Network Working Group
Internet Draft K. Kumaki, Ed.
Intended Status: Standards Track KDDI Corporation
Expires: October 29, 2012 T. Murai
Furukawa Network Solutions Corp.
D. Dhody
Huawei Technology
P. Jiang
KDDI Corporation
April 29, 2012
PCEP extensions for a BGP/MPLS IP-VPN
draft-kumaki-murai-pce-pcep-extension-l3vpn-09.txt
Abstract
IP Virtual Private Networks (IP-VPNs) allow Service Providers to
offer customers connectivity between sites across an IP Backbone.
These VPNs can be supported using BGP/MPLS and the connections can be
created by using MPLS Traffic Engineered (TE) Label Switched Paths
(LSPs). The paths of these LSPs must be computed to provide the
connectivity between customer sites. Path selection may be dependent
on a variety of factors including traffic engineering constraints
and bandwidth requirements.
It is highly desirable for VPN customers to be able to dynamically
establish their MPLS TE LSPs for interconnectivity between BGP/MPLS
IP-VPN sites. The Path Computation Element (PCE) can determine the
optimal paths of TE LSPs within an MPLS network. This document
defines the PCEP extensions for the dynamic creation of MPLS TE LSPs
between BGP/MPLS IP-VPN sites.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on October 29, 2012.
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Copyright Notice
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Table of Contents
1. Introduction.................................................3
2. Problem Statement............................................4
3. Protocol Extensions and Procedures...........................5
3.1 Type Definition..........................................5
3.2 PCE Capabilities.........................................6
3.2.1 PCReq message Processing at Ingress PE (PCE)...........6
3.2.2 PCReq message Processing at Egress PE (PCE)............7
3.2.3 PCRep message Processing at Egress PE (PCE)............7
3.2.4 PCRep message Processing at Ingress PE (PCE)...........7
4. Security Considerations......................................8
5. IANA Considerations..........................................8
6. References...................................................8
6.1 Normative References.....................................8
6.2 Informative References...................................8
7. Acknowledgments..............................................9
8. Authors' Addresses...........................................9
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1. Introduction
[RFC4364] describes how a Service Provider could use an IP backbone
to provide IP Virtual Private Networks (VPNs) to its customers. Each
VPN contains at least one Customer Edge (CE) router which is attached
to a Provider (PE) router. It is possible for CE routers to be
attached to multiple PE routers. The Border Gateway Protocol (BGP)
[RFC4271] can be used to exchange VPN route information between the
PE routers.
[RFC4655] describes the motivation and architecture for the Path
Computation Element (PCE). The PCE can be used to compute the routes
for MPLS and GMPLS Traffic Engineering (TE) Label Switched Paths
(LSPs). A path computation request is issued by a Path Computation
Client (PCC) to the PCE. The communication protocol between PCCs and
PCEs is called the Path Computation Element Communication Protocol
(PCEP) and is defined in [RFC5440].
This document examines why it would be advantageous to use the PCE
architecture to establish connectivity between IP/MPLS VPNs and
defines extensions to PCEP to support that function.
The requirements for establishing connectivity between CE and PE
sites are defined in [RFC5824]. The requirements placed on PCEP
for the use of a PCE in a variety of VPN environments are set out in
[PCE-VPN-REQ]. This work only examines a small subset of the
requirements from [PCE-VPN-REQ] because it limits the use of PCEs
to specific objectives in BGP/MPLS IP-VPNs.
In order to establish a customer MPLS TE LSP over a BGP/MPLS IP-VPN,
a PCE needs to know the VPNv4/VPNv6 tail-end addresses (source and
destination) and the addresses for the PEs that provide access to
them. Additionally the PCE needs to calculate the route of an
end-to-end customer MPLS TE LSP. [RFC5441] describes the Backward
Recursive Path Computation (BRPC) technique that could be used to
compute the route of a customer MPLS TE LSP.
In order to discover PCEs participating in a BGP/MPLS IP-VPNs,
[PCE-BGP-VPN] is proposed, but this information could be configured
or discovered through another means. Note that it is assumed that PCE
functions are normally included in PE routers they could also be
placed in other nodes that are fully accessible to all PCCs in the
VPN.
This document defines new object types in the PCEP END-POINTS object
to calculate the end-to-end customer MPLS TE LSP used for
BGP/IP-VPNs, and describes a procedure for the PCEP message
processing. The new object types are defined in Section 3.1 and the
specific procedure is described in Section 3.2.
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2. Problem Statement
PCEs in the context of BGP/MPLS IP-VPNs are shown in figure 1. Here,
we make the following set of assumptions.
