draft-ietf-ccamp-gmpls-mln-reqs-04.txt   draft-ietf-ccamp-gmpls-mln-reqs-05.txt 
skipping to change at page 1, line 14 skipping to change at page 1, line 14
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: February 2008 August 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-04.txt draft-ietf-ccamp-gmpls-mln-reqs-05.txt
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Abstract Abstract
Most of the initial efforts to utilize Generalized MPLS (GMPLS) have been Most of the initial efforts to utilize Generalized MPLS (GMPLS) have
related to environments hosting devices with a single switching capability. The been related to environments hosting devices with a single switching
complexity raised by the control of such data planes is similar to that seen in capability. The complexity raised by the control of such data planes
classical IP/MPLS networks. is similar to that seen in classical IP/MPLS networks.
By extending MPLS to support multiple switching technologies, GMPLS provides a By extending MPLS to support multiple switching technologies, GMPLS
comprehensive framework for the control of a multi-layered network of either a provides a comprehensive framework for the control of a multi-layered
single switching technology or multiple switching technologies. network of either a single switching technology or multiple switching
technologies.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
In GMPLS, a switching technology domain defines a region, and a network of In GMPLS, a switching technology domain defines a region, and a
multiple switching types is referred to in this document as a Multi-Region network of multiple switching types is referred to in this document
Network (MRN). When referring in general to a layered network, which may consist as a Multi-Region Network (MRN). When referring in general to a
of either a single or multiple regions, this document uses the term, Multi-Layer layered network, which may consist of either a single or multiple
Network (MLN). This document defines a framework for GMPLS based multi- regions, this document uses the term, Multi-Layer Network (MLN). This
region/multi-layer networks and lists a set of functional requirements. document defines a framework for GMPLS based multi-region/multi-layer
networks and lists a set of functional requirements.
Table of Contents Table of Contents
1. Introduction.....................................................2 1. Introduction ....................................................
2. Conventions Used in this Document....................................4 1.1. Scope .........................................................
2.1. List of acronyms................................................4 2. Conventions Used in this Document ...............................
3. Positioning......................................................5 2.1. List of Acronyms ..............................................
3.1. Data Plane Layers and Control Plane Regions..........................5 3. Positioning .....................................................
3.2. Service layer networks...........................................6 3.1. Data Plane Layers and Control Plane Regions ...................
3.3. Vertical and Horizontal interaction and integration...................6 3.2. Service Layer Networks .. .....................................
4. Key Concepts of GMPLS-Based MLNs and MRNs.............................8 3.3. Vertical and Horizontal Interaction and Integration ...........
4.1. Interface Switching Capability....................................8 3.4. Motivation ....................................................
4.2. Multiple Interface Switching Capabilities...........................8 4. Key Concepts of GMPLS-Based MLNs and MRNs .......................
4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes..............9 4.1. Interface Switching Capability ................................
4.3. Integrated Traffic Engineering (TE) and Resource Control..............10 4.2. Multiple Interface Switching Capabilities .....................
4.3.1. Triggered Signaling...........................................10 4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes .....
4.3.2. FA-LSPs.....................................................11 4.3. Integrated Traffic Engineering (TE) and Resource Control ......
4.3.3. Virtual Network Topology (VNT)..................................11 4.3.1. Triggered Signaling .........................................
5. Requirements....................................................12 4.3.2. FA-LSPs .....................................................
5.1. Handling Single-Switching and Multi-Switching-Type-Capable Nodes.......12 4.3.3. Virtual Network Topology (VNT) ..............................
5.2. Advertisement of the Available Adaptation Resource...................12 5. Requirements ....................................................
5.3. Scalability...................................................13 5.1. Handling Single-Switching and Multi-Switching-Type-Capable
5.4. Stability.....................................................13 Nodes .......................................................
5.5. Disruption Minimization.........................................14 5.2. Advertisement of the Available Adaptation Resource ............
5.6. LSP Attribute Inheritance........................................14 5.3. Scalability ...................................................
5.7. Computing Paths With and Without Nested Signaling....................15 5.4. Stability .....................................................
5.8. LSP Resource Utilization........................................15 5.5. Disruption Minimization .......................................
5.8.1. FA-LSP Release and Setup.......................................16 5.6. LSP Attribute Inheritance .....................................
5.8.2. Virtual TE-Links.............................................16 5.7. Computing Paths With and Without Nested Signaling .............
5.9. Verification of the LSPs........................................17 5.8. LSP Resource Utilization ......................................
6. Security Considerations...........................................18 5.8.1. FA-LSP Release and Setup ....................................
7. IANA Considerations..............................................18 5.8.2. Virtual TE-Links ............................................
8. References......................................................18 5.9. Verification of the LSPs ......................................
8.1. Normative Reference.............................................18 6. Security Considerations .........................................
8.2. Informative References..........................................18 7. IANA Considerations ............................................
9. Authors' Addresses...............................................19 8. Acknowledgements ................................................
10. Contributors' Addresses..........................................20 9. References ......................................................
11. Intellectual Property Considerations...............................20 9.1. Normative Reference ...........................................
12. Full Copyright Statement.........................................20 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
1. Introduction 1. Introduction
Generalized MPLS (GMPLS) extends MPLS to handle multiple switching technologies: Generalized MPLS (GMPLS) extends MPLS to handle multiple switching
packet switching, layer-2 switching, TDM switching, wavelength switching, and technologies: packet switching, layer-2 switching, TDM switching,
fiber switching (see [RFC3945]). The Interface Switching Capability (ISC) wavelength switching, and fiber switching (see [RFC3945]). The
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 Interface Switching Capability (ISC) concept is introduced for these
switching technologies and is designated as follows: PSC (packet
switch capable), L2SC (Layer-2 switch capable), TDM (Time Division
Multiplex capable), LSC (lambda switch capable), and FSC (fiber
switch capable).
concept is introduced for these switching technologies and is designated as The representation, in a GMPLS control plane, of a switching
follows: PSC (packet switch capable), L2SC (Layer-2 switch capable), TDM (Time technology domain is referred to as a region [RFC4206]. A switching
Division Multiplex capable), LSC (lambda switch capable), and FSC (fiber switch type describes the ability of a node to forward data of a particular
capable). data plane technology, and uniquely identifies a network region. A
layer describes a data plane switching granularity level (e.g., VC4,
VC-12). A data plane layer is associated with a region in the control
plane (e.g., VC4 is associated with TDM, MPLS is associated with
PSC). However, more than one data plane layer can be associated with
the same region (e.g., both VC4 and VC12 are associated with TDM).
Thus, a control plane region, identified by its switching type value
(e.g., TDM), can be sub-divided into smaller granularity component
networks based on "data plane switching layers". The Interface
Switching Capability Descriptor (ISCD) [RFC4202], identifying the
interface switching capability (ISC), the encoding type, and the
switching bandwidth granularity, enables the characterization of the
associated layers.
The representation, in a GMPLS control plane, of a switching technology domain In this document, we define a Multi Layer Network (MLN) to be a TE
is referred to as a region [RFC4206]. A switching type describes the ability of domain comprising multiple data plane switching layers either of the
a node to forward data of a particular data plane technology, and uniquely same ISC (e.g. TDM) or different ISC (e.g. TDM and PSC) and
identifies a network region. A layer describes a data plane switching controlled by a single GMPLS control plane instance. We further
granularity level (e.g., VC4, VC-12). A data plane layer is associated with a define a particular case of MLNs. A Multi Region Network (MRN) is
region in the control plane (e.g., VC4 is associated with TDM, MPLS is defined as a TE domain supporting at least two different switching
associated with PSC). However, more than one data plane layer can be associated technologies (e.g., PSC and TDM) hosted on the same devices (referred
with the same region (e.g., both VC4 and VC12 are associated with TDM). Thus, a to as multi-switching-type-capable LSRs, see below) and under the
control plane region, identified by its switching type value (e.g., TDM), can be control of a single GMPLS control plane instance.
sub-divided into smaller granularity component networks based on "data plane
switching layers". The Interface Switching Capability Descriptor (ISCD)
[RFC4202], identifying the interface switching capability (ISC), the encoding
type, and the switching bandwidth granularity, enables the characterization of
the associated layers.
In this document, we define a Multi Layer Network (MLN) to be a TE domain MLNs can be further categorized according to the distribution of the
comprising multiple data plane switching layers either of the same ISC (e.g. ISCs among the LSRs:
TDM) or different ISC (e.g. TDM and PSC) and controlled by a single GMPLS
control plane instance. We further define a particular case of MLNs. A Multi
Region Network (MRN) is defined as a TE domain supporting at least two different
switching technologies (e.g. PSC + TDM) hosted on the same device (referred to
as multi-switching-type-capable LSRs, see below) and 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:
- Each LSR may support just one ISC. - Each LSR may support just one ISC.
Such LSRs are known as single-switching-type-capable LSRs. Such LSRs are known as single-switching-type-capable LSRs. The MLN
The MLN may comprise a set of single-switching-type-capable LSRs may comprise a set of single-switching-type-capable LSRs some of
that support different ISCs. 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 Such LSRs are known as multi-switching-type-capable LSRs, and can
can be further classified as either ‘‘simplex’’ or hybrid’’ nodes be further classified as either "simplex" or "hybrid" nodes as
as defined in Section 4.2. defined in Section 4.2.
