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Versions: 00 01 02 03 draft-ietf-idr-te-pm-bgp

IDR Working Group                                                  Q. Wu
Internet-Draft                                                   D. Wang
Intended status: Standards Track                                  Huawei
Expires: April 24, 2014                                       S. Previdi
                                                                   Cisco
                                                              H. Gredler
                                                                 Juniper
                                                                  S. Ray
                                                                   Cisco
                                                        October 21, 2013


 BGP attribute for North-Bound Distribution of Traffic Engineering (TE)
                          performance Metrics
                       draft-wu-idr-te-pm-bgp-03

Abstract

   In order to populate network performance information like link
   latency, latency variation, packet loss and bandwidth into Traffic
   Engineering Database(TED) and ALTO server, this document describes
   extensions to BGP protocol, that can be used to distribute network
   performance information (such as link delay, delay variation, packet
   loss, residual bandwidth, available bandwidth and utilized bandwidth
   ).

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 http://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 April 24, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions used in this document  . . . . . . . . . . . . . .  4
   3.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  MPLS-TE with PCE . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  ALTO Server Network API  . . . . . . . . . . . . . . . . .  5
   4.  Carrying TE Performance information in BGP . . . . . . . . . .  7
   5.  Attribute TLV Details  . . . . . . . . . . . . . . . . . . . .  9
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Change Log  . . . . . . . . . . . . . . . . . . . . . 13
     A.1.  draft-wu-idr-te-pm-bgp-03  . . . . . . . . . . . . . . . . 13
     A.2.  draft-wu-idr-te-pm-bgp-02  . . . . . . . . . . . . . . . . 13
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14






















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1.  Introduction

   As specified in [RFC4655],a Path Computation Element (PCE) is an
   entity that is capable of computing a network path or route based on
   a network graph, and of applying computational constraints during the
   computation.  In order to compute an end to end path, the PCE needs
   to have a unified view of the overall topology[I-D.ietf-pce-pcep-
   service-aware].  [I.D-ietf-idr-ls-distribution] describes a mechanism
   by which links state and traffic engineering information can be
   collected from networks and shared with external components using the
   BGP routing protocol.  This mechanism can be used by both PCE and
   ALTO server to gather information about the topologies and
   capabilities of the network.

   With the growth of network virtualization technology, the needs for
   inter-connection between various overlay technologies (e.g.
   Enterprise BGP/MPLS IP VPNs) in the Wide Area Network (WAN) become
   important.  The Network performance or QoS requirements such as
   latency, limited bandwidth, packet loss, and jitter, are all critical
   factors that must be taken into account in the end to end path
   computation ([I-D.ietf-pce-pcep-service-aware]) and selection which
   enable establishing segment overlay tunnel between overlay nodes and
   stitching them together to compute end to end path.

   In order to populate network performance information like link
   latency, latency variation, packet loss and bandwidth into TED and
   ALTO server, this document describes extensions to BGP protocol, that
   can be used to distribute network performance information (such as
   link delay, delay variation, packet loss, residual bandwidth,
   available bandwidth, and utilized bandwidth).





















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2.  Conventions used in this document

   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 [RFC2119].














































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3.  Use Cases

3.1.  MPLS-TE with PCE

   In inter-AS path computation, PCE in each AS participant in different
   IGP.  In Hierarchy of PCE, A child PCE must be configured with the
   address of its parent PCE[RFC6805].Configuration system is challenged
   by handling changes in parent PCE identities and coping with failure
   events, especially when parent PCE and child PCE are not a part of
   the same routing domain.

   The following figure shows how a PCE can get its TE performance
   information beyond that contained in the LINK_STATE attributes [I.D-
   ietf-idr-ls-distribution] using the mechanism described in this
   document.

                  +----------+                           +---------+
                  |  -----   |                           |   BGP   |
                  | | TED |<-+-------------------------->| Speaker |
                  |  -----   |   TED synchronization     |         |
                  |    |     |        mechanism:         +---------+
                  |    |     | BGP with TE performance
                  |    v     |        NLRI
                  |  -----   |
                  | | PCE |  |
                  |  -----   |
                  +----------+
                       ^
                       | Request/
                       | Response
                       v
         Service  +----------+   Signaling  +----------+
         Request  | Head-End |   Protocol   | Adjacent |
         -------->|  Node    |<------------>|   Node   |
                  +----------+              +----------+

       Figure 1: External PCE node using a TED synchronization mechanism

3.2.  ALTO Server Network API

   The ALTO Server can aggregate information from multiple systems to
   provide an abstract and unified view that can be more useful to
   applications.

