draft-ietf-ccamp-gmpls-mln-reqs-05.txt   draft-ietf-ccamp-gmpls-mln-reqs-06.txt 
Network Working Group Kohei Shiomoto (NTT) Network Working Group Kohei Shiomoto (NTT)
Internet-Draft Dimitri Papadimitriou (Alcatel-Lucent) Internet-Draft Dimitri Papadimitriou (Alcatel-Lucent)
Intended Status: Informational Jean-Louis Le Roux (France Telecom) Intended Status: Informational Jean-Louis Le Roux (France Telecom)
Martin Vigoureux (Alcatel-Lucent) Martin Vigoureux (Alcatel-Lucent)
Deborah Brungard (AT&T) Deborah Brungard (AT&T)
Expires: February 2008 August 2007 Expires: April 2008 October 2007
Requirements for GMPLS-based multi-region and Requirements for GMPLS-based multi-region and
multi-layer networks (MRN/MLN) multi-layer networks (MRN/MLN)
draft-ietf-ccamp-gmpls-mln-reqs-05.txt draft-ietf-ccamp-gmpls-mln-reqs-06.txt
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Abstract Abstract
Most of the initial efforts to utilize Generalized MPLS (GMPLS) have Most of the initial efforts to utilize Generalized MPLS (GMPLS)
been related to environments hosting devices with a single switching have been related to environments hosting devices with a single
capability. The complexity raised by the control of such data planes switching capability. The complexity raised by the control of such
is similar to that seen in classical IP/MPLS networks. data planes is similar to that seen in classical IP/MPLS networks.
By extending MPLS to support multiple switching technologies, GMPLS By extending MPLS to support multiple switching technologies, GMPLS
provides a comprehensive framework for the control of a multi-layered provides a comprehensive framework for the control of a multi-
network of either a single switching technology or multiple switching layered network of either a single switching technology or multiple
technologies. switching technologies.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
In GMPLS, a switching technology domain defines a region, and a In GMPLS, a switching technology domain defines a region, and a
network of multiple switching types is referred to in this document network of multiple switching types is referred to in this document
as a Multi-Region Network (MRN). When referring in general to a as a Multi-Region Network (MRN). When referring in general to a
layered network, which may consist of either a single or multiple layered network, which may consist of either a single or multiple
regions, this document uses the term, Multi-Layer Network (MLN). This regions, this document uses the term, Multi-Layer Network (MLN).
document defines a framework for GMPLS based multi-region/multi-layer This document defines a framework for GMPLS based multi-
networks and lists a set of functional requirements. region/multi-layer networks and lists a set of functional
requirements.
Table of Contents Table of Contents
1. Introduction .................................................... 1. Introduction ....................................................
1.1. Scope ......................................................... 1.1. Scope ........................................................ 2.
2. Conventions Used in this Document ............................... Conventions Used in this Document ............................... 2.1.
2.1. List of Acronyms .............................................. List of Acronyms .............................................. 3.
3. Positioning ..................................................... Positioning ..................................................... 3.1.
3.1. Data Plane Layers and Control Plane Regions ................... Data Plane Layers and Control Plane Regions ................... 3.2.
3.2. Service Layer Networks .. ..................................... Service Layer Networks .. ..................................... 3.3.
3.3. Vertical and Horizontal Interaction and Integration ........... Vertical and Horizontal Interaction and Integration ........... 3.4.
3.4. Motivation .................................................... Motivation .................................................... 4. Key
4. Key Concepts of GMPLS-Based MLNs and MRNs ....................... Concepts of GMPLS-Based MLNs and MRNs ....................... 4.1.
4.1. Interface Switching Capability ................................ Interface Switching Capability ................................ 4.2.
4.2. Multiple Interface Switching Capabilities ..................... Multiple Interface Switching Capabilities ..................... 4.2.1.
4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes ..... Networks with Multi-Switching-Type-Capable Hybrid Nodes ..... 4.3.
4.3. Integrated Traffic Engineering (TE) and Resource Control ...... Integrated Traffic Engineering (TE) and Resource Control ...... 4.3.1.
4.3.1. Triggered Signaling ......................................... Triggered Signaling ......................................... 4.3.2.
4.3.2. FA-LSPs ..................................................... FA-LSPs ..................................................... 4.3.3.
4.3.3. Virtual Network Topology (VNT) .............................. Virtual Network Topology (VNT) .............................. 5.
5. Requirements .................................................... Requirements .................................................... 5.1.
5.1. Handling Single-Switching and Multi-Switching-Type-Capable Handling Single-Switching and Multi-Switching-Type-Capable
Nodes ....................................................... Nodes ....................................................... 5.2.
5.2. Advertisement of the Available Adaptation Resource ............ Advertisement of the Available Adjustment Resource ............ 5.3.
5.3. Scalability ................................................... Scalability ................................................... 5.4.
5.4. Stability ..................................................... Stability ..................................................... 5.5.
5.5. Disruption Minimization ....................................... Disruption Minimization ....................................... 5.6.
5.6. LSP Attribute Inheritance ..................................... LSP Attribute Inheritance ..................................... 5.7.
5.7. Computing Paths With and Without Nested Signaling ............. Computing Paths With and Without Nested Signaling ............. 5.8.
5.8. LSP Resource Utilization ...................................... LSP Resource Utilization ...................................... 5.8.1.
5.8.1. FA-LSP Release and Setup .................................... FA-LSP Release and Setup .................................... 5.8.2.
5.8.2. Virtual TE-Links ............................................ Virtual TE-Links ............................................ 5.9.
5.9. Verification of the LSPs ...................................... Verification of the LSPs ...................................... 6.
6. Security Considerations ......................................... Security Considerations ......................................... 7.
7. IANA Considerations ............................................ IANA Considerations ............................................ 8.
8. Acknowledgements ................................................ Acknowledgements ................................................ 9.
9. References ...................................................... References ...................................................... 9.1.
9.1. Normative Reference ........................................... Normative Reference ........................................... 9.2.
9.2. Informative References ........................................
10. Authors' Addresses .............................................
11. Contributors' Addresses ........................................
12. Intellectual Property Considerations ...........................
13. Full Copyright Statement .......................................
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
Informative References ........................................ 10.
Authors' Addresses ............................................. 11.
Contributors' Addresses ........................................ 12.
Intellectual Property Considerations ........................... 13.
Full Copyright Statement .......................................
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
1. Introduction 1. Introduction
Generalized MPLS (GMPLS) extends MPLS to handle multiple switching Generalized MPLS (GMPLS) extends MPLS to handle multiple switching
technologies: packet switching, layer-2 switching, TDM switching, technologies: packet switching, layer-2 switching, TDM switching,
wavelength switching, and fiber switching (see [RFC3945]). The wavelength switching, and fiber switching (see [RFC3945]). The
Interface Switching Capability (ISC) concept is introduced for these Interface Switching Capability (ISC) concept is introduced for
switching technologies and is designated as follows: PSC (packet these switching technologies and is designated as follows: PSC
switch capable), L2SC (Layer-2 switch capable), TDM (Time Division (packet switch capable), L2SC (Layer-2 switch capable), TDM (Time
Multiplex capable), LSC (lambda switch capable), and FSC (fiber Division Multiplex capable), LSC (lambda switch capable), and FSC
switch capable). (fiber switch capable).
The representation, in a GMPLS control plane, of a switching The representation, in a GMPLS control plane, of a switching
technology domain is referred to as a region [RFC4206]. A switching technology domain is referred to as a region [RFC4206]. A switching
type describes the ability of a node to forward data of a particular type describes the ability of a node to forward data of a
data plane technology, and uniquely identifies a network region. A particular data plane technology, and uniquely identifies a network
layer describes a data plane switching granularity level (e.g., VC4, region. A layer describes a data plane switching granularity level
VC-12). A data plane layer is associated with a region in the control (e.g., VC4, VC-12). A data plane layer is associated with a region
plane (e.g., VC4 is associated with TDM, MPLS is associated with in the control plane (e.g., VC4 is associated with TDM, MPLS is
PSC). However, more than one data plane layer can be associated with associated with PSC). However, more than one data plane layer can
the same region (e.g., both VC4 and VC12 are associated with TDM). be associated with the same region (e.g., both VC4 and VC12 are
Thus, a control plane region, identified by its switching type value associated with TDM). Thus, a control plane region, identified by
(e.g., TDM), can be sub-divided into smaller granularity component its switching type value (e.g., TDM), can be sub-divided into
networks based on "data plane switching layers". The Interface smaller granularity component networks based on "data plane
Switching Capability Descriptor (ISCD) [RFC4202], identifying the switching layers". The Interface Switching Capability Descriptor
interface switching capability (ISC), the encoding type, and the (ISCD) [RFC4202], identifying the interface switching capability
switching bandwidth granularity, enables the characterization of the (ISC), the encoding type, and the switching bandwidth granularity,
associated layers. enables the characterization of the associated layers.
In this document, we define a Multi Layer Network (MLN) to be a TE In this document, we define a Multi Layer Network (MLN) to be a TE
domain comprising multiple data plane switching layers either of the domain comprising multiple data plane switching layers either of
same ISC (e.g. TDM) or different ISC (e.g. TDM and PSC) and the same ISC (e.g. TDM) or different ISC (e.g. TDM and PSC) and
controlled by a single GMPLS control plane instance. We further controlled by a single GMPLS control plane instance. We further
define a particular case of MLNs. A Multi Region Network (MRN) is define a particular case of MLNs. A Multi Region Network (MRN) is
defined as a TE domain supporting at least two different switching defined as a TE domain supporting at least two different switching
technologies (e.g., PSC and TDM) hosted on the same devices (referred technologies (e.g., PSC and TDM) hosted on the same devices
to as multi-switching-type-capable LSRs, see below) and under the (referred to as multi-switching-type-capable LSRs, see below) and
control of a single GMPLS control plane instance. under the control of a single GMPLS control plane instance.
MLNs can be further categorized according to the distribution of the
ISCs among the LSRs:
MLNs can be further categorized according to the distribution of
the ISCs among the LSRs:
- Each LSR may support just one ISC. - Each LSR may support just one ISC.
Such LSRs are known as single-switching-type-capable LSRs. The MLN Such LSRs are known as single-switching-type-capable LSRs.
may comprise a set of single-switching-type-capable LSRs some of The MLN may comprise a set of single-switching-type-capable LSRs
which support different ISCs. some of which support different ISCs.
- Each LSR may support more than one ISC at the same time. - Each LSR may support more than one ISC at the same time.