- The MLN may be constructed from any combination of single-switching-type- draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
capable LSRs and multi-switching-type-capable LSRs.
Since GMPLS provides a comprehensive framework for the control of different - The MLN may be constructed from any combination of single-
switching capabilities, a single GMPLS instance controlling the MLN/MRN enables switching-type-capable LSRs and multi-switching-type-capable LSRs.
rapid service provisioning and efficient traffic engineering across all
switching capabilities. In such networks, TE Links are consolidated into a
single Traffic Engineering Database (TED). Since this TED contains the
information relative to all the different regions and layers existing in the
network, a path across multiple regions or layers can be computed using this TED.
Thus optimization of network resources can be achieved across the whole MLN/MRN.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 Since GMPLS provides a comprehensive framework for the control of
different switching capabilities, a single GMPLS instance may be used
to control the MLN/MRN. This enables rapid service provisioning and
efficient traffic engineering across all switching capabilities. In
such networks, TE Links are consolidated into a single Traffic
Engineering Database (TED). Since this TED contains the information
relative to all the different regions and layers existing in the
network, a path across multiple regions or layers can be computed
using this TED.
Consider, for example, a MRN consisting of packet-switch capable routers and TDM Thus optimization of network resources can be achieved across the
cross-connects. Assume that a packet LSP is routed between source and whole MLN/MRN. Consider, for example, a MRN consisting of packet-
destination packet-switch capable routers, and that the LSP can be routed across switch capable routers and TDM cross-connects. Assume that a packet
the PSC-region (i.e., utilizing only resources of the packet region topology). LSP is routed between source and destination packet-switch capable
If the performance objective for the packet LSP is not satisfied, new TE links routers, and that the LSP can be routed across the PSC-region (i.e.,
may be created between the packet-switch capable routers across the TDM-region utilizing only resources of the packet region topology). If the
(for example, VC-12 links) and the LSP can be routed over those TE links. performance objective for the packet LSP is not satisfied, new TE
Further, even if the LSP can be successfully established across the PSC-region, links may be created between the packet-switch capable routers across
TDM hierarchical LSPs across the TDM region between the packet-switch capable the TDM-region (for example, VC-12 links) and the LSP can be routed
routers may be established and used if doing so is necessary to meet the over those TE links.
operator's objectives for network resources availability (e.g., link bandwidth,
or adaptation ports between regions) across the regions. 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 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, or adaptation ports
between regions) across the regions. The same considerations hold
when VC4 LSPs are provisioned to provide extra flexibility for the
VC12 and/or VC11 layers in an MLN.
This document describes the requirements to support multi-region/multi-layer 1.1. Scope
networks. There is no intention to specify solution-specific and/or protocol
elements in this document. The applicability of existing GMPLS protocols and any
protocol extensions to the MRN/MLN is addressed in separate documents [MRN-EVAL].
This document covers the elements of a single GMPLS control plane instance This document describes the requirements to support multi-region/
controlling multiple layers within a given TE domain. A control plane instance multi-layer networks. There is no intention to specify solution-
can serve one, two or more layers. Other possible approaches such as having specific and/or protocol elements in this document. The applicability
multiple control plane instances serving disjoint sets of layers are outside the of existing GMPLS protocols and any protocol extensions to the
scope of this document. MRN/MLN is addressed in separate documents [MRN-EVAL].
For such TE domain to interoperate with edge nodes/domains supporting interfaces This document covers the elements of a single GMPLS control plane
by other SDOs e.g. ITU-T and OIF, an interworking function may be needed. instance controlling multiple layers within a given TE domain. A
Location and specification of this function are outside the scope of this control plane instance can serve one, two or more layers. Other
document (because interworking aspects are strictly under the responsibility of possible approaches such as having multiple control plane instances
the interworking function.) serving disjoint sets of layers are outside the scope of this
document. It is most probable that such a MLN or MRN would be
operated by a single Service Provider, but this document does not
exclude the possibility of two layers (or regions) being under
different administrative control (for example, by different Service
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
This document assumes that the interconnection of adjacent MRN/MLN TE domains Providers that share a single control plane instance) where the
makes use of [RFC4726] when their edges also support inter-domain GMPLS RSVP-TE administrative domains are prepared to share a limited amount of
extensions. information.
2. Conventions Used in this Document For such TE domain to interoperate with edge nodes/domains supporting
non-GMPLS interfaces (such as those defined by other SDOs), an
interworking function may be needed. Location and specification of
this function are outside the scope of this document (because
interworking aspects are strictly under the responsibility of the
interworking function).
Although this is not a protocol specification, the key words "MUST", "MUST NOT", This document assumes that the interconnection of adjacent MRN/MLN TE
"REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", domains makes use of [RFC4726] when their edges also support inter-
and "OPTIONAL" are used in this document to highlight requirements, and are to domain GMPLS RSVP-TE extensions.
be interpreted as described in RFC 2119 [RFC2119].
2.1.List of acronyms 2. Conventions Used in this Document
MLN: Multi-Layer Network Although this is not a protocol specification, the key words "MUST",
MRN: Multi-Region Network "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 "RECOMMENDED", "MAY", and "OPTIONAL" are used in this document to
highlight requirements, and are to be interpreted as described in
RFC 2119 [RFC2119].
2.1. List of Acronyms
FA: Forwarding Adjacency
FA-LSP: Forwarding Adjacency Label Switched Path
FSC: Fiber Switching Capable
ISC: Interface Switching Capability ISC: Interface Switching Capability
ISCD: Interface Switching Capability Descriptor ISCD: Interface Switching Capability Descriptor
PSC: Packet Switching Capable
L2SC: Layer-2 Switching Capable L2SC: Layer-2 Switching Capable
TDM: Time-Division Switch Capable
LSC: Lambda Switching Capable LSC: Lambda Switching Capable
FSC: Fiber Switching Capable LSP: Label Switched Path
LSR: Label Switching Router
MLN: Multi-Layer Network
MRN: Multi-Region Network
PSC: Packet Switching Capable
SRLG: Shared Risk Ling Group SRLG: Shared Risk Ling Group
VNT: Virtual Network Topology TDM: Time-Division Switch Capable
FA: Forwarding Adjacency
FA-LSP: Forwarding Adjacency Label Switched Path
TE: Traffic Engineering TE: Traffic Engineering
TED: Traffic Engineering Database TED: Traffic Engineering Database
LSP: Label Switched Path VNT: Virtual Network Topology
LSR: Label Switching Router
3. Positioning 3. Positioning
A multi-region network (MRN) is always a multi-layer network (MLN) since the A multi-region network (MRN) is always a multi-layer network (MLN)
network devices on region boundaries bring together different ISCs. A MLN, since the network devices on region boundaries bring together
however, is not necessarily a MRN since multiple layers could be fully contained different ISCs. A MLN, however, is not necessarily a MRN since
within a single region. For example, VC12, VC4, and VC4-4c are different layers multiple layers could be fully contained within a single region. For
of the TDM region. example, VC12, VC4, and VC4-4c are different layers of the TDM
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
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 terminating A data plane layer is a collection of network resources capable of
and/or switching data traffic of a particular format [RFC4397]. These resources terminating and/or switching data traffic of a particular format
can be used for establishing LSPs for traffic delivery. For example, VC-11 and [RFC4397]. These resources can be used for establishing LSPs for
VC4-64c represent two different layers. traffic delivery. For example, VC-11 and VC4-64c represent two
different layers.
From the control plane viewpoint, an LSP region is defined as a set of one or From the control plane viewpoint, an LSP region is defined as a set
more data plane layers that share the same type of switching technology, that is, of one or more data plane layers that share the same type of
the same switching type. For example, VC-11, VC-4, and VC-4-7v layers are part switching technology, that is, the same switching type. For example,
of the same TDM region. The regions that are currently defined are: PSC, L2SC, VC-11, VC-4, and VC-4-7v layers are part of the same TDM region. The
TDM, LSC, and FSC. Hence, an LSP region is a technology domain (identified by regions that are currently defined are: PSC, L2SC, TDM, LSC, and FSC.
the ISC type) for which data plane resources (i.e., data links) are represented Hence, an LSP region is a technology domain (identified by the ISC
into the control plane as an aggregate of TE information associated with a set type) for which data plane resources (i.e., data links) are
of links (i.e., TE links). For example VC-11 and VC4-64c capable TE links are represented into the control plane as an aggregate of TE information
part of the same TDM region. Multiple layers can thus exist in a single region associated with a set of links (i.e., TE links). For example VC-11
network. and VC4-64c capable TE links are part of the same TDM region.
Multiple layers can thus exist in a single region network.
Note also that the region may produce a distinction within the control plane. Note also that the region may produce a distinction within the
Layers of the same region share the same switching technology and, therefore, control plane. Layers of the same region share the same switching
use the same set of technology-specific signaling objects and technology- technology and, therefore, use the same set of technology-specific
specific value setting of TE link attributes within the control plane, but signaling objects and technology-specific value setting of TE link
layers from different regions may use different technology-specific objects and attributes within the control plane, but layers from different
TE attribute values. This means that it may not be possible to simply forward regions may use different technology-specific objects and TE
the signaling message between LSR hosting different switching technologies attribute values. This means that it may not be possible to simply
because change in some of the signaling objects (for example, the traffic forward the signaling message between LSR hosting different switching
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 technologies because change in some of the signaling objects (for
example, the traffic parameters) when crossing a region boundary even
if a single control plane instance is used to manage the whole MRN.
