BGP Extensions for Path Computation Element (PCE) Discovery
draft-dong-pce-discovery-proto-bgp-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 "Expired".
|
|
|---|---|---|---|
| Authors | Jie Dong , Mach Chen | ||
| Last updated | 2014-06-30 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-dong-pce-discovery-proto-bgp-00
Network Working Group J. Dong
Internet-Draft M. Chen
Intended status: Standards Track Huawei Technologies
Expires: January 1, 2015 June 30, 2014
BGP Extensions for Path Computation Element (PCE) Discovery
draft-dong-pce-discovery-proto-bgp-00
Abstract
In network scenarios where Path Computation Element (PCE) is used for
centralized path computation, it is desirable for Path Computation
Clients (PCCs) to automatically discover the set of PCEs. As BGP has
been extended for north-bound distribution of routing and LSP path
information to PCE, the PCEs may not participate in Interior Gateway
Protocol (IGP) for collecting the routing information, thus the IGP
based PCE discovery cannot be used directly in these scenarios. This
document specifies the BGP extensions for PCE discovery.
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."
This Internet-Draft will expire on January 1, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
Dong & Chen Expires January 1, 2015 [Page 1]
Internet-Draft BGP Extensions for PCE Discovery June 2014
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 Address Information . . . . . . . . . . . . . . . . . 3
2.2. PCE Discovery Attribute . . . . . . . . . . . . . . . . . 4
3. Operational Considerations . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
In network scenarios where Path Computation Element (PCE) is used for
centralized path computation, it is desirable for Path Computation
Clients (PCCs) to automatically discover the set of PCEs. As BGP
will be used for north-bound distribution of routing and Label
Switched Path (LSP) information to PCE[I-D.ietf-idr-ls-distribution]
[I-D.ietf-idr-te-lsp-distribution] [I-D.ietf-idr-te-pm-bgp], the PCEs
may not participate in Interior Gateway Protocol (IGP) for collecting
the routing information, thus the IGP based PCE discovery mechanisms
defined in [RFC5088] [RFC5089] cannot be used directly.
This document proposes to extend BGP for PCE discovery in such
scenarios. While in each IGP domain, the IGP based PCE discovery
mechanism may be used in conjunction with the BGP based PCE
discovery. Thus the BGP based PCE discovery is complemental to the
existing IGP based mechanisms.
Dong & Chen Expires January 1, 2015 [Page 2]
Internet-Draft BGP Extensions for PCE Discovery June 2014
+---------+
| PCE |
+---------+
^ |
| |
| V
+---------+
+--------->| BGP |<---------+
| +----| Speaker |----+ |
| | +---------+ | |
| | ^ | | |
| | | | | |
| V | V V |
+---------+ +---------+ +---------+
| BGP | | BGP | | BGP |
| Speaker | | Speaker | | Speaker |
+---------+ +---------+ +---------+
^ ^ ^
IGP(optional) | | |
V V V
+---------+ +---------+ +---------+
| PCC | | PCC | | PCC |
+---------+ +---------+ +---------+
Figure 1. BGP for routing collection and PCE discovery
As shown in the network architecture in Figure 1, BGP is used for
both routing information distribution and PCE information discovery.
The routing information is distributed from the network elements up
to PCE, while the PCE discovery information is advertised from PCE
down to PCCs. IGP based PCE discovery mechanism may be used for the
distribution of PCE discovery information in each IGP domain.
2. Carrying PCE Discovery Information in BGP
2.1. PCE Address Information
The PCE discovery information is advertised in BGP UPDATE messages
using the MP_REACH_NLRI and MP_UNREACH_NLRI attributes [RFC4760]. A
new NLRI called PCE_ADDR NLRI is defined for carrying the PCE address
information which can be used to reach the PCE. The AFI/SAFI value
for the PCE_ADDR NLRI is TBD. In order for two BGP speakers to
exchange PCE_ADDR NLRI, they MUST use BGP Capabilities Advertisement
[RFC4760] to ensure that both are capable of properly processing such
NLRI. This is done by using Capability Code 1 (which indicates
Multiprotocol Extensions capabilities), with the AFI/SAFI pair for
the PCE_ADDR NLRI.
