[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03

Network Working Group                                           K. Patel
Internet-Draft                                              Arrcus, Inc.
Intended status: Standards Track                               A. Lindem
Expires: June 24, 2017                                     Cisco Systems
                                                                S. Zandi
                                                                Linkedin
                                                         G. Van de Velde
                                                                   Nokia
                                                       December 21, 2016


           Shortest Path Routing Extensions for BGP Protocol
                   draft-keyupate-idr-bgp-spf-02.txt

Abstract

   Many Massively Scaled Data Centers (MSDCs) have converged on
   simplified layer 3 routing.  Furthermore, requirements for
   operational simplicity have lead many of these MSDCs to converge on
   BGP as their single routing protocol for both their fabric routing
   and their Data Center Interconnect (DCI) routing.  This document
   describes a solution which leverages BGP Link-State distribution and
   the Shortest Path First algorithm similar to Internal Gateway
   Protocols (IGPs) such as OSPF.

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 June 24, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





Patel, et al.             Expires June 24, 2017                 [Page 1]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  BGP Shortest Path First (SPF) Motivation  . . . . . . . .   4
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   2.  BGP Peering Models  . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  BGP Single-Hop Peering on Network Node Connections  . . .   5
     2.2.  BGP Peering Between Directly Connected Network Nodes  . .   5
     2.3.  BGP Peering in Route-Reflector or Controller Topology . .   6
   3.  BGP-LS Shortest Path Routing (SPF) SAFI . . . . . . . . . . .   6
   4.  Extensions to BGP-LS  . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Node NLRI Usage and Modifications . . . . . . . . . . . .   6
     4.2.  Link NLRI Usage . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Prefix NLRI Usage . . . . . . . . . . . . . . . . . . . .   7
   5.  Decision Process with SPF Algorithm . . . . . . . . . . . . .   8
     5.1.  Phase-1 BGP NLRI Selection  . . . . . . . . . . . . . . .   8
     5.2.  Dual Stack Support  . . . . . . . . . . . . . . . . . . .   9
     5.3.  NEXT_HOP Manipulation . . . . . . . . . . . . . . . . . .   9
     5.4.  Error Handling  . . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     7.1.  Acknowledgements  . . . . . . . . . . . . . . . . . . . .  10
     7.2.  Contributorss . . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     8.2.  Information References  . . . . . . . . . . . . . . . . .  12



Patel, et al.             Expires June 24, 2017                 [Page 2]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Many Massively Scaled Data Centers (MSDCs) have converged on
   simplified layer 3 routing.  Furthermore, requirements for
   operational simplicity have lead many of these MSDCs to converge on
   BGP [RFC4271] as their single routing protocol for both their fabric
   routing and their Data Center Interconnect (DCI) routing.
   Requirements and procedures for using BGP are described in [RFC7938].
   This document describes an alternative solution which leverages BGP-
   LS [RFC7752] and the Shortest Path First algorithm similar to
   Internal Gateway Protocols (IGPs) such as OSPF [RFC2328].

   [RFC4271] defines the Decision Process that is used to select routes
   for subsequent advertisement by applying the policies in the local
   Policy Information Base (PIB) to the routes stored in its Adj-RIBs-
   In.  The output of the Decision Process is the set of routes that are
   announced by a BGP speaker to its peers.  These selected routes are
   stored by a BGP speaker in the speaker's Adj-RIBs-Out according to
   policy.

   [RFC7752] describes a mechanism by which link-state and TE
   information can be collected from networks and shared with external
   components using BGP.  This is achieved by defining NLRI carried
   within BGP-LS AFI and BGP-LS SAFIs.  The BGP-LS extensions defined in
   [RFC7752] makes use of the Decision Process defined in [RFC4271].