1. VPN1 and VPN2 are completely different customers.
2. C0 and C4 are head-end routers.
3. C3 and C7 are tail-end routers.
4. The same address (e.g., 192.0.2.1) is assigned to both C3 and C7.
<---------------A customer MPLS TE LSP for VPN1----------->
(PCE1) (PCE2)
............ ............
. -- --- . --- --- --- --- . --- -- .
.|C0| |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |C3|.
. -- --- . --- --- --- --- . --- -- .
............ | | ............
(VPN1) | | (VPN1)
| |
............ | | ............
. -- --- . | | . --- -- .
.|C4| |CE5|-------+ +-------|CE6| |C7|.
. -- --- . . --- -- .
............ ............
(VPN2) (VPN2)
<--------------A customer MPLS TE LSP for VPN2------------>
^ ^
| |
VRF instance VRF instance
<--Customer--> <------BGP/MPLS IP-VPN------> <-Customer->
network network
Figure 1 PCEs in the context of BGP/MPLS IP-VPNs
Consider that customers in VPN1 and VPN2 would like to establish
customer MPLS TE LSPs between their sites (i.e., between CE0 and
CE3, and between CE4 and CE7). The following PCEP requests will
occur:
1. C0 send a PCReq message to PCE1 to compute a path for a
customer MPLS TE LSPs between C0 and C3.
2. C4 send a PCReq message to PCE1 to compute a path for a
customer MPLS TE LSPs between C4 and C7.
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PCE1 (PE1) is able to distinguish to which VPN the received requests
apply from the interface over which the requests were received. PCE1
can forward the request to PCE2 having been configured with or
discovered ([PCE-BGP-VPN]) the existence and address of PCE2.
However, based on the PCEP specification defined in [RFC5440] and the
fact that the two messages come from the same cooperating PCE (PCE1),
PCE2 cannot determine to which VPN the computation requests apply.
Therefore, PCE2 cannot calculate the requested paths.
In order to distinguish between the VPN1 PCReq messages and the VPN2
PCReq messages, a VPN identifier is required in PCReq messages. This
identifier can be duplicated into the PCRep messages to achieve
symmetry and allow cross-checking.
This document defines a new object type for the END-POINTS object to
be used to facilitate VPN identification.
3. Protocol Extensions and Procedures
The new END-POINTS Object-Types for the PCEP request allow the
PCE to distinguish the VRF instance that is associated with the
incoming PCEP message.
3.1 Type Definition
The END-POINTS Object is defined in [RFC5440].
Two new Object-Types are defined to carry VPN-IPv4 addresses and
VPN-IPv6 addresses.
END-POINTS Object-Type is to be assigned by IANA (recommended
values: 3 for VPN-IPv4 and 4 for VPN-IPv6)
The format of the END-POINTS object body for VPN-IPv4 is as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Source VPN-IPv4 address (12 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Destination VPN-IPv4 address (12 bytes) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format of the END-POINTS object body for VPN-IPv6 (Object-
Type=4) 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Source VPN-IPv6 address (24 bytes) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Destination VPN-IPv6 address (24 bytes) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2 PCE Capabilities
It is assumed that the BGP/MPLS IP-VPN ingress and egress PE routers
have PCE capabilities. External PCE architectures will require
further study and will be discussed in future revisions of this
document.
3.2.1 PCReq Message Processing at Ingress PE (PCE)
When an ingress PE (PCE) receives a PCReq message from a PCC/PCE, it
can distinguish the VRF instance that is associated with an incoming
interface:
1. The ingress PE processes the destination IPv4/IPv6 address
in the END-POINTS object as the destination VPN-IPv4/VPN-IPv6
address for the VRF instance.
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2. The destination VPN-IPv4/VPN-IPv6 address is looked up in the
context of VRF instance, and the BGP next-hop for this
destination is identified.
3. The destination VPN-IPv4/VPN-IPv6 address is then added to
END-POINTS object consisting of the original destination
IPv4/IPv6 address in END-POINTS object followed by the 8
octet Route Distinguisher (RD).
Note that the RD is specified by the BGP next-hop for the destination
VPN-IPv4/VPN-IPv6 address. The source VPN-IPv4/VPN-IPv6 address in
the new END-POINTS object consists of the original IPv4/IPv6 address
in END-POINTS object and the RD. Also the RD is used by this ingress
PE to advertise customer's prefix including the source
VPN-IPv4/VPN-IPv6 address into the VRF instance.
4. If necessary, the ingress PE will then send the PCReq message
to next PCE (the egress PE for BGP/MPLS IP-VPNs).
