Internet DRAFT - draft-dong-pce-discovery-proto-bgp
draft-dong-pce-discovery-proto-bgp
Network Working Group J. Dong
Internet-Draft M. Chen
Intended status: Standards Track D. Dhody
Expires: January 4, 2018 Huawei Technologies
J. Tantsura
Individual
K. Kumaki
KDDI Corporation
T. Murai
Furukawa Network Solution Corp.
July 3, 2017
BGP Extensions for Path Computation Element (PCE) Discovery
draft-dong-pce-discovery-proto-bgp-07
Abstract
In networks where a Path Computation Element (PCE) is used for path
computation, it is desirable for the Path Computation Clients (PCCs)
to discover dynamically and automatically a set of PCEs along with
certain information relevant for PCE selection. RFC 5088 and RFC
5089 define the PCE discovery mechanisms based on Interior Gateway
Protocols (IGP). This document defines extensions to BGP for the
advertisement of PCE Discovery information. The BGP based PCE
discovery mechanism is complementary to the existing IGP based
mechanisms.
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].
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."
Dong, et al. Expires January 4, 2018 [Page 1]
Internet-Draft BGP Extensions for PCE Discovery July 2017
This Internet-Draft will expire on January 4, 2018.
Copyright Notice
Copyright (c) 2017 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Carrying PCE Discovery Information in BGP . . . . . . . . . . 3
2.1. PCE NLRI . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1. PCE Descriptors . . . . . . . . . . . . . . . . . . . 4
2.2. PCE Attribute TLVs . . . . . . . . . . . . . . . . . . . 5
2.2.1. PCE Domain TLV . . . . . . . . . . . . . . . . . . . 6
2.2.2. Neighbor PCE Domain TLV . . . . . . . . . . . . . . . 6
3. Operational Considerations . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
In networks where a Path Computation Element (PCE) is used for path
computation, it is desirable for the Path Computation Clients (PCCs)
to discover dynamically and automatically a set of PCEs along with
certain information relevant for PCE selection. [RFC5088] and
[RFC5089] define the PCE discovery mechanisms based on Interior
Gateway Protocols (IGP). When PCCs are LSRs participating in the IGP
(OSPF or IS-IS), and PCEs are either LSRs or servers also
participating in the IGP, an effective mechanism for PCE discovery
within an IGP routing domain consists of utilizing IGP
advertisements.
Dong, et al. Expires January 4, 2018 [Page 2]
Internet-Draft BGP Extensions for PCE Discovery July 2017
[RFC4674] presents a set of requirements for a PCE discovery
mechanism. This includes the discovery by a PCC of a set of one or
more PCEs which may potentially be in some other domains. This is a
desirable function in the case of inter-domain path computation. For
example, Backward Recursive Path Computation (BRPC) [RFC5441] can be
used by cooperating PCEs to compute an inter-AS path, in which case
the discovery of PCE as well as the domain information is useful.
BGP has been extended for north-bound distribution of routing and TE
information to PCE [RFC7752] and [I-D.ietf-idr-te-pm-bgp]. Similary
this document extends BGP to also carry the PCE discovery
information.
This document defines extensions to BGP to allow a PCE to advertise
its location, along with some information useful to a PCC for the PCE
selection, so as to satisfy dynamic PCE discovery requirements set
forth in [RFC4674].
This specification contains two parts: definition of a new BGP-LS
NLRI [RFC7752] that describes PCE information and definition of PCE
Attribute TLVs as part of BGP-LS attributes.
2. Carrying PCE Discovery Information in BGP
2.1. PCE NLRI
The PCE discovery information is advertised in BGP UPDATE messages
using the MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC4760].
The "Link- State NLRI" defined in [RFC7752] is extended to carry the
PCE information. BGP speakers that wish to exchange PCE discovery
information MUST use the BGP Multiprotocol Extensions Capability Code
(1) to advertise the corresponding (AFI, SAFI) pair, as specified in
[RFC4760].
The format of "Link-State NLRI" is defined in [RFC7752]. A new "NLRI
Type" is defined for PCE Information as following:
o Type = TBD1: PCE NLRI
The format of PCE NLRI is shown in the following figure:
Dong, et al. Expires January 4, 2018 [Page 3]
Internet-Draft BGP Extensions for PCE Discovery July 2017
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
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ PCE Descriptors (variable) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1. PCE NLRI
The 'Protocol-ID' field is defined in [RFC7752], to be set to the
appropriate value that indicates the source of the PCE information.
