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Versions: 00 draft-ietf-grow-bmp-local-rib

Global Routing Operations                                       T. Evens
Internet-Draft                                              S. Bayraktar
Intended Status: Standards Track                             M. Bhardwaj
Expires: September 11, 2017                                Cisco Systems
March 10, 2017                                                P. Lucente
                                                      NTT Communications

         Support for Local RIB in BGP Monitoring Protocol (BMP)
                   draft-evens-grow-bmp-local-rib-00


Abstract

   The BGP Monitoring Protocol (BMP) defines access to the Adj-RIB-In
   and locally originated routes (e.g. routes distributed into BGP from
   protocols such as static) but not access to the BGP instance Loc-RIB.
   This document updates the BGP Monitoring Protocol (BMP) RFC 7854 by
   adding access to the BGP instance Local-RIB, as defined in RFC 4271
   the routes that have been selected by the local BGP speaker's
   Decision Process. These are the routes over all peers, locally
   originated, and after best-path selection.


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), its areas, and its working groups.  Note that
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   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
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   The list of current Internet-Drafts can be accessed at
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   http://www.ietf.org/shadow.html

   This Internet-Draft will expire on September 11, 2017.


Copyright and License Notice



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   Copyright (c) 2017 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.



Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1. Current Method to Monitor Loc-RIB . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  7
   4.  Per-Peer Header  . . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Peer Type  . . . . . . . . . . . . . . . . . . . . . . . .  7
     4.2.  Peer Flags . . . . . . . . . . . . . . . . . . . . . . . .  7
   5.  Loc-RIB Monitoring . . . . . . . . . . . . . . . . . . . . . .  8
     5.1.  Per-Peer Header  . . . . . . . . . . . . . . . . . . . . .  8
     5.2.  Peer UP Notification . . . . . . . . . . . . . . . . . . .  8
       5.2.1.  Peer UP Information  . . . . . . . . . . . . . . . . .  9
     5.3.  Peer Down Notification . . . . . . . . . . . . . . . . . .  9
     5.4.  Route Monitoring . . . . . . . . . . . . . . . . . . . . .  9
     5.5. Route Mirroring . . . . . . . . . . . . . . . . . . . . . .  9
     5.6  Statistics Report . . . . . . . . . . . . . . . . . . . . .  9
   6.  Other Considerations . . . . . . . . . . . . . . . . . . . . . 10
     6.1.  Loc-RIB Implementation . . . . . . . . . . . . . . . . . . 10
       6.1.1 Multiple Loc-RIB Peers . . . . . . . . . . . . . . . . . 10
       6.1.2 Filtering Loc-RIB to BMP Receivers . . . . . . . . . . . 10
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.1. URIs  . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.2.  Normative References . . . . . . . . . . . . . . . . . . . 11
     9.3.  Informative References . . . . . . . . . . . . . . . . . . 11
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12







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1.  Introduction

   The BGP Monitoring Protocol (BMP) suggests that locally originated
   routes are locally sourced routes, such as redistributed or otherwise
   added routes to the BGP instance by the local router.  It does not
   specify routes that are in the BGP instance Loc-RIB, such as routes
   after best-path selection.

   Figure 1 shows the flow of received routes from one or more BGP peers
   into the Loc-RIB.



                +------------------+      +------------------+
                | Peer-A           |      | Peer-B           |
            /-- |                  | ---- |                  | --\
            |   | Adj-RIB-In (Pre) |      | Adj-RIB-In (Pre) |   |
            |   +------------------+      +------------------+   |
            |                 |                         |        |
            | Filters/Policy -|         Filters/Policy -|        |
            |                 V                         V        |
            |   +------------------       +------------------+   |
            |   | Adj-RIB-In (Post)|      | Adj-RIB-In (Post)|   |
            |   +------------------       +------------------+   |
            |                |                          |        |
            |      Selected -|                Selected -|        |
            |                V                          V        |
            |    +-----------------------------------------+     |
            |    |                 Loc-RIB                 |     |
            |    +-----------------------------------------+     |
            |                                                    |
            | ROUTER/BGP Instance                                |
            \----------------------------------------------------/

             Figure 1: BGP peering Adj-RIBs-In into Loc-RIB
















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   As shown in Figure 2, Locally originated follows a similar flow where
   the redistributed or otherwise originated routes get installed into
   the Loc-RIB based on the decision process selection.