5. Finally, the ingress PE should replace the incoming END-POINTS
object from the PCC/PCE into the new END-POINTS object.
3.2.2 PCReq Message Processing at Egress PE (PCE)
When an egress PE (PCE) receives a PCReq message from an ingress
PE(PCE), it is able to distinguish the VRF instance from the
destination VPN-IPv4/VPN-IPv6 address in the new END-POINTS object.
The egress PE will send a PCReq message to next PCE (PE) if needed.
The egress PE will then remove the RD from the source and the
destination VPN-IPv4/VPN-IPv6 addresses in the new END-POINTS object
received from the ingress PE. Finally, the egress PE should store the
new END-POINTS object for a PCReq message in a VRF instance.
3.2.3 PCRep message Processing at Egress PE (PCE)
When an egress PE (PCE) receives a PCRep message for a PCReq message
from a previous PCE (i.e. CE), it will look up the new END-POINTS
object associated with the PCReq message for the PCRep message.
The egress PE performs a path computation. Note that the path
computation procedure itself is out of scope in this document.
Afterwards, the egress PE adds the new END-POINTS object in a PCRep
message and sends it to an ingress PE.
3.2.4 PCRep Message Processing at Ingress PE (PCE)
When an ingress PE (PCE) receives a PCRep message for a PCReq message
from an egress PE (PCE), it can distinguish a VRF instance from the
source VPN-IPv4/VPN-IPv6 address in the new END-POINTS object.
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Therefore, it is now possible to generate a PCRep message to send to
an appropriate PCC/PCE.
4. Security Considerations
This document defines PCEP extensions for BGP/MPLS IP-VPNs. The
security of the PCE extensions relies on the security of PCEP
[RFC5440]. It is important that implementations conform to security
features defined in [RFC5440].
5. IANA Considerations
IANA maintains a registry of PCEP parameters. As described in
Section 3.1 (Type Definition), two Object-Types have been defined.
IANA is requested to make the following allocations from the
"PCEP Objects" sub-registry.
Object-Class Name Object-Type Reference
Value
4 END-POINTS 1: IPv4 addresses [RFC5440]
2: IPv6 addresses [RFC5440]
3: VPN-IPv4 addresses [This.I-D]
4: VPN-IPv6 addresses [This.I-D]
5-15: Unassigned
The values 3 and 4 are suggested.
6. References
6.1 Normative References
[RFC4271] Rekhter, Y. and Li, T., "A Border Gateway Protocol 4
(BGP-4)", RFC 4271, January 2006.
[RFC5440] Vasseur, J.-P., et al., "Path Computation Element(PCE)
communication Protocol (PCEP) - Version 1", RFC5440,
March 2009.
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6.2 Informative References
[RFC4364] Rosen, E., Rekhter, Y., "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC4655] Farrel, A., Vasseur, J.-P., and Ash, J., "Path
Computation Element (PCE) Architecture", RFC 4655,
August 2006.
[RFC5824] Kumaki, K., Zhang, R. and Kamite, Y., "Requirements for
supporting Customer RSVP and RSVP-TE over a BGP/MPLS
IP-VPN", RFC 5824, April 2010.
[PCE-VPN-REQ] Yasukawa, S. and Farrel, A. "PCC-PCE Communication
Requirements for VPNs", draft-ietf-pce-vpn-req, March
2011.
[RFC5441] Vasseur, J.-P., et al., "A Backward Recursive PCE-
based Computation (BRPC) Procedure To Compute Shortest
Constrained Inter-domain Traffic Engineering Label
Switched Paths", RFC5441, April 2009.
[PCE-BGP-VPN] Kumaki, K. and Murai, "BGP protocol extensions for Path
Computation Element (PCE) Discovery in a BGP/MPLS IP-
VPN ", draft-kumaki-pce-bgp-disco-attribute, September 2010.
7. Acknowledgments
The author would like to express thanks to Makoto Nakamura for his
helpful and useful comments and feedback.
8. Authors' Addresses
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
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Dhruv Dhody
Huawei Technology
Leela Palace
Bangalore, Karnataka, 560008, INDIA
Email: dhruv.dhody@huawei.com
Peng Jiang
KDDI Corporation
Garden Air Tower
Iidabashi, Chiyoda-ku,
Tokyo 102-8460, JAPAN
Email: pe-jiang@kddi.com
Tomohiro Yamagata
KDDI Corporation
Garden Air Tower
Iidabashi, Chiyoda-ku,
Tokyo 102-8460, JAPAN
Email: to-yamagata@kddi.com
Chikara Sasaki
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Fujimino
Saitama 356-8502, JAPAN
Email: ch-sasaki@kddilabs.jp