Dong & Chen Expires January 1, 2015 [Page 3]
Internet-Draft BGP Extensions for PCE Discovery June 2014
The format of PCE_ADDR NLRI is shown as 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ PCE-Address (4 or 16 octets) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2. PCE_ADDR NLRI
For PCEs identified by IPv4 address, the Type field SHOULD be set to
1, and the Length field SHOULD be set to 4.
For PCEs identified by IPv6 address, the Type field SHOULD be set to
2, and the Length field SHOULD be set to 16.
2.2. PCE Discovery Attribute
The detailed PCE discovery information is carried in a new optional
non-transitive BGP attribute called PCE_DISC Attribute, which
consists of a series of PCE Discovery TLVs for specific PCE
information. The PCE_DISC attribute SHOULD only be used with
PCE_ADDR NLRI.
The format of the PCE Discovery TLV is shown as 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ PCE Discovery TLVs (variable) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3. PCE Discovery TLVs
The Type code and format of the PCE Discovery TLVs are consistent
with the IGP PCED Sub-TLVs defined in [RFC5088] [RFC5089]. Type 1 is
reserved, which is used in IGP based PCE discovery mechanisms to
carry PCE Address .
Dong & Chen Expires January 1, 2015 [Page 4]
Internet-Draft BGP Extensions for PCE Discovery June 2014
TLV-Type Length Name
2 3 PATH-SCOPE TLV
3 variable PCE-DOMAIN TLV
4 variable NEIG-PCE-DOMAIN TLV
5 variable PCE-CAP-FLAGS TLV
The PATH-SCOPE TLV MUST always be carried in the PCE_DISC Attribute.
Other TLVs are optional and may facilitate the PCE selection.
More PCE Discovery TLVs may be defined in future.
3. Operational Considerations
Existing BGP operational procedures apply to the advertisement of PCE
discovery information. Such information is treated as pure
application level data which has no immediate impact on forwarding
states.
PCE discovery 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 new AFI and SAFI codes for PCE_ADDR NLRI from
"Address Family Numbers" and "Subsequent Address Family Identifiers"
registry.
IANA needs to assign a new type code for "PCE_DISC" attribute from
"BGP Path Attributes" registry.
5. Security Considerations
Procedures and protocol extensions defined in this document do not
affect the BGP security model. See [RFC6952] for details.
6. Acknowledgements
The authors would like to thank Zhenbin Li for the discussion and
comments.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Dong & Chen Expires January 1, 2015 [Page 5]
Internet-Draft BGP Extensions for PCE Discovery June 2014
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, January
2007.
[RFC5088] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"OSPF Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5088, January 2008.
[RFC5089] Le Roux, JL., Vasseur, JP., Ikejiri, Y., and R. Zhang,
"IS-IS Protocol Extensions for Path Computation Element
(PCE) Discovery", RFC 5089, January 2008.
[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, May 2013.
7.2. Informative References
[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-05
(work in progress), May 2014.
[I-D.ietf-idr-te-lsp-distribution]
Dong, J., Chen, M., Gredler, H., and S. Previdi,
"Distribution of MPLS Traffic Engineering (TE) LSP State
using BGP", draft-ietf-idr-te-lsp-distribution-00 (work in
progress), January 2014.
[I-D.ietf-idr-te-pm-bgp]
Wu, Q., Danhua, W., Previdi, S., Gredler, H., and S. Ray,
"BGP attribute for North-Bound Distribution of Traffic
Engineering (TE) performance Metrics", draft-ietf-idr-te-
pm-bgp-00 (work in progress), January 2014.
Authors' Addresses
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com
Dong & Chen Expires January 1, 2015 [Page 6]
Internet-Draft BGP Extensions for PCE Discovery June 2014
Mach(Guoyi) Chen
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
Dong & Chen Expires January 1, 2015 [Page 7]