





Internet Engineering Task Force (IETF)                          L. Blunk
Request for Comments: 6396                                      M. Karir
Category: Standards Track                                  Merit Network
ISSN: 2070-1721                                              C. Labovitz
                                                      Deepfield Networks
                                                            October 2011


 Multi-Threaded Routing Toolkit (MRT) Routing Information Export Format

Abstract

   This document describes the MRT format for routing information
   export.  This format was developed in concert with the Multi-threaded
   Routing Toolkit (MRT) from whence the format takes it name.  The
   format can be used to export routing protocol messages, state
   changes, and routing information base contents.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6396.

Copyright Notice

   Copyright (c) 2011 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
   (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.





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   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.  Specification of Requirements  . . . . . . . . . . . . . .  4
   2.  MRT Common Header  . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Extended Timestamp MRT Header  . . . . . . . . . . . . . . . .  5
   4.  MRT Types  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  OSPFv2 Type  . . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  TABLE_DUMP Type  . . . . . . . . . . . . . . . . . . . . .  7
     4.3.  TABLE_DUMP_V2 Type . . . . . . . . . . . . . . . . . . . .  9
       4.3.1.  PEER_INDEX_TABLE Subtype . . . . . . . . . . . . . . .  9
       4.3.2.  AFI/SAFI-Specific RIB Subtypes . . . . . . . . . . . . 11
       4.3.3.  RIB_GENERIC Subtype  . . . . . . . . . . . . . . . . . 11
       4.3.4.  RIB Entries  . . . . . . . . . . . . . . . . . . . . . 12
     4.4.  BGP4MP Type  . . . . . . . . . . . . . . . . . . . . . . . 13
       4.4.1.  BGP4MP_STATE_CHANGE Subtype  . . . . . . . . . . . . . 13
       4.4.2.  BGP4MP_MESSAGE Subtype . . . . . . . . . . . . . . . . 14
       4.4.3.  BGP4MP_MESSAGE_AS4 Subtype . . . . . . . . . . . . . . 15
       4.4.4.  BGP4MP_STATE_CHANGE_AS4 Subtype  . . . . . . . . . . . 15
       4.4.5.  BGP4MP_MESSAGE_LOCAL Subtype . . . . . . . . . . . . . 16
       4.4.6.  BGP4MP_MESSAGE_AS4_LOCAL Subtype . . . . . . . . . . . 16
     4.5.  ISIS Type  . . . . . . . . . . . . . . . . . . . . . . . . 16
     4.6.  OSPFv3 Type  . . . . . . . . . . . . . . . . . . . . . . . 17
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
     5.1.  Type Codes . . . . . . . . . . . . . . . . . . . . . . . . 17
     5.2.  Subtype Codes  . . . . . . . . . . . . . . . . . . . . . . 18
     5.3.  Defined Type Codes . . . . . . . . . . . . . . . . . . . . 18
     5.4.  Defined BGP, BGP4PLUS, and BGP4PLUS_01 Subtype Codes . . . 19
     5.5.  Defined TABLE_DUMP Subtype Codes . . . . . . . . . . . . . 19
     5.6.  Defined TABLE_DUMP_V2 Subtype Codes  . . . . . . . . . . . 19
     5.7.  Defined BGP4MP and BGP4MP_ET Subtype Codes . . . . . . . . 20
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 21
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 21




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   Appendix A.  MRT Encoding Examples . . . . . . . . . . . . . . . . 23
   Appendix B.  Deprecated MRT Types  . . . . . . . . . . . . . . . . 26
     B.1.  Deprecated MRT Informational Types . . . . . . . . . . . . 26
       B.1.1.  NULL Type  . . . . . . . . . . . . . . . . . . . . . . 26
       B.1.2.  START Type . . . . . . . . . . . . . . . . . . . . . . 27
       B.1.3.  DIE Type . . . . . . . . . . . . . . . . . . . . . . . 27
       B.1.4.  I_AM_DEAD Type . . . . . . . . . . . . . . . . . . . . 27
       B.1.5.  PEER_DOWN Type . . . . . . . . . . . . . . . . . . . . 27
     B.2.  Other Deprecated MRT Types . . . . . . . . . . . . . . . . 27
       B.2.1.  BGP Type . . . . . . . . . . . . . . . . . . . . . . . 27
       B.2.2.  RIP Type . . . . . . . . . . . . . . . . . . . . . . . 30
       B.2.3.  IDRP Type  . . . . . . . . . . . . . . . . . . . . . . 30
       B.2.4.  RIPNG Type . . . . . . . . . . . . . . . . . . . . . . 31
       B.2.5.  BGP4PLUS and BGP4PLUS_01 Types . . . . . . . . . . . . 31
       B.2.6.  Deprecated BGP4MP Subtypes . . . . . . . . . . . . . . 32
   Appendix C.  Acknowledgements  . . . . . . . . . . . . . . . . . . 34

1.  Introduction

   Researchers and engineers often wish to analyze network behavior by
   studying routing protocol transactions and routing information base
   snapshots.  To this end, the MRT record format was developed to
   encapsulate, export, and archive this information in a standardized
   data representation.

   The BGP routing protocol, in particular, has been the subject of
   extensive study and analysis, which have been significantly aided by
   the availability of the MRT format.  Two examples of large-scale MRT-
   based BGP archival projects include the University of Oregon Route
   Views Project and the RIPE NCC Routing Information Service (RIS).

   The MRT format was initially defined in the MRT Programmer's Guide
   [MRT_PROG_GUIDE].  Subsequent extensions were made in the GNU Zebra
   software routing suite and the Sprint Advanced Technology Labs Python
   Routing Toolkit (PyRT).  Further extensions may be introduced at a
   later date through additional definitions of the MRT Type field and
   Subtype fields.

