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Versions: 00

RTGWG                                                        J. Tantsura
Internet-Draft                                                Individual
Intended status: Informational                              D. Afanasiev
Expires: May 3, 2018                                              YANDEX
                                                                K. Patel
                                                                  Arccus
                                                             P. Lapukhov
                                                                Facebook
                                                           P. Przygienda
                                                                 Juniper
                                                                R. White
                                                                LinkedIn
                                                                   Y. Qu
                                                                  Huawei
                                                               J. Uttaro
                                                                     ATT
                                                        October 30, 2017


                Requirements for the DataCenter Routing
                draft-dt-rtgwg-dcrouting-requirements-00

Abstract

   This document describes list of functional requirments towards a
   Routing Protocol for Data Center Networks.

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 https://datatracker.ietf.org/drafts/current/.

   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 May 3, 2018.








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Copyright Notice

   Copyright (c) 2017 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
   (https://trustee.ietf.org/license-info) 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.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Recommended Reading . . . . . . . . . . . . . . . . . . . . .   3
   4.  Goals and Requirements  . . . . . . . . . . . . . . . . . . .   3
   5.  For further study . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Network Topologies  . . . . . . . . . . . . . . . . . . . . .   5
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   10. Change Log  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   5
     11.2.  Informative References . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   It is common to host and build a network of more than tens of
   thousands of end points inside a data center.  Data Center Networks
   of such size have unique set of requirements with emphasis on scale,
   convergence, network stability and opertional simplicity.  Existing
   or new set of protocols and routing infrastructure needs to be
   augmented to support higher scale, faster convergence with increased
   optional simplicity in order to address the requirements of these
   networks.

   This document describes list of functional requirements that are
   required towards addressing scale, convergence and operational
   maintainance of such scaled networks.  The requirements described in
   this document can be used to augment existing solutions or used to
   design a new set of solutions.



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2.  Requirements Language

   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 [RFC2119] only when
   they appear in all upper case.  They may also appear in lower or
   mixed case as English words, without any normative meaning.

3.  Recommended Reading

   This document assumes knowledge of existing data center networks and
   data center network topologies [CLOS],[RFC7938].  This document also
   assumes knowledge of data center routing protocols like BGP
   [RFC4271], OSPF [RFC2328] and BFD [RFC5880] as well as data center
   layer 2 link layer protocols like LLDP [RFC4957].

4.  Goals and Requirements

   Following are general requirements for the Data Center Network Fabric
   and its Routing Protocols:

   o  The Fabric provides basic connectivity, with possibility to carry
      one or more overlays.
      The Fabric provides no domain separation, if needed, to be handled
      by an overlay.
      The Fabric MAY provide interconnect facility for other fabrics.
      The Fabric MUST support non equidistant end-points.

   o  The Fabric MUST support Spine and Leaf [CLOS] + isomorphic
      topologies within its network.
      The Fabric MAY support non Spine and Leaf topologies

   o  The KPI's below are single-dimensional and expected to be changed,
      as the document progresses, baseded on more feedback, we ask
      community to communicate their views.  Combination of # of routes
      vs # of paths vs desired convergence time will be discussed in a
      later version.

      The Fabric SHOULD support 250k routes @ 5k fabric nodes with
      convergence time below 250ms.
      The Fabric SHOULD support 500k routes @ 7.5k fabric nodes with
      convergence time below 500ms.
      The Fabric SHOULD support 1M routes @ 10k fabric nodes with
      convergence time below 1s.

   o  The Fabric routing protocol MUST support load balancing using
      ECMP, wECMP and UCMP.