   This document augments [RFC7752] by replacing its use of the existing
   Decision Process.  The BGP-LS-SPF and BGP-LS-SPF-VPN AFI/SAFI are
   introduced to insure backward compatibility.  The Phase 1 and 2
   decision functions of the Decision Process are replaced with the
   Shortest Path Algorithm (SPF) also known as the Dijkstra Algorithm.
   The Phase 3 decision function is also simplified since it is no
   longer dependent on the previous phases.  This solution avails the
   benefits of both BGP and SPF-based IGPs.  These include TCP based
   flow-control, no periodic link-state refresh, and completely
   incremental NLRI advertisement.  These advantages can reduce the
   overhead in MSDCs where there is a high degree of Equal Cost Multi-
   Path (ECMPs) and the topology is very stable.  Additionally, using a
   SPF-based computation can support fast convergence and the
   computation of Loop-Free Alternatives (LFAs) [RFC5286] in the event
   of link failures.  Furthermore, a BGP based solution lends itself to
   multiple peering models including those incorporating route-
   reflectors [RFC4456] or controllers.

   Support for Multiple Topology Routing (MTR) as described in [RFC4915]
   is an area for further study dependent on deployment requirements.



Patel, et al.             Expires June 24, 2017                 [Page 3]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


1.1.  BGP Shortest Path First (SPF) Motivation

   Given that [RFC7938] already describes how BGP could be used as the
   sole routing protocol in an MSDC, one might question the motivation
   for defining an alternate BGP deployment model when a mature solution
   exists.  For both alternatives, BGP offers the operational benefits
   of a single routing protocol.  However, BGP SPF offers some unique
   advantages above and beyond standard BGP distance-vector routing.

   A primary advantage is that all BGP speakers in the BGP SPF routing
   domain will have a complete view of the topology.  This will allow
   support of ECMP, IP fast-reroute (e.g., Loop-Free Alternatives),
   Shared Risk Link Groups (SRLGs), and other routing enhancements
   without advertisement of addition BGP paths or other extensions.  In
   short, the advantages of an IGP such as OSPF [RFC2328] are availed in
   BGP.

   With the simplified BGP decision process as defined in Section 5.1,
   NLRI changes can be disseminated throughout the BGP routing domain
   much more rapidly (equivalent to IGPs with the proper
   implementation).

   Another primary advantage is a potential reduction in NLRI
   advertisement.  With standard BGP distance-vector routing, a single
   link failure may impact 100s or 1000s prefixes and result in the
   withdrawal or re-advertisement of the attendant NLRI.  With BGP SPF,
   only the BGP speakers corresponding to the link NLRI need withdraw
   the corresponding BGP-LS Link NLRI.  This advantage will contribute
   to both faster convergence and better scaling.

   With controller and route-reflector peering models, BGP SPF
   advertisement and distributed computation require a minimal number of
   sessions and copies of the NLRI since only the latest verion of the
   NLRI from the originator is required.  Given that verification of the
   adjacencies is done outside of BGP (see Section 2), each BGP speaker
   will only need as many sessions and copies of the NLRI as required
   for redundancy (e.g., one for SPF computation and another for
   backup).  Functions such as Optimized Route Reflection (ORR) are
   supported without extension by virture of the primary advantages.
   Additionally, a controller could inject topology that is learned
   outside the BGP routing domain.

   Given that controllers are already consuming BGP-LS NLRI [RFC7752],
   reusing for the BGP-LS SPF leverages the existing controller
   implementations.

   Another potential advantage of BGP SPF is that both IPv6 and IPv4 can
   be supported in the same address family using the same topology.



Patel, et al.             Expires June 24, 2017                 [Page 4]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


   Although not described in this version of the document, multi-
   topology extensions can be used to support separate IPv4, IPv6,
   unicast, and multicast topologies while sharing the same NLRI.

   Finally, the BGP SPF topology can be used as an underlay for other
   BGP address families (using the existing model) and realize all the
   above advantages.  A simplified peering model using IPv6 link-local
   addresses as next-hops can be deployed similar to [RFC5549].

1.2.  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 RFC 2119 [RFC2119].