   A number of MRT record types listed in the MRT Programmer's Guide
   [MRT_PROG_GUIDE] are not known to have been implemented and, in some
   cases, were incompletely specified.  Further, several types were
   employed in early MRT implementations, but saw limited use and were
   updated by improved versions.  These types are considered to be
   deprecated and are documented in the Deprecated MRT Types
   (Appendix B) section at the end of this document.  The deprecated
   types consist of codes 0 through 10 inclusive.  Some of the
   deprecated types may be of interest to researchers examining
   historical MRT format archives.



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   Fields which contain multi-octet numeric values are encoded in
   network octet order from most significant octet to least significant
   octet.  Fields that contain routing message fields are encoded in the
   same order as they appear in the packet contents.

1.1.  Specification of Requirements

   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].

2.  MRT Common Header

   All MRT format records have a Common Header that consists of a
   Timestamp, Type, Subtype, and Length field.  The header is followed
   by a Message field.  The MRT Common Header is illustrated below.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Timestamp                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Type              |            Subtype            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                             Length                            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Message... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 1: MRT Common Header

   Header Field Descriptions:

      Timestamp:

         A 4-octet field whose integer value is the number of seconds,
         excluding leap seconds, elapsed since midnight proleptic
         Coordinated Universal Time (UTC).  This representation of time
         is sometimes called "UNIX time" [POSIX].  This time format
         cannot represent time values prior to January 1, 1970.  The
         latest UTC time value that can be represented by a 4-octet
         integer value is 03:14:07 on January 19, 2038, which is
         represented by the hexadecimal value 7FFFFFFF.  Implementations
         that wish to create MRT records after this date will need to
         provide an alternate EPOCH time base for the Timestamp field.
         Mechanisms for indicating this alternate EPOCH are currently
         outside the scope of this document.




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      Type:

         A 2-octet field that indicates the Type of information
         contained in the Message field.  Types 0 through 4 are
         informational messages pertaining to the state of an MRT
         collector, while Types 5 and higher are used to convey routing
         information.

      Subtype:

         A 2-octet field that is used to further distinguish message
         information within a particular record Type.

      Length:

         A 4-octet message length field.  The Length field contains the
         number of octets within the message.  The Length field does not
         include the length of the MRT Common Header.

      Message:

         A variable-length message.  The contents of this field are
         context dependent upon the Type and Subtype fields.

3.  Extended Timestamp MRT Header

   Several MRT format record types support a variant type with an
   extended timestamp field.  The purpose of this field is to support
   measurements at sub-second resolutions.  This field, Microsecond
   Timestamp, contains an unsigned 32BIT offset value in microseconds,
   which is added to the Timestamp field value.  The Timestamp field
   remains as defined in the MRT Common Header.  The Microsecond
   Timestamp immediately follows the Length field in the MRT Common
   Header and precedes all other fields in the message.  The Microsecond
   Timestamp is included in the computation of the Length field value.
   The Extended Timestamp MRT Header is illustrated below.















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        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Timestamp                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             Type              |            Subtype            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                             Length                            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Microsecond Timestamp                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Message... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 2: Extended Timestamp MRT Header

4.  MRT Types

   The following MRT Types are currently defined for the MRT format.
   The MRT Types that contain the "_ET" suffix in their names identify
   those types that use an Extended Timestamp MRT Header.  The Subtype
   and Message fields in these types remain as defined for the MRT Types
   of the same name without the "_ET" suffix.

       11   OSPFv2
       12   TABLE_DUMP
       13   TABLE_DUMP_V2
       16   BGP4MP
       17   BGP4MP_ET
       32   ISIS
       33   ISIS_ET
       48   OSPFv3
       49   OSPFv3_ET

4.1.  OSPFv2 Type

   This type supports the OSPFv2 protocol as defined in RFC 2328
   [RFC2328].  It is used to encode the exchange of OSPF protocol
   packets.












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   The format of the MRT Message field for the OSPFv2 Type is as
   follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Remote IP Address                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Local IP Address                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  OSPF Message Contents (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Figure 3: OSPFv2 Type

   The Remote IP Address field contains the Source IPv4 [RFC0791]
   address from the IP header of the OSPF message.  The Local IP Address
   contains the Destination IPv4 address from the IP header.  The OSPF
   Message Contents field contains the complete contents of the OSPF
   packet following the IP header.

4.2.  TABLE_DUMP Type

   The TABLE_DUMP Type is used to encode the contents of a BGP Routing
   Information Base (RIB).  Each RIB entry is encoded in a distinct
   sequential MRT record.  It is RECOMMENDED that new MRT encoding
   implementations use the TABLE_DUMP_V2 Type (see below) instead of the
   TABLE_DUMP Type due to limitations in this type.  However, due to the
   significant volume of historical data encoded with this type, MRT
   decoding applications MAY wish to support this type.

   The Subtype field is used to encode whether the RIB entry contains
   IPv4 or IPv6 [RFC2460] addresses.  There are two possible values for
   the Subtype as shown below.

       1    AFI_IPv4
       2    AFI_IPv6














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   The format of the TABLE_DUMP Type is illustrated below.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         View Number           |       Sequence Number         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Prefix (variable)                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Prefix Length |    Status     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Originated Time                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Peer IP Address (variable)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Peer AS             |       Attribute Length        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   BGP Attribute... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 4: TABLE_DUMP Type

   The View Number field is normally 0 and is intended for cases where
   an implementation may have multiple RIB views (such as a route
   server).  In cases where multiple RIB views are present, an
   implementation MAY use the View Number field to distinguish entries
   from each view.  The Sequence Number field is a simple incremental
   counter for each RIB entry.  A typical RIB dump will exceed the
   16-bit bounds of this counter, and an implementation SHOULD simply
   wrap back to zero and continue incrementing the counter in such
   cases.

   The Prefix field contains the IP address of a particular RIB entry.
   The size of this field is dependent on the value of the Subtype for
   this record.  The AFI_IPv4 Subtype value specifies an Address Family
   Identifier (AFI) type of IPv4 [IANA-AF].  It specifies a Prefix field
   length of 4 octets.  For AFI_IPv6, it is 16 octets in length.  The
   Prefix Length field indicates the length in bits of the prefix mask
   for the preceding Prefix field.

