Network Working Group J.P. Vasseur (Editor)
Cisco Systems, Inc.
IETF Internet Draft J.L. Le Roux (Editor)
France Telecom
Proposed Status: Standard Track
Expires: July 2007 S. Yasukawa
NTT
S. Previdi
P. Psenak
Cisco Systems, Inc.
Paul Mabey
Comcast
December 2006
IGP Routing Protocol Extensions for Discovery of Traffic Engineering
Node Capabilities
draft-ietf-ccamp-te-node-cap-04.txt
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Vasseur, Le Roux, et al. [Page 1]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
Abstract
It is highly desired in several cases, to take into account Traffic
Engineering (TE) node capabilities during Multi Protocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineered
Label Switched Path (TE-LSP) selection, such as for instance the
capability to act as a branch Label Switching Router (LSR) of a
Point-To-MultiPoint (P2MP) LSP. This requires advertising these
capabilities within the Interior Gateway Protocol (IGP). For that
purpose, this document specifies Open Shortest Path First (OSPF) and
Intermediate System-Intermediate System (IS-IS) traffic engineering
extensions for the advertisement of control plane and data plane
traffic engineering node capabilities.
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. Terminology.................................................3
2. Introduction................................................3
3. TE Node Capability Descriptor...............................4
3.1. Description.................................................4
3.2. Required Information........................................4
4. TE Node Capability Descriptor TLV formats...................5
4.1. OSPF TE Node Capability Descriptor TLV format...............5
4.2. IS-IS TE Node Capability Descriptor sub-TLV format..........6
5. Elements of procedure.......................................7
5.1. OSPF........................................................7
5.2. IS-IS.......................................................8
6. Backward compatibility......................................8
7. Security Considerations.....................................9
8. IANA considerations.........................................9
8.1. OSPF TLV....................................................9
8.2. ISIS sub-TLV................................................9
8.3. Capability Registry.........................................9
9. Acknowledgments............................................10
10. References.................................................10
10.1. Normative references.......................................10
10.2. Informative References.....................................11
11. Editors' Addresses.........................................11
12. Contributors' Addresses....................................11
13. Intellectual Property Statement............................12
Vasseur, Le Roux, et al. [Page 2]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
1. Terminology
This document uses terminologies defined in [RFC3031], [RFC3209] and
[RFC4461].
2. Introduction
Multi Protocol Label Switching-Traffic Engineering (MPLS-TE) routing
([RFC3784], [RFC3630], [OSPFv3-TE]) relies on extensions to link
state Interior Gateway Protocols (IGP) ([IS-IS], [RFC2328],
[RFC2740]) in order to advertise Traffic Engineering (TE) link
information used for constraint based routing. Further Generalized
MPLS (GMPLS) related routing extensions are defined in [RFC4205] and
[RFC4203].
It is desired to complement these routing extensions in order to
advertise TE node capabilities, in addition to TE link information.
These TE node capabilities will be taken into account as constraints
during path selection.
Indeed, it is useful to advertise data plane TE node capabilities,
such as the capability for a Label Switching Router (LSR) to be a
branch LSR or a bud-LSR of a Point-To-MultiPoint (P2MP) Label
Switched Path (LSP). These capabilities can then be taken into
account as constraints when computing the route of TE LSPs.
It is also useful to advertise control plane TE node capabilities
such as the capability to support GMPLS signaling for a packet LSR,
or the capability to support P2MP (Point to Multipoint) TE LSP
signaling. This allows selecting a path that avoids nodes that do
not support a given control plane feature, or triggering a mechanism
to support such nodes on a path. Hence this facilitates backward
compatibility.
For that purpose, this document specifies IGP (OSPF and IS-IS)
extensions in order to advertise data plane and control plane
capabilities of a node.
A new TLV is defined for OSPF, the TE Node Capability Descriptor TLV,
to be carried within the Router Information LSA ([OSPF-CAP]).
A new sub-TLV is defined for IS-IS, the TE Node Capability Descriptor
sub-TLV, to be carried within the IS-IS Capability TLV ([ISIS-CAP]).
Vasseur, Le Roux, et al. [Page 3]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
3. TE Node Capability Descriptor
3.1. Description
LSRs in a network may have distinct control plane and data plane
Traffic Engineering capabilities. The TE Node Capability Descriptor
information defined in this document describes data and control plane
capabilities of an LSR. Such information can be used during path
computation so as to avoid nodes that do not support a given TE
feature either in the control or data plane, or to trigger procedures
to handle these nodes along the path (e.g, trigger LSP hierarchy to
support a legacy transit LSR on a P2MP LSP (see [RSVP-P2MP])).