2.  BGP Peering Models

   Depending on the requirements, scaling, and capabilities of the BGP
   speakers, various peering models are supported.  The only requirement
   is that all BGP speakers in the BGP SPF routing domain receive link-
   state NLRI on a timely basis, run an SPF calculation, and update
   their data plane appropriately.  The content of the Link NLRI is
   described in Section 4.2.

2.1.  BGP Single-Hop Peering on Network Node Connections

   The simplest peering model is the one described in section 5.2.1 of
   [RFC7938].  In this model, EBGP single-hop sessions are established
   over direct point-to-point links interconnecting the network nodes.
   For the purposes of BGP SPF, Link NLRI is only advertised if a
   single-hop BGP session has been established and the Link-State/SPF
   adddress family capability has been exchanged [RFC4790] on the
   corresponding session.  If the session goes down, the NLRI will be
   withdrawn.

2.2.  BGP Peering Between Directly Connected Network Nodes

   In this model, BGP speakers peer with all directly connected network
   nodes but the sessions may be multi-hop and the direct connection
   discovery and liveliness detection for those connections are
   independent of the BGP protocol.  How this is accomplished is outside
   the scope of this document.  Consequently, there will be a single
   session even if there are multiple direct connections between BGP
   speakers.  For the purposes of BGP SPF, Link NLRI is advertised as
   long as a BGP session has been established, the Link-State/SPF
   address family capability has been exchanged [RFC4790] and the
   corresponding link is up and considered operational.




Patel, et al.             Expires June 24, 2017                 [Page 5]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


2.3.  BGP Peering in Route-Reflector or Controller Topology

   In this model, BGP speakers peer solely with one or more Route
   Reflectors [RFC4456] or controllers.  As in the previous model,
   direct connection discovery and liveliness detection for those
   connections are done outside the BGP protocol.  For the purposes of
   BGP SPF, Link NLRI is advertised as long as the corresponding link is
   up and considered operational.

3.  BGP-LS Shortest Path Routing (SPF) SAFI

   In order to replace the Phase 1 and 2 decision functions of the
   existing Decision Process with an SPF-based Decision Process and
   streamline the Phase 3 decision functions in a backward compatible
   manner, this draft introduces a couple AFI/SAFIs for BGP LS SPF
   operation.  The BGP-LS-SPF (AF 16388 / SAFI TBD1) and BGP-LS-SPF-VPN
   (AFI 16388 / SAFI TBD2) [RFC4790] are allocated by IANA as specified
   in the Section 6.

4.  Extensions to BGP-LS

   [RFC7752] describes a mechanism by which link-state and TE
   information can be collected from networks and shared with external
   components using BGP protocol.  It contains two parts: definition of
   a new BGP NLRI that describes links, nodes, and prefixes comprising
   IGP link-state information and definition of a new BGP path attribute
   (BGP-LS attribute) that carries link, node, and prefix properties and
   attributes, such as the link and prefix metric or auxiliary Router-
   IDs of nodes, etc.

   The BGP protocol will be used in the Protocol-ID field specified in
   table 1 of [I-D.ietf-idr-bgpls-segment-routing-epe].  The local and
   remote node descriptors for all NLRI will be the BGP Router-ID (TLV
   516) and either the AS Number (TLV 512) [RFC7752] or the BGP
   Confederation Member (TLV 517)
   [I-D.ietf-idr-bgpls-segment-routing-epe].  However, if the BGP
   Router-ID is known to be unique within the BGP Routing domain, it can
   be used as the sole descriptor.

4.1.  Node NLRI Usage and Modifications

   The SPF capability is a new Node Attribute TLV that will be added to
   those defined in table 7 of [RFC7752].  The new attribute TLV will
   only be applicable when BGP is specified in the Node NLRI Protocol ID
   field.  The TBD TLV type will be defined by IANA.  The new Node
   Attribute TLV will contain a single octet SPF algorithm field:





Patel, et al.             Expires June 24, 2017                 [Page 6]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              Type             |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | SPF Algorithm |
      +-+-+-+-+-+-+-+-+

    The SPF Algorithm may take the following values:

      1 - Normal SPF
      2 - Strict SPF


   When computing the SPF for a given BGP routing domain, only BGP nodes
   advertising the SPF capability attribute will be included the
   Shortest Path Tree (SPT).