   The Status octet is unused in the TABLE_DUMP Type and SHOULD be set
   to 1.

   The Originated Time contains the 4-octet time at which this prefix
   was heard.  The value represents the time in seconds since 1 January
   1970 00:00:00 UTC.





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   The Peer IP Address field is the IP address of the peer that provided
   the update for this RIB entry.  As with the Prefix field, the size of
   this field is dependent on the Subtype.  AFI_IPv4 indicates a 4-octet
   field and an IPv4 address, while a Subtype of AFI_IPv6 requires a
   16-octet field and an IPv6 address.  The Peer AS field contains the
   2-octet Autonomous System (AS) number of the peer.

   The TABLE_DUMP Type does not permit 4-byte Peer AS numbers, nor does
   it allow the AFI of the peer IP to differ from the AFI of the Prefix
   field.  The TABLE_DUMP_V2 Type MUST be used in these situations.

   Attribute Length contains the length of the Attribute field and is 2
   octets.  The BGP Attribute field contains the BGP attribute
   information for the RIB entry.  The AS_PATH attribute MUST only
   consist of 2-byte AS numbers.  The TABLE_DUMP_V2 supports 4-byte AS
   numbers in the AS_PATH attribute.

4.3.  TABLE_DUMP_V2 Type

   The TABLE_DUMP_V2 Type updates the TABLE_DUMP Type to include 4-byte
   Autonomous System Number (ASN) support and full support for BGP
   multiprotocol extensions.  It also improves upon the space efficiency
   of the TABLE_DUMP Type by employing an index table for peers and
   permitting a single MRT record per Network Layer Reachability
   Information (NLRI) entry.  The following subtypes are used with the
   TABLE_DUMP_V2 Type.

       1    PEER_INDEX_TABLE
       2    RIB_IPV4_UNICAST
       3    RIB_IPV4_MULTICAST
       4    RIB_IPV6_UNICAST
       5    RIB_IPV6_MULTICAST
       6    RIB_GENERIC

4.3.1.  PEER_INDEX_TABLE Subtype

   An initial PEER_INDEX_TABLE MRT record provides the BGP ID of the
   collector, an OPTIONAL view name, and a list of indexed peers.
   Following the PEER_INDEX_TABLE MRT record, a series of MRT records is
   used to encode RIB table entries.  This series of MRT records uses
   subtypes 2-6 and is separate from the PEER_INDEX_TABLE MRT record
   itself and includes full MRT record headers.  The RIB entry MRT
   records MUST immediately follow the PEER_INDEX_TABLE MRT record.

   The header of the PEER_INDEX_TABLE Subtype is shown below.  The View
   Name is OPTIONAL and, if not present, the View Name Length MUST be
   set to 0.  The View Name encoding MUST follow the UTF-8
   transformation format [RFC3629].



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        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Collector BGP ID                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       View Name Length        |     View Name (variable)      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Peer Count           |    Peer Entries (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 5: PEER_INDEX_TABLE Subtype

   The format of the Peer Entries is shown below.  The PEER_INDEX_TABLE
   record contains Peer Count number of Peer Entries.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Peer Type   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Peer BGP ID                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Peer IP Address (variable)                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Peer AS (variable)                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Figure 6: Peer Entries

   The Peer Type, Peer BGP ID, Peer IP Address, and Peer AS fields are
   repeated as indicated by the Peer Count field.  The position of the
   peer in the PEER_INDEX_TABLE is used as an index in the subsequent
   TABLE_DUMP_V2 MRT records.  The index number begins with 0.

   The Peer Type field is a bit field that encodes the type of the AS
   and IP address as identified by the A and I bits, respectively,
   below.

       0 1 2 3 4 5 6 7
      +-+-+-+-+-+-+-+-+
      | | | | | | |A|I|
      +-+-+-+-+-+-+-+-+

      Bit 6: Peer AS number size:  0 = 16 bits, 1 = 32 bits
      Bit 7: Peer IP Address family:  0 = IPv4,  1 = IPv6

                         Figure 7: Peer Type Field




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   The MRT records that follow the PEER_INDEX_TABLE MRT record consist
   of the subtypes listed below and contain the actual RIB table
   entries.  They include a header that specifies a sequence number, an
   NLRI field, and a count of the number of RIB entries contained within
   the record.

4.3.2.  AFI/SAFI-Specific RIB Subtypes

   The AFI/SAFI-specific RIB Subtypes consist of the RIB_IPV4_UNICAST,
   RIB_IPV4_MULTICAST, RIB_IPV6_UNICAST, and RIB_IPV6_MULTICAST
   Subtypes.  These specific RIB table entries are given their own MRT
   TABLE_DUMP_V2 subtypes as they are the most common type of RIB table
   instances, and providing specific MRT subtypes for them permits more
   compact encodings.  These subtypes permit a single MRT record to
   encode multiple RIB table entries for a single prefix.  The Prefix
   Length and Prefix fields are encoded in the same manner as the BGP
   NLRI encoding for IPv4 and IPv6 prefixes.  Namely, the Prefix field
   contains address prefixes followed by enough trailing bits to make
   the end of the field fall on an octet boundary.  The value of
   trailing bits is irrelevant.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Sequence Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Prefix Length |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Prefix (variable)                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Entry Count           |  RIB Entries (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 8: RIB Entry Header

4.3.3.  RIB_GENERIC Subtype

   The RIB_GENERIC header is shown below.  It is used to cover RIB
   entries that do not fall under the common case entries defined above.
   It consists of an AFI, Subsequent AFI (SAFI), and a single NLRI
   entry.  The NLRI information is specific to the AFI and SAFI values.
   An implementation that does not recognize particular AFI and SAFI
   values SHOULD discard the remainder of the MRT record.