We may solve this issue by using triggered signaling (see Section
4.3.1).
parameters) when crossing a region boundary even if a single control plane 3.2. Service Layer Networks
instance is used to manage the whole MRN. We may solve the issue by using
triggered signaling (See 4.3.1).
3.2. Service layer networks A service provider's network may be divided into different service
layers. The customer's network is considered from the provider's
perspective as the highest service layer. It interfaces to the
highest service layer of the service provider's network. Connectivity
across the highest service layer of the service provider's network
may be provided with support from successively lower service layers.
Service layers are realized via a hierarchy of network layers located
generally in several regions and commonly arranged according to the
switching capabilities of network devices.
A service provider's network may be divided into different service layers. The For instance some customers purchase Layer 1 (i.e., transport)
customer's network is considered from the provider's perspective as the highest services from the service provider, some Layer 2 (e.g., ATM), while
service layer. It interfaces to the highest service layer of the service draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
provider's network. Connectivity across the highest service layer of the service
provider's network may be provided with support from successively lower service
layers. Service layers are realized via a hierarchy of network layers located
generally in several regions and commonly arranged according to the switching
capabilities of network devices.
For instance some customers purchase Layer 1 (i.e., transport) services from the others purchase Layer 3 (IP/MPLS) services. The service provider
service provider, some Layer 2 (e.g., ATM), while others purchase Layer 3 realizes the services by a stack of network layers located within one
(IP/MPLS) services. The service provider realizes the services by a stack of or more network regions. The network layers are commonly arranged
network layers located within one or more network regions. The network layers according to the switching capabilities of the devices in the
are commonly 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 the GMPLS-based GMPLS-based multi-region/multi-layer network. For example, a Layer 1
multi-region/multi-layer network. For example, a Layer 1 service (realized via service (realized via the network layers of TDM, and/or LSC, and/or
the network layers of TDM, and/or LSC, and/or FSC regions) may support a Layer 2 FSC regions) may support a Layer 2 network (realized via ATM VP/VC)
network (realized via ATM VP/VC) which may itself support a Layer 3 network which may itself support a Layer 3 network (IP/MPLS region). The
(IP/MPLS region). The supported data plane relationship is a data plane client- supported data plane relationship is a data plane client-server
server relationship where the lower layer provides a service for the higher relationship where the lower layer provides a service for the higher
layer using the data links realized in the lower layer. layer using the data links realized in the lower layer.
Services provided by a GMPLS-based multi-region/multi-layer network are referred Services provided by a GMPLS-based multi-region/multi-layer network
to as "Multi-region/Multi-layer network services". For example, legacy IP and are referred to as "Multi-region/Multi-layer network services". For
IP/MPLS networks can be supported on top of multi-region/multi-layer networks. example, legacy IP and IP/MPLS networks can be supported on top of
It has to be emphasized that delivery of such diverse services is a strong multi-region/multi-layer networks. It has to be emphasized that
motivator for the deployment of multi-region/multi-layer networks. delivery of such diverse services is a strong motivator for the
deployment of multi-region/multi-layer networks.
A customer network may be provided on top of a server GMPLS-based MRN/MLN which A customer network may be provided on top of a server GMPLS-based
is operated by a service provider. For example, a pure IP and/or an IP/MPLS MRN/MLN which is operated by a service provider. For example, a pure
network can be provided on top of GMPLS-based packet over optical networks IP and/or an IP/MPLS network can be provided on top of GMPLS-based
[MPLS-GMPLS]. The relationship between the networks is a client/server packet over optical networks [MPLS-GMPLS]. The relationship between
relationship and, such services are referred to as "MRN/MLN services". In this the networks is a client/server relationship and, such services are
case, the customer network may form part of the MRN/MLN, or may be partially referred to as "MRN/MLN services". In this case, the customer network
separated, for example to maintain separate routing information but retain may form part of the MRN/MLN, or may be partially separated, for
common signaling. example to maintain separate routing information but 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 within a network Vertical interaction is defined as the collaborative mechanisms
element that is capable of supporting more than one layer or region and of within a network element that is capable of supporting more than one
realizing the client/server relationships between the layers or regions. layer or region and of realizing the client/server relationships
Protocol exchanges between two network controllers managing different regions or between the layers or regions. Protocol exchanges between two network
layers are also a vertical interaction. Integration of these interactions as controllers managing different regions or layers are also a vertical
part of the control plane is referred to as vertical integration. Thus, this interaction. Integration of these interactions as part of the control
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 plane is referred to as vertical integration. Thus, this refers to
the collaborative mechanisms within a single control plane instance
driving multiple network layers part of the same region or not. Such
a concept is useful in order to construct a framework that
facilitates efficient network resource usage and rapid service
provisioning in carrier networks that are based on multiple layers,
switching technologies, or ISCs.
refers to the collaborative mechanisms within a single control plane instance Horizontal interaction is defined as the protocol exchange between
driving multiple network layers part of the same region or not. Such a concept network controllers that manage transport nodes within a given layer
is useful in order to construct a framework that facilitates efficient network or region. For instance, the control plane interaction between two
resource usage and rapid service provisioning in carrier networks that are based TDM network elements switching at OC-48 is an example of horizontal
on multiple layers, switching technologies, or ISCs. draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
Horizontal interaction is defined as the protocol exchange between network interaction. GMPLS protocol operations handle horizontal interactions
controllers that manage transport nodes within a given layer or region. For within the same routing area. The case where the interaction takes
instance, the control plane interaction between two TDM network elements place across a domain boundary, such as between two routing areas
switching at OC-48 is an example of horizontal interaction. GMPLS protocol within the same network layer, is evaluated as part of the inter-
operations handle horizontal interactions within the same routing area. The case domain work [RFC4726], and is referred to as horizontal integration.
where the interaction takes place across a domain boundary, such as between two Thus, horizontal integration refers to the collaborative mechanisms
routing areas within the same network layer, is evaluated as part of the inter- between network partitions and/or administrative divisions such as
domain work [RFC4726], and is referred to as horizontal integration. Thus, routing areas or autonomous systems.
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 domains match This distinction needs further clarification when administrative
layer/region boundaries. Horizontal interaction is extended to cover such cases. domains match layer/region boundaries. Horizontal interaction is
For example, the collaborative mechanisms in place between two lambda switching extended to cover such cases. For example, the collaborative
capable areas relate to horizontal integration. On the other hand, the mechanisms in place between two lambda switching capable areas relate
collaborative mechanisms in place between a packet switching capable (e.g. to horizontal integration. On the other hand, the collaborative
IP/MPLS) domain over a different time division switching capable (eg VC4 SDH) mechanisms in place between a packet switching capable (e.g.,
domain is part of the horizontal integration while it can be seen as a first IP/MPLS) domain and a separate time division switching capable
step towards vertical integration. (e.g., VC4 SDH) domain over which it operates are part of the
horizontal integration while it can also be seen as a first step
towards vertical integration.
3.4.Motivation 3.4.Motivation
The applicability of GMPLS to multiple switching technologies provides the The applicability of GMPLS to multiple switching technologies
unified control management approach for both LSP provisioning and recovery. provides a unified control and management approach for both LSP
Indeed, one of the main motivations for unifying the capabilities and operations provisioning and recovery. Indeed, one of the main motivations for
GMPLS control plane is the desire to support multi LSP-region [RFC4206] routing unifying the capabilities and operations of the GMPLS control plane
and Traffic Engineering (TE) capability. For instance, this enables effective is the desire to support multi-LSP-region [RFC4206] routing and
network resource utilization of both the Packet/Layer2 LSP regions and the Time Traffic Engineering (TE) capabilities. For instance, this enables
Division Multiplexing (TDM) or Lambda LSP regions in high capacity networks. effective network resource utilization of both the Packet/Layer2 LSP
regions and the Time Division Multiplexing (TDM) or Lambda LSP
regions in high capacity networks.
The rationales for GMPLS controlled multi-layer/multi-region networks
are summarized below:
- The maintenance of multiple instances of the control plane on
devices hosting more than one switching capability not only
increases the complexity of their interactions but also increases
the total amount of processing individual instances would handle.
The rationales for GMPLS controlled multi-layer/multi-region networks context
are summarized here below:
- The maintenance of multiple instances of the control plane on devices hosting
more than one switching capability not only increases the complexity of their
interactions but also increases 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 multiple
identification for the same object (a link for instance or more generally any identifiers for the same object (a link, for instance, or more
network resource), on the other hand such aggregation does not impact the generally, any network resource). On the other hand such
separation between the control and the data plane. aggregation does not impact the separation between the control
- By maintaining a single routing protocol instance and a single TE database plane and the data plane.
per LSR, a unified control plane model prevents from maintaining a dedicated
routing topology per layer and therefore does not mandate a full mesh of
routing adjacencies as it is the case with overlaid control planes.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 - By maintaining a single routing protocol instance and a single TE
database per LSR, a unified control plane model removes the
requirement to maintain a dedicated routing topology per layer and
therefore does not mandate a full mesh of routing adjacencies as is
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
the case with overlaid control planes.
- The collaboration between technology layers where the control
channel is associated with the data channel (e.g. packet/framed
data planes) and technology layers where the control channel is not
directly associated with the data channel (SONET/SDH, G.709, etc.)
is facilitated by the capability within GMPLS to associate in-band
control plane signaling to the IP terminating interfaces of the
control plane.