4.2.  Link NLRI Usage

   The criteria for advertisement of Link NLRI are discussed in
   Section 2.

   Link NLRI is advertised with local and remote node descriptors as
   described above and unique link identifiers dependent on the
   addressing.  For IPv4 links, the links local IPv4 (TLV 259) and
   remote IPv4 (TLV 260) addresses will be used.  For IPv6 links, the
   local IPv6 (TLV 261) and remote IPv6 (TLV 262) addresses will be
   used.  For unnumbered links, the link local/remote identifiers (TLV
   258) will be used.  For links supporting having both IPv4 and IPv6
   addresses, both sets of descriptors may be included in the same Link
   NLRI.  The link identifiers are described in table 5 of [RFC7752].

   The link IGP metric attribute TLV (TLV 1095) as well as any others
   required for non-SPF purposes SHOULD be advertised.  Algorithms such
   as setting the metric inversely to the link speed as done in the OSPF
   MIB [RFC4750] may be supported.  However, this is beyond the scope of
   this document.

4.3.  Prefix NLRI Usage

   Prefix NLRI is advertised with a local descriptor as described above
   and the prefix and length used as the descriptors (TLV 265) as
   described in [RFC7752].  The prefix metric attribute TLV (TLV 1155)
   as well as any others required for non-SPF purposes SHOULD be
   advertised.  For loopback prefixes, the metric should be 0.  For non-
   loopback, the setting of the metric is beyond the scope of this
   document.



Patel, et al.             Expires June 24, 2017                 [Page 7]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


5.  Decision Process with SPF Algorithm

   The Decision Process described in [RFC4271] takes place in three
   distinct phases.  The Phase 1 decision function of the Decision
   Process is responsible for calculating the degree of preference for
   each route received from a Speaker's peer.  The Phase 2 decision
   function is invoked on completion of the Phase 1 decision function
   and is responsible for choosing the best route out of all those
   available for each distinct destination, and for installing each
   chosen route into the Loc-RIB.  The combination of the Phase 1 and 2
   decision functions is also known as a Path vector algorithm.

   When BGP-LS-SPF NLRI is received, all that is required is to
   determine whether it is the best-path by examining the Node-ID as
   described in Section 5.1.  If the best-path NLRI had changed, it will
   be advertised to other BGP-LS-SPF peers.  If the attributes have
   changed a BGP SPF calculation will be scheduled.  However, a changed
   best-path can be advertised to other peer immediately and propagation
   of changes can approach IGP convergence times.

   The SPF based Decision process starts with selecting only those Node
   NLRI whose SPF capability TLV matches with the local BGP speaker's
   SPF capability TLV value.  Since Link-State NLRI always contains the
   local descriptor [RFC7752], it will only be originated by a single
   BGP speaker in the BGP routing domain.  These selected Node NLRI and
   their Link/Prefix NLRI are used to build a directed graph during the
   SPF computation.  The best paths for BGP prefixes are installed as a
   result of the SPF process.

   The Phase 3 decision function of the Decision Process [RFC4271] is
   also simplified since under normal SPF operation, a BGP speaker would
   advertise the NLRI selected for the SPF to all BGP peers with the
   BGP-LS/BGP-SPF AFI/SAFI.  Application of policy would not be
   prevented but would normally not be necessary.

5.1.  Phase-1 BGP NLRI Selection

   The rules for NLRI selection are greatly simplified from [RFC4271].

   1.  If the NLRI is received from the BGP speaker originating the NLRI
       (as determined by the comparing BGP Router ID in the NLRI Node
       identifiers with the BGP speaker Router ID), then it is preferred
       over the same NLRI from non-originators.

