Internet Draft Igor Bryskin (ADVA Optical Networking)
Category: Standards Track Lou Berger (LabN Consulting, LLC)
Expiration Date: April 2007
October 2006
OSPF Based L1VPN Auto-Discovery
draft-ietf-l1vpn-ospf-auto-discovery-01.txt
Status of this Memo
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Abstract
This document defines an OSPF based layer-1 VPN auto-discovery
mechanism. This mechanism enables PEs using the OSPF IGP to
dynamically learn about existence of each other, and attributes of
currently configured CE-PE links and their associations with L1VPNs.
This document builds on [L1VPN-FRMWK] and provides an auto-discovery
mechanism as discussed in [L1VPN-BM].
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Contents
1 Terminology ............................................... 3
2 Introduction .............................................. 4
3 L1VPN LSA and its TLVs .................................... 5
3.1 L1VPN LSA ................................................. 5
3.2 L1VPN INFO TLV ............................................ 6
4 L1VPN LSA Advertising and Processing ...................... 7
4.1 Discussion and Example .................................... 7
5 Backward compatibility .................................... 8
6 Security Considerations ................................... 9
7 Intellectual Property Statement ........................... 9
8 Acknowledgement ........................................... 10
9 References ................................................ 10
9.1 Normative References ...................................... 10
9.2 Informative References .................................... 10
10 Authors' Addresses ........................................ 11
11 Full Copyright Statement .................................. 11
12 Intellectual Property ..................................... 11
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Conventions used in this document
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 [RFC2119].
1. Terminology
The reader of this document should be familiar with the terms used in
[L1VPN-FRMWK] and [L1VPN-BM]. In particular the following terms:
L1VPN - Layer One Virtual Private Network
CE - Customer (edge) network element directly connected to the
Provider network (terminates one or more links to one or
more PEs); it is also connected to one or more Cs and/or
other CEs
C - Customer network element that is not connected to the
Provider network but is connected to one or more other Cs
and/or CEs
PE - Provider (edge) network element directly connected to one or
more Customer networks (terminates one or more links to one
or more CEs associated with the same or different L1VPNs);
it is also connected to one or more Ps and/or other PEs
P - Provider (core) network element that is not directly
connected to any of Customer networks; P is connected to one
or more other Ps and/or PEs
LSDB - Link State Database: a data structure supported by an IGP
speaker
PIT - Port Information Table
CPI - Customer Port Identifier
PPI - Provider Port Identifier
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2. Introduction
The framework for Layer 1 VPNs is described in [L1VPN-FRMWK]. Basic
mode operation is further defined in [L1VPN-BM]. [L1VPN-BM] document
identifies the information that is necessary to map customer
information (ports identifiers) to provider information
(identifiers). It also states that this mapping information may be
provided via provisioning or via an auto-discovery mechanism. This
document provides such an auto-discovery mechanism using the OSPF
IGP. Figure 1 shows the L1VPN basic service being supported using
OSPF based L1VPN auto-discovery. See [L1VPN-BGP] for a parallel
L1VPN auto-discovery that uses BGP. The IGP approach described in
this document is particularly useful in networks where BGP is not
typically used.
PE PE
+---------+ +--------------+
+--------+ | +------+| | +----------+ | +--------+
| VPN-A | | |VPN-A || | | VPN-A | | | VPN-A |
| CE1 |--| |PIT || OSPF LSAs | | PIT | |-| CE2 |
+--------+ | | ||<----------->| | | | +--------+
| +------+| Distribution| +----------+ |
| | | |
+--------+ | +------+| | +----------+ | +--------+
| VPN-B | | |VPN-B || -------- | | VPN-B | | | VPN-B |
| CE1 |--| |PIT ||-( GMPLS )--| | PIT | |-| CE2 |
+--------+ | | || (Backbone ) | | | | +--------+
| +------+| --------- | +----------+ |
| | | |
+--------+ | +-----+ | | +----------+ | +--------+
| VPN-C | | |VPN-C| | | | VPN-C | | | VPN-C |
| CE1 |--| |PIT | | | | PIT | |-| CE2 |
+--------+ | | | | | | | | +--------+
| +-----+ | | +----------+ |
+---------+ +--------------+
Figure 1: OSPF Auto-Discovery for L1VPNs
The approach used in this document to provide OSPF based L1VPN auto-
discovery uses an Opaque LSA of a new Opaque Type (referred as a
L1VPN LSA).