- The collaboration between associated control planes (packet/framed data
planes) and non-associated control planes (SONET/SDH, G.709, etc.) is
facilitated due to the capability of hooking the associated in-band signaling
to the IP terminating interfaces 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 such
environment is facilitated (less control to management interactions) and more a MRN/MLN is made more simple (fewer control to management
scalable (through the use of aggregated information). interactions) and more scalable (through the use of aggregated
- Multi-region/multi-layer traffic engineering is facilitated as TE-links from information).
distinct regions/layers are stored within the same TE Database.
- Multi-region/multi-layer traffic engineering is facilitated as
TE-links from distinct regions/layers are stored within the same 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 of either A network comprising transport nodes with multiple data plane layers
the same ISC or different ISCs, controlled by a single GMPLS control plane of either the same ISC or different ISCs, controlled by a single
instance, is called a Multi-Layer Network (MLN). A sub-set of MLNs consists of GMPLS control plane instance, is called a Multi-Layer Network (MLN).
networks supporting LSPs of different switching technologies (ISCs). A network A sub-set of MLNs consists of networks supporting LSPs of different
supporting more than one switching technology is called a Multi-Region Network switching technologies (ISCs). A network supporting more than one
(MRN). 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 support The Interface Switching Capability (ISC) is introduced in GMPLS to
various kinds of switching technology in a unified way [RFC4202]. An ISC is support various kinds of switching technology in a unified way
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) describes A switching type (also referred to as the switching capability type)
the ability of a node to forward data of a particular data plane technology, and describes the ability of a node to forward data of a particular data
uniquely identifies a network region. The following ISC types (and, hence, plane technology, and uniquely identifies a network region. The
regions) are defined: PSC, L2SC, TDM, LSC, and FSC. Each end of a data link following ISC types (and, hence, regions) are defined: PSC, L2SC,
(more precisely, each interface connecting a data link to a node) in a GMPLS TDM, LSC, and FSC. Each end of a data link (more precisely, each
network is associated with an ISC. interface connecting a data link to a node) in a GMPLS network is
associated with an ISC.
The ISC value is advertised as a part of the Interface Switching Capability The ISC value is advertised as a part of the Interface Switching
Descriptor (ISCD) attribute (sub-TLV) of a TE link end associated with a Capability Descriptor (ISCD) attribute (sub-TLV) of a TE link end
particular link interface [RFC4202]. Apart from the ISC, the ISCD contains associated with a particular link interface [RFC4202]. Apart from the
information including the encoding type, the bandwidth granularity, and the ISC, the ISCD contains information including the encoding type, the
unreserved bandwidth on each of eight priorities at which LSPs can be bandwidth granularity, and the unreserved bandwidth on each of eight
established. The ISCD does not "identify" network layers, it uniquely priorities at which LSPs can be established. The ISCD does not
characterizes information associated to one or more network layers. "identify" network layers, it uniquely characterizes information
associated to one or more network layers.
TE link end advertisements may contain multiple ISCDs. This can be interpreted draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
as advertising a multi-layer (or multi-switching-capable) TE link end. That is,
the TE link end (and therefore the TE link) is present in multiple layers.
4.2. Multiple Interface Switching Capabilities TE link end advertisements may contain multiple ISCDs. This can be
interpreted as advertising a multi-layer (or multi-switching-capable)
TE link end. That is, the TE link end (and therefore the TE link) is
present in multiple layers.
In an MLN, network elements may be single-switching-type-capable or multi- 4.2. Multiple Interface Switching Capabilities
switching-type-capable nodes. Single-switching-type-capable 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). This case is described in [RFC4202].
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 In an MLN, network elements may be single-switching-type-capable or
multi-switching-type-capable nodes. Single-switching-type-capable
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).
This case is described in [RFC4202].
Multi-switching-type-capable LSRs are classified as "simplex" or "hybrid" nodes. Multi-switching-type-capable LSRs are classified as "simplex" or
Simplex and hybrid nodes are categorized according to the way they advertise "hybrid" nodes. Simplex and hybrid nodes are categorized according to
these multiple ISCs: the way they advertise these multiple ISCs:
- A simplex node can terminate data links with different switching capabilities - A simplex node can terminate data links with different switching
where each data link is connected to the node by a separate link interface. capabilities where each data link is connected to the node by a
So, it advertises several TE Links each with a single ISC value carried in separate link interface. So, it advertises several TE Links each
its ISCD sub-TLV. For example, an LSR with PSC and TDM links each of which is with a single ISC value carried in its ISCD sub-TLV. For example,
connected to the LSR via a separate interface. an LSR with PSC and TDM links each of which is connected to the LSR
via a separate interface.
- A hybrid node can terminate data links with different switching capabilities - A hybrid node can terminate data links with different switching
where the data links are connected to the node by the same interface. So, it capabilities where the data links are connected to the node by the
advertises a single TE Link containing more than one ISCD each with a same interface. So, it advertises a single TE Link containing more
different ISC value. For example, a node may terminate PSC and TDM data links than one ISCD each with a different ISC value. For example, a node
and interconnect those external data links via internal links. The external may terminate PSC and TDM data links and interconnect those
interfaces connected to the node have both PSC and TDM capabilities. external data links via internal links. The external interfaces
connected to the node have both PSC and TDM capabilities.
Additionally, TE link advertisements issued by a simplex or a hybrid node may Additionally, TE link advertisements issued by a simplex or a hybrid
need to provide information about the node's internal adaptation capabilities node may need to provide information about the node's internal
between the switching technologies supported. That is, the node's capability to adaptation capabilities between the switching technologies supported.
perform layer border node functions. That is, the node's capability to perform layer border node
functions. This information allows path computation to select an end-
to-end multi-layer or multi-region path that includes links of
different switching capabilities that are joined by LSRs that can
adapt the signal between the links.
4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes 4.2.1. Networks with Multi-Switching-Type-Capable Hybrid Nodes
This type of network contains at least one hybrid node, zero or more simplex This type of network contains at least one hybrid node, zero or more
nodes, and a set of single-switching-type-capable nodes. simplex nodes, and a set of single-switching-type-capable nodes.
Figure 1 shows an example hybrid node. The hybrid node has two switching Figure 1 shows an example hybrid node. The hybrid node has two
elements (matrices), which support, for instance, TDM and PSC switching switching elements (matrices), which support, for instance, TDM and
respectively. The node terminates a PSC and a TDM link (Link1 and Link2 PSC switching respectively. The node terminates a PSC and a TDM link
respectively). It also has an internal link connecting the two switching (Link1 and Link2 respectively). It also has an internal link
elements. draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
The two switching elements are internally interconnected in such a way that it connecting the two switching elements.
is possible to terminate some of the resources of, say, Link2 and provide
adaptation for PSC traffic received/sent over the PSC interface (#b). This The two switching elements are internally interconnected in such a
situation is modeled in GMPLS by connecting the local end of Link2 to the TDM way that it is possible to terminate some of the resources of, say,
switching element via an additional interface realizing the Link2 and provide adaptation for PSC traffic received/sent over the
termination/adaptation function. There are two possible ways to set up PSC LSPs PSC interface (#b). This situation is modeled in GMPLS by connecting
through the hybrid node. Available resource advertisement (i.e., Unreserved and the local end of Link2 to the TDM switching element via an additional
Min/Max LSP Bandwidth) should cover both of these methods. interface realizing the termination/adaptation function. There are
two possible ways to set up PSC LSPs through the hybrid node.
Available resource advertisement (i.e., Unreserved and Min/Max LSP
Bandwidth) should cover both of these methods.
Network element Network element
............................. .............................
: -------- : : -------- :
: | PSC | : : | PSC | :
Link1 -------------<->--|#a | : Link1 -------------<->--|#a | :
: | | :
: +--<->---|#b | : : +--<->---|#b | :
: | -------- : : | -------- :
TDM : | ---------- : : | ---------- :
+PSC : +--<->--|#c TDM | : TDM : +--<->--|#c TDM | :
+PSC : | | :
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
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 consolidated In GMPLS-based multi-region/multi-layer networks, TE Links may be
into a single Traffic Engineering Database (TED) for use by the single control consolidated into a single Traffic Engineering Database (TED) for use
plane instance. Since this TED contains the information relative to all the by the single control plane instance. Since this TED contains the
layers of all regions in the network, a path across multiple layers (possibly information relative to all the layers of all regions in the network,
crossing multiple regions) can be computed using the information in this TED. a path across multiple layers (possibly crossing multiple regions)
Thus, optimization of network resources across the multiple layers of the same can be computed using the information in this TED. Thus, optimization
region and across multiple regions can be achieved. of network resources across the multiple layers of the same region
and across multiple regions can be achieved.