Such LSRs are known as multi-switching-type-capable LSRs, and can - Such LSRs are known as multi-switching-type-capable LSRs, and
be further classified as either "simplex" or "hybrid" nodes as can be further classified as either "simplex" or "hybrid" nodes
defined in Section 4.2. as defined in Section 4.2.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
- The MLN may be constructed from any combination of single- -
switching-type-capable LSRs and multi-switching-type-capable LSRs. - - The MLN may be constructed from any combination of single-
switching-type-capable LSRs and multi-switching-type-capable
LSRs.
Since GMPLS provides a comprehensive framework for the control of Since GMPLS provides a comprehensive framework for the control of
different switching capabilities, a single GMPLS instance may be used different switching capabilities, a single GMPLS instance may be
to control the MLN/MRN. This enables rapid service provisioning and used to control the MLN/MRN. This enables rapid service
efficient traffic engineering across all switching capabilities. In provisioning and efficient traffic engineering across all switching
such networks, TE Links are consolidated into a single Traffic capabilities. In such networks, TE Links are consolidated into a
Engineering Database (TED). Since this TED contains the information single Traffic Engineering Database (TED). Since this TED contains
relative to all the different regions and layers existing in the the information relative to all the different regions and layers
network, a path across multiple regions or layers can be computed existing in the network, a path across multiple regions or layers
using this TED. can be computed using this TED. Thus optimization of network
resources can be achieved across the whole MLN/MRN.
Thus optimization of network resources can be achieved across the
whole MLN/MRN. Consider, for example, a MRN consisting of packet-
switch capable routers and TDM cross-connects. Assume that a packet
LSP is routed between source and destination packet-switch capable
routers, and that the LSP can be routed across the PSC-region (i.e.,
utilizing only resources of the packet region topology). If the
performance objective for the packet LSP is not satisfied, new TE
links may be created between the packet-switch capable routers across
the TDM-region (for example, VC-12 links) and the LSP can be routed
over those TE links.
Furthermore, even if the LSP can be successfully established across Consider, for example, a MRN consisting of packet- switch capable
the PSC-region, TDM hierarchical LSPs across the TDM region between routers and TDM cross-connects. Assume that a packet LSP is routed
the packet-switch capable routers may be established and used if between source and destination packet-switch capable routers, and
doing so is necessary to meet the operator's objectives for network that the LSP can be routed across the PSC-region (i.e., utilizing
resources availability (e.g., link bandwidth, or adaptation ports only resources of the packet region topology). If the performance
between regions) across the regions. The same considerations hold objective for the packet LSP is not satisfied, new TE links may be
when VC4 LSPs are provisioned to provide extra flexibility for the created between the packet-switch capable routers across the TDM-
VC12 and/or VC11 layers in an MLN. region (for example, VC-12 links) and the LSP can be routed over
those TE links. Furthermore, even if the LSP can be successfully
established across the PSC-region, TDM hierarchical LSPs across the
TDM region between the packet-switch capable routers may be
established and used if doing so is necessary to meet the
operator's objectives for network resources availability (e.g.,
link bandwidth.The same considerations hold when VC4 LSPs are
provisioned to provide extra flexibility for the VC12 and/or VC11
layers in an MLN.
1.1. Scope 1.1. Scope
This document describes the requirements to support multi-region/ This document describes the requirements to support multi-region/
multi-layer networks. There is no intention to specify solution- multi-layer networks. There is no intention to specify solution-
specific and/or protocol elements in this document. The applicability specific and/or protocol elements in this document. The
of existing GMPLS protocols and any protocol extensions to the applicability of existing GMPLS protocols and any protocol
MRN/MLN is addressed in separate documents [MRN-EVAL]. extensions to the MRN/MLN is addressed in separate documents [MRN-
EVAL].
This document covers the elements of a single GMPLS control plane This document covers the elements of a single GMPLS control plane
instance controlling multiple layers within a given TE domain. A instance controlling multiple layers within a given TE domain. A
control plane instance can serve one, two or more layers. Other control plane instance can serve one, two or more layers. Other
possible approaches such as having multiple control plane instances possible approaches such as having multiple control plane instances
serving disjoint sets of layers are outside the scope of this serving disjoint sets of layers are outside the scope of this
document. It is most probable that such a MLN or MRN would be document. It is most probable that such a MLN or MRN would be
operated by a single Service Provider, but this document does not operated by a single Service Provider, but this document does not
exclude the possibility of two layers (or regions) being under exclude the possibility of two layers (or regions) being under
different administrative control (for example, by different Service draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
different administrative control (for example, by different Service
Providers that share a single control plane instance) where the Providers that share a single control plane instance) where the
administrative domains are prepared to share a limited amount of administrative domains are prepared to share a limited amount of
information. information.
For such TE domain to interoperate with edge nodes/domains supporting For such TE domain to interoperate with edge nodes/domains
non-GMPLS interfaces (such as those defined by other SDOs), an supporting non-GMPLS interfaces (such as those defined by other
interworking function may be needed. Location and specification of SDOs), an interworking function may be needed. Location and
this function are outside the scope of this document (because specification of this function are outside the scope of this
interworking aspects are strictly under the responsibility of the document (because interworking aspects are strictly under the
interworking function). responsibility of the interworking function).
This document assumes that the interconnection of adjacent MRN/MLN TE This document assumes that the interconnection of adjacent MRN/MLN
domains makes use of [RFC4726] when their edges also support inter- TE domains makes use of [RFC4726] when their edges also support
domain GMPLS RSVP-TE extensions. inter- domain GMPLS RSVP-TE extensions.
2. Conventions Used in this Document 2. Conventions Used in this Document
Although this is not a protocol specification, the key words "MUST", Although this is not a protocol specification, the key words
"MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"RECOMMENDED", "MAY", and "OPTIONAL" are used in this document to "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are used in
highlight requirements, and are to be interpreted as described in this document to highlight requirements, and are to be interpreted
RFC 2119 [RFC2119]. as described in RFC 2119 [RFC2119].
2.1. List of Acronyms 2.1. List of Acronyms
FA: Forwarding Adjacency FA: Forwarding Adjacency
FA-LSP: Forwarding Adjacency Label Switched Path FA-LSP: Forwarding Adjacency Label Switched Path
FSC: Fiber Switching Capable FSC: Fiber Switching Capable
ISC: Interface Switching Capability ISC: Interface Switching Capability
ISCD: Interface Switching Capability Descriptor ISCD: Interface Switching Capability Descriptor
L2SC: Layer-2 Switching Capable L2SC: Layer-2 Switching Capable
LSC: Lambda Switching Capable LSC: Lambda Switching Capable
skipping to change at page 5, line 54 skipping to change at page 7, line 4
TDM: Time-Division Switch Capable TDM: Time-Division Switch Capable
TE: Traffic Engineering TE: Traffic Engineering
TED: Traffic Engineering Database TED: Traffic Engineering Database
VNT: Virtual Network Topology VNT: Virtual Network Topology
3. Positioning 3. Positioning
A multi-region network (MRN) is always a multi-layer network (MLN) A multi-region network (MRN) is always a multi-layer network (MLN)
since the network devices on region boundaries bring together since the network devices on region boundaries bring together
different ISCs. A MLN, however, is not necessarily a MRN since different ISCs. A MLN, however, is not necessarily a MRN since
multiple layers could be fully contained within a single region. For draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
example, VC12, VC4, and VC4-4c are different layers of the TDM
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
multiple layers could be fully contained within a single region.
For example, VC12, VC4, and VC4-4c are different layers of the TDM
region. region.
3.1. Data Plane Layers and Control Plane Regions 3.1. Data Plane Layers and Control Plane Regions
A data plane layer is a collection of network resources capable of A data plane layer is a collection of network resources capable of
terminating and/or switching data traffic of a particular format terminating and/or switching data traffic of a particular format
[RFC4397]. These resources can be used for establishing LSPs for [RFC4397]. These resources can be used for establishing LSPs for
traffic delivery. For example, VC-11 and VC4-64c represent two traffic delivery. For example, VC-11 and VC4-64c represent two
different layers. different layers.
From the control plane viewpoint, an LSP region is defined as a set From the control plane viewpoint, an LSP region is defined as a set
of one or more data plane layers that share the same type of of one or more data plane layers that share the same type of
switching technology, that is, the same switching type. For example, switching technology, that is, the same switching type. For example,
VC-11, VC-4, and VC-4-7v layers are part of the same TDM region. The VC-11, VC-4, and VC-4-7v layers are part of the same TDM region.
regions that are currently defined are: PSC, L2SC, TDM, LSC, and FSC. The regions that are currently defined are: PSC, L2SC, TDM, LSC,
Hence, an LSP region is a technology domain (identified by the ISC and FSC. Hence, an LSP region is a technology domain (identified by
type) for which data plane resources (i.e., data links) are the ISC type) for which data plane resources (i.e., data links) are
represented into the control plane as an aggregate of TE information represented into the control plane as an aggregate of TE
associated with a set of links (i.e., TE links). For example VC-11 information associated with a set of links (i.e., TE links). For
and VC4-64c capable TE links are part of the same TDM region. example VC-11 and VC4-64c capable TE links are part of the same TDM
Multiple layers can thus exist in a single region network. region. Multiple layers can thus exist in a single region network.
Note also that the region may produce a distinction within the Note also that the region may produce a distinction within the
control plane. Layers of the same region share the same switching control plane. Layers of the same region share the same switching
technology and, therefore, use the same set of technology-specific technology and, therefore, use the same set of technology-specific
signaling objects and technology-specific value setting of TE link signaling objects and technology-specific value setting of TE link
attributes within the control plane, but layers from different attributes within the control plane, but layers from different
regions may use different technology-specific objects and TE regions may use different technology-specific objects and TE
attribute values. This means that it may not be possible to simply attribute values. This means that it may not be possible to simply
forward the signaling message between LSR hosting different switching forward the signaling message between LSR hosting different
technologies because change in some of the signaling objects (for switching technologies because change in some of the signaling
example, the traffic parameters) when crossing a region boundary even objects (for example, the traffic parameters) when crossing a
if a single control plane instance is used to manage the whole MRN. region boundary even if a single control plane instance is used to
We may solve this issue by using triggered signaling (see Section manage the whole MRN. We may solve this issue by using triggered
4.3.1). signaling (see Section 4.3.1).
3.2. Service Layer Networks 3.2. Service Layer Networks
A service provider's network may be divided into different service A service provider's network may be divided into different service
layers. The customer's network is considered from the provider's layers. The customer's network is considered from the provider's
perspective as the highest service layer. It interfaces to the perspective as the highest service layer. It interfaces to the
highest service layer of the service provider's network. Connectivity highest service layer of the service provider's network.
across the highest service layer of the service provider's network Connectivity across the highest service layer of the service
may be provided with support from successively lower service layers. provider's network may be provided with support from successively
Service layers are realized via a hierarchy of network layers located lower service layers. Service layers are realized via a hierarchy
generally in several regions and commonly arranged according to the of network layers located generally in several regions and commonly
switching capabilities of network devices. arranged according to the switching capabilities of network devices.
