draft-ietf-mpls-number-0-bw-te-lsps-01.txt   draft-ietf-mpls-number-0-bw-te-lsps-02.txt 
Networking Working Group JP. Vasseur, Ed. Networking Working Group JP. Vasseur, Ed.
Internet-Draft Cisco Systems, Inc Internet-Draft Cisco Systems, Inc
Expires: November 25, 2006 Matthew. R. Meyer Expires: December 22, 2006 Matthew. R. Meyer
Global Crossing Global Crossing
K. Kumaki K. Kumaki
KDDI Corporation KDDI Corporation
Alberto. Tempia Bonda Alberto. Tempia Bonda
Telecom Italia Telecom Italia
May 24, 2006 June 20, 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 across a link
draft-ietf-mpls-number-0-bw-te-lsps-01 draft-ietf-mpls-number-0-bw-te-lsps-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on November 25, 2006. This Internet-Draft will expire on December 22, 2006.
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 convery some link context of MPLS Traffic Engineering in order to advertise some link
characteristics such as the available bandwidth, traffic enginering characteristics such as the available bandwidth, traffic engineering
metric, adminstrative group and so on. There are various metric, administrative group and so on. There are various
circumstances where it would be useful to also advertise the number circumstances (for example in order to load balance unconstrained TE
of unconstrained Traffic Engineering Label Switched Path(s) (TE LSP) Label Switched Path (LSP) across a set of equal cost paths) where it
signalled across a link. This document specifies a new Link-type would be useful to also advertise the number of unconstrained Traffic
Traffic Engineering sub-TLV used to advertise the number of Engineering Label Switched Path(s) (TE LSP) signalled across a link.
unconstrained TE LSP(s) 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. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
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8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 8
1. Introduction 1. Introduction
A set of Link-type sub-TLVs have been defined for OSPF and ISIS (see 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 [I-D.ietf-isis-te-bis] and [RFC3630]) in the context of MPLS Traffic
Engineering in order to advertise various link characteristics such Engineering in order to advertise various link characteristics such
as the available bandwidth, traffic enginering metric, administrative as the available bandwidth, traffic engineering metric,
group and so on. There are various circumstances where it would be administrative group and so on. There are various circumstances
useful to also advertise the number of unconstrained Traffic (detailed below) where it would be useful to also advertise the
Engineering Label Switch Path(s) (TE LSP). number of unconstrained Traffic Engineering Label Switch Path(s) (TE
LSP).
It is not uncommon to deploy MPLS Traffic Engineering for the sake of It is not uncommon to deploy MPLS Traffic Engineering for the sake of
fast recovery relying on a local protection recovery mechanism such fast recovery relying on a local protection recovery mechanism such
as MPLS TE Fast Reroute (see [RFC4090]). In this case, a deployment as MPLS TE Fast Reroute (see [RFC4090]). In this case, a deployment
model consists of deploying a full mesh of unconstrained TE LSPs model consists of deploying a full mesh of unconstrained TE LSPs
between a set of LSRs and protect these TE LSPs with pre-established between a set of LSRs and protect these TE LSPs with pre-established
backup tunnels against link, SRLG and/or node failures. The traffic backup tunnels against link, SRLG and/or node failures. The traffic
routed onto such unconstrained TE LSP simply follows the IGP shortest routed onto such unconstrained TE LSP simply follows the IGP shortest
path but is protected with MPLS TE Fast Reroute. path but is protected with MPLS TE Fast Reroute.