These concepts allow for the operation of one network layer over the topology These concepts allow for the operation of one network layer over the
(that is, TE links) provided by other network layers (for example, the use of a topology (that is, TE links) provided by other network layers (for
lower layer LSC LSP carrying PSC LSPs). In turn, a greater degree of control and example, the use of a lower layer LSC LSP carrying PSC LSPs). In
inter-working can be achieved, including (but not limited too): 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-switching- Note that in a multi-layer/multi-region network that includes multi-
type-capable nodes, an explicit route used to establish an end-to-end LSP can switching-type-capable nodes, an explicit route used to establish an
specify nodes that belong to different layers or regions. In this case, a end-to-end LSP can specify nodes that belong to different layers or
mechanism to control the dynamic creation of FA LSPs may be required (see regions. In this case, a mechanism to control the dynamic creation of
Sections 4.3.2 and 4.3.3). 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 dynamically There is a full spectrum of options to control how FA-LSPs are
established. The process can be subject to the control of a policy, which may be dynamically established. The process can be subject to the control of
set by a management component, and which may require that the management plane a policy, which may be set by a management component, and which may
is consulted at the time that the FA LSP is established. Alternatively, the FA require that the management plane is consulted at the time that the
LSP can be established at the request of the control plane without any FA-LSP is established. Alternatively, the FA-LSP can be established
management control. 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 may be When an LSP crosses the boundary from an upper to a lower layer, it
nested into a lower layer FA LSP that crosses the lower layer. From a signaling may be nested into a lower layer FA-LSP that crosses the lower layer.
perspective, there are two alternatives to establish the lower layer FA LSP: From a signaling perspective, there are two alternatives to establish
static (pre-provisioned) and dynamic (triggered). A pre-provisioned FA-LSP may the lower layer FA-LSP: static (pre-provisioned) and dynamic
be initiated either by the operator or automatically using features like TE (triggered). A pre-provisioned FA-LSP may be initiated either by the
auto-mesh [AUTO-MESH]. If such a lower layer LSP does not already exist, the LSP operator or automatically using features like TE auto-mesh
may be established dynamically. Such a mechanism is referred to as "triggered [RFC4972]. If such a lower layer LSP does not already exist, the LSP
signaling". may be established dynamically. Such a mechanism is referred to as
"triggered signaling".
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
4.3.2. FA-LSPs 4.3.2. FA-LSPs
Once an LSP is created across a layer from one layer border node to another, it Once an LSP is created across a layer from one layer border node to
can be used as a data link in an upper layer. 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 Furthermore, it can be advertised as a TE-link, allowing other nodes
the LSP as a TE link for their path computation [RFC4206]. An LSP created either to consider the LSP as a TE link for their path computation
statically or dynamically by one instance of the control plane and advertised as [RFC4206]. An LSP created either statically or dynamically by one
a TE link into the same instance of the control plane is called a Forwarding instance of the control plane and advertised as a TE link into the
Adjacency LSP (FA-LSP). The FA-LSP is advertised as a TE link, and that TE link same instance of the control plane is called a Forwarding Adjacency
is called a Forwarding Adjacency (FA). An FA has the special characteristic of LSP (FA-LSP). The FA-LSP is advertised as a TE link, and that TE link
not requiring a routing adjacency (peering) between its end points yet still is called a Forwarding Adjacency (FA). An FA has the special
guaranteeing control plane connectivity between the FA-LSP end points based on a characteristic of not requiring a routing adjacency (peering) between
signaling adjacency. An FA is a useful and powerful tool for improving the its end points yet still guaranteeing control plane connectivity
scalability of GMPLS Traffic Engineering (TE) capable networks since multiple between the FA-LSP end points based on a signaling adjacency. An FA
higher layer LSPs may be nested (aggregated) over a single FA-LSP. is a useful and powerful tool for improving the scalability of GMPLS
Traffic Engineering (TE) capable networks 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) LSP The aggregation of LSPs enables the creation of a vertical (nested)
Hierarchy. A set of FA-LSPs across or within a lower layer can be used during LSP Hierarchy. A set of FA-LSPs across or within a lower layer can be
path selection by a higher layer LSP. Likewise, the higher layer LSPs may be used during path selection by a higher layer LSP. Likewise, the
carried over dynamic data links realized via LSPs (just as they are carried over draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
any "regular" static data links). This process requires the nesting of LSPs
through a hierarchical process [RFC4206]. The TED contains a set of LSP
advertisements from different layers that are identified by the 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 to carry higher layer LSPs may be carried over dynamic data links realized via
higher layer LSPs across the lower layer. For example, if the LSP is set up LSPs (just as they are carried over any "regular" static data links).
using triggered signaling, it will be used to carry the higher layer LSP that This process requires the nesting of LSPs through a hierarchical
caused the trigger. Further, the lower layer remains available for use by other process [RFC4206]. The TED contains a set of LSP advertisements from
higher layer LSPs arriving at the boundary. different layers that are identified by the ISCD contained within the
TE link advertisement associated with the LSP [RFC4202].
Under some circumstances it may be useful to control the advertisement of LSPs If a lower layer LSP is not advertised as an FA, it can still be used
as FAs during the signaling establishment of the LSPs [DYN-HIER]. to carry higher layer LSPs across the lower layer. For example, if
the LSP is set up using triggered signaling, it will be used to carry
the higher layer LSP that caused the trigger. Further, the lower
layer remains available for use by other higher layer LSPs arriving
at the boundary.
Under some circumstances it may be useful to control the
advertisement of LSPs as FAs during the signaling establishment of
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 efficient path A set of one or more of lower-layer LSPs provides information for
handling in upper-layer(s) of the MLN, or, in other words, provides a virtual efficient path handling in upper-layer(s) of the MLN, or, in other
network topology (VNT) to the upper-layers. For instance, a set of LSPs, each of words, provides a virtual network topology (VNT) to the upper-layers.
which is supported by an LSC LSP, provides a virtual network topology to the For instance, a set of LSPs, each of which is supported by an LSC
layers of a PSC region, assuming that the PSC region is connected to the LSC LSP, provides a virtual network topology to the layers of a PSC
region. Note that a single lower-layer LSP is a special case of the VNT. The region, assuming that the PSC region is connected to the LSC region.
virtual network topology is configured by setting up or tearing down the lower Note that a single lower-layer LSP is a special case of the VNT. The
layer LSPs. By using GMPLS signaling and routing protocols, the virtual network virtual network topology is configured by setting up or tearing down
topology can be adapted to traffic demands. the lower layer LSPs. By using GMPLS signaling and 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 diversely-routed A lower-layer LSP appears as a TE-link in the VNT. Whether the
lower-layer LSPs are used or not, the routes of lower-layer LSPs are hidden from diversely-routed lower-layer LSPs are used or not, the routes of
the upper layer in the VNT. Thus, the VNT simplifies the upper-layer routing and lower-layer LSPs are hidden from the upper layer in the VNT. Thus,
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 the VNT simplifies the upper-layer routing and traffic engineering
decisions by hiding the routes taken by the lower-layer LSPs.
However, hiding the routes of the lower-layer LSPs may lose important
information that is needed to make the higher-layer LSPs reliable.
For instance, the routing and traffic engineering in the IP/MPLS
layer does not usually consider how the IP/MPLS TE links are formed
from optical paths that are routed in the fiber layer. Two optical
paths may share the same fiber link in the lower-layer and therefore
they may both fail if the fiber link is cut. Thus the shared risk
properties of the TE links in the VNT must be made available to the
higher layer during path computation. Further, the topology of the
VNT should be designed so that any single fiber cut does not bisect
the VNT. These issues are addressed later in this document.
traffic engineering decisions by hiding the routes taken by the lower-layer LSPs. Reconfiguration of the virtual network topology may be triggered by
However hiding the routes of the lower-layer LSPs may lose important information traffic demand changes, topology configuration changes, signaling
that is needed to make the higher-layer LSPs reliable. For instance, the routing draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
and traffic engineering in the IP/MPLS layer does not usually consider how the
IP/MPLS TE links are formed from optical paths that are routed in the fiber
layer. Two optical paths may share the same fiber link in the lower-layer and
therefore they may both fail if the fiber link is cut. Thus the shared risk
properties of the TE links in the VNT must be made available to the higher layer
during path computation. Further, the topology of the VNT should be designed so
that any single fiber cut does not bisect the VNT. These issues are addressed
later in this document.
Reconfiguration of the virtual network topology may be triggered by traffic requests from the upper layer, and network failures. For instance, by
demand changes, topology configuration changes, signaling requests from the reconfiguring the virtual network topology according to the traffic
upper layer, and network failures. For instance, by reconfiguring the virtual demand between source and destination node pairs, network performance
network topology according to the traffic demand between source and destination factors, such as maximum link utilization and residual capacity of
node pairs, network performance factors, such as maximum link utilization and the network, can be optimized. Reconfiguration is performed by
residual capacity of the network, can be optimized. Reconfiguration is performed computing the new VNT from the traffic demand matrix and optionally
by computing the new VNT from the traffic demand matrix and optionally from the from the current VNT. Exact details are outside the scope of this
current VNT. Exact details are outside the scope of this document. However, this document. However, this method may be tailored according to the
method may be tailored according to the service provider's policy regarding service provider's policy regarding network performance and quality
network performance and quality of service (delay, loss/disruption, utilization, of service (delay, loss/disruption, utilization, residual capacity,
residual capacity, reliability). 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 multi-switching- The MRN/MLN can consist of single-switching-type-capable and multi-
type-capable nodes. The path computation mechanism in the MLN SHOULD be able to switching-type-capable nodes. The path computation mechanism in the
compute paths consisting of any combination of such nodes. MLN SHOULD be able to compute paths consisting of any combination of
such nodes.