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
For instance some customers purchase Layer 1 (i.e., transport) For instance some customers purchase Layer 1 (i.e., transport)
services from the service provider, some Layer 2 (e.g., ATM), while services from the service provider, some Layer 2 (e.g., ATM), while
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
others purchase Layer 3 (IP/MPLS) services. The service provider others purchase Layer 3 (IP/MPLS) services. The service provider
realizes the services by a stack of network layers located within one realizes the services by a stack of network layers located within
or more network regions. The network layers are commonly arranged one or more network regions. The network layers are commonly
according to the switching capabilities of the devices in the arranged according to the switching capabilities of the devices in
networks. Thus, a customer network may be provided on top of the the networks. Thus, a customer network may be provided on top of
GMPLS-based multi-region/multi-layer network. For example, a Layer 1 the GMPLS-based multi-region/multi-layer network. For example, a
service (realized via the network layers of TDM, and/or LSC, and/or Layer 1 service (realized via the network layers of TDM, and/or LSC,
FSC regions) may support a Layer 2 network (realized via ATM VP/VC) and/or FSC regions) may support a Layer 2 network (realized via ATM
which may itself support a Layer 3 network (IP/MPLS region). The VP/VC) which may itself support a Layer 3 network (IP/MPLS region).
supported data plane relationship is a data plane client-server The supported data plane relationship is a data plane client-server
relationship where the lower layer provides a service for the higher relationship where the lower layer provides a service for the
layer using the data links realized in the lower layer. higher layer using the data links realized in the lower layer.
Services provided by a GMPLS-based multi-region/multi-layer network Services provided by a GMPLS-based multi-region/multi-layer network
are referred to as "Multi-region/Multi-layer network services". For are referred to as "Multi-region/Multi-layer network services". For
example, legacy IP and IP/MPLS networks can be supported on top of example, legacy IP and IP/MPLS networks can be supported on top of
multi-region/multi-layer networks. It has to be emphasized that multi-region/multi-layer networks. It has to be emphasized that
delivery of such diverse services is a strong motivator for the delivery of such diverse services is a strong motivator for the
deployment of multi-region/multi-layer networks. deployment of multi-region/multi-layer networks.
A customer network may be provided on top of a server GMPLS-based A customer network may be provided on top of a server GMPLS-based
MRN/MLN which is operated by a service provider. For example, a pure MRN/MLN which is operated by a service provider. For example, a
IP and/or an IP/MPLS network can be provided on top of GMPLS-based pure IP and/or an IP/MPLS network can be provided on top of GMPLS-
packet over optical networks [MPLS-GMPLS]. The relationship between based packet over optical networks [MPLS-GMPLS]. The relationship
the networks is a client/server relationship and, such services are between the networks is a client/server relationship and, such
referred to as "MRN/MLN services". In this case, the customer network services are referred to as "MRN/MLN services". In this case, the
may form part of the MRN/MLN, or may be partially separated, for customer network may form part of the MRN/MLN, or may be partially
example to maintain separate routing information but retain common separated, for example to maintain separate routing information but
signaling. retain common signaling.
3.3. Vertical and Horizontal Interaction and Integration 3.3. Vertical and Horizontal Interaction and Integration
Vertical interaction is defined as the collaborative mechanisms Vertical interaction is defined as the collaborative mechanisms
within a network element that is capable of supporting more than one within a network element that is capable of supporting more than
layer or region and of realizing the client/server relationships one layer or region and of realizing the client/server
between the layers or regions. Protocol exchanges between two network relationships between the layers or regions. Protocol exchanges
controllers managing different regions or layers are also a vertical between two network controllers managing different regions or
interaction. Integration of these interactions as part of the control layers are also a vertical interaction. Integration of these
plane is referred to as vertical integration. Thus, this refers to interactions as part of the control plane is referred to as
the collaborative mechanisms within a single control plane instance vertical integration. Thus, this refers to the collaborative
driving multiple network layers part of the same region or not. Such mechanisms within a single control plane instance driving multiple
a concept is useful in order to construct a framework that network layers part of the same region or not. Such a concept is
facilitates efficient network resource usage and rapid service useful in order to construct a framework that facilitates efficient
provisioning in carrier networks that are based on multiple layers, network resource usage and rapid service provisioning in carrier
switching technologies, or ISCs. networks that are based on multiple layers, switching technologies,
or ISCs.
Horizontal interaction is defined as the protocol exchange between draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
network controllers that manage transport nodes within a given layer
or region. For instance, the control plane interaction between two
TDM network elements switching at OC-48 is an example of horizontal
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
interaction. GMPLS protocol operations handle horizontal interactions Horizontal interaction is defined as the protocol exchange between
within the same routing area. The case where the interaction takes network controllers that manage transport nodes within a given
place across a domain boundary, such as between two routing areas layer or region. For instance, the control plane interaction
within the same network layer, is evaluated as part of the inter- between two TDM network elements switching at OC-48 is an example
domain work [RFC4726], and is referred to as horizontal integration. of horizontal interaction. GMPLS protocol operations handle
Thus, horizontal integration refers to the collaborative mechanisms horizontal interactions within the same routing area. The case
between network partitions and/or administrative divisions such as where the interaction takes place across a domain boundary, such as
routing areas or autonomous systems. between two routing areas within the same network layer, is
evaluated as part of the inter- domain work [RFC4726], and is
referred to as horizontal integration. Thus, horizontal integration
refers to the collaborative mechanisms between network partitions
and/or administrative divisions such as routing areas or autonomous
systems.
This distinction needs further clarification when administrative This distinction needs further clarification when administrative
domains match layer/region boundaries. Horizontal interaction is domains match layer/region boundaries. Horizontal interaction is
extended to cover such cases. For example, the collaborative extended to cover such cases. For example, the collaborative
mechanisms in place between two lambda switching capable areas relate mechanisms in place between two lambda switching capable areas
to horizontal integration. On the other hand, the collaborative relate to horizontal integration. On the other hand, the
mechanisms in place between a packet switching capable (e.g., collaborative mechanisms in place between a packet switching
IP/MPLS) domain and a separate time division switching capable capable (e.g., IP/MPLS) domain and a separate time division
(e.g., VC4 SDH) domain over which it operates are part of the switching capable (e.g., VC4 SDH) domain over which it operates are
horizontal integration while it can also be seen as a first step part of the horizontal integration while it can also be seen as a
towards vertical integration. first step towards vertical integration.
3.4. Motivation 3.4. Motivation
The applicability of GMPLS to multiple switching technologies The applicability of GMPLS to multiple switching technologies
provides a unified control and management approach for both LSP provides a unified control and management approach for both LSP
provisioning and recovery. Indeed, one of the main motivations for provisioning and recovery. Indeed, one of the main motivations for
unifying the capabilities and operations of the GMPLS control plane unifying the capabilities and operations of the GMPLS control plane
is the desire to support multi-LSP-region [RFC4206] routing and is the desire to support multi-LSP-region [RFC4206] routing and
Traffic Engineering (TE) capabilities. For instance, this enables Traffic Engineering (TE) capabilities. For instance, this enables
effective network resource utilization of both the Packet/Layer2 LSP effective network resource utilization of both the Packet/Layer2
regions and the Time Division Multiplexing (TDM) or Lambda LSP LSP regions and the Time Division Multiplexing (TDM) or Lambda LSP
regions in high capacity networks. regions in high capacity networks.
The rationales for GMPLS controlled multi-layer/multi-region networks The rationales for GMPLS controlled multi-layer/multi-region
are summarized below: networks are summarized below:
- The maintenance of multiple instances of the control plane on - The maintenance of multiple instances of the control plane on
devices hosting more than one switching capability not only devices hosting more than one switching capability not only
increases the complexity of their interactions but also increases increases the complexity of their interactions but also increases
the total amount of processing individual instances would handle. the total amount of processing individual instances would handle.
- The unification of the addressing spaces helps in avoiding multiple - The unification of the addressing spaces helps in avoiding
identifiers for the same object (a link, for instance, or more multiple identifiers for the same object (a link, for instance,
generally, any network resource). On the other hand such or more generally, any network resource). On the other hand such
aggregation does not impact the separation between the control aggregation does not impact the separation between the control
plane and the data plane. plane and the data plane.
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
- By maintaining a single routing protocol instance and a single TE - By maintaining a single routing protocol instance and a single TE
database per LSR, a unified control plane model removes the database per LSR, a unified control plane model removes the
requirement to maintain a dedicated routing topology per layer and requirement to maintain a dedicated routing topology per layer
therefore does not mandate a full mesh of routing adjacencies as is and therefore does not mandate a full mesh of routing adjacencies
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 as is the case with overlaid control planes.
the case with overlaid control planes.
- The collaboration between technology layers where the control - The collaboration between technology layers where the control
channel is associated with the data channel (e.g. packet/framed channel is associated with the data channel (e.g. packet/framed
data planes) and technology layers where the control channel is not data planes) and technology layers where the control channel is
directly associated with the data channel (SONET/SDH, G.709, etc.) not directly associated with the data channel (SONET/SDH, G.709,
is facilitated by the capability within GMPLS to associate in-band etc.) is facilitated by the capability within GMPLS to associate
control plane signaling to the IP terminating interfaces of the in-band control plane signaling to the IP terminating interfaces
control plane. of the control plane.
- Resource management and policies to be applied at the edges of such - Resource management and policies to be applied at the edges of
a MRN/MLN is made more simple (fewer control to management such a MRN/MLN is made more simple (fewer control to management
interactions) and more scalable (through the use of aggregated interactions) and more scalable (through the use of aggregated
information). information).
- Multi-region/multi-layer traffic engineering is facilitated as - Multi-region/multi-layer traffic engineering is facilitated as
TE-links from distinct regions/layers are stored within the same TE TE-links from distinct regions/layers are stored within the same
Database. TE Database.
4. Key Concepts of GMPLS-Based MLNs and MRNs 4. Key Concepts of GMPLS-Based MLNs and MRNs
A network comprising transport nodes with multiple data plane layers A network comprising transport nodes with multiple data plane
of either the same ISC or different ISCs, controlled by a single layers of either the same ISC or different ISCs, controlled by a
GMPLS control plane instance, is called a Multi-Layer Network (MLN). single GMPLS control plane instance, is called a Multi-Layer
A sub-set of MLNs consists of networks supporting LSPs of different Network (MLN). A sub-set of MLNs consists of networks supporting
switching technologies (ISCs). A network supporting more than one LSPs of different switching technologies (ISCs). A network
switching technology is called a Multi-Region Network (MRN). supporting more than one switching technology is called a Multi-
Region Network (MRN).