   2.  The final tie-breaker is the NLRI from the BGP Speaker with the
       numerically largest BGP Router ID.





Patel, et al.             Expires June 24, 2017                 [Page 8]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


   The modified Decision Process with SPF algorithm uses the metric from
   Link and Prefix NLRI Attribute TLVs [RFC7752].  As a result, any
   attributes that would influence the Decision process defined in
   [RFC4271] like ORIGIN, MULTI_EXIT_DISC, and LOCAL_PREF attributes are
   ignored by the SPF algorithm.  Furthermore, the NEXT_HOP attribute
   value is preserved and validated but otherwise ignored during the SPF
   or best-path.

5.2.  Dual Stack Support

   The SPF based decision process operates on Node, Link, and Prefix
   NLRIs that support both IPv4 and IPv6 addresses.  Whether to run a
   single SPF instance or multiple SPF instances for separate AFs is a
   matter of a local implementation.  Normally, IPv4 next-hops are
   calculated for IPv4 prefixes and IPv6 next-hops are calculated for
   IPv6 prefixes.  However, an interesting use-case is deployment of
   [RFC5549] where IPv6 link-local next-hops are calculated for both
   IPv4 and IPv6 prefixes.  As stated in Section 1, support for Multiple
   Topology Routing (MTR) is an area for future study.

5.3.  NEXT_HOP Manipulation

   A BGP speaker that supports SPF extensions MAY interact with peers
   that don't support SPF extensions.  If the BGP Link-State address
   family is advertised to a peer not supporting the SPF extensions
   described herein, then the BGP speaker MUST conform to the NEXT_HOP
   rules mentioned in [RFC4271] when announcing the Link-State address
   family routes to those peers.

   All BGP peers that support SPF extensions would locally compute the
   NEXT_HOP values as result of the SPF process.  As a result, the
   NEXT_HOP attribute is always ignored on receipt.  However BGP
   speakers should set the NEXT_HOP address according to the NEXT_HOP
   attribute rules mentioned in [RFC4271].

5.4.  Error Handling

   When a BGP speaker receives a BGP Update containing a malformed SPF
   Capability TLV in the Node NLRI BGP-LS Attribute [RFC7752], it MUST
   ignore the received TLV and the Node NLRI and not pass it to other
   BGP peers as specified in [RFC7606].  When discarding a Node NLRI
   with malformed TLV, a BGP speaker SHOULD log an error for further
   analysis.








Patel, et al.             Expires June 24, 2017                 [Page 9]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


6.  IANA Considerations

   This document defines a couple AFI/SAFIs for BGP LS SPF operation and
   requests IANA to assign the BGP-LS-SPF AFI 16388 / SAFI TBD1 and the
   BGP-LS-SPF-VPN AFI 16388 / SAFI TBD2 as described in [RFC4750].

   This document also defines two attribute TLV for BGP LS NLRI.  We
   request IANA to assign TLVs for the SPF capability from the "BGP-LS
   Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
   TLVs" Registry.  Additionally, IANA is requested to create a new
   registry for "BGP-LS SPF Capability Algorithms" for the value of the
   algorithm both in the BGP-LS Node Attribute TLV and the BGP SPF
   Capability.  The initial assignments are:

           +-------------+-----------------------------------+
           | Value(s)    | Assignment Policy                 |
           +-------------+-----------------------------------+
           | 0           | Reserved (not to be assigned)     |
           |             |                                   |
           | 1           | SPF                               |
           |             |                                   |
           | 2           | Strict SPF                        |
           |             |                                   |
           | 3-254       | Unassigned (IETF Review)          |
           |             |                                   |
           | 255         | Reserved (not to be assigned)     |
           +-------------+-----------------------------------+

                     BGP-LS SPF Capability Algorithms

7.  Security Considerations

   This extension to BGP does not change the underlying security issues
   inherent in the existing [RFC4724] and [RFC4271].

7.1.  Acknowledgements

   The authors would like to thank .... for the review and comments.