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        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Sequence Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Address Family Identifier  |Subsequent AFI |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Network Layer Reachability Information (variable)         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Entry Count           |  RIB Entries (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 9: RIB_GENERIC Entry Header

4.3.4.  RIB Entries

   The RIB Entries are repeated Entry Count times.  These entries share
   a common format as shown below.  They include a Peer Index from the
   PEER_INDEX_TABLE MRT record, an originated time for the RIB Entry,
   and the BGP path attribute length and attributes.  All AS numbers in
   the AS_PATH attribute MUST be encoded as 4-byte AS numbers.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Peer Index            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Originated Time                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Attribute Length         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    BGP Attributes... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Figure 10: RIB Entries

   There is one exception to the encoding of BGP attributes for the BGP
   MP_REACH_NLRI attribute (BGP Type Code 14) [RFC4760].  Since the AFI,
   SAFI, and NLRI information is already encoded in the RIB Entry Header
   or RIB_GENERIC Entry Header, only the Next Hop Address Length and
   Next Hop Address fields are included.  The Reserved field is omitted.
   The attribute length is also adjusted to reflect only the length of
   the Next Hop Address Length and Next Hop Address fields.








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4.4.  BGP4MP Type

   This type was initially defined in the Zebra software package for the
   BGP protocol with multiprotocol extension support as defined by RFC
   4760 [RFC4760].  The BGP4MP Type has six Subtypes, which are defined
   as follows:

       0    BGP4MP_STATE_CHANGE
       1    BGP4MP_MESSAGE
       4    BGP4MP_MESSAGE_AS4
       5    BGP4MP_STATE_CHANGE_AS4
       6    BGP4MP_MESSAGE_LOCAL
       7    BGP4MP_MESSAGE_AS4_LOCAL

4.4.1.  BGP4MP_STATE_CHANGE Subtype

   This message is used to encode state changes in the BGP finite state
   machine (FSM).  The BGP FSM states are encoded in the Old State and
   New State fields to indicate the previous and current state.  In some
   cases, the Peer AS Number may be undefined.  In such cases, the value
   of this field MAY be set to zero.  The format is illustrated below:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Peer AS Number        |        Local AS Number        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Interface Index        |        Address Family         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Peer IP Address (variable)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Local IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Old State          |          New State            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 11: BGP4MP_STATE_CHANGE Subtype

   The FSM states are defined in RFC 4271 [RFC4271], Section 8.2.2.
   Both the Old State value and the New State value are encoded as
   2-octet numbers.  The state values are defined numerically as
   follows:









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       1    Idle
       2    Connect
       3    Active
       4    OpenSent
       5    OpenConfirm
       6    Established

   The BGP4MP_STATE_CHANGE message also includes Interface Index and
   Address Family fields.  The Interface Index provides the interface
   number of the peering session.  The index value is OPTIONAL and MAY
   be zero if unknown or unsupported.  The Address Family indicates what
   types of addresses are in the address fields.  At present, the
   following AFI Types are supported:

       1    AFI_IPv4
       2    AFI_IPv6

4.4.2.  BGP4MP_MESSAGE Subtype

   This subtype is used to encode BGP messages.  It can be used to
   encode any Type of BGP message.  The entire BGP message is
   encapsulated in the BGP Message field, including the 16-octet marker,
   the 2-octet length, and the 1-octet type fields.  The BGP4MP_MESSAGE
   Subtype does not support 4-byte AS numbers.  The AS_PATH contained in
   these messages MUST only consist of 2-byte AS numbers.  The
   BGP4MP_MESSAGE_AS4 Subtype updates the BGP4MP_MESSAGE Subtype in
   order to support 4-byte AS numbers.  The BGP4MP_MESSAGE fields are
   shown below:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Peer AS Number        |        Local AS Number        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Interface Index        |        Address Family         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Peer IP Address (variable)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Local IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    BGP Message... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 12: BGP4MP_MESSAGE Subtype







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   The Interface Index provides the interface number of the peering
   session.  The index value is OPTIONAL and MAY be zero if unknown or
   unsupported.  The Address Family indicates what types of addresses
   are in the subsequent address fields.  At present, the following AFI
   Types are supported:

       1    AFI_IPv4
       2    AFI_IPv6

   The Address Family value only applies to the IP addresses contained
   in the MRT header.  The BGP4MP_MESSAGE Subtype is otherwise
   transparent to the contents of the actual message that may contain
   any valid AFI/SAFI values.  Only one BGP message SHALL be encoded in
   the BGP4MP_MESSAGE Subtype.

4.4.3.  BGP4MP_MESSAGE_AS4 Subtype

   This subtype updates the BGP4MP_MESSAGE Subtype to support 4-byte AS
   numbers.  The BGP4MP_MESSAGE_AS4 Subtype is otherwise identical to
   the BGP4MP_MESSAGE Subtype.  The AS_PATH in these messages MUST only
   consist of 4-byte AS numbers.  The BGP4MP_MESSAGE_AS4 fields are
   shown below:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Peer AS Number                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Local AS Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Interface Index        |        Address Family         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Peer IP Address (variable)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Local IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    BGP Message... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 13: BGP4MP_MESSAGE_AS4 Subtype

4.4.4.  BGP4MP_STATE_CHANGE_AS4 Subtype

   This subtype updates the BGP4MP_STATE_CHANGE Subtype to support
   4-byte AS numbers.  As with the BGP4MP_STATE_CHANGE Subtype, the BGP
   FSM states are encoded in the Old State and New State fields to
   indicate the previous and current state.  Aside from the extension of
   the Peer and Local AS Number fields to 4 bytes, this subtype is



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   otherwise identical to the BGP4MP_STATE_CHANGE Subtype.  The
   BGP4MP_STATE_CHANGE_AS4 fields are shown below:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Peer AS Number                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Local AS Number                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Interface Index        |        Address Family         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Peer IP Address (variable)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Local IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Old State          |          New State            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 14: BGP4MP_STATE_CHANGE_AS4 Subtype

4.4.5.  BGP4MP_MESSAGE_LOCAL Subtype

   Implementations of MRT have largely focused on collecting remotely
   generated BGP messages in a passive route collector role.  However,
   for active BGP implementations, it can be useful to archive locally
   generated BGP messages in addition to remote messages.  This subtype
   is added to indicate a locally generated BGP message.  The fields
   remain identical to the BGP4MP_MESSAGE type including the Peer and
   Local IP and AS fields.  The Local fields continue to refer to the
   local IP and AS number of the collector that generated the BGP
   message, and the Peer IP and AS fields refer to the recipient of the
   generated BGP messages.