There is a TLV type defined for use within a L1VPN LSA. The TLV,
which is referred to as L1VPN Info TLV, is used to propagate <CPI,
PPI> tuple and VPIN ID mappings.
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3. L1VPN LSA and its TLVs
This section defines the L1VPN LSA and its TLVs.
3.1. L1VPN LSA
The format of a L1VPN LSA 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS age | Options | LS Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque Type | Opaque ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L1VPN Info TLV |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Link TLV |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LS age
As defined in [RFC2328]
Options
As defined in [RFC2328].
LS Type
This field MUST be set to 11.
Opaque Type
The value of this field MUST be set to TBA (by IANA).
Opaque ID
As defined in [RFC2370]
Advertising Router
As defined in [RFC2328].
LS Sequence Number
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As defined in [RFC2328].
LS checksum
As defined in [RFC2328].
Length
As defined in [RFC2328].
L1VPN Info TLV
A single TLV, as defined in section 3.2
TE Link TLV
A single TE Link TLV (as defined in [RFC3630] and [RFC4203])
MAY be included in a L1VPN LSA
3.2. L1VPN INFO TLV
The following TLV is introduced:
Name: L1VPN IPv4 Info
Type: 1
Length: Variable
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L1VPN TLV length | L1VPN TLV Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L1VPN Globally unique identifier |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PE TE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
| L1VPN Auto-Discovery Information |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV length
The length of the TLV in bytes, including the 4 bytes of
the TLV header.
L1VPN TLV Type
The type of the TLV.
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L1VPN Globally unique identifier
As defined in [L1VPN-BM].
PE TE Address
Valid PE TE address: either TE Router ID specified in the
Router Address TLV or local numbered TE link ID specified in
the Local interface IP address sub-TLV of the TE Link TLV of the
TE LSA originated by the PE
L1VPN Auto-discovery information
As defined in [L1VPN-BM].
4. L1VPN LSA Advertising and Processing
PEs advertise local <CPI, PPI> tuples in L1VPN LSAs containing L1VPN
Info TLVs. Each PE MUST originate a separate L1VPN LSA with AS
flooding scope for each local CE-PE link. The LSA MUST be originated
once on the PE restart and every time when there is a change in the
PIT entry associated with a local CE-PE link. The LSA MUST include a
single L1VPN Info TLV and MAY include a single TE Link TLV as per
[RFC3630] and [RFC4203].
L1VPN LSAs are flooded to all PEs within the AS according to
[RFC2370] or [2370BIS]. Every time a PE receives a new, removed or
modified such LSA, the PE MUST check whether it maintains a PIT
associated with the L1VPN specified in the L1VPN Globally unique
identifier field. If this is the case (the appropriate PIT will be
found if one or more local CE-PE links that belong to the L1VPN are
configured), the PE SHOULD add, remove or modify the PIT entry
associated with each of the advertised CE-PE links accordingly. Thus,
in the steady mode all PEs associated with a particular L1VPN
maintain identical local PITs for the L1VPN.
4.1. Discussion and Example
The L1VPN auto-discovery mechanism described in this document does
not prevent a PE from applying any local policy with respect to PIT
management. For example, it should be possible to configure permanent
(static) PIT entries, blocking information carried in L1VPN LSAs that
are advertised by some remote PEs from making it to the PITs and so
forth.
The reason why it is required that the value specified in the PE TE
Address field of the L1VPN Info TLV matches a valid PE TE Router ID
or numbered TE Link ID is to ensure that CEs attached to this PE
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could be resolved to the PE as it is known to the Traffic Engineering
Database (TED) and hence TE paths towards the CEs across the Provider
domain could be computed.
Let us consider example presented on Figure 2.
