Internet DRAFT - draft-petrie-grow-mrt-add-paths
draft-petrie-grow-mrt-add-paths
Network Working Group C. Petrie
Internet-Draft RIPE NCC
Intended status: Informational October 11, 2015
Expires: April 13, 2016
Multi-Threaded Routing Toolkit (MRT) Routing Information Export Format
with BGP Additional Paths Extensions
draft-petrie-grow-mrt-add-paths-00
Abstract
This document updates the Multi-threaded Routing Toolkit (MRT) export
format for Border Gateway Protocol (BGP) routing information by
extending it to support the Advertisement of Multiple Paths in BGP
extensions.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 13, 2016.
Copyright Notice
Copyright (c) 2015 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.
Petrie Expires April 13, 2016 [Page 1]
Internet-Draft Additional Paths Extensions in MRT October 2015
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4. MRT Subtypes for Type BGP4MP . . . . . . . . . . . . . . . . 3
5. MRT Subtypes for Type TABLE_DUMP_V2 . . . . . . . . . . . . . 4
5.1. AFI/SAFI specific RIB Subtypes . . . . . . . . . . . . . 4
5.2. RIB_GENERIC_AP Subtype . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
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 [RFC6396] was
developed to encapsulate, export, and archive this information in a
standardized data representation.
The Advertisement of Multiple Paths in BGP [I-D.ietf-idr-add-paths]
defines a BGP extension to allow the advertisement of multiple paths
for the same address prefix without the new paths implicitly
replacing any previous ones. The essence of the extension is that
each path is identified by a path identifier in addition to the
addres prefix
This memo documents an optional extension to the MRT format RFC6396
[RFC6396] and introduces additional definitions of MRT Subtype fields
to permit representation of Multiple Path advertisements
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Rationale
When a BGP message requires information about the capabilities
negotiated during the setup of the BGP session for a parser to
interpret the message, this information is carried by the MRT
subtypes.
Petrie Expires April 13, 2016 [Page 2]
Internet-Draft Additional Paths Extensions in MRT October 2015
The MRT specification defines the following BGP4MP subtypes:
o BGP4MP_MESSAGE
o BGP4MP_MESSAGE_AS4
o BGP4MP_MESSAGE_LOCAL
o BGP4MP_MESSAGE_AS4_LOCAL
These indicate to a parser whether the AS_PATH and AGGREGATOR
attributes should be interpretted according to the rules in RFC6793
[RFC6793]
Additional Paths in BGP [I-D.ietf-idr-add-paths] alters the encoding
of the BGP NLRI format for withdraws and announcements. Therefore
new BGP4MP subtypes are required to signal to a parser how to parse
the NLRI.
The MRT specification defines the following TABLE_DUMP_V2 subtypes:
o RIB_IPV4_UNICAST
o RIB_IPV4_MULTICAST
o RIB_IPV6_UNICAST
o RIB_IPV6_MULTICAST
o RIB_GENERIC
The existing TABLE_DUMP_V2 AFI/SAFI-Specific RIB Subtypes specify
that the Prefix Length and Prefix fields are encoded in the same
manner as the BGP NLRI encoding. These also require new subtypes to
retain the path identifier information in Additional Paths.
The TABLE_DUMP_V2 RIB_GENERIC subtype contains a single raw NLRI
entry, the encoding of which is defined by the AFI and SAFI.
Additional Paths alter the NLRI encoding. Therefore a new subtype is
required to indicate the change in NLRI format.
4. MRT Subtypes for Type BGP4MP
This document defines the following new Subtypes:
o BGP4MP_MESSAGE_AP
o BGP4MP_MESSAGE_AS4_AP
Petrie Expires April 13, 2016 [Page 3]
Internet-Draft Additional Paths Extensions in MRT October 2015
o BGP4MP_MESSAGE_LOCAL_AP
o BGP4MP_MESSAGE_AS4_LOCAL_AP
The fields of these message types are identical to the equivalent
non-additional-path versions specified in RFC 6396 [RFC6396], and
continues to encapsulate the entire BGP message in the BGP Message
field.