4.4.6.  BGP4MP_MESSAGE_AS4_LOCAL Subtype

   As with the BGP4MP_MESSAGE_LOCAL type, this type indicates locally
   generated messages.  The fields are identical to the
   BGP4MP_MESSAGE_AS4 message type.

4.5.  ISIS Type

   This type supports the IS-IS routing protocol as defined in RFC 1195
   [RFC1195].  There is no Type-specific header for the ISIS Type.  The
   Subtype code for this type is undefined.  The ISIS PDU directly
   follows the MRT Common Header fields.





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4.6.  OSPFv3 Type

   The OSPFv3 Type extends the original OSPFv2 Type to support IPv6
   addresses for the OSPFv3 protocol as defined in RFC 5340 [RFC5340].
   The format of the MRT Message field for the OSPFv3 Type is as
   follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Address Family         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Remote IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Local IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  OSPF Message Contents (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Figure 15: OSPFv3 Type

5.  IANA Considerations

   This section provides guidance to the Internet Assigned Numbers
   Authority (IANA) regarding registration of values related to the MRT
   specification, in accordance with BCP 26, RFC 5226 [RFC5226].

   There are two name spaces in MRT that have been registered: Type
   Codes and Subtype Codes.  Type Codes and Subtype Codes are each 16
   bits in length.

   MRT is not intended as a general-purpose specification for protocol
   information export, and allocations should not be made for purposes
   unrelated to routing protocol information export.

   The following policies are used here with the meanings defined in BCP
   26: "Specification Required", "IETF Consensus", "Experimental Use",
   "First Come First Served".  Assignments consist of a name and the
   value.

5.1.  Type Codes

   Type Codes have a range from 0 to 65535, of which 0-64 are reserved.
   New Type Codes MUST be allocated starting at 65.  Type Codes 65-511
   are assigned by IETF Review.  Type Codes 512-2047 are assigned based
   on Specification Required.  Type Codes 2048-64511 are available on a





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   First Come First Served policy.  Type Codes 64512 - 65534 are
   available for Experimental Use.  The Type Code Value 65535 is
   reserved.

5.2.  Subtype Codes

   Subtype Codes have a range from 0 to 65535.  Subtype definitions are
   specific to a particular Type Code definition.  New Subtype Code
   definitions must reference an existing Type Code to which the Subtype
   belongs.  Subtype assignments follow the assignment rules for the
   Type Codes to which they belong.

5.3.  Defined Type Codes

   This document defines the following message Type Codes:

            Name             Value       Definition
            ----             -----       ----------
            NULL             0           See Appendix B.1.1
            START            1           See Appendix B.1.2
            DIE              2           See Appendix B.1.3
            I_AM_DEAD        3           See Appendix B.1.4
            PEER_DOWN        4           See Appendix B.1.5
            BGP              5           See Appendix B.2.1
            RIP              6           See Appendix B.2.2
            IDRP             7           See Appendix B.2.3
            RIPNG            8           See Appendix B.2.4
            BGP4PLUS         9           See Appendix B.2.5
            BGP4PLUS_01      10          See Appendix B.2.5
            OSPFv2           11          See Section 4.1
            TABLE_DUMP       12          See Section 4.2
            TABLE_DUMP_V2    13          See Section 4.3
            BGP4MP           16          See Section 4.4
            BGP4MP_ET        17          See Section 4.4
            ISIS             32          See Section 4.5
            ISIS_ET          33          See Section 4.5
            OSPFv3           48          See Section 4.6
            OSPFv3_ET        49          See Section 4.6













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5.4.  Defined BGP, BGP4PLUS, and BGP4PLUS_01 Subtype Codes

   This document defines the following message Subtype Codes for the
   BGP, BGP4PLUS, and BGP4PLUS_01 Types:

            Name               Value       Definition
            ----               -----       ----------
            BGP_NULL           0           See Appendix B.2.1
            BGP_UPDATE         1           See Appendix B.2.1
            BGP_PREF_UPDATE    2           See Appendix B.2.1
            BGP_STATE_CHANGE   3           See Appendix B.2.1
            BGP_SYNC           4           See Appendix B.2.1
            BGP_OPEN           5           See Appendix B.2.1
            BGP_NOTIFY         6           See Appendix B.2.1
            BGP_KEEPALIVE      7           See Appendix B.2.1

5.5.  Defined TABLE_DUMP Subtype Codes

   This document defines the following message Subtype Codes for the
   TABLE_DUMP Type:

            Name                Value       Definition
            ----                -----       ----------
            AFI_IPv4            1           See Section 4.2
            AFI_IPv6            2           See Section 4.2

5.6.  Defined TABLE_DUMP_V2 Subtype Codes

   This document defines the following message Subtype Codes for the
   TABLE_DUMP_V2 Type:

            Name                Value       Definition
            ----                -----       ----------
            PEER_INDEX_TABLE    1           See Section 4.3
            RIB_IPV4_UNICAST    2           See Section 4.3
            RIB_IPV4_MULTICAST  3           See Section 4.3
            RIB_IPV6_UNICAST    4           See Section 4.3
            RIB_IPV6_MULTICAST  5           See Section 4.3
            RIB_GENERIC         6           See Section 4.3












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5.7.  Defined BGP4MP and BGP4MP_ET Subtype Codes

   This document defines the following message Subtype Codes for the
   BGP4MP Type:

            Name                     Value       Definition
            ----                     -----       ----------
            BGP4MP_STATE_CHANGE      0           See Section 4.4
            BGP4MP_MESSAGE           1           See Section 4.4
            BGP4MP_ENTRY             2           See Section 4.4
            BGP4MP_SNAPSHOT          3           See Section 4.4
            BGP4MP_MESSAGE_AS4       4           See Section 4.4
            BGP4MP_STATE_CHANGE_AS4  5           See Section 4.4
            BGP4MP_MESSAGE_LOCAL     6           See Section 4.4
            BGP4MP_MESSAGE_AS4_LOCAL 7           See Section 4.4

6.  Security Considerations

   The MRT Format utilizes a structure that can store routing protocol
   information data.  The fields defined in the MRT specification are of
   a descriptive nature and provide information that is useful to
   facilitate the analysis of routing data.  As such, the fields
   currently defined in the MRT specification do not in themselves
   create additional security risks, since the fields are not used to
   induce any particular behavior by the recipient application.

