Networking Working Group JP Vasseur (Ed.)
Cisco System Inc.
IETF Internet Draft JL Le Roux (Ed.)
France Telecom
Proposed Status: Standard
Expires: May 2006 November 2005
Routing extensions for discovery of Multiprotocol (MPLS) Label Switch
Router (LSR) Traffic Engineering (TE) mesh membership
draft-ietf-ccamp-automesh-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2005). All Rights Reserved.
Abstract
The set up of a full mesh of MPLS TE LSPs among a set of Label Switch
Router (LSR) is common deployment scenario of MPLS Traffic
Engineering either for bandwidth optimization, bandwidth guarantees
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or fast rerouting with MPLS Fast Reroute. Such deployment requires
the configuration of potentially a large number of TE LSPs (on the
order of the square of the number LSRs). This document specifies IGP
(OSPF and IS-IS) traffic engineering extensions so as to provide an
automatic discovery of the set of LSRs members of a mesh, leading to
an automatic mechanism to set up TE LSP mesh(es) (also referred to as
a mesh-group in this document).
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 RFC-2119.
Table of Contents
1. Contributors------------------------- 2
2. Terminology-------------------------- 3
3. Introduction------------------------- 3
4. TE mesh-roup------------------------- 4
4.1. Description------------------------ 4
4.2. Required Information--------------- 4
5. TE-MESH-GROUP TLV formats------------ 4
5.1. OSPF TE-MESH-GROUP TLV format------ 5
5.2. IS-IS TE-MESH-GROUP TLV format----- 6
6. Elements of procedure---------------- 7
6.1. OSPF------------------------------- 7
6.2. IS-IS------------------------------ 7
7. Backward compatibility--------------- 8
8. Security Considerations-------------- 8
9. Intellectual Property Statement------ 8
10. Acknowledgment---------------------- 9
11. References-------------------------- 9
11.1. Normative references-------------- 9
11.2. Informative References------------ 9
12. Editors' Address-------------------- 10
1. Contributors
This document was the collective work of several. The text and
content of this document was contributed by the editors and the
co-authors listed below (the contact information for the editors
appears in section 12, and is not repeated below):
Paul Mabey Seisho Yasukawa
Qwest Communications NTT
950 17th street 9-11, Midori-Cho 3-Chome
Denver, CO 80202 Musashino-Shi, Tokyo 180-8585
USA JAPAN
Email: pmabey@qwest.com Email: yasukawa.seisho@lab.ntt.co.jp
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Stefano Previdi Peter Psenak
Cisco System, Inc. Cisco System, Inc.
Via del Serafico 200 Pegasus Park
00142 Roma DE Kleetlaan 6A
ITALY 1831, Diegmen
Email: sprevidi@cisco.com BELGIUM
Email: ppsenak@cisco.com
2. Terminology
Terminology used in this document
LSR: Label Switch Router.
TE LSP: Traffic Engineering Label Switched Path.
TE LSP head-end: head/source of the TE LSP.
TE LSP tail-end: tail/destination of the TE LSP.
IGP Area: OSPF Area or IS-IS level
Link State Advertisement: An OSPF LSA or IS-IS LSP
Intra-area TE LSP: TE LSP whose path does not transit across
areas.
Inter-area TE LSP: A TE LSP whose path transits across at least
two different IGP areas.
Inter-AS MPLS TE LSP: A TE LSP whose path transits across at least
two different ASes or sub-ASes (BGP confederations).
3. Introduction
As of today, there are different approaches in deploying MPLS Traffic
Engineering:
(1) The 'systematic' approach consisting of setting up a full
mesh of TE LSPs between a set of LSRs,
(2) The 'by exception' approach whereby a set of TE LSPs are
provisioned on hot spots to alleviate a congestion resulting
for instance from an unexpected traffic growth in some part
of the network.
The set up of a full mesh of MPLS TE LSPs among a set of LSRs is a
common deployment scenario of MPLS Traffic Engineering either for
bandwidth optimization, bandwidth guarantees or fast rerouting with
MPLS Fast Reroute ([FRR]). Setting up a full mesh of TE LSPs between
a set of LSRs requires the configuration of a potentially large
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number of TE LSPs on every head-end LSR. The resulting total number
of TE LSP in a full TE mesh of n LSRs is O(n^2). Furthermore, the
addition of any new LSR in the mesh requires the configuration of n
additional TE LSPs on the new LSR and one new TE LSP on every LSR of
the existing mesh terminating to this new LSR, which gives a total of
2*n TE LSPs. Such operation is not only time consuming but also a
risky operation for Service Providers. Hence, a more automatic
mechanism to setting up one or more full meshes of TE LSPs is
desirable and requires the ability to automatically discover the LSRs
that belong to the mesh.
MPLS Traffic Engineering (MPLS-TE) routing ([IS-IS-TE], [OSPF-TE])
relies on extensions to link state IGP routing protocols ([OSPF],
[IS-IS]) in order to carry Traffic Engineering link information used
for constraint based routing. Generalized MPLS (GMPLS) related
routing extensions are defined in [IS-IS-G] and [OSPF-G].
