1. BGP extensions for Path Computation Element (PCE) Discovery in a BGP/MPLS IP-VPN draft-kumaki-pce-bgp-disco-attribute-03.txt
Kenji Kumaki KDDI R&D Labs, Editor
Tomoki Murai Furukawa Network Solution Corp.
March 2009
74th

2. Motivation
Service Providers will provide customer LSPs in BGP/MPLS VPNs.
Requirements for PCE in BGP/MPLS VPNs are described.
draft-ietf-l3vpn-e2e-rsvp-te-reqts-02 (Will start the LC.)
PCEs are quite useful to establish an end-to-end MPLS TE LSP between customer sites.
It is highly desirable for a Path Computation Element (PCE) to be able to dynamically discover a set of Path Computation Elements (PCEs) that know VPN routes within a BGP/MPLS IP-VPN.
Our goal is to discover PCEs selectively and automatically in BGP/MPLS VPNs. The point here is that only specific PCEs that know VPN routes should be discovered automatically.
March 2009
74th

3. Problem Statement
Offers customers an end-to-end MPLS TE LSP within a BGP/MPLS IP-VPN.
All PEs are PCE.
A PCC sends a PCReq message including a tail-end address for VPN1.
PE(PCE)
PE(PCE)
PE(PCE)
PE(PCE)
CE(PCC) CE
BGP/MPLS VPNs
VPN1
VPN1
PE(PCE)
VPN routes (including the tail-end address) and BGP next hop are advertised by MP-BGP.
A PCE needs to know a remote PCE that knows a tail-end address.
PE(PCE)
PE(PCE)
CE(PCC) CE
BGP/MPLS VPNs
VPN1
VPN1
It’s natural for MP-BGP to carry PCE addresses (PE addresses) that know the VPN routes.
March 2009
74th

4. PCE discovery attribute
The PCE discovery information is carried in the Path Attributes of the UPDATE message described in [RFC4271]. This attribute is never propagated to other BGP speakers in neighbor ASs.
The Attribute Flags will be set as follows:
The Optional bit set to 1 (optional).
The Transitive bit set to 1 (transitive).
The Partial bit set to 0 (complete).
The Extended Length bit set to 1 (2 octets).
The Attribute Type will be set to a value. <TBD>
The Path Attributes will be encoded as < Length, List of TLV >.
| Length (2 octets) |
|List of TLVs(variable)|
March 2009
74th

5. BGP PCE Discovery TLV : PCE-ADDRESS sub-TLV : March 2009
| Type | Length |
| |
// sub-TLVs //
Type: 1
Length: Variable
Value: This comprises one or more sub-TLVs
One sub-TLV is defined:
Sub-TLV type Length Name
variable PCE-ADDRESS sub-TLV
BGP PCE Discovery TLV :
| Type = | Length |
| address-type | Reserved |
| |
// PCE IP Address //
PCE-ADDRESS sub-TLV format
Type: 1
Length: 8 (IPv4) or 20 (IPv6)
Address-type:
1 IPv4
2 IPv6
PCE-ADDRESS sub-TLV :
March 2009
74th

6. Clarified the following sections.
Major Changes from -02
Clarified the following sections.
Abstract
Introduction
Problem statement
PCE Discovery Information
BGP PCE Discovery Attribute
BGP PCE Discovery TLV
PCE-ADDRESS Sub-TLV
March 2009
74th

7. Next Steps Need more comments and feedback from WG
Request WG to accept this I-D as a WG document
March 2009
74th

8. Discussion (OSPF vs. BGP)
① requests discovery information
PCE
OSPF
② receives discovery information
③ requests a BGP next hop address for a VPN route
④ receives the BGP next hop address for a VPN route (BGP next hop address = PCE address)
BGP
IGP Discovery
process for a vpn route
PCE
OSPF
Don’t need a request to OSPF process.
① requests discovery information for a vpn route
② receives a next PCE address for a VPN route
BGP
BGP Discovery
process for a vpn route
March 2009
74th