   Some information contained in an MRT data structure might be
   considered sensitive or private.  For example, a BGP peer that sends
   a message to an MRT-enabled router might not expect that message to
   be shared beyond the AS to which it is sent.

   Information that could be considered sensitive includes BGP peer IP
   addresses, BGP Next Hop IP addresses, and BGP Path Attributes.  Such
   information could be useful to mount attacks against the BGP protocol
   and routing infrastructure.  RFC 4272 [RFC4272] examines a number of
   weaknesses in the BGP protocol that could potentially be exploited.

   An organization that intends to use the MRT structure to export
   routing information beyond the domain where it is normally accessible
   (e.g., publishing MRT dumps for use by researchers) should verify
   with any peers whose information might be included, and possibly
   remove sensitive fields.

   The proposed geolocation extension to MRT could reveal the location
   of an MRT router's peers [GEOMRT].






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7.  References

7.1.  Normative References

   [IANA-AF]         IANA, "Address Family Numbers",
                     <http://www.iana.org/numbers.html>.

   [RFC0791]         Postel, J., "Internet Protocol", STD 5, RFC 791,
                     September 1981.

   [RFC1195]         Callon, R., "Use of OSI IS-IS for routing in TCP/IP
                     and dual environments", RFC 1195, December 1990.

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

   [RFC2328]         Moy, J., "OSPF Version 2", STD 54, RFC 2328,
                     April 1998.

   [RFC2460]         Deering, S. and R. Hinden, "Internet Protocol,
                     Version 6 (IPv6) Specification", RFC 2460,
                     December 1998.

   [RFC3629]         Yergeau, F., "UTF-8, a transformation format of ISO
                     10646", STD 63, RFC 3629, November 2003.

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

   [RFC4760]         Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
                     "Multiprotocol Extensions for BGP-4", RFC 4760,
                     January 2007.

   [RFC5226]         Narten, T. and H. Alvestrand, "Guidelines for
                     Writing an IANA Considerations Section in RFCs",
                     BCP 26, RFC 5226, May 2008.

   [RFC5340]         Coltun, R., Ferguson, D., Moy, J., and A. Lindem,
                     "OSPF for IPv6", RFC 5340, July 2008.

7.2.  Informative References

   [GEOMRT]          Manderson, T., "Multi-Threaded Routing Toolkit
                     (MRT) Border Gateway Protocol (BGP) Routing
                     Information Export Format with Geo-Location
                     Extensions", RFC 6397, October 2011.




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   [MRT_PROG_GUIDE]  Labovitz, C., "MRT Programmer's Guide",
                     November 1999, <http://www.merit.edu/
                     networkresearch/mrtprogrammer.pdf>.

   [POSIX]           Institute of Electrical and Electronics Engineers,
                     "P1003.1, Information Technology Portable Operating
                     System Interface (POSIX) Part 1: System Application
                     Program Interface (API) [C Language], 1990.",
                     IEEE Standard P1003.1.

   [RFC2080]         Malkin, G. and R. Minnear, "RIPng for IPv6",
                     RFC 2080, January 1997.

   [RFC2453]         Malkin, G., "RIP Version 2", STD 56, RFC 2453,
                     November 1998.

   [RFC4272]         Murphy, S., "BGP Security Vulnerabilities
                     Analysis", RFC 4272, January 2006.

































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Appendix A.  MRT Encoding Examples

   This appendix, which is not normative, contains MRT encoding
   examples.

   The following example shows the encoding for an MRT record type of
   BGP4MP and subtype BGP4MP_MESSAGE_AS4.  The Peer AS and Local AS
   numbers are encoded in 4-byte fields due to the use of the
   BGP4MP_MESSAGE_AS4 subtype.  The encoded BGP Update is shown in
   hexadecimal.  The AS numbers in the ASPATH in the BGP Update are
   encoded as 4-byte values in accord with the MRT BGP4MP_MESSAGE_AS4
   subtype.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Timestamp = 1300475700 epoch sec (2011-03-18 19:15:00)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Type = 16            |         Subtype = 4           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Length = 82                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Peer AS = 64496                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Local AS = 64497                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Interface Index = 0       |     Address Family  = 1       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Peer IP Address = 192.0.2.85                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |               Local IP Address = 198.51.100.4                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  BGP Update =

                ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                00 3e 02 00 00 00 1f 40 01 01 02 40 02 0e 02 03
                00 00 fb f0 00 00 fb ff 00 00 fb f6 40 03 04 c6
                33 64 55 c0 08 04 fb f0 00 0e 18 cb 00 71

                 Figure 16: MRT BGP4MP_MESSAGE_AS4 Example











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   The contents of the BGP Update Message above are as follows:

     ORIGIN: INCOMPLETE
     ASPATH: 64496 64511 64502
     NEXT_HOP: 198.51.100.188
     COMMUNITY: 64496:14
     NLRI: 203.0.113.0/24

