draft-ietf-mpls-number-0-bw-te-lsps-02.txt   draft-ietf-mpls-number-0-bw-te-lsps-03.txt 
Networking Working Group JP. Vasseur, Ed. Networking Working Group JP. Vasseur, Ed.
Internet-Draft Cisco Systems, Inc Internet-Draft Cisco Systems, Inc
Expires: December 22, 2006 Matthew. R. Meyer Intended status: Standards Track Matthew. R. Meyer
Global Crossing Expires: June 1, 2007 Global Crossing
K. Kumaki K. Kumaki
KDDI Corporation KDDI Corporation
Alberto. Tempia Bonda Alberto. Tempia Bonda
Telecom Italia Telecom Italia
June 20, 2006 November 28, 2006
A Link-Type sub-TLV to convey the number of Traffic Engineering Label A Link-Type sub-TLV to convey the number of Traffic Engineering Label
Switch Paths signalled across a link Switch Paths signalled signalled with zero reserved bandwidth across a
draft-ietf-mpls-number-0-bw-te-lsps-02 link
draft-ietf-mpls-number-0-bw-te-lsps-03
Status of this Memo Status of this Memo
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This Internet-Draft will expire on December 22, 2006. This Internet-Draft will expire on June 1, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
Several Link-type sub-TLVs have been defined for OSPF and ISIS in the Several Link-type sub-TLVs have been defined for OSPF and ISIS in the
context of MPLS Traffic Engineering in order to advertise some link context of Multiprotocol Label Switching (MPLS) Traffic Engineering
characteristics such as the available bandwidth, traffic engineering (TE) in order to advertise some link characteristics such as the
metric, administrative group and so on. There are various available bandwidth, traffic engineering metric, administrative group
circumstances (for example in order to load balance unconstrained TE and so on. By making statistical assumption on the aggregated
Label Switched Path (LSP) across a set of equal cost paths) where it traffic carried onto a set of TE Label Switched Paths (LSPs)
would be useful to also advertise the number of unconstrained Traffic signalled with zero bandwdith (referred to as unconstrained TE LSP in
Engineering Label Switched Path(s) (TE LSP) signalled across a link. this document), and with the knowledge of the number of unconstrained
This document specifies a new Link-type Traffic Engineering sub-TLV TE LSPs signalled across a link, algorithms can be designed to load
used to advertise the number of unconstrained TE LSP(s) signalled balance (existing or newly configured) unconstrained TE LSP across a
across a link. set of equal cost paths. This requires the knowledge of the number
of unconstrained TE LSPs signalled across a link. This document
specifies a new Link-type Traffic Engineering sub-TLV used to
advertise the number of unconstrained TE LSP(s) signalled across a
link.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Protocol extensions . . . . . . . . . . . . . . . . . . . . . . 4 3. Protocol extensions . . . . . . . . . . . . . . . . . . . . . . 5
3.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Elements of procedure . . . . . . . . . . . . . . . . . . . . . 5 4. Elements of procedure . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 9
1. Introduction
A set of Link-type sub-TLVs have been defined for OSPF and ISIS (see
[I-D.ietf-isis-te-bis] and [RFC3630]) in the context of MPLS Traffic
Engineering in order to advertise various link characteristics such
as the available bandwidth, traffic engineering metric,
administrative group and so on. There are various circumstances
(detailed below) where it would be useful to also advertise the
number of unconstrained Traffic Engineering Label Switch Path(s) (TE
LSP).
It is not uncommon to deploy MPLS Traffic Engineering for the sake of
fast recovery relying on a local protection recovery mechanism such
as MPLS TE Fast Reroute (see [RFC4090]). In this case, a deployment
model consists of deploying a full mesh of unconstrained TE LSPs
between a set of LSRs and protect these TE LSPs with pre-established
backup tunnels against link, SRLG and/or node failures. The traffic
routed onto such unconstrained TE LSP simply follows the IGP shortest
path but is protected with MPLS TE Fast Reroute.
With MPLS Traffic Engineering a usual rerouting criteria is the 1. Terminology
discovery of a better path for a TE LSP where a better path is
defined as a path with a lower cost according to a specific metric;
other metric such that the percentage of reserved bandwidth or the
number of hops can also be used. Unfortunately, for instance in the
presence of ECMPs (Equal Cost Multi-Paths) in symmetrical networks
when unconstrained TE LSP are used, such metrics are usually
ineffective and may lead to poorly load balanced traffic. If the
number of unconstrained TE LSPs traversing each link in the network
is known, various algorithms can be designed so as to efficiently
load balance the traffic carried onto such unconstrained TE LSPs. As
currently defined in [RFC3630] and [I-D.ietf-isis-te-bis] the
information related to the number of unconstrained TE LSP(s) is not
available. This document specifies a new Link-type Traffic
Engineering sub-TLV used to indicate the number of unconstrained TE
LSP signalled across a link.