7.2.  Contributorss

   In addition to the authors listed on the front page, the following
   co-authors have contributed to the document.








Patel, et al.             Expires June 24, 2017                [Page 10]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


     Derek Yeung
     Arrcus, Inc.
     derek@arrcus.com

     Abhay Roy
     Cisco Systems
     akr@cisco.com

     Venu Venugopal
     Cisco Systems
     venuv@cisco.com

8.  References

8.1.  Normative References

   [I-D.ietf-idr-bgpls-segment-routing-epe]
              Previdi, S., Filsfils, C., Ray, S., Patel, K., Dong, J.,
              and M. Chen, "Segment Routing Egress Peer Engineering BGP-
              LS Extensions", draft-ietf-idr-bgpls-segment-routing-
              epe-00 (work in progress), June 2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [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,
              <http://www.rfc-editor.org/info/rfc4271>.

   [RFC7606]  Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
              Patel, "Revised Error Handling for BGP UPDATE Messages",
              RFC 7606, DOI 10.17487/RFC7606, August 2015,
              <http://www.rfc-editor.org/info/rfc7606>.

   [RFC7752]  Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
              S. Ray, "North-Bound Distribution of Link-State and
              Traffic Engineering (TE) Information Using BGP", RFC 7752,
              DOI 10.17487/RFC7752, March 2016,
              <http://www.rfc-editor.org/info/rfc7752>.

   [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,
              <http://www.rfc-editor.org/info/rfc7938>.




Patel, et al.             Expires June 24, 2017                [Page 11]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


8.2.  Information References

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

   [RFC4456]  Bates, T., Chen, E., and R. Chandra, "BGP Route
              Reflection: An Alternative to Full Mesh Internal BGP
              (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,
              <http://www.rfc-editor.org/info/rfc4456>.

   [RFC4724]  Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
              Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
              DOI 10.17487/RFC4724, January 2007,
              <http://www.rfc-editor.org/info/rfc4724>.

   [RFC4750]  Joyal, D., Ed., Galecki, P., Ed., Giacalone, S., Ed.,
              Coltun, R., and F. Baker, "OSPF Version 2 Management
              Information Base", RFC 4750, DOI 10.17487/RFC4750,
              December 2006, <http://www.rfc-editor.org/info/rfc4750>.

   [RFC4790]  Newman, C., Duerst, M., and A. Gulbrandsen, "Internet
              Application Protocol Collation Registry", RFC 4790,
              DOI 10.17487/RFC4790, March 2007,
              <http://www.rfc-editor.org/info/rfc4790>.

   [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
              Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
              RFC 4915, DOI 10.17487/RFC4915, June 2007,
              <http://www.rfc-editor.org/info/rfc4915>.

   [RFC5286]  Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for
              IP Fast Reroute: Loop-Free Alternates", RFC 5286,
              DOI 10.17487/RFC5286, September 2008,
              <http://www.rfc-editor.org/info/rfc5286>.

   [RFC5549]  Le Faucheur, F. and E. Rosen, "Advertising IPv4 Network
              Layer Reachability Information with an IPv6 Next Hop",
              RFC 5549, DOI 10.17487/RFC5549, May 2009,
              <http://www.rfc-editor.org/info/rfc5549>.

Authors' Addresses

   Keyur Patel
   Arrcus, Inc.

   Email: keyur@arrcus.com




Patel, et al.             Expires June 24, 2017                [Page 12]


Internet-Draft         BGP Protocol SPF Extensions         December 2016


   Acee Lindem
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: acee@cisco.com


   Shawn Zandi
   Linkedin
   222 2nd Street
   San Francisco, CA  94105
   USA

   Email: szandi@linkedin.com


   Gunter Van de Velde
   Nokia
   Antwerp
   Belgium

   Email: gunter.van_de_velde@nokia.com



























Patel, et al.             Expires June 24, 2017                [Page 13]


Html markup produced by rfcmarkup 1.122, available from https://tools.ietf.org/tools/rfcmarkup/