                      Figure 17: BGP Message Contents

   The following example displays the encoding for an MRT record type of
   TABLE_DUMP_V2 and subtype PEER_INDEX_TABLE.  The table in this
   example contains 2 entries.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Timestamp = 1300475700 epoch sec (2011-03-18 19:15:00)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Type = 13            |         Subtype = 1           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Length = 34                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |               Collector BGP ID = 198.51.100.4                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     View Name Length = 0      |       Peer Count = 2          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Peer Type = 2  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Peer BGP ID  = 198.51.100.5                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Peer IP Address = 198.51.100.5                |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Peer AS = 65541                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Peer Type = 2  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Peer BGP ID  = 192.0.2.33                   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Peer IP Address = 192.0.2.33                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Peer AS = 65542                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 18: MRT PEER_INDEX_TABLE Example






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   The following example displays the encoding for an MRT record type of
   TABLE_DUMP_V2 and subtype RIB_IPV6_UNICAST.  This entry applies to
   the NLRI prefix of 2001:0DB8::/32.  There is a single entry for this
   prefix.  The entry applies to the peer identified by index location
   15 in a preceding MRT PEER_INDEX_TABLE record.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Timestamp = 1300475700 epoch sec (2011-03-18 19:15:00)     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Type = 13            |         Subtype = 4           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                           Length = 87                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Sequence Number = 42                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Preflen = 32  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Prefix  =  2001:0DB8::/32                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Entry Count = 1            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    Peer Index =  15           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Originated Time = 1300475700 epoch sec (2011-03-18 19:15:00)   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Attribute Length  =  68     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   BGP Path Attributes =

              40 01 01 00 50 02 00 0e 02 03 00 00 fb f0 00 00
              fb ff 00 00 fb f6 80 0e 2b 00 02 01 20 20 01 0d
              b8 00 0d 00 ff 00 00 00 00 00 00 01 87 fe 80 00
              00 00 00 00 00 02 12 f2 ff fe 9f 1b 00 00 00 20
              20 01 0d b8

                  Figure 19: MRT RIB_IPV6_UNICAST Example













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   The contents of the BGP Path Attribute field above are as follows:

   ORIGIN: IGP
   ASPATH: 64496 64511 64502
   MP_REACH_NLRI(IPv6 Unicast)
   NEXT_HOP: 2001:db8:d:ff::187
   NEXT_HOP: fe80::212:f2ff:fe9f:1b00
   NLRI: 2001:0DB8::/32

                  Figure 20: BGP Path Attribute Contents

Appendix B.  Deprecated MRT Types

   This appendix lists deprecated MRT types.  These types are documented
   for informational purposes.

B.1.  Deprecated MRT Informational Types

   The initial MRT format defined five Informational Type records.
   These records were intended to signal the state of an MRT data
   collector and do not contain routing information.  These records were
   intended for use when MRT records were sent over a network to a
   remote repository store.  However, MRT record repository stores have
   traditionally resided on the same device as the collector, and these
   Informational Types are not known to be implemented.  Further,
   transport mechanisms for MRT records are considered to be outside the
   scope of this document.

   The Message field MAY contain an OPTIONAL string for diagnostic
   purposes.  The message string encoding MUST follow the UTF-8
   transformation format [RFC3629].  The Subtype field is unused for
   these Types and SHOULD be set to 0.

   The MRT Informational Types are defined below:

       0    NULL
       1    START
       2    DIE
       3    I_AM_DEAD
       4    PEER_DOWN

B.1.1.  NULL Type

   The NULL Type message causes no operation.







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B.1.2.  START Type

   The START Type indicates that a collector is about to begin
   generating MRT records.

B.1.3.  DIE Type

   The DIE Type signals a remote MRT repository that it SHOULD stop
   accepting messages.

B.1.4.  I_AM_DEAD Type

   An I_AM_DEAD MRT record indicates that a collector has shut down and
   has stopped generating MRT records.

B.1.5.  PEER_DOWN Type

   The PEER_DOWN message was intended to indicate that a collector had
   lost association with a BGP peer.  However, the MRT format provides
   BGP state change message types that duplicate this functionality.

B.2.  Other Deprecated MRT Types

       5    BGP
       6    RIP
       7    IDRP
       8    RIPNG
       9    BGP4PLUS
       10   BGP4PLUS_01

B.2.1.  BGP Type

   The BGP Type indicates that the Message field contains BGP routing
   information.  The BGP routing protocol is defined in RFC 4271
   [RFC4271].  The information in the message is dependent on the
   Subtype value.  The BGP Type and all associated Subtypes below are
   considered to be deprecated by the BGP4MP Type.

   The following BGP Subtypes are defined for the MRT BGP Type.  As with
   the BGP Type itself, they are all considered to be deprecated.











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       0    BGP_NULL
       1    BGP_UPDATE
       2    BGP_PREF_UPDATE
       3    BGP_STATE_CHANGE
       4    BGP_SYNC
       5    BGP_OPEN
       6    BGP_NOTIFY
       7    BGP_KEEPALIVE

B.2.1.1.  BGP_NULL Subtype

   The BGP_NULL Subtype is a reserved Subtype.

B.2.1.2.  BGP_UPDATE Subtype

   The BGP_UPDATE Subtype is used to encode BGP UPDATE messages.  The
   format of the MRT Message field for this subtype is as follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Peer AS Number        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Peer IP Address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Local AS Number        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Local IP Address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    BGP UPDATE Contents (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 21: BGP_UPDATE Subtype

   The BGP UPDATE Contents include the entire BGP UPDATE message, which
   follows the BGP Message Header.  The BGP Message Header itself is not
   included.  The Peer AS Number and IP Address fields contain the AS
   number and IP address of the remote system that is generating the BGP
   UPDATE messages.  The Local AS Number and IP Address fields contain
   the AS number and IP address of the local collector system that is
   archiving the messages.

B.2.1.3.  BGP_PREF_UPDATE Subtype

   The BGP_PREF_UPDATE Subtype is not defined.






