BMP Extension for Path Marking TLV
draft-cppy-grow-bmp-path-marking-tlv-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|---|---|---|---|
| Authors | Camilo Cardona , Paolo Lucente , Pierre Francois , Yunan Gu | ||
| Last updated | 2019-07-05 | ||
| Replaced by | draft-ietf-grow-bmp-path-marking-tlv | ||
| RFC stream | (None) | ||
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| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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draft-cppy-grow-bmp-path-marking-tlv-00
Network Working Group C. Cardona
Internet-Draft P. Lucente
Intended status: Standards Track NTT
Expires: January 6, 2020 P. Francois
INSA
Y. Gu
Huawei
July 05, 2019
BMP Extension for Path Marking TLV
draft-cppy-grow-bmp-path-marking-tlv-00
Abstract
The BGP Monitoring Protocol (BMP) provides the monitoring of BGP adj-
rib-in [RFC7854], BGP local-rib [I-D.ietf-grow-bmp-local-rib] and BGP
adj-rib-out [I-D.ietf-grow-bmp-adj-rib-out] through Route Monitoring
(RM) messages. With the capability of allowing optional data to be
added to the RM Messages in the format of TLV draft-lucente-bmp-tlv
[I-D.lucente-bmp-tlv], more information about the BGP Update message
encapsulated in the RM can be revealed. This document proposes an
extension to BMP to describe the BGP path status through the
definition and use of Path Marking TLV.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
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 https://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."
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This Internet-Draft will expire on January 6, 2020.
Copyright Notice
Copyright (c) 2019 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
(https://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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Path Marking TLV for the RM Message . . . . . . . . . . . . . 3
2.1. Path Type . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Reason String . . . . . . . . . . . . . . . . . . . . . . 4
3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4.1. Path Marking TLV . . . . . . . . . . . . . . . . . . . . 6
4.2. Path Marking TLV Reason String . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
For a given prefix, multiple paths with different path status, e.g.,
the "best-path", the "best-external-path" and so on, may co-exist in
the BGP module upon the local policy processing. In addition, during
the whole process, from receiving a BGP route to advertising it, a
path can also undergo various status in different processing states.
Such path status information is currently not carried in the BGP
Update Message RFC4271 [RFC4271]. However, they can be useful to
enable a lot of applications. For example, for traffic steering
purposes in a SDN enviroment, the operator/SDN controller needs the
reachability information of multiple paths to ensure the selected
optimized route is reachable.
This document defines a so-called Path Marking TLV to convey the BGP
path status information to the BMP server. The BMP Path Marking is
defined to be prepended in the BMP Route Monitoring (RM) Message.
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2. Path Marking TLV for the RM Message
Per RFC4271 [RFC4271], the BMP RM Message consists of the Common
Header, Per-Peer Header, and the BGP Update PDU. According to draft-
lucente-bmp-tlv [I-D.lucente-bmp-tlv], optional trailing data in TLV
format is allowed in the BMP RM Message to convey characteristics of
transported NLRIs (ie. to help stateless parsing) or vendor-specific
data. Such TLV types are to be defined per each application.
To include the path status along with each BGP path, we define the
Path Marking TLV, shown as follows.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-------------------------------+-------------------------------+
| Type (2 octets) | Length (2 octets) |
+-------------------------------+-------------------------------+
| Path Type(4 octets) |
+---------------------------------------------------------------+
| Reason String(Variable) |
+---------------------------------------------------------------+
Figure 1: Path Marking TLV
o Type = TDB1 (2 Octets): Path Marking.
o Length (2 Octets): indicates the length of the value field of the
Path Marking TLV. The value field further consists of the Path-
Type field and Reason String field.
o Path-Type (4 Octets): indicates the path status of the BGP Update
PDU encapsulated in the RM Message. Currently 8 types of path
status are defined, as shown in Table 1.
o Reason String (Variable): indicates the reasons/explanations of
the path status indicated in the Path Type field. The detailed
Reason String format is defined in Figure 2.
2.1. Path Type
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+--------+----------------------+
| Value | Path type |
+-------------------------------+
| 0x0000 | Unknown |
| 0x0001 | Best path |
| 0x0002 | Best external path |
| 0x0004 | Primary path |
| 0x0008 | Backup path |
| 0x0010 | Non-installed path |
| 0x0020 | Unreachable next-hop |
+--------+----------------------+
Table 1: Path Type
The Path type field contains a bitfield where each bit encodes a
specific role of the path. Multiple bits may be set when a path is
used in multiple roles.
The best-path is defined in RFC4271 [RFC4271] and the best-external
path is defined in draft-ietf-idr-best-external
[I-D.ietf-idr-best-external].