4.1. Interface Switching Capability 4.1. Interface Switching Capability
The Interface Switching Capability (ISC) is introduced in GMPLS to The Interface Switching Capability (ISC) is introduced in GMPLS to
support various kinds of switching technology in a unified way support various kinds of switching technology in a unified way
[RFC4202]. An ISC is identified via a switching type. [RFC4202]. An ISC is identified via a switching type.
A switching type (also referred to as the switching capability type) A switching type (also referred to as the switching capability
describes the ability of a node to forward data of a particular data type) describes the ability of a node to forward data of a
plane technology, and uniquely identifies a network region. The particular data plane technology, and uniquely identifies a network
following ISC types (and, hence, regions) are defined: PSC, L2SC, region. The following ISC types (and, hence, regions) are defined:
TDM, LSC, and FSC. Each end of a data link (more precisely, each PSC, L2SC, TDM, LSC, and FSC. Each end of a data link (more
interface connecting a data link to a node) in a GMPLS network is precisely, each interface connecting a data link to a node) in a
associated with an ISC. GMPLS network is associated with an ISC.
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
The ISC value is advertised as a part of the Interface Switching The ISC value is advertised as a part of the Interface Switching
Capability Descriptor (ISCD) attribute (sub-TLV) of a TE link end Capability Descriptor (ISCD) attribute (sub-TLV) of a TE link end
associated with a particular link interface [RFC4202]. Apart from the associated with a particular link interface [RFC4202]. Apart from
ISC, the ISCD contains information including the encoding type, the the ISC, the ISCD contains information including the encoding type,
bandwidth granularity, and the unreserved bandwidth on each of eight the bandwidth granularity, and the unreserved bandwidth on each of
priorities at which LSPs can be established. The ISCD does not eight priorities at which LSPs can be established. The ISCD does
"identify" network layers, it uniquely characterizes information not "identify" network layers, it uniquely characterizes
associated to one or more network layers. information associated to one or more network layers.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
TE link end advertisements may contain multiple ISCDs. This can be TE link end advertisements may contain multiple ISCDs. This can be
interpreted as advertising a multi-layer (or multi-switching-capable) interpreted as advertising a multi-layer (or multi-switching-
TE link end. That is, the TE link end (and therefore the TE link) is capable) TE link end. That is, the TE link end (and therefore the
present in multiple layers. TE link) is present in multiple layers.
4.2. Multiple Interface Switching Capabilities 4.2. Multiple Interface Switching Capabilities
In an MLN, network elements may be single-switching-type-capable or In an MLN, network elements may be single-switching-type-capable or
multi-switching-type-capable nodes. Single-switching-type-capable multi-switching-type-capable nodes. Single-switching-type-capable
nodes advertise the same ISC value as part of their ISCD sub-TLV(s) nodes advertise the same ISC value as part of their ISCD sub-TLV(s)
to describe the termination capabilities of each of their TE Link(s). to describe the termination capabilities of each of their TE
This case is described in [RFC4202]. Link(s). This case is described in [RFC4202].
Multi-switching-type-capable LSRs are classified as "simplex" or Multi-switching-type-capable LSRs are classified as "simplex" or
"hybrid" nodes. Simplex and hybrid nodes are categorized according to "hybrid" nodes. Simplex and hybrid nodes are categorized according
the way they advertise these multiple ISCs: to the way they advertise these multiple ISCs:
- A simplex node can terminate data links with different switching - A simplex node can terminate data links with different switching
capabilities where each data link is connected to the node by a capabilities where each data link is connected to the node by a
separate link interface. So, it advertises several TE Links each separate link interface. So, it advertises several TE Links each
with a single ISC value carried in its ISCD sub-TLV. For example, with a single ISC value carried in its ISCD sub-TLV. For example,
an LSR with PSC and TDM links each of which is connected to the LSR an LSR with PSC and TDM links each of which is connected to the
via a separate interface. LSR via a separate interface.
- A hybrid node can terminate data links with different switching - A hybrid node can terminate data links with different switching
capabilities where the data links are connected to the node by the capabilities where the data links are connected to the node by
same interface. So, it advertises a single TE Link containing more the same interface. So, it advertises a single TE Link
than one ISCD each with a different ISC value. For example, a node containing more than one ISCD each with a different ISC value.
may terminate PSC and TDM data links and interconnect those For example, a node may terminate PSC and TDM data links and
external data links via internal links. The external interfaces interconnect those external data links via internal links. The
connected to the node have both PSC and TDM capabilities. external interfaces connected to the node have both PSC and TDM
capabilities.
Additionally, TE link advertisements issued by a simplex or a hybrid Additionally, TE link advertisements issued by a simplex or a
node may need to provide information about the node's internal hybrid node may need to provide information about the node's
adaptation capabilities between the switching technologies supported. internal adjustment capacity between the switching technologies
That is, the node's capability to perform layer border node supported. The term "adjustment" capacity refers to the property of
functions. This information allows path computation to select an end- an hybrid node to interconnect different switching capabilities it
to-end multi-layer or multi-region path that includes links of provides through its external interfaces.. This information allows
different switching capabilities that are joined by LSRs that can path computation to select an end- to-end multi-layer or multi-
adapt the signal between the links. draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes region path that includes links of different switching capabilities
that are joined by LSRs that can adapt the signal between the links.
This type of network contains at least one hybrid node, zero or more 4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes
simplex nodes, and a set of single-switching-type-capable nodes. This type of network contains at least one hybrid node, zero or
more simplex nodes, and a set of single-switching-type-capable
nodes.
Figure 1 shows an example hybrid node. The hybrid node has two Figure 1 shows an example hybrid node. The hybrid node has two
switching elements (matrices), which support, for instance, TDM and switching elements (matrices), which support, for instance, TDM and
PSC switching respectively. The node terminates a PSC and a TDM link PSC switching respectively. The node terminates a PSC and a TDM
(Link1 and Link2 respectively). It also has an internal link link (Link1 and Link2 respectively). It also has an internal link
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
connecting the two switching elements. connecting the two switching elements.
The two switching elements are internally interconnected in such a The two switching elements are internally interconnected in such a
way that it is possible to terminate some of the resources of, say, way that it is possible to terminate some of the resources of, say,
Link2 and provide adaptation for PSC traffic received/sent over the Link2 and provide adjustment for PSC traffic received/sent over the
PSC interface (#b). This situation is modeled in GMPLS by connecting PSC interface (#b). This situation is modeled in GMPLS by
the local end of Link2 to the TDM switching element via an additional connecting the local end of Link2 to the TDM switching element via
interface realizing the termination/adaptation function. There are an additional interface realizing the termination/adjustment
two possible ways to set up PSC LSPs through the hybrid node. function. There are two possible ways to set up PSC LSPs through
Available resource advertisement (i.e., Unreserved and Min/Max LSP the hybrid node. Available resource advertisement (i.e., Unreserved
Bandwidth) should cover both of these methods. and Min/Max LSP Bandwidth) should cover both of these methods.
Network element Network element
............................. .............................
: -------- : : -------- :
: | PSC | : : | PSC | :
Link1 -------------<->--|#a | : Link1 -------------<->--|#a | :
: | | : : | | :
: +--<->---|#b | : : +--<->---|#b | :
: | -------- : : | -------- :
: | ---------- : : | ---------- :
skipping to change at page 11, line 38 skipping to change at page 12, line 50
+PSC : | | : +PSC : | | :
Link2 ------------<->--|#d | : Link2 ------------<->--|#d | :
: ---------- : : ---------- :
:............................ :............................
Figure 1. Hybrid node. Figure 1. Hybrid node.
4.3. Integrated Traffic Engineering (TE) and Resource Control 4.3. Integrated Traffic Engineering (TE) and Resource Control
In GMPLS-based multi-region/multi-layer networks, TE Links may be In GMPLS-based multi-region/multi-layer networks, TE Links may be
consolidated into a single Traffic Engineering Database (TED) for use consolidated into a single Traffic Engineering Database (TED) for
by the single control plane instance. Since this TED contains the use by the single control plane instance. Since this TED contains
information relative to all the layers of all regions in the network, the information relative to all the layers of all regions in the
a path across multiple layers (possibly crossing multiple regions) network, a path across multiple layers (possibly crossing multiple
can be computed using the information in this TED. Thus, optimization regions) can be computed using the information in this TED. Thus,
of network resources across the multiple layers of the same region draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
and across multiple regions can be achieved.
These concepts allow for the operation of one network layer over the optimization of network resources across the multiple layers of the
topology (that is, TE links) provided by other network layers (for same region and across multiple regions can be achieved.
example, the use of a lower layer LSC LSP carrying PSC LSPs). In
turn, a greater degree of control and inter-working can be achieved, These concepts allow for the operation of one network layer over
including (but not limited too): the topology (that is, TE links) provided by other network layers
(for example, the use of a lower layer LSC LSP carrying PSC LSPs).
In turn, a greater degree of control and inter-working can be
achieved, including (but not limited too):
- Dynamic establishment of Forwarding Adjacency (FA) LSPs - Dynamic establishment of Forwarding Adjacency (FA) LSPs
[RFC4206] (see Sections 4.3.2 and 4.3.3). [RFC4206] (see Sections 4.3.2 and 4.3.3).
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
- Provisioning of end-to-end LSPs with dynamic triggering of FA - Provisioning of end-to-end LSPs with dynamic triggering of FA
LSPs. LSPs.
Note that in a multi-layer/multi-region network that includes multi- Note that in a multi-layer/multi-region network that includes
switching-type-capable nodes, an explicit route used to establish an multi- switching-type-capable nodes, an explicit route used to
end-to-end LSP can specify nodes that belong to different layers or establish an end-to-end LSP can specify nodes that belong to
regions. In this case, a mechanism to control the dynamic creation of different layers or regions. In this case, a mechanism to control
FA-LSPs may be required (see Sections 4.3.2 and 4.3.3). the dynamic creation of FA-LSPs may be required (see Sections 4.3.2
and 4.3.3).
There is a full spectrum of options to control how FA-LSPs are There is a full spectrum of options to control how FA-LSPs are
dynamically established. The process can be subject to the control of dynamically established. The process can be subject to the control
a policy, which may be set by a management component, and which may of a policy, which may be set by a management component, and which
require that the management plane is consulted at the time that the may require that the management plane is consulted at the time that
FA-LSP is established. Alternatively, the FA-LSP can be established the FA-LSP is established. Alternatively, the FA-LSP can be
at the request of the control plane without any management control. established at the request of the control plane without any
management control.