   The following figure shows how an ALTO Server can get TE performance
   information from the underlying network beyond that contained in the
   LINK_STATE attributes [I.D-ietf-idr-ls-distribution] using the
   mechanism described in this document.



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   +--------+
   | Client |<--+
   +--------+   |
                |    ALTO    +--------+     BGP with    +---------+
   +--------+   |  Protocol  |  ALTO  |  TE Performance |   BGP   |
   | Client |<--+------------| Server |<----------------| Speaker |
   +--------+   |            |        |      NLR        |         |
                |            +--------+                 +---------+
   +--------+   |
   | Client |<--+
   +--------+
     Figure 2: ALTO Server using network performance information







































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4.  Carrying TE Performance information in BGP

   This document proposes new BGP TE performance TLVs that can be
   announced as attribute in the BGP-LS attribute (defined in [I.D-ietf-
   idr- ls-distribution]) to distribute network performance information.
   The extensions in this document build on the ones provided in BGP-LS
   [I.D -ietf-idr-ls-distribution] and BGP-4 [RFC4271].

   BGP-LS attribute defined in [I.D-ietf-idr-ls-distribution] has nested
   TLVs which allow the BGP-LS attribute to be readily extended.  This
   document proposes seven additional TLVs as its attributes:

      Type            Value

      TBD1        Unidirectional Link Delay

      TBD2        Min/Max Unidirectional Link Delay

      TBD3        Unidirectional Delay Variation

      TBD4        Unidirectional Packet Loss

      TBD5        Unidirectional Residual Bandwidth

      TBD6        Unidirectional Available Bandwidth

      TBD7        Unidirectional Utilized Bandwidth


   As can be seen in the list above, the TLVs described in this document
   carry different types of network performance information.  These TLVs
   include a bit called the Anomalous (or "A") bit at the left-most bit
   after length field of each TLV.  The other bits in the first octets
   after length field of each TLV is reserved for future use.  When the
   A bit is clear (or when the TLV does not include an A bit), the TLV
   describes steady state link performance.  This information could
   conceivably be used to construct a steady state performance topology
   for initial tunnel path computation, or to verify alternative
   failover paths.

   When network performance downgrades and exceeds configurable maximum
   thresholds, a TLV with the A bit set is advertised.  These TLVs could
   be used by the receiving BGP peer to determine whether to redirect
   failing traffic to a backup path, or whether to calculate an entirely
   new path.  If link performance improves later and falls below a
   configurable value, that TLV can be re- advertised with the Anomalous
   bit cleared.  In this case, a receiving BGP peer can conceivably do
   whatever re-optimization (or failback) it wishes to do (including



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   nothing).

   Note that when a TLV does not include the A bit, that TLV cannot be
   used for failover purposes.  The A bit was intentionally omitted from
   some TLVs to help mitigate oscillations.

   Consistent with existing ISIS TE specifications [ISIS-TE-METRIC], the
   bandwidth advertisements,the delay and delay variation
   advertisements, packetloss defined in this document MUST be encoded
   in the same unit as one defined in IS-IS Extended IS Reachability
   sub-TLVs [ISIS-TE-METRIC].  All values (except residual bandwidth)
   MUST be calculated as rolling averages where the averaging period
   MUST be a configurable period of time.






































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5.  Attribute TLV Details

   Link attribute TLVs defined in section 3.2.2 of [I-D.ietf-idr-ls-
   distribution]are TLVs that may be encoded in the BGP-LS attribute
   with a link NLRI.  Each 'Link Attribute' is a Type/Length/ Value
   (TLV) triplet formatted as defined in Section 3.1 of [I-D.ietf-id r-
   ls-distribution].  The format and semantics of the 'value' fields in
   some 'Link Attribute' TLVs correspond to the format and semantics of
   value fields in IS-IS Extended IS Reachability sub-TLVs, defined in
   [RFC5305].  Although the encodings for 'Link Attribute' TLVs were
   originally defined for IS-IS, the TLVs can carry data sourced either
   by IS-IS or OSPF.