         /--------------------------------------------------------\
         |                                                        |
         | +----------+  +----------+  +----------+  +----------+ |
         | |  IS-IS   |  |   OSPF   |  |  Static  |  |    BGP   | |
         | +----------+  +----------+  +----------+  +----------+ |
         |       |            |             |              |      |
         |       |                                         |      |
         |       |  Redistributed or originated into BGP   |      |
         |       |                                         |      |
         |       |            |             |              |      |
         |       V            V             V              V      |
         |    +----------------------------------------------+    |
         |    |                 Loc-RIB                      |    |
         |    +----------------------------------------------+    |
         |                                                        |
         | ROUTER/BGP Instance                                    |
         \--------------------------------------------------------/

               Figure 2: Locally Originated into Loc-RIB



   BGP instance Loc-RIB usually provides a similar, if not exact,
   forwarding information base (FIB) view of the routes from BGP that
   the router will use.  The following are some use-cases for Loc-RIB
   access:

      o  Adj-RIBs-In Post-Policy may still contain hundreds of thousands
         of routes per-peer but only a handful are selected and
         installed in the Loc-RIB as part of the best-path selection.
         Some monitoring applications, such as ones that need only to
         correlate flow records to Loc-RIB entries, only need to collect
         and monitor the routes that are actually selected and used.

         Requiring the applications to collect all Adj-RIB-In Post-
         Policy data forces the applications to receive a potentially
         large unwanted data set and to perform the BGP decision process
         selection, which includes having access to the IGP next-hop
         metrics.  While it is possible to obtain the IGP topology
         information using BGP-LS, it requires the application to
         implement SPF and possibly CSPF based on additional policies.
         This is overly complex for such a simple application that only



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         needed to have access to the Loc-RIB.

      o  It is common to see frequent changes over many BGP peers, but
         those changes do not always result in the router's Loc-RIB
         changing.  The change in the Loc-RIB can have a direct impact
         on the forwarding state.  It can greatly reduce time to
         troubleshoot and resolve issues if operators had the history of
         Loc-RIB changes. For example, a performance issue might have
         been seen for only a duration of 5 minutes.  Post
         troubleshooting this issue without Loc-RIB history hides any
         decision based routing changes that might have happened during
         those five minutes.

      o  Operators may wish to validate the impact of policies applied
         to Adj-RIB-In by analyzing the final decision made by the
         router when installing into the Loc-RIB. For example, in order
         to validate if multi-path prefixes are installed as expected
         for all advertising peers, the Adj-RIB-In Post-Policy and Loc-
         RIB needs to be compared. This is only possible if the Loc-RIB
         is available.  Monitoring the Adj-RIB-In for this router from
         another router to derive the Loc-RIB is likely to not show same
         installed prefixes. For example, the received Adj-RIB-In will
         be different if add-paths is not enabled or if maximum number
         of equal paths are different from Loc-RIB to routes
         advertised.

   This document adds Loc-RIB to the BGP Monitoring Protocol and
   replaces Section 8.2 [RFC7854] Locally Originated Routes.


1.1. Current Method to Monitor Loc-RIB

   Loc-RIB is used to build Adj-RIB-Out when advertising routes to a
   peer.  It is therefore possible to derive the Loc-RIB of a router by
   monitoring the Adj-RIB-In Pre-Policy from another router.  While it
   is possible to derive the Loc-RIB, it is also error prone and
   complex.

   The setup needed to monitor the Loc-RIB of a router requires another
   router with a peering session to the target router that is to be
   monitored.  The target router Loc-RIB is advertised via Adj-RIB-Out
   to the BMP router over a standard BGP peering session.  The BMP
   router then forwards Adj-RIB-In Pre-Policy to the BMP receiver.


      Unnecessary resources needed for current method:

      o  Requires at least two routers when only one router was to be



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         monitored.

      o  Requires additional BGP peering to collect the received updates
         when peering may have not even been required in the first
         place.  For example, VRF's with no peers, redistributed bgp-ls
         with no peers, segment routing egress peer engineering where no
         peers have link-state address family enabled.


      Complexities introduced with current method in order to derive
      (e.g. correlate) peer to router Loc-RIB:

      o  Adj-RIB-Out received as Adj-RIB-In from another router may have
      a policy applied that filters, generates aggregates, suppresses
      more specifics, manipulates attributes, or filters routes.  Not
      only does this invalidate the Loc-RIB view, it adds complexity
      when multiple BMP routers may have peering sessions to the same
      router.  The BMP receiver user is left with the erroneous task of
      identifying which peering session is the best representative of
      the Loc-RIB.

      o  BGP peering is designed to work between administrative domains
      and therefore does not need to include internal system level
      information of each peering router (e.g. the system name or
      version information).  In order to derive a Loc-RIB to a router,
      the router name or other system information is needed.   The BMP
      receiver and user are forced to do some type of correlation using
      what information is available in the peering session (e.g. peering
      addresses, ASNs, and BGP-ID's).  This leads to error prone
      correlations.

      o  The BGP-ID's and session addresses to router correlation
      requires additional data, such as router inventory. This
      additional data provides the BMP receiver the ability to map and
      correlate the BGP-ID's and/or session addresses, but requires the
      BMP receiver to somehow obtain this data outside of BMP.  How this
      data is obtained and the accuracy of the data directly effects the
      integrity of the correlation.