4.3.1. Triggered Signaling 4.3.1. Triggered Signaling
When an LSP crosses the boundary from an upper to a lower layer, it When an LSP crosses the boundary from an upper to a lower layer, it
may be nested into a lower layer FA-LSP that crosses the lower layer. may be nested into a lower layer FA-LSP that crosses the lower
From a signaling perspective, there are two alternatives to establish layer. From a signaling perspective, there are two alternatives to
the lower layer FA-LSP: static (pre-provisioned) and dynamic establish the lower layer FA-LSP: static (pre-provisioned) and
(triggered). A pre-provisioned FA-LSP may be initiated either by the dynamic (triggered). A pre-provisioned FA-LSP may be initiated
operator or automatically using features like TE auto-mesh either by the operator or automatically using features like TE
[RFC4972]. If such a lower layer LSP does not already exist, the LSP auto-mesh [RFC4972]. If such a lower layer LSP does not already
may be established dynamically. Such a mechanism is referred to as exist, the LSP may be established dynamically. Such a mechanism is
"triggered signaling". referred to as "triggered signaling".
4.3.2. FA-LSPs 4.3.2. FA-LSPs
Once an LSP is created across a layer from one layer border node to Once an LSP is created across a layer from one layer border node
another, it can be used as a data link in an upper layer. to another, it can be used as a data link in an upper layer.
Furthermore, it can be advertised as a TE-link, allowing other
nodes to consider the LSP as a TE link for their path computation
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
Furthermore, it can be advertised as a TE-link, allowing other nodes
to consider the LSP as a TE link for their path computation
[RFC4206]. An LSP created either statically or dynamically by one [RFC4206]. An LSP created either statically or dynamically by one
instance of the control plane and advertised as a TE link into the instance of the control plane and advertised as a TE link into the
same instance of the control plane is called a Forwarding Adjacency same instance of the control plane is called a Forwarding Adjacency
LSP (FA-LSP). The FA-LSP is advertised as a TE link, and that TE link LSP (FA-LSP). The FA-LSP is advertised as a TE link, and that TE
is called a Forwarding Adjacency (FA). An FA has the special link is called a Forwarding Adjacency (FA). An FA has the special
characteristic of not requiring a routing adjacency (peering) between characteristic of not requiring a routing adjacency (peering)
its end points yet still guaranteeing control plane connectivity between its end points yet still guaranteeing control plane
between the FA-LSP end points based on a signaling adjacency. An FA connectivity between the FA-LSP end points based on a signaling
is a useful and powerful tool for improving the scalability of GMPLS adjacency. An FA is a useful and powerful tool for improving the
Traffic Engineering (TE) capable networks since multiple higher layer scalability of GMPLS Traffic Engineering (TE) capable networks
LSPs may be nested (aggregated) over a single FA-LSP. since multiple higher layer LSPs may be nested (aggregated) over a
single FA-LSP.
The aggregation of LSPs enables the creation of a vertical (nested) The aggregation of LSPs enables the creation of a vertical (nested)
LSP Hierarchy. A set of FA-LSPs across or within a lower layer can be LSP Hierarchy. A set of FA-LSPs across or within a lower layer can
used during path selection by a higher layer LSP. Likewise, the be used during path selection by a higher layer LSP. Likewise, the
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
higher layer LSPs may be carried over dynamic data links realized via higher layer LSPs may be carried over dynamic data links realized
LSPs (just as they are carried over any "regular" static data links). via LSPs (just as they are carried over any "regular" static data
This process requires the nesting of LSPs through a hierarchical links). This process requires the nesting of LSPs through a
process [RFC4206]. The TED contains a set of LSP advertisements from hierarchical process [RFC4206]. The TED contains a set of LSP
different layers that are identified by the ISCD contained within the advertisements from different layers that are identified by the
TE link advertisement associated with the LSP [RFC4202]. ISCD contained within the TE link advertisement associated with the
LSP [RFC4202].
If a lower layer LSP is not advertised as an FA, it can still be used If a lower layer LSP is not advertised as an FA, it can still be
to carry higher layer LSPs across the lower layer. For example, if used to carry higher layer LSPs across the lower layer. For example,
the LSP is set up using triggered signaling, it will be used to carry if the LSP is set up using triggered signaling, it will be used to
the higher layer LSP that caused the trigger. Further, the lower carry the higher layer LSP that caused the trigger. Further, the
layer remains available for use by other higher layer LSPs arriving lower layer remains available for use by other higher layer LSPs
at the boundary. arriving at the boundary.
Under some circumstances it may be useful to control the Under some circumstances it may be useful to control the
advertisement of LSPs as FAs during the signaling establishment of advertisement of LSPs as FAs during the signaling establishment of
the LSPs [DYN-HIER]. the LSPs [DYN-HIER].
4.3.3. Virtual Network Topology (VNT) 4.3.3. Virtual Network Topology (VNT)
A set of one or more of lower-layer LSPs provides information for A set of one or more of lower-layer LSPs provides information for
efficient path handling in upper-layer(s) of the MLN, or, in other efficient path handling in upper-layer(s) of the MLN, or, in other
words, provides a virtual network topology (VNT) to the upper-layers. words, provides a virtual network topology (VNT) to the upper-
For instance, a set of LSPs, each of which is supported by an LSC layers. For instance, a set of LSPs, each of which is supported by
LSP, provides a virtual network topology to the layers of a PSC an LSC LSP, provides a virtual network topology to the layers of a
region, assuming that the PSC region is connected to the LSC region. PSC region, assuming that the PSC region is connected to the LSC
Note that a single lower-layer LSP is a special case of the VNT. The region. Note that a single lower-layer LSP is a special case of the
virtual network topology is configured by setting up or tearing down VNT. The virtual network topology is configured by setting up or
the lower layer LSPs. By using GMPLS signaling and routing protocols, tearing down the lower layer LSPs. By using GMPLS signaling and
the virtual network topology can be adapted to traffic demands. routing protocols, the virtual network topology can be adapted to
traffic demands.
A lower-layer LSP appears as a TE-link in the VNT. Whether the A lower-layer LSP appears as a TE-link in the VNT. Whether the
diversely-routed lower-layer LSPs are used or not, the routes of diversely-routed lower-layer LSPs are used or not, the routes of
lower-layer LSPs are hidden from the upper layer in the VNT. Thus, lower-layer LSPs are hidden from the upper layer in the VNT. Thus,
the VNT simplifies the upper-layer routing and traffic engineering the VNT simplifies the upper-layer routing and traffic engineering
decisions by hiding the routes taken by the lower-layer LSPs. decisions by hiding the routes taken by the lower-layer LSPs.
However, hiding the routes of the lower-layer LSPs may lose important However, hiding the routes of the lower-layer LSPs may lose
information that is needed to make the higher-layer LSPs reliable. important information that is needed to make the higher-layer LSPs
For instance, the routing and traffic engineering in the IP/MPLS reliable. For instance, the routing and traffic engineering in the
layer does not usually consider how the IP/MPLS TE links are formed IP/MPLS layer does not usually consider how the IP/MPLS TE links
from optical paths that are routed in the fiber layer. Two optical are formed from optical paths that are routed in the fiber layer.
paths may share the same fiber link in the lower-layer and therefore Two optical paths may share the same fiber link in the lower-layer
they may both fail if the fiber link is cut. Thus the shared risk and therefore they may both fail if the fiber link is cut. Thus the
properties of the TE links in the VNT must be made available to the shared risk properties of the TE links in the VNT must be made
higher layer during path computation. Further, the topology of the available to the higher layer during path computation. Further, the
VNT should be designed so that any single fiber cut does not bisect topology of the VNT should be designed so that any single fiber cut
the VNT. These issues are addressed later in this document. draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
does not bisect the VNT. These issues are addressed later in this
document.
Reconfiguration of the virtual network topology may be triggered by Reconfiguration of the virtual network topology may be triggered by
traffic demand changes, topology configuration changes, signaling traffic demand changes, topology configuration changes, signaling
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 requests from the upper layer, and network failures. For instance,
by reconfiguring the virtual network topology according to the
requests from the upper layer, and network failures. For instance, by traffic demand between source and destination node pairs, network
reconfiguring the virtual network topology according to the traffic performance factors, such as maximum link utilization and residual
demand between source and destination node pairs, network performance capacity of the network, can be optimized. Reconfiguration is
factors, such as maximum link utilization and residual capacity of performed by computing the new VNT from the traffic demand matrix
the network, can be optimized. Reconfiguration is performed by and optionally from the current VNT. Exact details are outside the
computing the new VNT from the traffic demand matrix and optionally scope of this document. However, this method may be tailored
from the current VNT. Exact details are outside the scope of this according to the service provider's policy regarding network
document. However, this method may be tailored according to the performance and quality of service (delay, loss/disruption,
service provider's policy regarding network performance and quality utilization, residual capacity, reliability).
of service (delay, loss/disruption, utilization, residual capacity,
reliability).
5. Requirements 5. Requirements
5.1. Handling Single-Switching and Multi-Switching-Type-Capable Nodes 5.1. Handling Single-Switching and Multi-Switching-Type-Capable Nodes
The MRN/MLN can consist of single-switching-type-capable and
The MRN/MLN can consist of single-switching-type-capable and multi- multi- switching-type-capable nodes. The path computation mechanism
switching-type-capable nodes. The path computation mechanism in the in the MLN SHOULD be able to compute paths consisting of any
MLN SHOULD be able to compute paths consisting of any combination of combination of such nodes.
such nodes.
Both single-switching-type-capable and multi-switching-type-capable Both single-switching-type-capable and multi-switching-type-capable
(simplex or hybrid) nodes could play the role of layer boundary. (simplex or hybrid) nodes could play the role of layer boundary.
MRN/MLN Path computation SHOULD handle TE topologies built of any MRN/MLN Path computation SHOULD handle TE topologies built of any
combination of nodes. combination of nodes.
5.2. Advertisement of the Available Adaptation Resource 5.2. Advertisement of the Available Adjustment Resource
A hybrid node SHOULD maintain resources on its internal links (the A hybrid node SHOULD maintain resources on its internal links (the
links required for vertical (layer) integration) and SHOULD advertise links required for vertical (layer) integration) and SHOULD
the resource information for those links. Likewise, path computation advertise the resource information for those links. Likewise, path
elements SHOULD be prepared to use the availability of termination/ computation elements SHOULD be prepared to use the availability of
adaptation resources as a constraint in MRN/MLN path computations to termination/ adjustment resources as a constraint in MRN/MLN path
reduce the higher layer LSP setup blocking probability caused by the computations to reduce the higher layer LSP setup blocking
lack of necessary termination/adaptation resources in the lower probability caused by the lack of necessary termination/adjustment
layer(s). resources in the lower layer(s).