3.2. Required Information
The TE Node Capability Descriptor contains a variable length set of
bit flags, where each bit corresponds to a given TE node capability.
Five TE Node Capabilities are defined in this document:
- B bit: when set, this flag indicates that the LSR can act
as a branch node on a P2MP LSP (see [RFC4461]);
- E bit: when set, this flag indicates that the LSR can act
as a bud LSR on a P2MP LSP, i.e. an LSR that is both
transit and egress (see [RFC4461]).
- M bit: when set, this flag indicates that the LSR supports
MPLS-TE signaling ([RFC3209]);
- G bit: when set this flag indicates that the LSR supports
GMPLS signaling ([RFC3473]);
- P bit: when set, this flag indicates that the LSR supports
P2MP MPLS-TE signaling ([RSVP-P2MP]).
Note that new capability bits may be added in the future if required.
Vasseur, Le Roux, et al. [Page 4]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
4. TE Node Capability Descriptor TLV formats
4.1. OSPF TE Node Capability Descriptor TLV format
The OSPF TE Node Capability Descriptor TLV is a variable length TLV
that contains a series of bit flags, where each bit correspond to a
TE node capability.
The OSPF TE Node Capability Descriptor TLV is carried within an OSPF
Router Information LSA which is defined in [OSPF-CAP].
The format of the OSPF TE Node Capability Descriptor TLV is the same
as the TLV format used by the Traffic Engineering Extensions to OSPF
[RFC3630]. That is, the TLV is composed of 2 octets for the type, 2
octets specifying the length of the value field and a value field.
The OSPF TE Node Capability Descriptor TLV has the following format:
TYPE To be assigned by IANA (suggested value =1).
LENGTH Variable (multiple of 4).
VALUE Array of units of 32 flags numbered from the most
significant bit as bit zero, where each bit represents
a TE node capability.
The following bits are defined:
Bit Capabilities
0 B bit: P2MP Branch Node capability: When set this indicates
that the LSR can act as a branch node on a P2MP LSP
[RFC4461].
1 E bit: P2MP Bud-LSR capability: When set, this indicates
that the LSR can act as a bud LSR on a P2MP LSP, i.e. an
LSR that is both transit and egress [RFC4461].
2 M bit: If set this indicates that the LSR supports MPLS-TE
signaling ([RFC3209]).
3 G bit: If set this indicates that the LSR supports GMPLS
signaling ([RFC3473]).
4 P bit: If set this indicates that the LSR supports P2MP
MPLS-TE signaling ([RSVP-P2MP]).
5-31 Reserved for future assignments by IANA.
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Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
4.2. IS-IS TE Node Capability Descriptor sub-TLV format
The IS-IS TE Node Capability Descriptor sub-TLV is a variable length
sub-TLV that contains a series of bit flags, where each bit
correspond to a TE node capability.
The IS-IS TE Node Capability Descriptor sub-TLV is carried within an
IS-IS CAPABILITY TLV which is defined in [ISIS-CAP].
The format of the IS-IS TE Node Capability sub-TLV is the same as the
TLV format used by the Traffic Engineering Extensions to IS-IS
[RFC3784]. That is, the TLV is composed of 1 octet for the type, 1
octet specifying the TLV length and a value field.
The IS-IS TE Node Capability Descriptor sub-TLV has the following
format:
TYPE: To be assigned by IANA (Suggested value =1)
LENGTH: Variable
VALUE: Array of units of 8 flags numbered from the most
significant bit as bit zero, where each bit represents
a TE node capability.
The following bits are defined:
Bit Capabilities
0 B bit: P2MP Branch Node capability: When set this indicates
that the LSR can act as a branch node on a P2MP LSP
[RFC4461].
1 E bit: P2MP Bud-LSR capability: When set, this indicates
that the LSR can act as a bud LSR on a P2MP LSP, i.e. an
LSR that is both transit and egress [RFC4461].
2 M bit: If set this indicates that the LSR supports MPLS-TE
signaling ([RFC3209]).
3 G bit: If set this indicates that the LSR supports GMPLS
signaling ([RFC3473]).
4 P bit: If set this indicates that the LSR supports P2MP
MPLS-TE signaling ([RSVP-P2MP]).