Further routing extensions have been defined in [OSPF-CAPS] and [IS-
IS-CAPS] so as to advertise router capabilities. This document
specifies IGP (OSPF and IS-IS) traffic engineering capability TLVs in
order to provide a mechanism to automatically discover the LSR
members of a mesh, leading to an automatic mechanism to set up TE LSP
mesh (also referred to as a mesh-group in this document) in a
network. The routing extensions specified in this document provide
the ability to signal multiple TE meshes whereby an LSR can belong to
one or more TE meshes.
4. TE mesh-group
4.1. Description
A TE mesh-group is defined as a group of LSRs that are connected by a
full mesh of TE LSPs. It is useful to dynamically advertise the
desire of a node to join/leave a particular TE mesh-group. This
allows for an automatic provisioning of a full mesh of TE LSPs, and
thus drastically reduces the configuration overhead and risk of mis-
configuration.
4.2. Required Information
This document specifies a TE-MESH-GROUP TLV that indicates the set of
TE mesh-group(s) an LSR belongs to. For each TE mesh group announced
by the LSR, the TE-MESH-GROUP TLV carries the following information:
-A mesh-group number identifying the TE mesh-group,
-A Tail-end address (address used as a tail end address by other
LSRs belonging to the same mesh-group),
-A Tail-end name: string used to ease the TE-LSP naming (e.g.
'head-name->tail-name').
5. TE-MESH-GROUP TLV formats
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5.1. OSPF TE-MESH-GROUP TLV format
The OSPF TE-MESH-GROUP TLV (carried in an OSPF router information LSA
as defined in [OSPF-CAP]) has the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Value //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
OSPF TE-MESH-GROUP TLV format
Where
Type: identifies the TLV type
Length: length of the value field in octets
The format of the OSPF TE-MESH-GROUP TLV is the same as the TLV
format used by the Traffic Engineering Extensions to OSPF [OSPF-TE].
The TLV is padded to four-octet alignment; padding is not included in
the length field (so a three octet value would have a length of
three, but the total size of the TLV would be eight octets). Nested
TLVs are also 32-bit aligned. Unrecognized types are ignored. All
types between 32768 and 65535 are reserved for vendor-specific
extensions. All other undefined type codes are reserved for future
assignment by IANA.
The TE-MESH-GROUP TLV is used to advertise the desire to
join/leave a given MPLS TE mesh group. No sub-TLV is currently
defined for the TE-mesh-group TLV.
The TE-MESH-GROUP TLV has the following format:
CODE: 3
LENGTH: Variable (N*12 octets)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| mesh-group-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tail-end address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tail-end name |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TE-MESH-GROUP TLV format
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N is the number of mesh-groups.
For each TE mesh group announced by the LSR, the TE-MESH-GROUP TLV
contains:
- A mesh-group-number: identifies the mesh-group number,
- A Tail-end address: user configurable IP address to be used as a
tail-end address by other LSRs belonging to the same mesh-group.
- A Tail-end name: 32-bits string which facilitates the TE LSP
identification which can be very useful in some environments such
as inter-area/AS MPLS TE environments.
5.2. IS-IS TE-MESH-GROUP TLV format
The IS-IS TE-MESH-GROUP TLV is composed of 1 octet for the type, 1
octet specifying the TLV length and a value field.
The format of the TE-MESH-GROUP TLV is identical to the TLV format
used by the Traffic Engineering Extensions to IS-IS [IS-IS-TE].
The TE-MESH-GROUP TLV is used to advertise the desire to join/leave a
given TE mesh group. No sub-TLV is currently defined for the TE-MESH-
GROUP TLV.
The TE-MESH-GROUP TLV has the following format:
CODE: 2
LENGTH: Variable (N*12 octets)
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| mesh-group-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tail-end address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tail-end name |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TE-MESH-GROUP TLV format
N is the number of mesh-groups.
For each Mesh-group announced by an LSR, the TLV contains:
- A mesh-group-number: identifies the mesh-group number,
- A Tail-end address: user configurable IP address to be used as a
tail-end address by other LSRs belonging to the same mesh-group.
- A Tail-end name: 32-bits string which facilitates the TE LSP
identification which can be very useful in inter-area/AS MPLS TE
environments.
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6. Elements of procedure
The TE-MESH-GROUP TLV is carried in Link State Advertisements (LSA)
and Router capability TLV (carried itself within a Link State Packet
(LSP)) for OSPF and ISIS respectively. As such, elements of
procedures are inherited from those defined in [OSPF-CAPS] and [IS-
IS-CAPS]. Specifically, a router MUST originate a new LSA/LSP
whenever the content of this information changes, or whenever
required by regular routing procedure (e.g. refresh).
The TE-MESH-GROUP TLV is OPTIONAL.
6.1. OSPF
The TE-MESH-GROUP TLV is carried within an OSPF router information
opaque LSA (opaque type of 4, opaque ID of 0) as defined in [OSPF-
CAP].
A router MUST originate a new OSPF router information LSA whenever
the content of the any of the carried TLV changes or whenever
required by the regular OSPF procedure (LSA refresh (every
LSRefreshTime)).