The advertisement of the adaptation capability to terminate LSPs of The advertisement of the adjustment capability to terminate LSPs of
lower-region and forward traffic in the upper-region is REQUIRED, as lower-region and forward traffic in the upper-region is REQUIRED,
it provides critical information when performing multi-region path as it provides critical information when performing multi-region
computation. path computation.
The mechanism SHOULD cover the case where the upper-layer links which The mechanism SHOULD cover the case where the upper-layer links
are directly connected to upper-layer switching element and the ones which are directly connected to upper-layer switching element and
which are connected through internal links between upper-layer draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
element and lower-layer element coexist (see Section 4.2.1).
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 the ones which are connected through internal links between upper-
layer element and lower-layer element coexist (see Section 4.2.1).
5.3. Scalability 5.3. Scalability
The MRN/MLN relies on unified routing and traffic engineering The MRN/MLN relies on unified routing and traffic engineering
models. models.
- Unified routing model: By maintaining a single routing protocol - Unified routing model: By maintaining a single routing protocol
instance and a single TE database per LSR, a unified control plane instance and a single TE database per LSR, a unified control
model removes the requirement to maintain a dedicated routing plane model removes the requirement to maintain a dedicated
topology per layer, and therefore does not mandate a full mesh of routing topology per layer, and therefore does not mandate a
routing adjacencies per layer. full mesh of routing adjacencies per layer.
- Unified TE model: The TED in each LSR is populated with TE-links - Unified TE model: The TED in each LSR is populated with TE-links
from all layers of all regions (TE link interfaces on multiple- from all layers of all regions (TE link interfaces on multiple-
switching-capability LSRs can be advertised with multiple ISCDs). switching-capability LSRs can be advertised with multiple ISCDs).
This may lead to an increase in the amount of information that has This may lead to an increase in the amount of information that
to be flooded and stored within the network. has to be flooded and stored within the network.
Furthermore, path computation times, which may be of great importance Furthermore, path computation times, which may be of great
during restoration, will depend on the size of the TED. importance during restoration, will depend on the size of the TED.
Thus MRN/MLN routing mechanisms MUST be designed to scale well with Thus MRN/MLN routing mechanisms MUST be designed to scale well with
an increase of any of the following: an increase of any of the following:
- Number of nodes - Number of nodes
- Number of TE-links (including FA-LSPs) - Number of TE-links (including FA-LSPs)
- Number of LSPs - Number of LSPs - Number of regions and layers
- Number of regions and layers
- Number of ISCDs per TE-link. - Number of ISCDs per TE-link.
Further, design of the routing protocols MUST NOT prevent TE Further, design of the routing protocols MUST NOT prevent TE
information filtering based on ISCDs. The path computation mechanism information filtering based on ISCDs. The path computation
and the signaling protocol SHOULD be able to operate on partial TE mechanism and the signaling protocol SHOULD be able to operate on
information. partial TE information.
Since TE Links can advertise multiple Interface Switching Since TE Links can advertise multiple Interface Switching
Capabilities (ISCs), the number of links can be limited (by Capabilities (ISCs), the number of links can be limited (by
combination) by using specific topological maps referred to as VNT combination) by using specific topological maps referred to as VNT
(Virtual Network Topologies). The introduction of virtual topological (Virtual Network Topologies). The introduction of virtual
maps leads us to consider the concept of emulation of data plane topological maps leads us to consider the concept of emulation of
overlays. data plane overlays.
5.4. Stability 5.4. Stability
Path computation is dependent on the network topology and associated Path computation is dependent on the network topology and
link state. The path computation stability of an upper layer may be associated link state. The path computation stability of an upper
impaired if the VNT changes frequently and/or if the status and TE layer may be impaired if the VNT changes frequently and/or if the
parameters (the TE metric, for instance) of links in the VNT changes status and TE parameters (the TE metric, for instance) of links in
frequently. In this context, robustness of the VNT is defined as the the VNT changes frequently. In this context, robustness of the VNT
capability to smooth changes that may occur and avoid their draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
propagation into higher layers. Changes to the VNT may be caused by
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
the creation, deletion, or modification of LSPs. is defined as the capability to smooth changes that may occur and
avoid their propagation into higher layers. Changes to the VNT may
be caused by the creation, deletion, or modification of LSPs.
Creation, deletion, and modification of LSPs MAY be triggered by Creation, deletion, and modification of LSPs MAY be triggered by
adjacent layers or through operational actions to meet traffic demand adjacent layers or through operational actions to meet traffic
changes, topology changes, signaling requests from the upper layer, demand changes, topology changes, signaling requests from the upper
and network failures. Routing robustness SHOULD be traded with layer, and network failures. Routing robustness SHOULD be traded
adaptability with respect to the change of incoming traffic requests. with adaptability with respect to the change of incoming traffic
requests.
5.5. Disruption Minimization 5.5. Disruption Minimization
When reconfiguring the VNT according to a change in traffic demand, When reconfiguring the VNT according to a change in traffic demand,
the upper-layer LSP might be disrupted. Such disruption to the upper the upper-layer LSP might be disrupted. Such disruption to the
layers MUST be minimized. upper layers MUST be minimized.
When residual resource decreases to a certain level, some lower layer When residual resource decreases to a certain level, some lower
LSPs MAY be released according to local or network policies. There is layer LSPs MAY be released according to local or network policies.
a trade-off between minimizing the amount of resource reserved in the There is a trade-off between minimizing the amount of resource
lower layer and disrupting higher layer traffic (i.e. moving the reserved in the lower layer and disrupting higher layer traffic
traffic to other TE-LSPs so that some LSPs can be released). Such (i.e. moving the traffic to other TE-LSPs so that some LSPs can be
traffic disruption MAY be allowed, but MUST be under the control of released). Such traffic disruption MAY be allowed, but MUST be
policy that can be configured by the operator. Any repositioning of under the control of policy that can be configured by the operator.
traffic MUST be as non-disruptive as possible (for example, using Any repositioning of traffic MUST be as non-disruptive as possible
make-before-break). (for example, using make-before-break).
5.6. LSP Attribute Inheritance 5.6. LSP Attribute Inheritance
TE-Link parameters SHOULD be inherited from the parameters of the LSP TE-Link parameters SHOULD be inherited from the parameters of the
that provides the TE-link, and so from the TE-links in the lower LSP that provides the TE-link, and so from the TE-links in the
layer that are traversed by the LSP. lower layer that are traversed by the LSP.
These include: These include:
- Interface Switching Capability - Interface Switching Capability
- TE metric - TE metric
- Maximum LSP bandwidth per priority level - Maximum LSP bandwidth per priority level
- Unreserved bandwidth for all priority levels - Unreserved bandwidth for all priority levels
- Maximum Reservable bandwidth - Maximum Reservable bandwidth
- Protection attribute - Protection attribute
- Minimum LSP bandwidth (depending on the Switching Capability) - Minimum LSP bandwidth (depending on the Switching Capability)
- SRLG - SRLG
Inheritance rules MUST be applied based on specific policies. Inheritance rules MUST be applied based on specific policies.
Particular attention should be given to the inheritance of TE metric Particular attention should be given to the inheritance of TE
(which may be other than a strict sum of the metrics of the component metric (which may be other than a strict sum of the metrics of the
TE links at the lower layer), protection attributes, and SRLG. draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
As described earlier, hiding the routes of the lower-layer LSPs may component TE links at the lower layer), protection attributes, and
lose important information necessary to make LSPs in the higher layer SRLG.
network reliable. SRLGs may be used to identify which lower-layer
LSPs share the same failure risk so that the potential risk of the
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
VNT becoming disjoint can be minimized, and so that resource disjoint As described earlier, hiding the routes of the lower-layer LSPs may
protection paths can be set up in the higher layer. How to inherit lose important information necessary to make LSPs in the higher
the SRLG information from the lower layer to the upper layer needs layer network reliable. SRLGs may be used to identify which lower-
more discussion and is out of scope of this document. layer LSPs share the same failure risk so that the potential risk
of the VNT becoming disjoint can be minimized, and so that resource
disjoint protection paths can be set up in the higher layer. How to
inherit the SRLG information from the lower layer to the upper
layer needs more discussion and is out of scope of this document.
5.7. Computing Paths With and Without Nested Signaling 5.7. Computing Paths With and Without Nested Signaling
Path computation MAY take into account LSP region and layer Path computation MAY take into account LSP region and layer
boundaries when computing a path for an LSP. For example, path boundaries when computing a path for an LSP. For example, path
computation MAY restrict the path taken by an LSP to only the links computation MAY restrict the path taken by an LSP to only the links
whose interface switching capability is PSC. whose interface switching capability is PSC.
Interface switching capability is used as a constraint in path Interface switching capability is used as a constraint in path
computation. For example, a TDM-LSP is routed over the topology computation. For example, a TDM-LSP is routed over the topology
composed of TE links of the same TDM layer. In calculating the path composed of TE links of the same TDM layer. In calculating the path
for the LSP, the TED MAY be filtered to include only links where both for the LSP, the TED MAY be filtered to include only links where
end include requested LSP switching type. In this way hierarchical both end include requested LSP switching type. In this way
routing is done by using a TED filtered with respect to switching hierarchical routing is done by using a TED filtered with respect
capability (that is, with respect to particular layer). to switching capability (that is, with respect to particular layer).
If triggered signaling is allowed, the path computation mechanism MAY If triggered signaling is allowed, the path computation mechanism
produce a route containing multiple layers/regions. The path is MAY produce a route containing multiple layers/regions. The path is
computed over the multiple layers/regions even if the path is not computed over the multiple layers/regions even if the path is not
"connected" in the same layer as the endpoints of the path exist. "connected" in the same layer as the endpoints of the path exist.
Note that here we assume that triggered signaling will be invoked to Note that here we assume that triggered signaling will be invoked
make the path "connected", when the upper-layer signaling request to make the path "connected", when the upper-layer signaling
arrives at the boundary node. request arrives at the boundary node.
The upper-layer signaling request may contain an ERO that includes The upper-layer signaling request may contain an ERO that includes
only hops in the upper layer, in which case the boundary node is only hops in the upper layer, in which case the boundary node is
responsible for triggered creation of the lower-layer FA-LSP using a responsible for triggered creation of the lower-layer FA-LSP using
path of its choice, or for the selection of any available lower layer a path of its choice, or for the selection of any available lower
LSP as a data link for the higher layer. This mechanism is layer LSP as a data link for the higher layer. This mechanism is
appropriate for environments where the TED is filtered in the higher appropriate for environments where the TED is filtered in the
layer, where separate routing instances are used per layer, or where higher layer, where separate routing instances are used per layer,
administrative policies prevent the higher layer from specifying or where administrative policies prevent the higher layer from
paths through the lower layer. specifying paths through the lower layer.