5-7 Reserved for future assignments by IANA.
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Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
5. Elements of procedure
5.1. OSPF
The TE Node Capability Descriptor TLV is advertised, within an OSPFv2
Router Information LSA (Opaque type of 4 and Opaque ID of 0)
or an OSPFv3 Router Information LSA (function code of 12) which are
defined in [OSPF-CAP]. As such, elements of procedure are inherited
from those defined in [RFC2328], [RFC2740], and [OSPF-CAP].
The TE Node Capability Descriptor TLV advertises capabilities that
may be taken into account as constraints during path selection. Hence
its flooding scope is area-local, and it MUST be carried within
OSPFv2 type 10 Router Information LSA (as defined in [RFC2370]) or an
OSPFv3 Router Information LSA with the S1 bit set and the S2 bit
cleared (as defined in [RFC2740]).
A router MUST originate a new OSPF router information LSA whenever
the content of the TE Node Capability Descriptor TLV changes or
whenever required by the regular OSPF procedure (LSA refresh (every
LSRefreshTime)).
The TE Node Capability Descriptor TLV is OPTIONAL and MUST NOT appear
more than once in an OSPF Router Information LSA. If a TE Node
Capability Descriptor TLV appears more than once in an OSPF Router
Information LSA, only the first occurrence MUST be processed and
other MUST be ignored.
When an OSPF LSA does not contain any TE Node capability Descriptor
TLV, this means that the TE Capabilities of that LSR are unknown.
Note that a change in any of these capabilities MAY trigger CSPF
computation, but MUST NOT trigger normal SPF computation.
Note also that TE node capabilities are expected to be fairly static.
They may change as the result of configuration change, or software
upgrade. This is expected not to appear more than once a day.
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Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
5.2. IS-IS
The TE Node Capability sub-TLV is carried within an IS-IS CAPABILITY
TLV defined in [IS-IS-CAP]. As such, elements of procedure are
inherited from those defined in [IS-IS-CAP].
The TE Node Capability Descriptor sub-TLV advertises capabilities
that may be taken into account as constraints during path selection.
Hence its flooding is area-local, and MUST be carried within an IS-IS
CAPABILITY TLV having the S flag cleared.
An IS-IS router MUST originate a new IS-IS LSP whenever the content
of any of the TE Node Capability sub-TLV changes or whenever required
by the regular IS-IS procedure (LSP refresh).
The TE Node Capability Descriptor sub-TLV is OPTIONAL and MUST NOT
appear more than once in an ISIS Router Capability TLV.
When an IS-IS LSP does not contain any TE Node capability Descriptor
sub-TLV, this means that the TE Capabilities of that LSR are unknown.
Note that a change in any of these capabilities MAY trigger CSPF
computation, but MUST NOT trigger normal SPF computation.
Note also that TE node capabilities are expected to be fairly static.
They may change as the result of configuration change, or software
upgrade. This is expected not to appear more than once a day.
6. Backward compatibility
The TE Node Capability Descriptor TLVs defined in this document do
not introduce any interoperability issue. For OSPF, a router not
supporting the TE Node Capability Descriptor TLV will just silently
ignore the TLV as specified in [OSPF-CAP]. For IS-IS a router not
supporting the TE Node Capability Descriptor sub-TLV will just
silently ignore the sub-TLV as specified in [IS-IS-CAP].
When the TE Node capability Descriptor TLV is absent, this means that
the TE Capabilities of that LSR are unknown.
The absence of a word of capability flags in OSPF or an octet of
capability flags in IS-IS means that these capabilities are unknown.
Vasseur, Le Roux, et al. [Page 8]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
7. Security Considerations
This document specifies the content of the TE Node Capability
Descriptor TLV in ISIS and OSPF, to be used for (G)MPLS-TE path
computation. As this TLV is not used for SPF computation or normal
routing, the extensions specified here have no direct effect on IP
routing. Tampering with this TLV may have an effect on Traffic
Engineering computation. Mechanisms defined to secure ISIS Link State
PDUs [RFC3567], OSPF LSAs [RFC2154], and their TLVs, can be used to
secure this TLV as well.
8. IANA considerations
8.1. OSPF TLV
IANA is in charge of the assignment of TLV code points for the Router
Information LSA defined in [OSPF-CAP].
IANA will assign a new codepoint for the TE Node Capability
Descriptor TLV defined in this document and carried within the Router
Information LSA (suggested value = 1).