As defined in RFC2370, an opaque LSA has a flooding scope determined
by its LSA type:
- link-local (type 9),
- area-local (type 10)
- entire OSPF routing domain (type 11). In this case, the
flooding scope is equivalent to the Type 5 LSA flooding scope.
A router may generate multiple OSPF router information LSAs with
different flooding scopes.
The TE-MESH-GROUP TLV may be carried within a type 10 or 11 router
information LSA depending on the MPLS TE mesh group profile:
- If the MPLS TE mesh-group is contained within a single area
(all the LSRs have their head-end and tail-end LSR within the
same OSPF area), the TE-MESH-GROUP TLV MUST be generated
within a Type 10 router information LSA,
- If the MPLS TE mesh-group spans multiple OSPF areas, the TE
mesh-group TLV MUST be generated within a Type 11 router
information LSA,
6.2. IS-IS
The TE-MESH-GROUP TLV is carried within the IS-IS Router CAPABILITY
TLV defined in [IS-IS-CAP].
An IS-IS router MUST originate a new IS-IS LSP whenever the content
of the any of the carried sub-TLV changes or whenever required by the
regular IS-IS procedure (LSP refresh).
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If the flooding scope of an MPLS Traffic Engineering capability is
limited to an IS-IS level/area, the TLV MUST not be leaked across
level/area and the S flag of the Router CAPABILITY TLV MUST be
cleared. Conversely, if the flooding scope of an MPLS Traffic
Engineering capability is the entire routing domain, the TLV MUST be
leaked across levels for IS-IS the S flag of the CAPABILITY TLV MUST
be set.
In both cases the flooding rules as specified in [IS-IS-CAP] apply.
As specified in [IS-IS-CAP], a router may generate multiple IS-IS
CAPABILITY TLVs within an IS-IS LSP with different flooding scopes.
7. Backward compatibility
The TE-MESH-GROUP TLVs defined in this document do not introduce any
interoperability issue. For OSPF, a router not supporting the TE-
MESH-GROUP TLV SHOULD just silently ignore the TLV as specified in
RFC2370. For IS-IS a router not supporting the TE-MESH-GROUP TLV
SHOULD just silently ignore the TLV.
8. Security Considerations
No new security issues are raised in this document.
9. 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.
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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".
10. Acknowledgment
We would like to thank Yannick Le Louedec for his useful comments.
11. References
11.1. Normative references
[RFC] Bradner, S., "Key words for use in RFCs to indicate
requirements levels", RFC 2119, March 1997.
[RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78,
RFC 3667, February 2004.
[RFC3668] Bradner, S., Ed., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004.
[OSPF-v2] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[IS-IS] "Intermediate System to Intermediate System Intra-Domain
Routing Exchange Protocol " ISO 10589.
[IS-IS-IP] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[OSPF-TE] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
Extensions to OSPF Version 2", RFC 3630, September 2003.
[IS-IS-TE] Li, T., Smit, H., "IS-IS extensions for Traffic
Engineering", RFC 3784, June 2004.
[OSPF-CAP] Lindem, A., Shen, N., Aggarwal, R., Shaffer, S., Vasseur,
J.P., "Extensions to OSPF for advertising Optional Router
Capabilities", draft-ietf-ospf-cap, work in progress.
[IS-IS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising
router information", draft-ietf-isis-caps, work in progress.
11.2. Informative References
[GMPLS-RTG] Kompella, K., Rekhter, Y., "Routing Extensions in Support
of Generalized Multi-Protocol Label Switching", draft-ietf-ccamp-
gmpls-routing-09.txt (work in progress)
[OSPF-G] Kompella, K., Rekhter, Y., "OSPF extensions in support of
Generalized Multi-protocol Label Switching", draft-ietf-ccamp-ospf-
gmpls-extensions-12.txt, work in progress.
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[IS-IS-G] Kompella, K., Rekhter, Y., "IS-IS extensions in support of
Generalized Multi-protocol Label Switching", draft-ietf-isis-gmpls-
extensions-19.txt, work in progress.
[INT-AREA-REQ] Le Roux, J.L., Vasseur, J.P., Boyle, J. et al,
"Requirements for inter-area MPLS Traffic Engineering", RFC4105, June
2005.
[INT-AS-REQ] Zhang, R., Vasseur, J.P. et al, "MPLS Inter-AS Traffic
Engineering Requirements", draft-ietf-tewg-interas-mpls-te-req, work
in progress.
[INT-DOMAIN-FRWK] Farrel, A., Vasseur, J.P., Ayyangar, A., "A
Framework for Inter-Domain MPLS Traffic Engineering", draft-ietf-
ccamp-inter-domain-framework, work in progress.
12. Editors' Address
Jean-Philippe Vasseur
Cisco Systems, Inc.
300 Beaver Brook Road
Boxborough , MA - 01719
USA
Email: jpv@cisco.com
Jean-Louis Le Roux
France Telecom
2, avenue Pierre-Marzin
22307 Lannion Cedex
FRANCE
Email: jeanlouis.leroux@francetelecom.com
Full Copyright Statement
Copyright (C) The Internet Society (2005).
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."
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