2.  Terminology

   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].






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3.  Definitions
   o  Adj-RIB-In: As defined in [RFC4271], "The Adj-RIBs-In contains
      unprocessed routing information that has been advertised to the
      local BGP speaker by its peers."  This is also referred to as the
      pre-policy Adj-RIB-In in this document.

   o  Adj-RIB-Out: As defined in [RFC4271], "The Adj-RIBs-Out contains
      the routes for advertisement to specific peers by means of the
      local speaker's UPDATE messages."

   o  Loc-RIB: As defined in [RFC4271], "The Loc-RIB contains the routes
      that have been selected by the local BGP speaker's Decision
      Process."  It is further defined that the routes selected include
      locally originated and routes from all peers.

   o  Pre-Policy Adj-RIB-Out: The result before applying the outbound
      policy to an Adj-RIB-Out. This normally would match what is in the
      local RIB.

   o  Post-Policy Adj-RIB-Out: The result of applying outbound policy to
      an Adj-RIB-Out. This MUST be what is actually sent to the peer.


4.  Per-Peer Header

4.1.  Peer Type

   This document defines the following new peer type:

   o  Peer Type = 3: Loc-RIB Instance Peer

4.2.  Peer Flags

   In section 4.2 [RFC7854], the "locally sourced routes" comment in the
   L flag description is removed.  Locally sourced routes MUST be
   conveyed using the Loc-RIB instance peer type.

   The per-peer header flags for Loc-RIB Instance Peer type are defined
   as follows:

                                 0 1 2 3 4 5 6 7
                                +-+-+-+-+-+-+-+-+
                                |V|F| Reserved  |
                                +-+-+-+-+-+-+-+-+

      o  The V flag indicates that the Peer address is an IPv6 address.
         For IPv4 peers, this is set to 0.




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      o  The F flag indicates that the Loc-RIB is filtered.  This
         indicates that the Loc-RIB does not represent the complete
         routing table.

      The remaining bits are reserved for future use. They MUST be
      transmitted as 0 and their values MUST be ignored on receipt.

5.  Loc-RIB Monitoring

   Loc-RIB contains all routes from BGP peers as well as any and all
   routes redistributed or otherwise locally originated.  In this
   context, only the BGP instance Loc-RIB is included.  Routes from
   other routing protocols that have not been redistributed or received
   via Adj-RIB-In are not considered.

5.1.  Per-Peer Header

   All peer messages that include a per-peer header MUST use the
   following values:

   o  Peer Type: Set to 3 to indicate Loc-RIB Instance Peer.

   o  Peer Distinguisher: Zero filled if the Loc-RIB represents the
      global instance.  Otherwise set to the route distinguisher or
      unique locally defined value of the particular instance the Loc-
      RIB belongs to.

   o  Peer Address: Zero-filled as remote peer address is not
      applicable.

   o  Peer AS: Set to the BGP instance global or default ASN value.

   o  Peer BGP ID: Set to the BGP instance global or RD (e.g. VRF)
      specific router-id.

5.2.  Peer UP Notification

   Peer UP notifications follow section 4.10 [RFC7854] with the
   following clarifications:

   o  Local Address: Zero-filled, local address is not applicable.

   o  Local Port: Set to 0, local port is not applicable.

   o  Remote Port: Set to 0, remote port is not applicable.

   o  Sent OPEN Message: This is a fabricated BGP OPEN message.
      Capabilities MUST include 4-octet ASN and all necessary



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      capabilities to represent the Loc-RIB route monitoring messages.
      Only include capabilities if they will be used for Loc-RIB
      monitoring messages.  For example, if add-paths is enabled for
      IPv6 and Loc-RIB contains additional paths, the add-paths
      capability should be included for IPv6.  In the case of add-paths,
      the capability intent of advertise, receive or both can be ignored
      since the presence of the capability indicates enough that add-
      paths will be used for IPv6.

   o  Received OPEN Message: Repeat of the same Sent Open Message.  The
      duplication allows the BMP receiver to use existing parsing.

