Area IETF Work                 July 2019

   [RFC8309]  Wu, Q., Liu, W., and A. Farrel, "Service Models
              Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,

   [RFC8466]  Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG
              Data Model for Layer 2 Virtual Private Network (L2VPN)
              Service Delivery", RFC 8466, DOI 10.17487/RFC8466, October
              2018, <>.

Author's Address

   Zhenbin Li
   Huawei Technologies
   Huawei Bld., No.156 Beiqing Rd.
   Beijing  100095


Li                      Expires January 27, 2020               [Page 13]