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      The Fabric routing protocol MAY support any custom or adaptive
      load balancing algorithms.
      The Fabric routing protocol MUST support and provide facility for
      topology-specific algorithms that enable correct operations in
      that specific topology.

   o  The Fabric routing protocol SHOULD support route scale and
      convergence times of a Fabric mentioned above.
      The Fabric routing protocol SHOULD support ECMP as wide as 256
      paths.

   o  The Fabric routing protocol MUST support various address families
      that covers IP as well as MPLS forwarding.
      The Fabric routing protocol MUST support extensions to carry 3rd
      party data and Opaque data.

   o  The Fabric routing protocol MUST support Traffic Engineering paths
      that are host and/or router based paths.
      The Fabric routing protocol MUST provide facility to address
      constituents in an ECMP bundle.

   o  The Fabric routing protocol MUST support inband as well as out of
      band management.

   o  The Fabric routing protocol MUST support Zero Touch Provisioning
      (ZTP).
      The Fabric routing protocol MUST support Neighbor Discovery to
      facilitate ZTP.

   o  The Fabric routing protocol MUST be able to leverage BFD [RFC5880]
      for neighbor state.
      The Fabric routing protocol SHOULD be capable of bootstrapping a
      BFD session [RFC5882].

   o  The Fabric routing protocol MUST be able to support real time
      state notifications of routes and its neighbors state to
      facilitate control plane telemetry.
      The Fabric routing protocol MUST be able to support on-demand
      snapshots of protocol state and real time state notifications of
      routes and its neighbors state to remote node(s) to facilitate
      control plane telemetry.

   o  The Fabric routing protocol MUST be able handle commission/
      decommission of a node as well as any node restart with a minimal
      data plane impact.






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5.  For further study

   Following topics have been identified to be studied at a later time:

   o  gRPC/THRIFT/similar encodings.

   o  Ability to function as an overlay.

   o  Flowlets signaling.

   o  Multicast.

   o  State representation NB.

   o  Integration with PCE/SDNc.

6.  Network Topologies

7.  IANA Considerations

8.  Security Considerations

   This document describes list of functional requirements towards a
   routing protocol for Data Center Networks.  It does not raise any
   security concerns or issues in addition to ones common to a routing
   protocol for Data Center Networks.

9.  Acknowledgements

10.  Change Log

   Initial Version:  October 31 2017

11.  References

11.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

11.2.  Informative References

   [CLOS]     "A Study of Non-Blocking Switching Networks",  The Bell
              System Technical Journal, Vol. 32(2), DOI
              10.1002/j.1538-7305.1953.tb01433.x, March 1953.




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   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4957]  Krishnan, S., Ed., Montavont, N., Njedjou, E., Veerepalli,
              S., and A. Yegin, Ed., "Link-Layer Event Notifications for
              Detecting Network Attachments", RFC 4957,
              DOI 10.17487/RFC4957, August 2007,
              <https://www.rfc-editor.org/info/rfc4957>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5882]  Katz, D. and D. Ward, "Generic Application of
              Bidirectional Forwarding Detection (BFD)", RFC 5882,
              DOI 10.17487/RFC5882, June 2010,
              <https://www.rfc-editor.org/info/rfc5882>.

   [RFC7938]  Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of
              BGP for Routing in Large-Scale Data Centers", RFC 7938,
              DOI 10.17487/RFC7938, August 2016,
              <https://www.rfc-editor.org/info/rfc7938>.

Authors' Addresses

   Jeff Tantsura
   Individual
   USA

   Email: jefftant.ietf@gmail.com


   Dmitry Afanasiev
   YANDEX
   RU

   Email: dmitry.afanasiev@gmail.com








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   Keyur Patel
   Arccus
   San Jose
   USA

   Email: keyur@arrcus.com


   Petr Lapukhov
   Facebook
   USA

   Email: petr@fb.com


   Tony Przygienda
   Juniper
   1137 Innovation Way
   Sunnyvale, CA
   USA

   Email: prz@juniper.net


   Russ White
   LinkedIn
   USA

   Email: russ@riw.us


   Yingzhen Qu
   Huawei
   Santa Clara
   USA

   Email: yingzhen.ietf@gmail.com


   Jim Uttaro
   ATT
   USA

   Email: juttaro@ieee.org







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