Obviously, if the lower layer LSP has been advertised as a TE link Obviously, if the lower layer LSP has been advertised as a TE link
(virtual or real) into the higher layer, then the higher layer (virtual or real) into the higher layer, then the higher layer
signaling request may contain the TE link identifier and so indicate signaling request may contain the TE link identifier and so
the lower layer resources to be used. But in this case, the path of indicate the lower layer resources to be used. But in this case,
the lower layer LSP can be dynamically changed by the lower layer at draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
any time.
the path of the lower layer LSP can be dynamically changed by the
lower layer at any time.
Alternatively, the upper-layer signaling request may contain an ERO Alternatively, the upper-layer signaling request may contain an ERO
specifying the lower layer FA-LSP route. In this case, the boundary specifying the lower layer FA-LSP route. In this case, the boundary
node is responsible for decision as to which it should use the path node is responsible for decision as to which it should use the path
contained in the strict ERO or it should re-compute the path within contained in the strict ERO or it should re-compute the path within
in the lower-layer. in the lower-layer.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
Even in case the lower-layer FA-LSPs are already established, a Even in case the lower-layer FA-LSPs are already established, a
signaling request may also be encoded as loose ERO. In this signaling request may also be encoded as loose ERO. In this
situation, it is up to the boundary node to decide whether it should situation, it is up to the boundary node to decide whether it
a new lower-layer FA-LSP or it should use the existing lower-layer should a new lower-layer FA-LSP or it should use the existing
FA-LSPs. lower-layer FA-LSPs.
The lower-layer FA-LSP can be advertised just as an FA-LSP in the The lower-layer FA-LSP can be advertised just as an FA-LSP in the
upper-layer or an IGP adjacency can be brought up on the lower-layer upper-layer or an IGP adjacency can be brought up on the lower-
FA-LSP. layer FA-LSP.
5.8. LSP Resource Utilization 5.8. LSP Resource Utilization
It MUST be possible to utilize network resources efficiently. It MUST be possible to utilize network resources efficiently.
Particularly, resource usage in all layers SHOULD be optimized as a Particularly, resource usage in all layers SHOULD be optimized as a
whole (i.e., across all layers), in a coordinated manner, (i.e., whole (i.e., across all layers), in a coordinated manner, (i.e.,
taking all layers into account). The number of lower-layer LSPs taking all layers into account). The number of lower-layer LSPs
carrying upper-layer LSPs SHOULD be minimized (note that multiple carrying upper-layer LSPs SHOULD be minimized (note that multiple
LSPs MAY be used for load balancing). Lower-layer LSPs that could LSPs MAY be used for load balancing). Lower-layer LSPs that could
have their traffic re-routed onto other LSPs are unnecessary and have their traffic re-routed onto other LSPs are unnecessary and
SHOULD be avoided. SHOULD be avoided.
5.8.1. FA-LSP Release and Setup 5.8.1. FA-LSP Release and Setup
Statistical multiplexing can only be employed in PSC and L2SC Statistical multiplexing can only be employed in PSC and L2SC
regions. A PSC or L2SC LSP may or may not consume the maximum regions. A PSC or L2SC LSP may or may not consume the maximum
reservable bandwidth of the TE link (FA-LSP) that carries it. On the reservable bandwidth of the TE link (FA-LSP) that carries it. On
other hand, a TDM, or LSC LSP always consumes a fixed amount of the other hand, a TDM, or LSC LSP always consumes a fixed amount of
bandwidth as long as it exists (and is fully instantiated) because bandwidth as long as it exists (and is fully instantiated) because
statistical multiplexing is not available. statistical multiplexing is not available.
If there is low traffic demand, some FA-LSPs that do not carry any If there is low traffic demand, some FA-LSPs that do not carry any
higher-layer LSP MAY be released so that lower-layer resources are higher-layer LSP MAY be released so that lower-layer resources are
released and can be assigned to other uses. Note that if a small released and can be assigned to other uses. Note that if a small
fraction of the available bandwidth of an FA-LSP is still in use, the fraction of the available bandwidth of an FA-LSP is still in use,
nested LSPs can also be re-routed to other FA-LSPs (optionally using the nested LSPs can also be re-routed to other FA-LSPs (optionally
the make-before-break technique) to completely free up the FA-LSP. using the make-before-break technique) to completely free up the
Alternatively, unused FA-LSPs MAY be retained for future use. Release FA-LSP. Alternatively, unused FA-LSPs MAY be retained for future
or retention of underutilized FA-LSPs is a policy decision. use. Release or retention of underutilized FA-LSPs is a policy
decision.
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
As part of the re-optimization process, the solution MUST allow As part of the re-optimization process, the solution MUST allow
rerouting of an FA-LSP while keeping interface identifiers of rerouting of an FA-LSP while keeping interface identifiers of
corresponding TE links unchanged. Further, this process MUST be corresponding TE links unchanged. Further, this process MUST be
possible while the FA-LSP is carrying traffic (higher layer LSPs) possible while the FA-LSP is carrying traffic (higher layer LSPs)
with minimal disruption to the traffic. with minimal disruption to the traffic.
Additional FA-LSPs MAY also be created based on policy, which might Additional FA-LSPs MAY also be created based on policy, which might
consider residual resources and the change of traffic demand across consider residual resources and the change of traffic demand across
the region. By creating the new FA-LSPs, the network performance such the region. By creating the new FA-LSPs, the network performance
as maximum residual capacity may increase. such as maximum residual capacity may increase.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
As the number of FA-LSPs grows, the residual resource may decrease. As the number of FA-LSPs grows, the residual resource may decrease.
In this case, re-optimization of FA-LSPs MAY be invoked according to In this case, re-optimization of FA-LSPs MAY be invoked according
policy. to policy.
Any solution MUST include measures to protect against network Any solution MUST include measures to protect against network
destabilization caused by the rapid setup and teardown of LSPs as destabilization caused by the rapid setup and teardown of LSPs as
traffic demand varies near a threshold. traffic demand varies near a threshold.
Signaling of lower-layer LSPs SHOULD include a mechanism to rapidly Signaling of lower-layer LSPs SHOULD include a mechanism to rapidly
advertise the LSP as a TE link and to coordinate into which routing advertise the LSP as a TE link and to coordinate into which routing
instances the TE link should be advertised. instances the TE link should be advertised.
5.8.2. Virtual TE-Links 5.8.2. Virtual TE-Links
It may be considered disadvantageous to fully instantiate (i.e. pre- It may be considered disadvantageous to fully instantiate (i.e.
provision) the set of lower layer LSPs that provide the VNT since pre- provision) the set of lower layer LSPs that provide the VNT
this might reserve bandwidth that could be used for other LSPs in the since this might reserve bandwidth that could be used for other
absence of upper-layer traffic. LSPs in the absence of upper-layer traffic.
However, in order to allow path computation of upper-layer LSPs However, in order to allow path computation of upper-layer LSPs
across the lower-layer, the lower-layer LSPs MAY be advertised into across the lower-layer, the lower-layer LSPs MAY be advertised into
the upper-layer as though they had been fully established, but the upper-layer as though they had been fully established, but
without actually establishing them. Such TE links that represent the without actually establishing them. Such TE links that represent
possibility of an underlying LSP are termed "virtual TE-links." It is the possibility of an underlying LSP are termed "virtual TE-links."
an implementation choice at a layer boundary node whether to create It is an implementation choice at a layer boundary node whether to
real or virtual TE-links, and the choice if available in an create real or virtual TE-links, and the choice if available in an
implementation MUST be under the control of operator policy. Note implementation MUST be under the control of operator policy. Note
that there is no requirement to support the creation of virtual TE- that there is no requirement to support the creation of virtual TE-
links, since real TE-links (with established LSPs) may be used, and links, since real TE-links (with established LSPs) may be used, and
even if there are no TE-links (virtual or real) advertised to the even if there are no TE-links (virtual or real) advertised to the
higher layer, it is possible to route a higher layer LSP into a lower higher layer, it is possible to route a higher layer LSP into a
layer on the assumptions that proper hierarchical LSPs in the lower lower layer on the assumptions that proper hierarchical LSPs in the
layer will be dynamically created (triggered) as needed. lower layer will be dynamically created (triggered) as needed.
If an upper-layer LSP that makes use of a virtual TE-Link is set up, If an upper-layer LSP that makes use of a virtual TE-Link is set up,
the underlying LSP MUST be immediately signaled in the lower layer. the underlying LSP MUST be immediately signaled in the lower layer.
If virtual TE-Links are used in place of pre-established LSPs, the If virtual TE-Links are used in place of pre-established LSPs, the
TE-links across the upper-layer can remain stable using pre-computed TE-links across the upper-layer can remain stable using pre-
paths while wastage of bandwidth within the lower-layer and computed paths while wastage of bandwidth within the lower-layer
unnecessary reservation of adaptation ports at the border nodes can draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
be avoided.
The solution SHOULD provide operations to facilitate the build-up of and unnecessary reservation of adaptation resource at the border
such virtual TE-links, taking into account the (forecast) traffic nodes can be avoided.
demand and available resource in the lower-layer.
The solution SHOULD provide operations to facilitate the build-up
of such virtual TE-links, taking into account the (forecast)
traffic demand and available resource in the lower-layer.
Virtual TE-links MAY be added, removed or modified dynamically (by Virtual TE-links MAY be added, removed or modified dynamically (by
changing their capacity) according to the change of the (forecast) changing their capacity) according to the change of the (forecast)
traffic demand and the available resource in the lower-layer. The traffic demand and the available resource in the lower-layer. The
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
maximum number of virtual TE links that can be defined SHOULD be maximum number of virtual TE links that can be defined SHOULD be
configurable. configurable.
Any solution MUST include measures to protect against network Any solution MUST include measures to protect against network
destabilization caused by the rapid changes in the virtual network destabilization caused by the rapid changes in the virtual network
topology as traffic demand varies near a threshold. topology as traffic demand varies near a threshold.
The concept of the VNT can be extended to allow the virtual TE-links The concept of the VNT can be extended to allow the virtual TE-
to form part of the VNT. The combination of the fully provisioned TE- links to form part of the VNT. The combination of the fully
links and the virtual TE-links defines the VNT provided by the lower provisioned TE- links and the virtual TE-links defines the VNT
layer. The VNT can be changed by setting up and/or tearing down provided by the lower layer. The VNT can be changed by setting up
virtual TE links as well as by modifying real links (i.e., the fully and/or tearing down virtual TE links as well as by modifying real
provisioned LSPs). How to design the VNT and how to manage it are out links (i.e., the fully provisioned LSPs). How to design the VNT and
of scope of this document. how to manage it are out of scope of this document.