If BGP speaker and PCE are co-located, the Protocol-ID SHOULD be set
to "Direct". If PCE information to advertise is configured at the
BGP speaker, the Protocol-ID SHOULD be set to "Static configuration".
As defined in [RFC7752], the 64-Bit 'Identifier' field is used to
identify the "routing universe" where the PCE belongs.
2.1.1. PCE Descriptors
The PCE Descriptor field is a set of Type/Length/Value (TLV)
triplets. The format of each TLV is as per Section 3.1 of [RFC7752].
The PCE Descriptor TLVs uniquely identify a PCE. The following PCE
descriptor are defined -
+-----------+-----------------------+----------+
| Codepoint | Descriptor TLV | Length |
+-----------+-----------------------+----------+
| TBD2 | IPv4 PCE Address | 4 |
| TBD3 | IPv6 PCE Address | 16 |
+-----------+-----------------------+----------+
Table 1: PCE Descriptors
The PCE address TLVs specifies an IP address that can be used to
reach the PCE. The PCE-ADDRESS Sub-TLV defined in [RFC5088] and
[RFC5089] is used in the OSPF and IS-IS respectively. The format of
the PCE address TLV are -
Dong, et al. Expires January 4, 2018 [Page 4]
Internet-Draft BGP Extensions for PCE Discovery July 2017
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD2 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 PCE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD3 | Length=16 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 PCE Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2. PCE Address TLVs
When the PCE has both an IPv4 and IPv6 address, both the TLVs MAY be
included.
2.2. PCE Attribute TLVs
PCE Attribute TLVs are TLVs that may be encoded in the BGP-LS
attribute [RFC7752] with a PCE NLRI. The format of each TLV is as
per Section 3.1 of [RFC7752]. The format and semantics of the Value
fields in some PCE Attribute TLVs correspond to the format and
semantics of the Value fields in IS-IS PCED Sub-TLV, defined in
[RFC5089]. Other PCE Attribute TLVs are defined in this document.
The following PCE Attribute TLVs are valid in the BGP-LS attribute
with a PCE NLRI:
+-----------+---------------------+--------------+------------------+
| TLV Code | Description | IS-IS TLV | Reference |
| Point | | /Sub-TLV | (RFC/Section) |
+-----------+---------------------+--------------+------------------+
| TBD4 | Path Scope | 5/2 | [RFC5089]/4.2 |
| TBD5 | PCE Domain | - | - |
| TBD6 | Neighbor PCE | - | - |
| | Domain | | |
| TBD7 | PCE Capability | 5/5 | [RFC5089]/4.5 |
+-----------+---------------------+--------------+------------------+
Table 2: PCE Attribute TLVs
Dong, et al. Expires January 4, 2018 [Page 5]
Internet-Draft BGP Extensions for PCE Discovery July 2017
The format and semantics of Path Scope and PCE capability is as per
[RFC5089]. The Path Scope TLV is mandatory.
2.2.1. PCE Domain TLV
The PCE Domain TLV specifies a PCE-Domain (IGP area and/or AS) where
the PCE has topology visibility and through which the PCE can compute
paths.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD5 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Domain Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The length of this TLV is variable. The value contains one or more
domain sub-TLVs as listed below -
+--------------------+-------------------+----------+
| Sub-TLV Code Point | Description | Length |
+--------------------+-------------------+----------+
| 512 | Autonomous System | 4 |
| 514 | OSPF Area-ID | 4 |
| 1027 | IS-IS Area | Variable |
| | Identifier | |
+--------------------+-------------------+----------+
Multiple sub-TLVs MAY be included, when the PCE has visibility into
multiple PCE-Domains.
2.2.2. Neighbor PCE Domain TLV
The Neighbor PCE Domain TLV specifies a neighbor PCE-Domain (IGP area
and/or AS) toward which a PCE can compute paths.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=TBD6 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Domain Sub-TLVs (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Dong, et al. Expires January 4, 2018 [Page 6]
Internet-Draft BGP Extensions for PCE Discovery July 2017
The length of this TLV is variable. The value contains one or more
domain sub-TLVs as listed above. Multiple sub-TLVs MAY be included,
when the PCE can compute paths towards several neighbor PCE-Domains.