5. MRT Subtypes for Type TABLE_DUMP_V2
This document defines the following new Subtypes:
o RIB_IPV4_UNICAST_AP
o RIB_IPV4_MULTICAST_AP
o RIB_IPV6_UNICAST_AP
o RIB_IPV6_MULTICAST_AP
o RIB_GENERIC_AP
The fields of these message types are identical to the equivalent
non-additional-path versions specified in RFC 6396 [RFC6396].
However, for the specific case of the 4 AFI/SAFI specific RIB
Subtypes, the existing RIB Entries field is re-defined as detailed in
the sections below.
5.1. AFI/SAFI specific RIB Subtypes
In order to preserve the record compaction achieved by using the most
common subtypes, and allowing multiple RIB entries to be stored in a
single TABLE_DUMP_V2 record, the existing RIB Entries field is
redefined for use within the new AFI/SAFI specific RIB Subtypes
defined by this document as follows:
Petrie Expires April 13, 2016 [Page 4]
Internet-Draft Additional Paths Extensions in MRT October 2015
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attribute Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BGP Attributes... (variable)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: RIB Entries for AFI/SAFI-specific RIB Subtypes with
additional-paths support
This adds a field to the RIB Entries record, to store the Path
Identifier, when used with the RIB_IPV4_UNICAST_AP,
RIB_IPV4_MULTICAST_AP, RIB_IPV6_UNICAST_AP and RIB_IPV6_MULTICAST_AP
Subtypes
5.2. RIB_GENERIC_AP Subtype
The fields of this message types is identical to the equivalent non-
additional-path versions specified in RFC 6396 [RFC6396], and
continues to encapsulate the raw AFI/SAFI/NLRI in the record, and the
raw attributes in the RIB Entries.
The RIB entries are unchanged, and should be interpreted according to
RFC 6396 [RFC6396]
6. IANA Considerations
This document requests that IANA add the appropriate Type Codes and
Subtype Codes (to be assigned). This is currently a placeholder.
7. Security Considerations
It is not believed that this document adds any additional security
considerations
However, the security considerations of RFC6396 [RFC6396] are equally
applicable to this document, and this document permits the export of
more detailed routing data.
An organisation which uses the MRT format to store their BGP routing
information should be aware that supporting these extensions permits
Petrie Expires April 13, 2016 [Page 5]
Internet-Draft Additional Paths Extensions in MRT October 2015
more detailed network path information to be stored, and should
consider the implications of this within their environment
An network that peers with public BGP collectors, and enable the
additional-paths capability on a the peering session, should be aware
that they are exporting not only their best paths, but potentially
other paths within their network. The BGP peer should consider any
implications of exposing this additional data.
8. References
8.1. Normative References
[I-D.ietf-idr-add-paths]
Walton, D., Retana, A., Chen, E., and J. Scudder,
"Advertisement of Multiple Paths in BGP", draft-ietf-idr-
add-paths-11 (work in progress), October 2015.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6396] Blunk, L., Karir, M., and C. Labovitz, "Multi-Threaded
Routing Toolkit (MRT) Routing Information Export Format",
RFC 6396, DOI 10.17487/RFC6396, October 2011,
<http://www.rfc-editor.org/info/rfc6396>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793, DOI
10.17487/RFC6793, December 2012,
<http://www.rfc-editor.org/info/rfc6793>.
8.2. Informative References
[I-D.narten-iana-considerations-rfc2434bis]
Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", draft-narten-iana-
considerations-rfc2434bis-09 (work in progress), March
2008.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, DOI
10.17487/RFC2629, June 1999,
<http://www.rfc-editor.org/info/rfc2629>.
Petrie Expires April 13, 2016 [Page 6]
Internet-Draft Additional Paths Extensions in MRT October 2015
[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC
Text on Security Considerations", BCP 72, RFC 3552, DOI
10.17487/RFC3552, July 2003,
<http://www.rfc-editor.org/info/rfc3552>.
Author's Address
Colin Petrie
RIPE NCC
Amsterdam
NL
Email: cpetrie@ripe.net
Petrie Expires April 13, 2016 [Page 7]