In some situations, selective advertisement of the preferred
connectivity among a set of border nodes between layers may be
appropriate. Further decreasing the number of advertisement of the
virtual connectivity can be achieved by abstracting the topology
(between border nodes) using models similar to those detailed in
[RFC4847].
5.9. Verification of the LSPs 5.9. Verification of the LSPs
When a lower layer LSP is established for use as a data link by a When a lower layer LSP is established for use as a data link by a
higher layer, the LSP MAY be verified for correct connectivity and higher layer, the LSP MAY be verified for correct connectivity and
data integrity. Such mechanisms are data technology-specific and are data integrity. Such mechanisms are data technology-specific and
beyond the scope of this document, but may be coordinated through the are beyond the scope of this document, but may be coordinated
GMPLS control plane. through the GMPLS control plane.
6. Security Considerations 6. Security Considerations
The MLN/MRN architecture does not introduce any new security The MLN/MRN architecture does not introduce any new security
requirements over the general GMPLS architecture described in requirements over the general GMPLS architecture described in
[RFC3945]. Additional security considerations form MPLS and GMPLS [RFC3945]. Additional security considerations form MPLS and GMPLS
networks are described in [MPLS-SEC]. networks are described in [MPLS-SEC].
However, where the separate layers of a MLN/MRN network are operated However, where the separate layers of a MLN/MRN network are
as different administrative domains, additional security operated as different administrative domains, additional security
considerations may be given to the mechanisms for allowing inter- considerations may be given to the mechanisms for allowing inter-
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
layer LSP setup, for triggering lower-layer LSPs, or for VNT layer LSP setup, for triggering lower-layer LSPs, or for VNT
management. Similarly, consideration may be given to the amount of management. Similarly, consideration may be given to the amount of
information shared between administrative domains, and the trade-off information shared between administrative domains, and the trade-
between multi-layer TE and confidentiality of information belonging off between multi-layer TE and confidentiality of information
to each administrative domain. belonging to each administrative domain.
It is expected that solution documents will include a full analysis It is expected that solution documents will include a full analysis
of the security issues that any protocol extensions introduce. of the security issues that any protocol extensions introduce.
7. IANA Considerations 7. IANA Considerations
This informational document makes no requests to IANA for action. This informational document makes no requests to IANA for action.
8. Acknowledgements 8. Acknowledgements
The authors would like to thank Adrian Farrel and the participants of The authors would like to thank Adrian Farrel and the participants
ITU-T Study Group 15 Question 14 for their careful review. of ITU-T Study Group 15 Question 14 for their careful review.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
9. References 9. References
9.1. Normative Reference 9.1. Normative Reference
[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.
[RFC4202] Kompella, K., and Rekhter, Y., "Routing Extensions in [RFC4202] Kompella, K., and Rekhter, Y., "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)," RFC4202, October 2005. (GMPLS)," RFC4202, October 2005.
[RFC4726] Farrel, A., Vasseur, JP., and Ayyangar, A., "A Framework [RFC4726] Farrel, A., Vasseur, JP., and Ayyangar, A., "A
for Inter-Domain Multiprotocol Label Switching Traffic Framework for Inter-Domain Multiprotocol Label
Engineering", RFC 4726, November 2006. Switching Traffic Engineering", RFC 4726, November 2006.
[RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP) [RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths
Hierarchy with Generalized Multi-Protocol Label Switching (LSP) Hierarchy with Generalized Multi-Protocol Label
(GMPLS) Traffic Engineering (TE)," RFC4206, Oct. 2005. Switching (GMPLS) Traffic Engineering (TE)," RFC4206,
Oct. 2005.
[RFC3945] E. Mannie (Editor), "Generalized Multi-Protocol Label [RFC3945] E. Mannie (Editor), "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3945, October 2004. Switching (GMPLS) Architecture", RFC 3945, October 2004.
[RFC4397] Bryskin, I., and Farrel, A., "A Lexicography for the [RFC4397] Bryskin, I., and Farrel, A., "A Lexicography for the
Interpretation of Generalized Multiprotocol Label Switching Interpretation of Generalized Multiprotocol Label
(GMPLS) Terminology within the Context of the ITU-T's Switching (GMPLS) Terminology within the Context of the
Automatically Switched Optical Network (ASON) ITU-T's Automatically Switched Optical Network (ASON)
Architecture", RFC 4397, February 2006. Architecture", RFC 4397, February 2006.
9.2. Informative References 9.2. Informative References
[MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou, D., [MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou,
Shiomoto, K., Vigoureux, M., "Evaluation of Existing D., Shiomoto, K., Vigoureux, M., "Evaluation of
GMPLS Protocols Against Multi-Layer and Multi-Region Existing GMPLS Protocols Against Multi-Layer and
Network (MLN/MRN) Requirements", draft-ietf-ccamp-gmpls- Multi-Region Network (MLN/MRN) Requirements", draft-
mln-eval, work in progress. ietf-ccamp-gmpls- mln-eval, work in progress.
[MPLS-GMPLS] K. Kumaki (Editor), "Interworking Requirements to [MPLS-GMPLS] K. Kumaki (Editor), "Interworking Requirements to
Support Operation of MPLS-TE over GMPLS Networks", Support Operation of MPLS-TE over GMPLS Networks",
draft-ietf-ccamp-mpls-gmpls-interwork-reqts, work in draft-ietf-ccamp-mpls-gmpls-interwork-reqts, work in
progress. progress.
[DYN-HIER] Shiomoto, K., Rabbat, R., Ayyangar, A., Farrel, A.
[DYN-HIER] Shiomoto, K., Rabbat, R., Ayyangar, A., Farrel, A. and and Ali, Z., "Procedures for Dynamically Signaled
Ali, Z., "Procedures for Dynamically Signaled
Hierarchical Label Switched Paths", draft-ietf-ccamp- Hierarchical Label Switched Paths", draft-ietf-ccamp-
lsp-hierarchy-bis, work in progress. lsp-hierarchy-bis, work in progress.
[MPLS-SEC] Fang, L., et al., " Security Framework for MPLS and [MPLS-SEC] Fang, L., et al., " Security Framework for MPLS and
GMPLS Networks", draft-fang-mpls-gmpls-security- GMPLS Networks", draft-fang-mpls-gmpls-security-
framework, work in progress. framework, work in progress.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
[RFC4972] Vasseur, JP., Le Roux, JL., et al., "Routing Extensions [RFC4972] Vasseur, JP., Le Roux, JL., et al., "Routing
for Discovery of Multiprotocol (MPLS) Label Switch Extensions for Discovery of Multiprotocol (MPLS)
Router (LSR) Traffic Engineering (TE) Mesh Membership", Label Switch Router (LSR) Traffic Engineering (TE)
RFC 4972, July 2007. Mesh Membership", RFC 4972, July 2007.
[RFC4847] T. Takeda (Editor), " Framework and Requirements for
Layer 1 Virtual Private Networks", RFC 4847, April
2007.
10. Authors' Addresses 10. Authors' Addresses
Kohei Shiomoto Kohei Shiomoto
NTT Network Service Systems Laboratories NTT Network Service Systems Laboratories
3-9-11 Midori-cho, 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan
Musashino-shi, Tokyo 180-8585, Japan
Email: shiomoto.kohei@lab.ntt.co.jp Email: shiomoto.kohei@lab.ntt.co.jp
Dimitri Papadimitriou Dimitri Papadimitriou
Alcatel-Lucent Alcatel-Lucent
Copernicuslaan 50, Copernicuslaan 50,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Phone : +32 3 240 8491 Phone : +32 3 240 8491
Email: dimitri.papadimitriou@alcatel-lucent.be Email: dimitri.papadimitriou@alcatel-lucent.be
Jean-Louis Le Roux Jean-Louis Le Roux
skipping to change at page 22, line 50 skipping to change at page 25, line 52
AT&T AT&T
Rm. D1-3C22 - 200 Rm. D1-3C22 - 200
S. Laurel Ave., Middletown, NJ 07748, USA S. Laurel Ave., Middletown, NJ 07748, USA
Phone: +1 732 420 1573 Phone: +1 732 420 1573
Email: dbrungard@att.com Email: dbrungard@att.com
11. Contributors' Addresses 11. Contributors' Addresses
Eiji Oki Eiji Oki
NTT Network Service Systems Laboratories NTT Network Service Systems Laboratories
3-9-11 Midori-cho, 3-9-11 Midori-cho, Musashino-shi,
Musashino-shi,
Tokyo 180-8585, Tokyo 180-8585,
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
Japan Japan
Phone: +81 422 59 3441 Phone: +81 422 59 3441
Email: oki.eiji@lab.ntt.co.jp Email: oki.eiji@lab.ntt.co.jp
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
Ichiro Inoue Ichiro Inoue
NTT Network Service Systems Laboratories NTT Network Service Systems Laboratories
3-9-11 Midori-cho, 3-9-11 Midori-cho,
Musashino-shi, Musashino-shi,
Tokyo 180-8585, Tokyo 180-8585,
Japan Japan
Phone: +81 422 59 3441 Phone: +81 422 59 3441
Email: ichiro.inoue@lab.ntt.co.jp Email: ichiro.inoue@lab.ntt.co.jp
skipping to change at page 23, line 26 skipping to change at page 26, line 30
Alcatel-Lucent Alcatel-Lucent
Route de Nozay, Route de Nozay,
91461 Marcoussis cedex, 91461 Marcoussis cedex,
France France
Phone : +33 1 6963 4723 Phone : +33 1 6963 4723
Email: emmanuel.dotaro@alcatel-lucent.fr Email: emmanuel.dotaro@alcatel-lucent.fr
12. Intellectual Property Considerations 12. Intellectual Property Considerations
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
pertain to the implementation or use of the technology described in to pertain to the implementation or use of the technology described
this document or the extent to which any license under such rights in this document or the extent to which any license under such
might or might not be available; nor does it represent that it has rights might or might not be available; nor does it represent that
made any independent effort to identify any such rights. Information it has made any independent effort to identify any such rights.
on the procedures with respect to rights in RFC documents can be Information on the procedures with respect to rights in RFC
found in BCP 78 and BCP 79. documents can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an 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 attempt made to obtain a general license or permission for the use
such proprietary rights by implementers or users of this of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository
http://www.ietf.org/ipr. at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at ietf-
ietf-ipr@ietf.org. ipr@ietf.org.
13. Full Copyright Statement 13. Full Copyright Statement
draft-ietf-ccamp-gmpls-mln-reqs-06.txt October 2007
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007 This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
This document and the information contained herein are provided on an REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY FOR A PARTICULAR PURPOSE.
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE.
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