3. Operational Considerations
Existing BGP-LS operational procedures apply to the advertisement of
PCE information as per [RFC7752]. This information is treated as
pure application level data which has no immediate impact on
forwarding states. The PCE information SHOULD be advertised only to
the domains where such information is allowed to be used. This can
be achieved by policy control on the ASBRs.
The PCE information is considered relatively stable and does not
change frequently, thus this information will not bring significant
impact on the amount of BGP updates in the network.
4. IANA Considerations
IANA needs to assign a new NLRI Type for 'PCE NLRI' from the "BGP-LS
NLRI-Types" registry.
IANA needs to assign new TLV code point as per Table 1 and 2 from the
"BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and
Attribute TLVs" registry.
[Editor's Note - Check if name of the registry should be changes with
following instructions - Further IANA is requested to rename the
registry as "BGP-LS Node Descriptor, Link Descriptor, Prefix
Descriptor, PCE Descriptor, and Attribute TLVs".]
5. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See the 'Security Considerations'
section of [RFC4271] for a discussion of BGP security. Also refer to
[RFC4272] and [RFC6952] for analysis of security issues for BGP.
Existing BGP-LS security considerations as per [RFC7752] continue to
apply.
6. Contributors
The following individuals gave significant contributions to this
document:
Dong, et al. Expires January 4, 2018 [Page 7]
Internet-Draft BGP Extensions for PCE Discovery July 2017
Takuya Miyasaka
KDDI Corporation
ta-miyasaka@kddi.com
7. Acknowledgements
The authors would like to thank Zhenbin Li, Hannes Gredler, Jan
Medved, Adrian Farrel, Julien Meuric and Jonathan Hardwick for the
valuable discussion and comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760,
DOI 10.17487/RFC4760, January 2007,
<http://www.rfc-editor.org/info/rfc4760>.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
January 2008, <http://www.rfc-editor.org/info/rfc5088>.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
January 2008, <http://www.rfc-editor.org/info/rfc5089>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<http://www.rfc-editor.org/info/rfc7752>.
Dong, et al. Expires January 4, 2018 [Page 8]
Internet-Draft BGP Extensions for PCE Discovery July 2017
8.2. Informative References
[I-D.ietf-idr-te-pm-bgp]
Previdi, S., Wu, Q., Gredler, H., Ray, S.,
jefftant@gmail.com, j., Filsfils, C., and L. Ginsberg,
"BGP-LS Advertisement of IGP Traffic Engineering
Performance Metric Extensions", draft-ietf-idr-te-pm-
bgp-06 (work in progress), June 2017.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, DOI 10.17487/RFC4272, January 2006,
<http://www.rfc-editor.org/info/rfc4272>.
[RFC4674] Le Roux, J., Ed., "Requirements for Path Computation
Element (PCE) Discovery", RFC 4674, DOI 10.17487/RFC4674,
October 2006, <http://www.rfc-editor.org/info/rfc4674>.
[RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux,
"A Backward-Recursive PCE-Based Computation (BRPC)
Procedure to Compute Shortest Constrained Inter-Domain
Traffic Engineering Label Switched Paths", RFC 5441,
DOI 10.17487/RFC5441, April 2009,
<http://www.rfc-editor.org/info/rfc5441>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<http://www.rfc-editor.org/info/rfc6952>.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com
Mach(Guoyi) Chen
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
Dong, et al. Expires January 4, 2018 [Page 9]
Internet-Draft BGP Extensions for PCE Discovery July 2017
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
Email: dhruv.ietf@gmail.com
Jeff Tantsura
Individual
US
Email: jefftant.ietf@gmail.com
Kenji Kumaki
KDDI Corporation
Garden Air Tower, Iidabashi, Chiyoda-ku
Tokyo 102-8460
Japan
Email: ke-kumaki@kddi.com
Tomoki Murai
Furukawa Network Solution Corp.
5-1-9, Higashi-Yawata, Hiratsuka
Kanagawa 254-0016
Japan
Email: murai@fnsc.co.jp
Dong, et al. Expires January 4, 2018 [Page 10]