Note that the specification of load balancing algorithms is outside Terminology used in this document
of the scope of this document and merely listed for the sake of
illustration of the motivation for gathering such information.
Furthermore, the knowledge of the number of unconstrained TE LSPs CSPF: Constraint Shortest Path First
signalled across each link can be used for other purposes (e.g.
management, ...).
2. Terminology MPLS: Multiprotocol Label Switching
Terminology used in this document
LSA: Link State Advertisement. LSA: Link State Advertisement.
LSP: Link State Packet. LSP: Link State Packet.
LSR: Label Switching Router. LSR: Label Switching Router.
TE LSP: Traffic Engineering Label Switched Path. TE LSP: Traffic Engineering Label Switched Path.
Unconstrained TE LSP: A TE LSP signalled with a bandwidth equal to 0. Unconstrained TE LSP: A TE LSP signalled with a bandwidth equal to 0.
2. Introduction
It is not uncommon to deploy MPLS TE for the sake of fast recovery
relying on a local protection recovery mechanism such as MPLS TE Fast
Reroute (see [RFC4090]). In this case, a deployment model consists
of deploying a full mesh of unconstrained TE LSPs (TE LSP signalled
with zero bandwidth) between a set of LSRs and protecting these TE
LSPs against link, SRLG and/or node failures with pre-established
backup tunnels. The traffic routed onto such unconstrained TE LSP
simply follows the IGP shortest path (since the TE LSP computed by
the path computation algorithm (e.g. CSPF) will be no different than
the IGP shortest path should the TE metric be equal to the IGP
metric) but is protected with MPLS TE Fast Reroute.
When a reoptimization process is triggered for an existing TE LSP,
the decision on whether to reroute that TE LSP onto a different path
is governed by the discovery of a lower cost path satisfying the
constraints (other metric such that the percentage of reserved
bandwidth or the number of hops can also be used). Unfortunately,
for instance in the presence of ECMPs (Equal Cost Multi-Paths) in
symmetrical networks when unconstrained TE LSPs are used, such
metrics are usually ineffective and may lead to poorly load balanced
traffic.
By making statistical assumption on the aggregated traffic carried
onto a set of TE LSPs signalled with no bandwidth requirement
(referred to as unconstrained TE LSP in this document), algorithms
can be designed to load balance (existing or newly configured)
unconstrained TE Label Switched Path (LSP) across a set of equal cost
paths. This requires the knowledge of the number of unconstrained
Traffic Engineering Label Switched Path(s) (TE LSP) signalled across
a link.
A set of Link-type sub-TLVs have been defined for OSPF and IS-IS (see
[RFC3630] and [RFC3784]) in the context of MPLS Traffic Engineering
in order to advertise various link characteristics such as the
available bandwidth, traffic engineering metric, administrative group
and so on. As currently defined in [RFC3630] and [RFC3784] the
information related to the number of unconstrained TE LSP(s) is not
available. This document specifies a new Link-type Traffic
Engineering sub-TLV used to indicate the number of unconstrained TE
LSPs signalled across a link.
Note that the specification of load balancing algorithms is outside
of the scope of this document and merely listed for the sake of
illustration of the motivation for gathering such information.
TE LSPs signalled with zero bandwidth that are configured and
provisioned through a management system are not included in the count
that is reported.
Furthermore, the knowledge of the number of unconstrained TE LSPs
signalled across each link can be used for other purposes (for
example to evaluate the number of affected TE LSPs in case of a link
failure).
3. Protocol extensions 3. Protocol extensions
A new Sub-TLV named NB-O-BW-LSP is defined that specifies the number The Number of 0-bandwidth TE LSP(s) Sub-TLV is defined that specifies
of unconstrained TE LSPs signalled across a link. the number of TE LSPs signalled with zero bandwidth across a link.
3.1. IS-IS 3.1. IS-IS
The NB-0-BW-LSP sub-TLV is OPTIONAL and MUST appear at most once The Number of 0-bandwidth TE LSP(s) sub-TLV is OPTIONAL and MUST
within the extended IS reachability TLV (type 22) specified in appear at most once within the extended IS reachability TLV (type 22)
[I-D.ietf-isis-te-bis]. specified in [RFC3784]. If a second instance of the Number of
0-bandwidth TE LSP(s) sub-TLV is present, the receiving system MUST
only process the first instance of the sub-TLV.
The IS-IS NB-0-BW-LSP sub-TLV format is defined below: The IS-IS Number of 0-bandwidth TE LSP(s) sub-TLV format is defined
below:
Type (1 octet): To be assigned by IANA (suggested value = 19) Type (1 octet): To be assigned by IANA (suggested value = 18)
Length (1 octet): 4 Length (1 octet): 4
Value (4 octets): number of unconstrained TE LSP(s) signalled across Value (4 octets): number of unconstrained TE LSP(s) signalled across
the link. the link.
