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IETF RFC 6396
Last modified on Tuesday, November 1st, 2011
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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/RFC 6396.
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.
Blunk, et al. Standards Track PAGE 1 
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 2
RFC 6396 MRT Format October 2011
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.
Blunk, et al. Standards Track PAGE 3
RFC 6396 MRT Format October 2011
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 [RFC 2119].
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.
Blunk, et al. Standards Track PAGE 4
RFC 6396 MRT Format October 2011
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.
Blunk, et al. Standards Track PAGE 5
RFC 6396 MRT Format October 2011
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
[RFC 2328]. It is used to encode the exchange of OSPF protocol
packets.
Blunk, et al. Standards Track PAGE 6
RFC 6396 MRT Format October 2011
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 [RFC 791]
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 [RFC 2460] addresses. There are two possible values for
the Subtype as shown below.
1 AFI_IPv4
2 AFI_IPv6
Blunk, et al. Standards Track PAGE 7
RFC 6396 MRT Format October 2011
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.
Blunk, et al. Standards Track PAGE 8
RFC 6396 MRT Format October 2011
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 [RFC 3629].
Blunk, et al. Standards Track PAGE 9
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 10
RFC 6396 MRT Format October 2011
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.
Blunk, et al. Standards Track PAGE 11
RFC 6396 MRT Format October 2011
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) [RFC 4760]. 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.
Blunk, et al. Standards Track PAGE 12
RFC 6396 MRT Format October 2011
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 [RFC 4760]. 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 [RFC 4271], 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:
Blunk, et al. Standards Track PAGE 13
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 14
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 15
RFC 6396 MRT Format October 2011
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
[RFC 1195]. 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.
Blunk, et al. Standards Track PAGE 16
RFC 6396 MRT Format October 2011
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 [RFC 5340].
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 [RFC 5226].
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
Blunk, et al. Standards Track PAGE 17
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 18
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 19
RFC 6396 MRT Format October 2011
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 [RFC 4272] 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].
Blunk, et al. Standards Track PAGE 20
RFC 6396 MRT Format October 2011
7. References
7.1. Normative References
[IANA-AF] IANA, "Address Family Numbers",
<http://www.iana.org/numbers.html>.
[RFC 791] Postel, J., "Internet Protocol", STD 5, RFC 791,
September 1981.
[RFC 1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP
and dual environments", RFC 1195, December 1990.
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
April 1998.
[RFC 2460] Deering, S. and R. Hinden, "Internet Protocol,
Version 6 (IPv6) Specification", RFC 2460,
December 1998.
[RFC 3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC 4271] Rekhter, Y., Li, T., and S. Hares, "A Border
Gateway Protocol 4 (BGP-4)", RFC 4271,
January 2006.
[RFC 4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
January 2007.
[RFC 5226] Narten, T. and H. Alvestrand, "Guidelines for
Writing an IANA Considerations Section in RFCs",
BCP 26, RFC 5226, May 2008.
[RFC 5340] 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.
Blunk, et al. Standards Track PAGE 21
RFC 6396 MRT Format October 2011
[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.
[RFC 2080] Malkin, G. and R. Minnear, "RIPng for IPv6",
RFC 2080, January 1997.
[RFC 2453] Malkin, G., "RIP Version 2", STD 56, RFC 2453,
November 1998.
[RFC 4272] Murphy, S., "BGP Security Vulnerabilities
Analysis", RFC 4272, January 2006.
Blunk, et al. Standards Track PAGE 22
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 23
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 24
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 25
RFC 6396 MRT Format October 2011
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 [RFC 3629]. 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.
Blunk, et al. Standards Track PAGE 26
RFC 6396 MRT Format October 2011
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
[RFC 4271]. 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.
Blunk, et al. Standards Track PAGE 27
RFC 6396 MRT Format October 2011
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.
Blunk, et al. Standards Track PAGE 28
RFC 6396 MRT Format October 2011
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
[RFC 4271], 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
Blunk, et al. Standards Track PAGE 29
RFC 6396 MRT Format October 2011
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
[RFC 2453]. 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.
Blunk, et al. Standards Track PAGE 30
RFC 6396 MRT Format October 2011
B.2.4. RIPNG Type
The RIPNG Type is used to export RIPNG protocol packets as defined in
RFC 2080 [RFC 2080]. 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.
Blunk, et al. Standards Track PAGE 31
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 32
RFC 6396 MRT Format October 2011
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
Blunk, et al. Standards Track PAGE 33
RFC TOTAL SIZE: 73982 bytes
PUBLICATION DATE: Tuesday, November 1st, 2011
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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