5.2.1.  Peer UP Information

   The following peer UP information TLV Type is added:

   o  Type = 3: VRF Name.  The Information field contains an ASCII
      string whose value MUST be equal to the value of the VRF name
      (e.g. RD instance name) configured. This type is only relevant and
      used when the Loc-RIB represents a VRF/RD instance.

   It is RECOMMENDED that the VRF Name be defined as "global" for the
   global/default Loc-RIB instance.

5.3.  Peer Down Notification

   Peer down notification SHOULD follow the section 4.9 [RFC7854] reason
   2.

5.4.  Route Monitoring

   Route Monitoring messages are used for initial synchronization of the
   Loc-RIB.  They are also used for incremental updates upon every
   change to the RIB.  State compression on interval, such as 1 or
   greater seconds, can mask critical RIB changes.  Therefore state
   compression SHOULD be avoided.  If the Loc-RIB changes, a route
   monitor message should be sent.

   As defined in section 4.3 [RFC7854], "Following the common BMP header
   and per-peer header is a BGP Update PDU."

5.5. Route Mirroring

   Route mirroring is not applicable to Loc-RIB.

5.6  Statistics Report

   Not all Stat Types are relevant to Loc-RIB.  The Stat Types that are



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   relevant are listed below:

   o  Stat Type = 8: (64-bit Gauge) Number of routes in Loc-RIB.

   o  Stat Type = 10: Number of routes in per-AFI/SAFI Loc-RIB.  The
      value is structured as: 2-byte AFI, 1-byte SAFI, followed by a 64-
      bit Gauge.


6.  Other Considerations

6.1.  Loc-RIB Implementation

   There are several methods to implement Loc-RIB efficiently.  In all
   methods, the implementation emulates a peer with Peer UP and DOWN
   messages to convey capabilities as well as Route Monitor messages to
   convey Loc-RIB.  In this sense, the peer that conveys the Loc-RIB is
   a local router emulated peer.

6.1.1 Multiple Loc-RIB Peers

   There MUST be multiple emulated peers for each Loc-RIB instance, such
   as with VRF's. The BMP receiver identifies the Loc-RIB's by the peer
   header distinguisher and BGP ID.  The BMP receiver uses the VRF Name
   from the PEER UP to name the Loc-RIB.

   In some implementations, it might be required to have more than one
   emulated peer for Loc-RIB to convey different address families for
   the same Loc-RIB.  In this case, the peer distinguisher and BGP ID
   should be the same since it represents the same Loc-RIB instance.
   Each emulated peer instance MUST send a PEER UP with the OPEN message
   indicating the address family capabilities.  A BMP receiver MUST
   process these capabilities to know which peer belongs to which
   address family.

6.1.2 Filtering Loc-RIB to BMP Receivers

   There maybe be use-cases where BMP receivers should only receive
   specific routes from Loc-RIB. For example, IPv4 unicast routes may
   include IBGP, EBGP, and IGP but only routes from EBGP should be sent
   to the BMP receiver.  Alternatively, it may be that only IBGP and
   EBGP that should be sent and IGP redistributed routes should be
   excluded.  In these cases where the Loc-RIB is filtered, the F flag
   is set to 1 to indicate to the BMP receiver that the Loc-RIB is
   partial.






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7.  Security Considerations

   It is not believed that this document adds any additional security
   considerations.


8.  IANA Considerations

   This document requests that IANA assign the following new peer types
   to the BMP parameters name space [1].

   o  Peer Type = 3: Loc-RIB Instance Peer

9.  References

9.1. URIs

   [1]  https://www.iana.org/assignments/bmp-parameters/bmp-
              parameters.xhtml


9.2.  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, <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>.

   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854, DOI
              10.17487/RFC7854, June 2016, <http://www.rfc-
              editor.org/info/rfc7854>.

9.3.  Informative References


   [I-ID.ietf-grow-bmp-adj-rib-out] TBD.








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Acknowledgments

   TBD.

Authors' Addresses


   Tim Evens
   Cisco Systems
   2901 Third Avenue, Suite 600
   Seattle, WA 98121
   USA

   Email: tievens@cisco.com



   Serpil Bayraktar
   Cisco Systems
   3700 Cisco Way
   San Jose, CA 95134
   USA

   Email: serpil@cisco.com



   Manish Bhardwaj
   Cisco Systems
   3700 Cisco Way
   San Jose, CA 95134
   USA

   Email: manbhard@cisco.com



   Paolo Lucente
   NTT Communications
   Siriusdreef 70-72
   Hoofddorp  2132 WT
   NL

   Email: paolo@ntt.net







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