   The following 'Link Attribute' TLVs are valid in the LINK_STATE
   attribute:

   +------------+---------------------+--------------+-----------------+
   |  TLV Code  | Description         |     IS-IS    | Defined in:     |
   |    Point   |                     |  TLV/Sub-TLV |                 |
   +------------+---------------------+--------------+-----------------+
   |    xxxx    | Unidirectional      |    22/xx     | [ISIS-TE]/4.1   |
   |            | Link Delay          |              |                 |
   |            |                     |              |                 |
   |    xxxx    | Min/Max Unidirection|    22/xx     | [ISIS-TE]/4.2   |
   |            | Link Delay          |              |                 |
   |            |                     |              |                 |
   |    xxxx    | Unidirectional      |    22/xx     | [ISIS-TE]/4.3   |
   |            | Delay Variation     |              |                 |
   |            |                     |              |                 |
   |    xxxx    | Unidirectional      |    22/xx     | [ISIS-TE]/4.4   |
   |            | Link Loss           |              |                 |
   |            |                     |              |                 |
   |    xxxx    | Unidirectional      |    22/xx     | [ISIS-TE]/4.5   |
   |            |Residual Bandwidth   |              |                 |
   |            |                     |              |                 |
   |    xxxx    | Unidirectional      |    22/xx     | [ISIS-TE]/4.6   |
   |            |Available Bandwidth  |              |                 |
   |            |                     |              |                 |
   |    xxxx    | Unidirectional      |    22/xx     | [ISIS-TE]/4.7   |
   |            |Utilized Bandwidth   |              |                 |
   +------------+---------------------+--------------+-----------------+

                       Table 1: Link Attribute TLVs








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6.  Security Considerations

   This document does not introduce security issues beyond those
   discussed in [I.D-ietf-idr-ls-distribution] and [RFC4271].















































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7.  IANA Considerations

   IANA maintains the registry for the TLVs.  BGP TE Performance TLV
   will require one new type code per TLV defined in this document.















































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8.  References

8.1.  Normative References

   [I-D.ietf-idr-ls-distribution]
              Gredler, H., "North-Bound Distribution of Link-State and
              TE Information using BGP",
              ID draft-ietf-idr-ls-distribution-03, May 2013.

   [I-D.ietf-pce-pcep-service-aware]
              Dhruv, D., "Extensions to the Path Computation Element
              Communication Protocol (PCEP) to compute service aware
              Label Switched Path (LSP)",
              ID draft-ietf-pce-pcep-service-aware-01, July 2013.

   [ISIS-TE-METRIC]
              Giacalone, S., "ISIS Traffic Engineering (TE) Metric
              Extensions", ID draft-ietf-isis-te-metric-extensions-00,
              June 2013.

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

   [RFC4271]  Rekhter, Y., "A Border Gateway Protocol 4 (BGP-4)",
              RFC 4271, January 2006.

   [RFC5305]  Li, T., "IS-IS Extensions for Traffic Engineering",
              RFC 5305, October 2008.

8.2.  Informative References

   [ALTO]     Yang, Y., "ALTO Protocol",
              ID http://tools.ietf.org/html/draft-ietf-alto-protocol-16,
              May 2013.

   [RFC4655]  Farrel, A., "A Path Computation Element (PCE)-Based
              Architecture", RFC 4655, August 2006.














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Appendix A.  Change Log

   Note to the RFC-Editor: please remove this section prior to
   publication as an RFC.

A.1.  draft-wu-idr-te-pm-bgp-03

   The following are the major changes compared to previous version 02:


   o  Add unidirectional utilized bandwidth metric as the seventh metric
      Carried in a new BGP attribute.

A.2.  draft-wu-idr-te-pm-bgp-02

   The following are the major changes compared to previous version 01:


   o  Taking out link utilization metric and channel throughput metric
      from this version and will add link utilization metric back to the
      update when there was agreement on what measurement unit is used
      for link utilization.

   o  Some additional texts in BGP extension section 4 to explain how to
      position 'A' bit in the BGP TE performance TLV.

   o  Add two editor notes to explain the status of this draft and open
      issue that need be resolved.

   o  Some additional text in the use case sections to clarify how to
      use these TE performance metrics.




















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Authors' Addresses

   Qin Wu
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: sunseawq@huawei.com


   Danhua Wang
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing, Jiangsu  210012
   China

   Email: wangdanhua@huawei.com


   Stefano Previdi
   Cisco Systems, Inc.
   Via Del Serafico 200
   Rome  00191
   Italy

   Email: sprevidi@cisco.com


   Hannes Gredler
   Juniper Networks, Inc.
   1194 N. Mathilda Ave.
   Sunnyvale, CA  94089
   US

   Email: hannes@juniper.net


   Saikat Ray
   Cisco Systems, Inc.
   170, West Tasman Drive
   San Jose, CA  95134
   US

   Email: sairay@cisco.com






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