3.2. OSPF 3.2. OSPF
The NB-0-BW-LSP sub-TLV is OPTIONAL and MUST appear at most once The Number of 0-bandwidth TE LSP(s) sub-TLV is OPTIONAL and MUST
within the Link TLV (Type 2) that is itself carried within the appear at most once within the Link TLV (Type 2) that is itself
Traffic Engineering LSA specified in [RFC3630]. carried within the Traffic Engineering LSA specified in [RFC3630] or
the OSPFv3 Intra-Area-TE LSA (function code 10) defined in
[OSPFv3-TE]. If a second instance of the Number of
0-bandwidth TE LSP(s) sub-TLV is present, the receiving
system MUST only process the first instance of the sub-TLV.
The OSPF NB-0-BW-LSP sub-TLV format is defined below: The OSPF Number of 0-bandwidth TE LSP(s) sub-TLV format is defined
below:
Type (2 octets): To be assigned by IANA (suggested value = 19) Type (2 octets): To be assigned by IANA (suggested value = 18)
Length (2 octets): 4 Length (2 octets): 4
Value (4 octets): number of unconstrained TE LSP(s) signalled across Value (4 octets): number of unconstrained TE LSP(s) signalled across
the link. the link.
4. Elements of procedure 4. Elements of procedure
An implementation may decide to implement a dual-thresholds mechanism An implementation MAY decide to implement a dual-thresholds mechanism
to govern the origination of updated OSPF LSA or ISIS LSP. Similarly based on the number of unconstrained TE LSPs to govern the
to other MPLS Traffic Engineering link characteristics, LSA/LSP origination of updated OSPF LSA or ISIS LSP. Similarly to other MPLS
origination trigger mechanisms are outside of the scope of this Traffic Engineering link characteristics, LSA/LSP origination trigger
document. mechanisms are outside of the scope of this document.
5. IANA Considerations 5. IANA Considerations
IANA will assign a new code point for the newly defined IS-IS sub-TLV IANA will assign a new code point for the newly defined IS-IS Number
(NB-0-BW-LSP) carried within the TLV 22 (suggested value =19) of 0-bandwidth TE LSP(s) sub-TLV carried within the TLV 22 (suggested
value =18).
IANA will assign a new code point for the newly defined OSPF sub-TLV IANA will assign a new code point for the newly defined OSPF Number
(NB-0-BW-LSP) carried within the Link TLV (Type 2) of the Traffic of 0-bandwidth TE LSP(s) sub-TLV carried within the Link TLV (Type 2)
Engineering LSA (suggested value=19). of the Traffic Engineering LSA (suggested value=18).
6. Security Considerations 6. Security Considerations
This document raises no new security issues for IS-IS and OSPF. The function described in this document does not create any new
security issues for the OSPF and the IS-IS protocols. Security
considerations are covered in [RFC2328] and [RFC2470] for the base
OSPF protocol and in [RFC1194] for IS-IS.
7. Acknowledgements 7. Acknowledgements
The authors would like to thank Jean-Louis Le Roux for his useful The authors would like to thank Jean-Louis Le Roux, Adrian Farrel,
inputs. Daniel King, Acee Lindem and Loa Anderson for their useful inputs.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-isis-te-bis] [RFC1194] Zimmerman, D., "Finger User Information Protocol",
Li, T. and H. Smit, "IS-IS extensions for Traffic RFC 1194, November 1990.
Engineering", draft-ietf-isis-te-bis-00 (work in
progress), September 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2470] Crawford, M., Narten, T., and S. Thomas, "Transmission of
IPv6 Packets over Token Ring Networks", RFC 2470,
December 1998.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, (TE) Extensions to OSPF Version 2", RFC 3630,
September 2003. September 2003.
[RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)",
RFC 3784, June 2004.
8.2. Informative References 8.2. Informative References
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090, Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005. May 2005.
[OSPFv3-TE] Lindem, A. et al., "Traffic Engineering Extensions to OSPF
version 3", draft-ietf-ospf-ospfv3-traffic, work in progress.
Authors' Addresses Authors' Addresses
JP Vasseur (editor) JP Vasseur (editor)
Cisco Systems, Inc Cisco Systems, Inc
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
Email: jpv@cisco.com Email: jpv@cisco.com
skipping to change at page 8, line 5 skipping to change at page 9, line 5
Email: ke-kumaki@kddi.com Email: ke-kumaki@kddi.com
Alberto Tempia Bonda Alberto Tempia Bonda
Telecom Italia Telecom Italia
via G. Reiss Romoli 274 via G. Reiss Romoli 274
Torino, 10148 Torino, 10148
ITALIA ITALIA
Email: alberto.tempiabonda@telecomitalia.it Email: alberto.tempiabonda@telecomitalia.it
Intellectual Property Statement 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.
Intellectual Property
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
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found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
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such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
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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.
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.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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