Both single-switching-type-capable and multi-switching-type-capable (simplex or Both single-switching-type-capable and multi-switching-type-capable
hybrid) nodes could play the role of layer boundary. MRN/MLN Path computation (simplex or hybrid) nodes could play the role of layer boundary.
SHOULD handle TE topologies built of any combination of nodes MRN/MLN Path computation SHOULD handle TE topologies built of any
combination of nodes.
5.2. Advertisement of the Available Adaptation Resource 5.2. Advertisement of the Available Adaptation Resource
A hybrid node SHOULD maintain resources on its internal links (the links A hybrid node SHOULD maintain resources on its internal links (the
required for vertical (layer) integration) and SHOULD advertise the resource links required for vertical (layer) integration) and SHOULD advertise
information for those links. Likewise, path computation elements SHOULD be the resource information for those links. Likewise, path computation
prepared to use the availability of termination/adaptation resources as a elements SHOULD be prepared to use the availability of termination/
constraint in MRN/MLN path computations to reduce the higher layer LSP setup adaptation resources as a constraint in MRN/MLN path computations to
blocking probability caused by the lack of necessary termination/ adaptation reduce the higher layer LSP setup blocking probability caused by the
resources in the lower layer(s). lack of necessary termination/adaptation resources in the lower
layer(s).
The advertisement of the adaptation capability to terminate LSPs of lower-region The advertisement of the adaptation capability to terminate LSPs of
and forward traffic in the upper-region is REQUIRED, as it provides critical lower-region and forward traffic in the upper-region is REQUIRED, as
information when performing multi-region path computation. it provides critical information when performing multi-region path
computation.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 The mechanism SHOULD cover the case where the upper-layer links which
are directly connected to upper-layer switching element and the ones
which are connected through internal links between upper-layer
element and lower-layer element coexist (see Section 4.2.1).
The mechanism SHOULD cover the case where the upper-layer links which are draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
directly connected to upper-layer switching element and 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 a unified traffic engineering and routing model. The MRN/MLN relies on unified routing and traffic engineering
- Unified routing model: by maintaining a single routing protocol instance and models.
a single TE database per LSR, a unified control plane model prevents from
maintaining a dedicated routing topology per layer and therefore does not
mandate a full mesh of routing adjacencies per layer.
- Unified TE model: the TED in each LSR is populated with TE-links from all
layers of all regions (TE links interfaces on multiple-switching capability
LSR can be advertised with multiple ISCD). This may lead to a large amount of
information that has to be flooded and stored within the network.
Furthermore, path computation times, which may be of great importance during - Unified routing model: By maintaining a single routing protocol
restoration, will depend on the size of the TED. instance and a single TE database per LSR, a unified control plane
model removes the requirement to maintain a dedicated routing
topology per layer, and therefore does not mandate a full mesh of
routing adjacencies per layer.
- Unified TE model: The TED in each LSR is populated with TE-links
from all layers of all regions (TE link interfaces on multiple-
switching-capability LSRs can be advertised with multiple ISCDs).
This may lead to an increase in the amount of information that has
to be flooded and stored within the network.
Furthermore, path computation times, which may be of great importance
during restoration, will depend on the size of the TED.
Thus MRN/MLN routing mechanisms MUST be designed to scale well with
an increase of any of the following:
Thus MRN/MLN routing mechanisms MUST be designed to scale well with 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 information Further, design of the routing protocols MUST NOT prevent TE
filtering based on ISCDs. The path computation mechanism and the signaling information filtering based on ISCDs. The path computation mechanism
protocol SHOULD be able to operate on partial TE information. and the signaling protocol SHOULD be able to operate on partial TE
information.
Since TE Links can advertise multiple Interface Switching Capabilities (ISC), Since TE Links can advertise multiple Interface Switching
the number of links can be limited (by combination) by using specific Capabilities (ISCs), the number of links can be limited (by
topological maps referred to as VNT (Virtual Network Topologies). The combination) by using specific topological maps referred to as VNT
introduction of virtual topological maps leads us to consider the concept of (Virtual Network Topologies). The introduction of virtual topological
emulation of data plane overlays. maps leads us to consider the concept of emulation of data plane
overlays.
5.4.Stability 5.4.Stability
Path computation is dependent on the network topology and associated link state. Path computation is dependent on the network topology and associated
The path computation stability of an upper layer may be impaired if the VNT link state. The path computation stability of an upper layer may be
changes frequently and/or if the status and TE parameters (the TE metric, for impaired if the VNT changes frequently and/or if the status and TE
instance) of links in the VNT changes frequently. In this context, robustness of parameters (the TE metric, for instance) of links in the VNT changes
the VNT is defined as the capability to smooth changes that may occur and avoid frequently. In this context, robustness of the VNT is defined as the
their propagation into higher layers. Changes to the VNT may be caused by the capability to smooth changes that may occur and avoid their
creation, deletion, or modification of LSPs. propagation into higher layers. Changes to the VNT may be caused by
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
Creation, deletion, and modification of LSPs MAY be triggered by adjacent layers the creation, deletion, or modification of LSPs.
or through operational actions to meet traffic demand changes, topology changes,
signaling requests from the upper layer, and network failures. Routing
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
robustness SHOULD be traded with adaptability with respect to the change of Creation, deletion, and modification of LSPs MAY be triggered by
incoming traffic requests. adjacent layers or through operational actions to meet traffic demand
changes, topology changes, signaling requests from the upper layer,
and network failures. Routing robustness SHOULD be traded 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, the upper- When reconfiguring the VNT according to a change in traffic demand,
layer LSP might be disrupted. Such disruption to the upper layers MUST be the upper-layer LSP might be disrupted. Such disruption to the upper
minimized. layers MUST be minimized.
When residual resource decreases to a certain level, some lower layer LSPs MAY When residual resource decreases to a certain level, some lower layer
be released according to local or network policies. There is a trade-off between LSPs MAY be released according to local or network policies. There is
minimizing the amount of resource reserved in the lower layer and disrupting a trade-off between minimizing the amount of resource reserved in the
higher layer traffic (i.e. moving the traffic to other TE-LSPs so that some LSPs lower layer and disrupting higher layer traffic (i.e. moving the
can be released). Such traffic disruption MAY be allowed, but MUST be under the traffic to other TE-LSPs so that some LSPs can be released). Such
control of policy that can be configured by the operator. Any repositioning of traffic disruption MAY be allowed, but MUST be under the control of
traffic MUST be as non-disruptive as possible (for example, using make-before- policy that can be configured by the operator. Any repositioning of
break). traffic MUST be as non-disruptive as possible (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 that TE-Link parameters SHOULD be inherited from the parameters of the LSP
provides the TE-link, and so from the TE-links in the lower layer that are that provides the TE-link, and so from the TE-links in the lower
traversed by the LSP. 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. Particular Inheritance rules MUST be applied based on specific policies.
attention should be given to the inheritance of TE metric (which may be other Particular attention should be given to the inheritance of TE metric
than a strict sum of the metrics of the component TE links at the lower layer), (which may be other than a strict sum of the metrics of the component
protection attributes, and SRLG. TE links at the lower layer), protection attributes, and SRLG.
As described earlier, hiding the routes of the lower-layer LSPs may lose As described earlier, hiding the routes of the lower-layer LSPs may
important information necessary to make LSPs in the higher layer network lose important information necessary to make LSPs in the higher layer
reliable. SRLGs may be used to identify which lower-layer LSPs share the same network reliable. SRLGs may be used to identify which lower-layer
failure risk so that the potential risk of the VNT becoming disjoint can be LSPs share the same failure risk so that the potential risk of the
minimized, and so that resource disjoint protection paths can be set up in the draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
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.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 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 boundaries when Path computation MAY take into account LSP region and layer
computing a path for an LSP. For example, path computation MAY restrict the path boundaries when computing a path for an LSP. For example, path
taken by an LSP to only the links whose interface switching capability is PSC. computation MAY restrict the path taken by an LSP to only the links
whose interface switching capability is PSC.
Interface switching capability is used as a constraint in path computation. For Interface switching capability is used as a constraint in path
example, a TDM-LSP is routed over the topology composed of TE links of the same computation. For example, a TDM-LSP is routed over the topology
TDM layer. In calculating the path for the LSP, the TED MAY be filtered to composed of TE links of the same TDM layer. In calculating the path
include only links where both end include requested LSP switching type. In this for the LSP, the TED MAY be filtered to include only links where both
way hierarchical routing is done by using a TED filtered with respect to end include requested LSP switching type. In this way hierarchical
switching capability (that is, with respect to particular layer). routing is done by using a TED filtered with respect to switching
capability (that is, with respect to particular layer).
If triggered signaling is allowed, the path computation mechanism MAY produce a If triggered signaling is allowed, the path computation mechanism MAY
route containing multiple layers/regions. The path is computed over the multiple produce a route containing multiple layers/regions. The path is
layers/regions even if the path is not "connected" in the same layer as the computed over the multiple layers/regions even if the path is not
endpoints of the path exist. Note that here we assume that triggered signaling "connected" in the same layer as the endpoints of the path exist.
will be invoked to make the path "connected", when the upper-layer signaling Note that here we assume that triggered signaling will be invoked to
request arrives at the boundary node. make the path "connected", when the upper-layer signaling request
arrives at the boundary node.