A primary path is a recursive or non-recursive path that can be used
all the time as long as a walk starting from this path can end to an
adjacency draft-ietf-rtgwg-bgp-pic [I-D.ietf-rtgwg-bgp-pic]. A
prefix can have more than one primary path. A best-path is also
considered as a primary path.
A backup path is also installed in the RIB, but it is not used until
some or all primary paths become unreachable. Backup paths are used
for fast convergence in the event of failures.
All other reachable paths are marked as 'Non-installed'.
Lastly, all paths that are considered unreachable are marked as
'Unreachable next-hop'. Unreachable paths may be sent only in
special cases.
2.2. Reason String
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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
+-------------------------------+-------------------------------+
| Sub Type 1 (2 octets) | Length (2 octets) |
+-------------------------------+-------------------------------+
| Non-Best Reason String(Variable) |
+-------------------------------+-------------------------------+
| Sub Type 2 (2 octets) | Length (2 octets) |
+-------------------------------+-------------------------------+
| Uninstall Reason String(Variable) |
+-------------------------------+-------------------------------+
| Sub Type 3 (2 octets) | Length (2 octets) |
+-------------------------------+-------------------------------+
| Unreachable Reason String(Variable) |
+---------------------------------------------------------------+
Figure 2: Reason String field
o Sub Type 1 (2 Octets) = TDB2: Non-Best Reason String.
o Length (2 Octets): indicates the length of the value field of the
Non-Best Reason String.
o Non-Best Reaon String (Variable): includes user specific
description of the non-best reason in the format of ASCII string.
o Sub Type 2 (2 Octets) = TDB3: Uninstalled Reason String.
o Length (2 Octets): indicates the length of the value field of the
Non-Best Reason String.
o Uninstalled Reason String (Variable): includes user specific
description of the uninstalled (into RIB) reason in the format of
ASCII string.
o Sub Type 3 (2 Octets) = TDB4: Unreachable Reason String.
o Length (2 Octets): indicates the length of the value field of the
Non-Best Reason String.
o Unreachable Reason String (Variable): includes user specific
description of the unreachable reason in the format of ASCII
string.
3. Acknowledgements
TBD.
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4. IANA Considerations
This document requests that IANA assign the following new parameters
to the BMP parameters name space.
4.1. Path Marking TLV
This document defines the Path Marking TLV with Type = TDB1: Path
Marking (Section 2).
4.2. Path Marking TLV Reason String
This document defines three new sub types of the Reason String in the
Path Marking TLV (Section 2.2).
Sub Type 1 = TDB2: Non-Best Reason String.
Sub Type 2 = TDB3: Uninstalled Reason String.
Sub Type 3 = TDB4: Unreachable Reason String.
5. Security Considerations
It is not believed that this document adds any additional security
considerations.
6. Normative References
[I-D.ietf-grow-bmp-adj-rib-out]
Evens, T., Bayraktar, S., Lucente, P., Mi, K., and S.
Zhuang, "Support for Adj-RIB-Out in BGP Monitoring
Protocol (BMP)", draft-ietf-grow-bmp-adj-rib-out-06 (work
in progress), June 2019.
[I-D.ietf-grow-bmp-local-rib]
Evens, T., Bayraktar, S., Bhardwaj, M., and P. Lucente,
"Support for Local RIB in BGP Monitoring Protocol (BMP)",
draft-ietf-grow-bmp-local-rib-04 (work in progress), June
2019.
[I-D.ietf-idr-best-external]
Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H.
Gredler, "Advertisement of the best external route in
BGP", draft-ietf-idr-best-external-05 (work in progress),
January 2012.
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[I-D.ietf-rtgwg-bgp-pic]
Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix
Independent Convergence", draft-ietf-rtgwg-bgp-pic-09
(work in progress), April 2019.
[I-D.lucente-bmp-tlv]
Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP
Route Monitoring and Peer Down Messages", draft-lucente-
bmp-tlv-00 (work in progress), July 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement
with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
2009, <https://www.rfc-editor.org/info/rfc5492>.
[RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
Monitoring Protocol (BMP)", RFC 7854,
DOI 10.17487/RFC7854, June 2016,
<https://www.rfc-editor.org/info/rfc7854>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Camilo Cardona
NTT
164-168, Carrer de Numancia
Barcelona 08029
Spain
Email: camilo@ntt.net
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Paolo Lucente
NTT
Siriusdreef 70-72
Hoofddorp, WT 2132
Netherlands
Email: paolo@ntt.net
Pierre Francois
INSA
Lyon
France
Email: Pierre.Francois@insa-lyon.fr
Yunan Gu
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: guyunan@huawei.com
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