CE11 CE13
| |
CE22---PE1--------P------PE2
| |
CE15 PE3
|
CE24
Figure 2: Single area configuration
Let us assume that PE1 is connected to CE11 and CE15 in L1VPN1 and to
CE22 in L1VPN2; PE2 is connected to CE13 in L1VPN1; PE3 is connected
to CE24 in L1VPN2. In this configuration PE1 manages two PITs: PIT1
for L1VPN1 and PIT2 for L1VPN2; PE2 manages only PIT1, and PE3
manages only PIT2. PE1 originates three L1VPN LSAs, each containing a
L1VPN Info TLV advertising links PE1-CE11, PE1-CE22 and PE1-CE15
respectively. PE2 originates a single L1VPN LSA for link PE2-CE13 and
PE3 originates a single L1VPN LSA for link PE3-CE24. In the steady
mode PIT1 on PE1 and PE3 will contain information on links PE1-CE11,
PE1-CE15 and PE2-CE13; PIT2 on PE1 and PE2 will contain entries for
links PE1-CE22 and PE3-CE24. Thus, all PEs will learn about all
remote PE-CE links for all L1VPNs supported by PEs.
Note that P in this configuration does not have links connecting it
to any of L1VPNs. It neither originates L1VPN LSAs nor maintains any
PITs. However, it does participate in the flooding of all of the
L1VPN LSA and hence maintains the LSAs in its LSDB. This is a cause
for scalability concerns and could prove to be problematic on large
networks.
5. Backward compatibility
Neither the TLV nor the LSA introduced in this document present any
interoperability issues. OSPF speakers that do not support L1VPN
auto-discovery application (Ps for example) just participate in the
L1VPN LSAs flooding process but should ignore the LSAs contents.
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6. Security Considerations
The solution presented in this document describes how PEs dynamically
learn L1VPN specific information. Mechanisms to deliver the VPN
membership information to CEs are explicitly out of scope of this
document. Therefore, no new security issues are raised in this
document.
7. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
groups may also distribute working documents as Internet- Drafts.
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".
Bryskin & Berger [Page 9]
Internet Draft draft-ietf-l1vpn-ospf-auto-discovery-01.txt October 2006
8. Acknowledgement
We would like to thank Adrian Farrel for his useful comments.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to indicate
requirements levels", RFC 2119, March 1997.
[RFC2328] Moy, J., " OSPF Version 2 ", RFC 2328, April 1998.
[RFC2370] Coltun, R., " The OSPF Opaque LSA Option ", RFC 2730,
July 1998.
[RFC3630] Ktaz, D., Kompela, K., Yeung. D.., " Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September
2003.
[RFC4203] Kompela, K., Rekhter, Y. " OSPF Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)", RFC
4203, October 2005.
[L1VPN-BM] Fedyk, D., Rekhter, Y. (Eds.), "Layer 1 VPN Basic
Mode", draft-fedyk-l1vpn-basic-mode-01.txt, January
2006, work in progress.
9.2. Informative References
[2370BIS] Berger, L., Bryskin, I., Zinin, A., "The OSPF Opaque LSA
Option", work in progress, draft-berger-ospf-rfc2370bis,
October, 2006.
[L1VPN-FRMWK] Tomonori Takeda, et al., " Framework and
Requirements for Layer 1 Virtual Private Networks",
draft-ietf-l1vpn-framework-00.txt, August 2005, work
in progress
[L1VPN-BGP] Ould-Brahim H., Fedyk D., Rekhter, Y., "BGP-based Auto-
Discovery for L1VPNs ", work in progress,
draft-ouldbrahim-l1vpn-bgp-auto-discovery-
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10. Authors' Addresses
Igor Bryskin
ADVA Optical Networking Inc
7926 Jones Branch Drive
Suite 615
McLean, VA - 22102
Email: ibryskin@advaoptical.com
Lou Berger
LabN Consulting, LLC
Email: lberger@labn.net
11. Full Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
12. Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
Bryskin & Berger [Page 11]
Internet Draft draft-ietf-l1vpn-ospf-auto-discovery-01.txt October 2006
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
Bryskin & Berger [Page 12]