The upper-layer signaling request may contain an ERO that includes only hops in The upper-layer signaling request may contain an ERO that includes
the upper layer, in which case the boundary node is responsible for triggered only hops in the upper layer, in which case the boundary node is
creation of the lower-layer FA-LSP using a path of its choice, or for the responsible for triggered creation of the lower-layer FA-LSP using a
selection of any available lower layer LSP as a data link for the higher layer. path of its choice, or for the selection of any available lower layer
This mechanism is appropriate for environments where the TED is filtered in the LSP as a data link for the higher layer. This mechanism is
higher layer, where separate routing instances are used per layer, or where appropriate for environments where the TED is filtered in the higher
administrative policies prevent the higher layer from specifying paths through layer, where separate routing instances are used per layer, or where
the lower layer. administrative policies prevent the higher layer from specifying
paths through the lower layer.
Obviously, if the lower layer LSP has been advertised as a TE link (virtual or Obviously, if the lower layer LSP has been advertised as a TE link
real) into the higher layer, then the higher layer signaling request may contain (virtual or real) into the higher layer, then the higher layer
the TE link identifier and so indicate the lower layer resources to be used. But signaling request may contain the TE link identifier and so indicate
in this case, the path of the lower layer LSP can be dynamically changed by the the lower layer resources to be used. But in this case, the path of
lower layer at any time. 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 specifying Alternatively, the upper-layer signaling request may contain an ERO
the lower layer FA-LSP route. In this case, the boundary node is responsible for specifying the lower layer FA-LSP route. In this case, the boundary
decision as to which it should use the path contained in the strict ERO or it node is responsible for decision as to which it should use the path
should re-compute the path within in the lower-layer. contained in the strict ERO or it should re-compute the path within
in the lower-layer.
Even in case the lower-layer FA-LSPs are already established, a signaling draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
request may also be encoded as loose ERO. In this situation, it is up to the
boundary node to decide whether it should a new lower-layer FA-LSP or it should
use the existing lower-layer FA-LSPs.
The lower-layer FA-LSP can be advertised just as an FA-LSP in the upper-layer or Even in case the lower-layer FA-LSPs are already established, a
an IGP adjacency can be brought up on the lower-layer FA-LSP. signaling request may also be encoded as loose ERO. In this
situation, it is up to the boundary node to decide whether it should
a new lower-layer FA-LSP or it should use the existing lower-layer
FA-LSPs.
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
FA-LSP.
5.8. LSP Resource Utilization 5.8. LSP Resource Utilization
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
It MUST be possible to utilize network resources efficiently. Particularly, It MUST be possible to utilize network resources efficiently.
resource usage in all layers SHOULD be optimized as a whole (i.e., across all Particularly, resource usage in all layers SHOULD be optimized as a
layers), in a coordinated manner, (i.e., taking all layers into account). The whole (i.e., across all layers), in a coordinated manner, (i.e.,
number of lower-layer LSPs carrying upper-layer LSPs SHOULD be minimized (note taking all layers into account). The number of lower-layer LSPs
that multiple LSPs MAY be used for load balancing). Lower-layer LSPs that could carrying upper-layer LSPs SHOULD be minimized (note that multiple
have their traffic re-routed onto other LSPs are unnecessary and SHOULD be LSPs MAY be used for load balancing). Lower-layer LSPs that could
avoided. have their traffic re-routed onto other LSPs are unnecessary and
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 regions. A PSC or Statistical multiplexing can only be employed in PSC and L2SC
L2SC LSP may or may not consume the maximum reservable bandwidth of the TE link regions. A PSC or L2SC LSP may or may not consume the maximum
(FA LSP) that carries it. On the other hand, a TDM, or LSC LSP always consumes a reservable bandwidth of the TE link (FA-LSP) that carries it. On the
fixed amount of bandwidth as long as it exists (and is fully instantiated) other hand, a TDM, or LSC LSP always consumes a fixed amount of
because statistical multiplexing is not available. bandwidth as long as it exists (and is fully instantiated) because
statistical multiplexing is not available.
If there is low traffic demand, some FA LSPs that do not carry any higher-layer If there is low traffic demand, some FA-LSPs that do not carry any
LSP MAY be released so that lower-layer resources are released and can be higher-layer LSP MAY be released so that lower-layer resources are
assigned to other uses. Note that if a small fraction of the available bandwidth released and can be assigned to other uses. Note that if a small
of an FA-LSP is still in use, the nested LSPs can also be re-routed to other FA- fraction of the available bandwidth of an FA-LSP is still in use, the
LSPs (optionally using the make-before-break technique) to completely free up nested LSPs can also be re-routed to other FA-LSPs (optionally using
the FA-LSP. Alternatively, unused FA LSPs MAY be retained for future use. the make-before-break technique) to completely free up the FA-LSP.
Release or retention of underutilized FA LSPs is a policy decision. Alternatively, unused FA-LSPs MAY be retained for future use. Release
or retention of underutilized FA-LSPs is a policy decision.
As part of the re-optimization process, the solution MUST allow rerouting of an As part of the re-optimization process, the solution MUST allow
FA LSP while keeping interface identifiers of corresponding TE links unchanged. rerouting of an FA-LSP while keeping interface identifiers of
Further, this process MUST be possible while the FA LSP is carrying traffic corresponding TE links unchanged. Further, this process MUST be
(higher layer LSPs) with minimal disruption to the traffic. possible while the FA-LSP is carrying traffic (higher layer LSPs)
with minimal disruption to the traffic.
Additional FA LSPs MAY also be created based on policy, which might consider Additional FA-LSPs MAY also be created based on policy, which might
residual resources and the change of traffic demand across the region. By consider residual resources and the change of traffic demand across
creating the new FA LSPs, the network performance such as maximum residual the region. By creating the new FA-LSPs, the network performance such
capacity may increase. as maximum residual capacity may increase.
As the number of FA LSPs grows, the residual resource may decrease. In this case, draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
re-optimization of FA LSPs MAY be invoked according to policy.
Any solution MUST include measures to protect against network destabilization As the number of FA-LSPs grows, the residual resource may decrease.
caused by the rapid setup and teardown of LSPs as traffic demand varies near a In this case, re-optimization of FA-LSPs MAY be invoked according to
threshold. policy.
Signaling of lower-layer LSPs SHOULD include a mechanism to rapidly advertise Any solution MUST include measures to protect against network
the LSP as a TE link and to coordinate into which routing instances the TE link destabilization caused by the rapid setup and teardown of LSPs as
should be advertised. traffic demand varies near a threshold.
Signaling of lower-layer LSPs SHOULD include a mechanism to rapidly
advertise the LSP as a TE link and to coordinate into which routing
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-provision) It may be considered disadvantageous to fully instantiate (i.e. pre-
the set of lower layer LSPs that provide the VNT since this might reserve provision) the set of lower layer LSPs that provide the VNT since
bandwidth that could be used for other LSPs in the absence of upper-layer this might reserve bandwidth that could be used for other LSPs in the
traffic. absence of upper-layer traffic.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 However, in order to allow path computation of upper-layer LSPs
across the lower-layer, the lower-layer LSPs MAY be advertised into
the upper-layer as though they had been fully established, but
without actually establishing them. Such TE links that represent the
possibility of an underlying LSP are termed "virtual TE-links." It is
an implementation choice at a layer boundary node whether to create
real or virtual TE-links, and the choice if available in an
implementation MUST be under the control of operator policy. Note
that there is no requirement to support the creation of virtual TE-
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
higher layer, it is possible to route a higher layer LSP into a lower
layer on the assumptions that proper hierarchical LSPs in the lower
layer will be dynamically created (triggered) as needed.
However, in order to allow path computation of upper-layer LSPs across the If an upper-layer LSP that makes use of a virtual TE-Link is set up,
lower-layer, the lower-layer LSPs MAY be advertised into the upper-layer as the underlying LSP MUST be immediately signaled in the lower layer.
though they had been fully established, but without actually establishing them.
Such TE links that represent the possibility of an underlying LSP are termed
"virtual TE-links." It is an implementation choice at a layer boundary node
whether to create real or virtual TE-links, and the choice if available in an
implementation MUST be under the control of operator policy. Note that there is
no requirement to support the creation of virtual TE-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 higher layer, it is possible to route a higher layer
LSP into a lower layer on the assumptions that proper hierarchical LSPs in the
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, the If virtual TE-Links are used in place of pre-established LSPs, the
underlying LSP MUST be immediately signaled in the lower layer. TE-links across the upper-layer can remain stable using pre-computed
paths while wastage of bandwidth within the lower-layer and
unnecessary reservation of adaptation ports at the border nodes can
be avoided.
If virtual TE-Links are used in place of pre-established LSPs, the TE-links The solution SHOULD provide operations to facilitate the build-up of
across the upper-layer can remain stable using pre-computed paths while wastage such virtual TE-links, taking into account the (forecast) traffic
of bandwidth within the lower-layer and unnecessary reservation of adaptation demand and available resource in the lower-layer.
ports at the border nodes can be avoided.
The solution SHOULD provide operations to facilitate the build-up of such Virtual TE-links MAY be added, removed or modified dynamically (by
virtual TE-links, taking into account the (forecast) traffic demand and changing their capacity) according to the change of the (forecast)
available resource in the lower-layer. traffic demand and the available resource in the lower-layer. The
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
Virtual TE-links MAY be added, removed or modified dynamically (by changing maximum number of virtual TE links that can be defined SHOULD be
their capacity) according to the change of the (forecast) traffic demand and the configurable.
available resource in the lower-layer. The maximum number of virtual TE links
that can be defined SHOULD be configurable.