8.2. ISIS sub-TLV
IANA is in charge of the assignment of sub-TLV code points for the
ISIS CAPABILITY TLV defined in [ISIS-CAP].
IANA will assign a new codepoint for the TE Node Capability
Descriptor sub-TLV defined in this document, and carried within the
ISIS CAPABILITY TLV (suggested value = 1).
8.3. Capability Registry
IANA is requested to manage the space of capability bit flags carried
within the OSPF and ISIS TE Node Capability Descriptor, numbering
them in the usual IETF notation starting at zero, with the most
significant bit as bit zero. A single registry must be defined for
both protocols.
New bit numbers may be allocated only by an IETF Consensus action.
Each bit should be tracked with the following qualities:
- Bit number
- Defining RFC
- Name of bit
Five TE node capabilities are defined in this document and must be
assigned by IANA. Here are the suggested values:
1 : B Bit = P2MP Branch LSR capability ([RFC4461])
2 : E bit = P2MP Bud LSR capability ([RFC4461])
3 : M bit = MPLS-TE support ([RFC3209])
4 : G bit = GMPLS support (RFC3473))
5 : P bit = P2MP RSVP-TE support ([RSVP-P2MP])
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Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
9. Acknowledgments
We would like to thank Benoit Fondeviole, Adrian Farrel, Dimitri
Papadimitriou, Acee Lindem and David Ward for their useful comments
and suggestions.
We would also like to thank authors of [RFC4420] and [OSPF-CAP] from
which some text of this document has been inspired.
10. References
10.1. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
RFC 2740, December 1999.
[RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370,
July 1998.
[RFC4461] Yasukawa, S., et. al., "Signaling Requirements for Point to
Multipoint Traffic Engineered MPLS LSPs", RFC4461, April 2006.
[IS-IS] "Intermediate System to Intermediate System Intra-Domain
Routing Exchange Protocol " ISO 10589.
[RFC3630] Katz, D., Yeung, D., Kompella, K., "Traffic Engineering
Extensions to OSPF Version 2", RFC 3630, September 2003.
[RFC3784] 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.
[RFC3567] Li, T. and R. Atkinson, "Intermediate System to
Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567,
July 2003.
[RFC2154] Murphy, S., Badger, M., and B. Wellington, "OSPF with
Digital Signatures", RFC 2154, June 1997.
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Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
[RFC3209] Awduche, D., et. al., "RSVP-TE: Extensions to RSVP for LSP
tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L, et. al., "GMPLS Signaling RSVP-TE extensions",
RFC 3473, January 2003.
[RSVP-P2MP] Aggarwal, Papadimitriou, Yasukawa, et. al. "Extensions to
RSVP-TE for point-to-multipoint TE LSPs", draft-ietf-mpls-rsvp-te-
p2mp, work in progress.
10.2. Informative References
[RFC4203] Kompella, K., Rekhter, Y., "OSPF extensions in support of
Generalized Multi-protocol Label Switching", RFC4203, October 2005.
[RFC4205] Kompella, K., Rekhter, Y., "IS-IS extensions in support of
Generalized Multi-protocol Label Switching", RFC4205, October 2005.
[RFC4420] Farrel, A., and al., "Encoding of attributes for MPLS LSPs
establishment Using RSVP-TE", RFC4420, February 2006.
11. Editors' Addresses
Jean-Philippe Vasseur
Cisco Systems, Inc.
1414 Massachusetts Avenue
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@orange-ftgroup.com
12. Contributors' Addresses
Seisho Yasukawa
NTT
3-9-11 Midori-cho,
Musashino-shi, Tokyo 180-8585, Japan
Email: s.yasukawa@hco.ntt.co.jp
Stefano Previdi
Cisco Systems, Inc
Via Del Serafico 200
Roma, 00142
Italy
Email: sprevidi@cisco.com
Vasseur, Le Roux, et al. [Page 11]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
Peter Psenak
Cisco Systems, Inc
Pegasus Park DE Kleetlaan 6A
Diegmen, 1831
BELGIUM
Email: ppsenak@cisco.com
Paul Mabbey
Comcast
USA
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Vasseur, Le Roux, et al. [Page 12]
Internet Draft draft-ietf-ccamp-te-node-cap-04.txt December 2006
Copyright Statement
Copyright (C) The IETF Trust (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.
Vasseur, Le Roux, et al. [Page 13]