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B.2.1.4.  BGP_STATE_CHANGE Subtype

   The BGP_STATE_CHANGE Subtype is used to reflect changes in the BGP
   finite state machine.  These FSM states are defined in RFC 4271
   [RFC4271], Section 8.2.2.  Both the Old State value and the New State
   value are encoded as 2-octet numbers.  The state values are defined
   numerically as follows:

       1    Idle
       2    Connect
       3    Active
       4    OpenSent
       5    OpenConfirm
       6    Established

   The format of the BGP_STATE_CHANGE Subtype MRT Message field is as
   follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Peer AS Number        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Peer IP Address                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            Old State          |          New State            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 22: BGP_STATE_CHANGE Subtype

B.2.1.5.  BGP_SYNC Subtype

   The BGP_SYNC Subtype was intended to convey a system file name where
   BGP Table Dump messages MAY be recorded.  The View Number was to
   correspond to the View Number provided in the TABLE_DUMP Type
   records.  There are no known implementations of this subtype, and it
   SHOULD be ignored.  The following format applies to this subtype:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        View Number            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            File Name... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 23: BGP_SYNC Subtype




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   The File Name is terminated with a NULL (0) character.

B.2.1.6.  BGP_OPEN Subtype

   The BGP_OPEN Subtype is used to encode BGP OPEN messages.  The format
   of the MRT Message field for this subtype is the same as the
   BGP_UPDATE; however, the last field contains the contents of the BGP
   OPEN message.

B.2.1.7.  BGP_NOTIFY Subtype

   The BGP_NOTIFY Subtype is used to encode BGP NOTIFICATION messages.
   The format of the MRT Message field for this subtype is the same as
   the BGP_UPDATE; however, the last field contains the contents of the
   BGP NOTIFICATION message.

B.2.1.8.  BGP_KEEPALIVE Subtype

   The BGP_KEEPALIVE Subtype is used to encode BGP KEEPALIVE messages.
   The format of the MRT Message field for this subtype is the same as
   the BGP_UPDATE; however, the last field contains no information.

B.2.2.  RIP Type

   The RIP Type is used to export RIP packets as defined in RFC 2453
   [RFC2453].  The Subtype field is currently reserved for this type and
   SHOULD be set to 0.

   The format of the MRT Message field for the RIP Type is as follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Peer IP Address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Local IP Address                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    RIP Message Contents (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            Figure 24: RIP Type

B.2.3.  IDRP Type

   The IDRP Type was intended to be used to export Inter-Domain Routing
   Protocol (IDRP) information as defined in the ISO/IEC 10747 standard.
   However, this type has seen no known use, and there are no details on
   protocol encoding for this type.



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B.2.4.  RIPNG Type

   The RIPNG Type is used to export RIPNG protocol packets as defined in
   RFC 2080 [RFC2080].  The RIPNG protocol updates the RIP protocol to
   support IPv6.  The Subtype field is currently reserved for this type
   and SHOULD be set to 0.

   The format of the MRT Message field for the RIPNG Type is as follows:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       ~                        Peer IPv6 Address                      ~
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       ~                        Local IPv6 Address                     ~
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  RIPNG Message Contents (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Figure 25: RIPNG Type

B.2.5.  BGP4PLUS and BGP4PLUS_01 Types

   The BGP4PLUS and BGP4PLUS_01 Types were defined to support IPv6 BGP
   routing information.  The BGP4PLUS Type was specified based on the
   initial Internet-Draft that became RFC 4760, "Multiprotocol
   Extensions to BGP-4".  The BGP4PLUS_01 Type was specified to
   correspond to the -01 revision of that Internet-Draft.  The two Types
   share the same definitions in terms of their MRT format
   specifications.

   The Subtype field definitions are shared with the BGP Type; however,
   the address fields in the BGP_UPDATE, BGP_OPEN, BGP_NOTIFY,
   BGP_KEEPALIVE, and BGP_STATE_CHANGE Subtype records are extended to
   16 octets for IPv6 addresses.  As with the BGP Type, the BGP4PLUS and
   BGP4PLUS_01 Types are deprecated as they were superseded by the
   BGP4MP Type.










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B.2.6.  Deprecated BGP4MP Subtypes

   The following two subtypes of the BGP4MP Type are considered to be
   deprecated.

       2    BGP4MP_ENTRY
       3    BGP4MP_SNAPSHOT

B.2.6.1.  BGP4MP_ENTRY Subtype

   This subtype is similar to the TABLE_DUMP Type and is used to record
   RIB table entries.  It was intended to include true multiprotocol
   support.  However, this subtype does not support 4-byte AS numbers
   and has not been widely implemented.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Peer AS Number        |        Local AS Number        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Interface Index        |        Address Family         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Peer IP Address (variable)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      Local IP Address (variable)              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         View Number           |             Status            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                        Time Last Change                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Address Family         |    SAFI       | Next-Hop-Len  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Next Hop Address (variable)               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Prefix Length  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                     Address Prefix (variable)                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       Attribute Length        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    BGP Attribute... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 26: BGP4MP_ENTRY Subtype







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B.2.6.2.  BGP4MP_SNAPSHOT Subtype

   This subtype was intended to convey a system file name where
   BGP4MP_ENTRY records MAY be recorded.  It is similar to the BGP_SYNC
   Subtype and is deprecated.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        View Number            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |            File Name... (variable)
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 27: BGP4MP_SNAPSHOT Subtype

Appendix C.  Acknowledgements

   The initial MRT specification was developed by Craig Labovitz for use
   in the Multi-thread Routing Toolkit (MRT) project.  The BGP4MP Type
   was introduced in the Zebra routing software project by Kunihiro
   Ishiguro.  The BGP4MP_ET, ISIS, and ISIS_ET Types were defined in the
   Python Routing Toolkit (PyRT) developed by Richard Mortier while at
   Sprint Advanced Technology Labs.

Authors' Addresses

   Larry Blunk
   Merit Network

   EMail: ljb@merit.edu


   Manish Karir
   Merit Network

   EMail: mkarir@merit.edu


   Craig Labovitz
   Deepfield Networks

   EMail: labovit@deepfield.net








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