Any solution MUST include measures to protect against network destabilization Any solution MUST include measures to protect against network
caused by the rapid changes in the virtual network topology as traffic demand destabilization caused by the rapid changes in the virtual network
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 to form The concept of the VNT can be extended to allow the virtual TE-links
part of the VNT. The combination of the fully provisioned TE-links and the to form part of the VNT. The combination of the fully provisioned TE-
virtual TE-links defines the VNT provided by the lower layer. The VNT can be links and the virtual TE-links defines the VNT provided by the lower
changed by setting up and/or tearing down virtual TE links as well as by layer. The VNT can be changed by setting up and/or tearing down
modifying real links (i.e. the fully provisioned LSPs). How to design the VNT virtual TE links as well as by modifying real links (i.e., the fully
and how to manage it are out of scope of this document. provisioned LSPs). How to design the VNT and how to manage it are out
of scope of this document.
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 higher layer, When a lower layer LSP is established for use as a data link by a
the LSP MAY be verified for correct connectivity and data integrity. Such higher layer, the LSP MAY be verified for correct connectivity and
mechanisms are data technology-specific and are beyond the scope of this data integrity. Such mechanisms are data technology-specific and are
document, but may be coordinated through the GMPLS control plane. beyond the scope of this document, but may be coordinated through the
GMPLS control plane.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
6. Security Considerations 6. Security Considerations
The current version of this document does not introduce any new security The MLN/MRN architecture does not introduce any new security
considerations as it only lists a set of requirements. requirements over the general GMPLS architecture described in
[RFC3945]. Additional security considerations form MPLS and GMPLS
networks are described in [MPLS-SEC].
It is expected that solution documents will include a full analysis of the However, where the separate layers of a MLN/MRN network are operated
security issues that any protocol extensions introduce. as different administrative domains, additional security
considerations may be given to the mechanisms for allowing inter-
layer LSP setup, for triggering lower-layer LSPs, or for VNT
management. Similarly, consideration may be given to the amount of
information shared between administrative domains, and the trade-off
between multi-layer TE and confidentiality of information belonging
to each administrative domain.
It is expected that solution documents will include a full analysis
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. References 8. Acknowledgements
8.1. Normative Reference The authors would like to thank Adrian Farrel and the participants of
ITU-T Study Group 15 Question 14 for their careful review.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
9. References
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] K.Kompella and Y.Rekhter, "Routing Extensions in Support of [RFC4202] Kompella, K., and Rekhter, Y., "Routing Extensions in
Generalized Multi-Protocol Label Switching (GMPLS)," RFC4202, Support of Generalized Multi-Protocol Label Switching
October 2005. (GMPLS)," RFC4202, October 2005.
[RFC4726] A.Farrel, J-P. Vasseur, and A.Ayyangar, "A Framework for Inter-
Domain Multiprotocol Label Switching Traffic Engineering", RFC
4726, November 2006.
[RFC4206] K.Kompella and Y.Rekhter, "Label Switched Paths (LSP) Hierarchy [RFC4726] Farrel, A., Vasseur, JP., and Ayyangar, A., "A Framework
with Generalized Multi-Protocol Label Switching (GMPLS) Traffic for Inter-Domain Multiprotocol Label Switching Traffic
Engineering (TE)," RFC4206, Oct. 2005. Engineering", RFC 4726, November 2006.
[RFC3945] E.Mannie (Ed.), "Generalized Multi-Protocol Label Switching [RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP)
(GMPLS) Architecture", RFC 3945, October 2004. Hierarchy with Generalized Multi-Protocol Label Switching
[RFC4397] I.Bryskin and A. Farrel, "A Lexicography for the Interpretation of (GMPLS) Traffic Engineering (TE)," RFC4206, Oct. 2005.
Generalized Multiprotocol Label Switching (GMPLS)
Terminology within the Context of the ITU-T's Automatically
Switched Optical Network (ASON) Architecture", RFC 4397,
February 2006.
8.2. Informative References [RFC3945] E. Mannie (Editor), "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3945, October 2004.
[MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou, D., Shiomoto, [RFC4397] Bryskin, I., and Farrel, A., "A Lexicography for the
K., Vigoureux, M.,"Evaluation of existing GMPLS Protocols Interpretation of Generalized Multiprotocol Label Switching
against Multi Layer and Multi Region Networks (MLN/MRN)", (GMPLS) Terminology within the Context of the ITU-T's
draft-ietf-ccamp-gmpls-mrn-eval, work in progress. Automatically Switched Optical Network (ASON)
Architecture", RFC 4397, February 2006.
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007 9.2. Informative References
[MPLS-GMPLS] K. Kumaki (Editor), "Interworking Requirements to Support [MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou, D.,
operation of MPLS-TE over GMPLS networks", draft- Shiomoto, K., Vigoureux, M., "Evaluation of Existing
ietf-ccamp-mpls-gmpls-interwork-reqts, work in progress. GMPLS Protocols Against Multi-Layer and Multi-Region
Network (MLN/MRN) Requirements", draft-ietf-ccamp-gmpls-
mln-eval, work in progress.
[DYN-HIER] Shiomoto, K., Rabbat, R., Ayyangar, A., Farrel, A. and Ali, Z., [MPLS-GMPLS] K. Kumaki (Editor), "Interworking Requirements to
"Procedures for Dynamically Signaled Hierarchical Label Support Operation of MPLS-TE over GMPLS Networks",
Switched Paths", draft-ietf-ccamp-lsp-hierarchy-bis, work in draft-ietf-ccamp-mpls-gmpls-interwork-reqts, work in
progress. progress.
[AUTO-MESH] Vasseur, JP., Le Roux, JL., et al., "Routing extensions for [DYN-HIER] Shiomoto, K., Rabbat, R., Ayyangar, A., Farrel, A. and
discovery of Multiprotocol (MPLS) Label Switch Router (LSR) Ali, Z., "Procedures for Dynamically Signaled
Traffic Engineering (TE) mesh membership", draft-ietf-ccamp- Hierarchical Label Switched Paths", draft-ietf-ccamp-
automesh, work in progress. lsp-hierarchy-bis, work in progress.
9. Authors' Addresses [MPLS-SEC] Fang, L., et al., " Security Framework for MPLS and
GMPLS Networks", draft-fang-mpls-gmpls-security-
framework, work in progress.
draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
[RFC4972] Vasseur, JP., Le Roux, JL., et al., "Routing Extensions
for Discovery of Multiprotocol (MPLS) Label Switch
Router (LSR) Traffic Engineering (TE) Mesh Membership",
RFC 4972, July 2007.
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,
skipping to change at page 20, line 4 skipping to change at page 22, line 45
Route de Nozay, 91461 Marcoussis cedex, France Route de Nozay, 91461 Marcoussis cedex, France
Phone: +33 (0)1 69 63 18 52 Phone: +33 (0)1 69 63 18 52
Email: martin.vigoureux@alcatel-lucent.fr Email: martin.vigoureux@alcatel-lucent.fr
Deborah Brungard Deborah Brungard
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
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
10.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,
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
Emmanuel Dotaro Emmanuel Dotaro
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
11. Intellectual Property Considerations 12. Intellectual Property Considerations
The IETF takes no position regarding the validity or scope of any Intellectual The IETF takes no position regarding the validity or scope of any
Property Rights or other rights that might be claimed to pertain to the Intellectual Property Rights or other rights that might be claimed to
implementation or use of the technology described in this document or the extent pertain to the implementation or use of the technology described in
to which any license under such rights might or might not be available; nor does this document or the extent to which any license under such rights
it represent that it has made any independent effort to identify any such rights. might or might not be available; nor does it represent that it has
Information on the procedures with respect to rights in RFC documents can be made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any assurances of Copies of IPR disclosures made to the IETF Secretariat and any
licenses to be made available, or the result of an attempt made to obtain a assurances of licenses to be made available, or the result of an
general license or permission for the use of such proprietary rights by attempt made to obtain a general license or permission for the use of
implementers or users of this specification can be obtained from the IETF on- such proprietary rights by implementers or users of this
line IPR repository at http://www.ietf.org/ipr. specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any copyrights, The IETF invites any interested party to bring to its attention any
patents or patent applications, or other proprietary rights that may cover copyrights, patents or patent applications, or other proprietary
technology that may be required to implement this standard. Please address the rights that may cover technology that may be required to implement
information to the IETF at ietf-ipr@ietf.org. this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
12. Full Copyright Statement 13. Full Copyright Statement
draft-ietf-ccamp-gmpls-mln-reqs-04.txt August 2007
Copyright (C) The IETF Trust (2007). This document is subject to the rights, Copyright (C) The IETF Trust (2007).
licenses and restrictions contained in BCP 78, and except as set forth therein,
the authors retain all their rights.
This document and the information contained herein are provided on an "AS IS" This document is subject to the rights, licenses and restrictions
basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY contained in BCP 78, and except as set forth therein, the authors
(IF ANY), THE INTERNET SOCIETY, THE IETF TRUST, AND THE INTERNET ENGINEERING retain all their rights.
TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE draft-ietf-ccamp-gmpls-mln-reqs-05.txt August 2007
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE. This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST
AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT
THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE.
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