With MPLS Traffic Engineering a usual rerouting criteria is the With MPLS Traffic Engineering a usual rerouting criteria is the
discovery of a better path for a TE LSP where a better path is 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; defined as a path with a lower cost according to a specific metric;
other metric such that the percentage of reserved bandwidth or the other metric such that the percentage of reserved bandwidth or the
number of hops can also be used. Unfortunately, for instance in the number of hops can also be used. Unfortunately, for instance in the
presence of ECMPs (Equal Cost Multi-Paths) in symetrical networks presence of ECMPs (Equal Cost Multi-Paths) in symmetrical networks
when unconstrained TE LSP are used, such metrics are usually when unconstrained TE LSP are used, such metrics are usually
inneffective and may lead to poorly load balanced traffic. If the ineffective and may lead to poorly load balanced traffic. If the
number of unconstrained TE LSPs traversing each link in the network number of unconstrained TE LSPs traversing each link in the network
is known, various algorithms can be designed so as to efficiently is known, various algorithms can be designed so as to efficiently
load balance the traffic carried by such unconstrained TE LSPs. As load balance the traffic carried onto such unconstrained TE LSPs. As
currently defined in [RFC3630] and [I-D.ietf-isis-te-bis] the currently defined in [RFC3630] and [I-D.ietf-isis-te-bis] the
information related to the number of unconstrained TE LSP(s) is not information related to the number of unconstrained TE LSP(s) is not
available. This document specifies a new Link-type Traffic available. This document specifies a new Link-type Traffic
Engineering sub-TLV used to indicate the number of unconstrained TE Engineering sub-TLV used to indicate the number of unconstrained TE
LSP signalled across a link. LSP signalled across a link.
Note that the specification of load balancing algorithms is outside Note that the specification of load balancing algorithms is outside
of the scope of this document and merely listed for the sake of of the scope of this document and merely listed for the sake of
illustration of the motivation for gathering such information. illustration of the motivation for gathering such information.
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Note that the specification of load balancing algorithms is outside Note that the specification of load balancing algorithms is outside
of the scope of this document and merely listed for the sake of of the scope of this document and merely listed for the sake of
illustration of the motivation for gathering such information. illustration of the motivation for gathering such information.
Furthermore, the knowledge of the number of unconstrained TE LSPs Furthermore, the knowledge of the number of unconstrained TE LSPs
signalled across each link can be used for other purposes (e.g. signalled across each link can be used for other purposes (e.g.
management, ...). management, ...).
2. Terminology 2. Terminology
Terminology used in this document 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 metric Unconstrained TE LSP: A TE LSP signalled with a bandwidth equal to 0.
equal to 0.
3. Protocol extensions 3. Protocol extensions
A new Sub-TLV named NB-O-BW-LSP is defined that specifies the number A new Sub-TLV named NB-O-BW-LSP is defined that specifies the number
of unconstrained TE LSPs signalled across a link. of unconstrained TE LSPs signalled across a link.
3.1. IS-IS 3.1. IS-IS
The NB-0-BW-LSP TLV is OPTIONAL and MUST appear at most once within The NB-0-BW-LSP sub-TLV is OPTIONAL and MUST appear at most once
the extended IS reachability TLV (type 22) specified in [I-D.ietf- within the extended IS reachability TLV (type 22) specified in
isis-te-bis]. [I-D.ietf-isis-te-bis].
The IS-IS NB-0-BW-LSP TLV format is defined below: The IS-IS NB-0-BW-LSP 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 = 19)
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 is OPTIONAL and MUST appear at most once within the The NB-0-BW-LSP sub-TLV is OPTIONAL and MUST appear at most once
Link TLV (Type 2) that is itself carried within the Traffic within the Link TLV (Type 2) that is itself carried within the
Engineering LSA specified in [RFC3630]. Traffic Engineering LSA specified in [RFC3630].
The OSPF NB-0-BW-LSP TLV format is defined below: The OSPF NB-0-BW-LSP 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 = 19)
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 (). to govern the origination of updated OSPF LSA or ISIS LSP. Similarly
Similalry to other MPLS Traffic Engineering link characteristics, to other MPLS Traffic Engineering link characteristics, LSA/LSP
LSA/LSP origination trigger mechanisms are outside of the scope of origination trigger mechanisms are outside of the scope of this
this document. 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 sub-TLV
(NB-0-BW-LSP) carried within the TLV 22 (suggested value =19) (NB-0-BW-LSP) carried within the TLV 22 (suggested value =19)
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 sub-TLV
(NB-0-BW-LSP) carried within the Link TLV (Type 2) of the Traffic (NB-0-BW-LSP) carried within the Link TLV (Type 2) of the Traffic
Engineering LSA (suggested value=19). Engineering LSA (suggested value=19).
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