draft-ietf-ccamp-gmpls-mln-reqs-00.txt   draft-ietf-ccamp-gmpls-mln-reqs-01.txt 
Network Working Group Kohei Shiomoto (NTT) Network Working Group Kohei Shiomoto (NTT)
Internet Draft Dimitri Papadimitriou (Alcatel) Internet Draft Dimitri Papadimitriou (Alcatel)
Jean-Louis Le Roux (France Telecom) Jean-Louis Le Roux (France Telecom)
Martin Vigoureux (Alcatel) Martin Vigoureux (Alcatel)
Deborah Brungard (AT&T) Deborah Brungard (AT&T)
Expires: July 2006 January 2006
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-00.txt draft-ietf-ccamp-gmpls-mln-reqs-01.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
Most of the initial efforts on Generalized MPLS (GMPLS) have been Most of the initial efforts on Generalized MPLS (GMPLS) have been
related to environments hosting devices with a single switching related to environments hosting devices with a single switching
capability. The complexity raised by the control of such data capability. The complexity raised by the control of such data
planes is similar to that seen in classical IP/MPLS networks. planes is similar to that seen in classical IP/MPLS networks.
By extending MPLS to support multiple switching technologies, GMPLS By extending MPLS to support multiple switching technologies, GMPLS
provides a comprehensive framework for the control of a multi- provides a comprehensive framework for the control of a multi-
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
layered network of either a single switching technology or multiple layered network of either a single switching technology or multiple
switching technologies. In GMPLS, a switching technology domain switching technologies. In GMPLS, a switching technology domain
defines a region, and a network of multiple switching types is defines a region, and a network of multiple switching types is
referenced in this document as a multi-region network (MRN). When referenced in this document as a multi-region network (MRN). When
referring in general to a layered network, which may consist of referring in general to a layered network, which may consist of
either a single or multiple regions, this document uses the term, either a single or multiple regions, this document uses the term,
Multi-layer Network (MLN). This draft defines a framework for GMPLS Multi-layer Network (MLN). This draft defines a framework for GMPLS
based multi-region/multi-layer networks and lists a set of based multi-region/multi-layer networks and lists a set of
functional requirements. functional requirements.
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction...................................................2
2. Conventions used in this document..............................4 2. Conventions used in this document..............................4
3. Positioning....................................................4 3. Positioning....................................................4
3.1. Data plane layers and control plane regions..................5 3.1. Data plane layers and control plane regions..................5
3.2. Services.....................................................5 3.2. Service layer networks.......................................5
3.3. Vertical and Horizontal interaction and integration..........6 3.3. Vertical and Horizontal interaction and integration..........6
4. Key concepts of GMPLS-based MLNs and MRNs......................6 4. Key concepts of GMPLS-based MLNs and MRNs......................7
4.1. Interface Switching Capability...............................7 4.1. Interface Switching Capability...............................7
4.2. Multiple Interface Switching Capabilities....................7 4.2. Multiple Interface Switching Capabilities....................8
4.2.1. Networks with multi-switching capable hybrid nodes.........8 4.2.1. Networks with multi-switching-type-capable hybrid nodes....8
4.3. Integrated Traffic Engineering (TE) and Resource Control.....9 4.3. Integrated Traffic Engineering (TE) and Resource Control.....9
4.3.1. Triggered signaling........................................9 4.3.1. Triggered signaling.......................................10
4.3.2. FA-LSP....................................................10 4.3.2. FA-LSP....................................................10
4.3.3. Virtual network topology (VNT)............................10 4.3.3. Virtual network topology (VNT)............................11
5. Service networks provided over MRN/MLN........................11 5. Requirements..................................................11
6. Requirements..................................................11 5.1. Scalability.................................................11
6.1. Scalability.................................................11 5.2. LSP resource utilization....................................12
6.2. LSP resource utilization....................................12 5.2.1. FA-LSP release and setup..................................12
6.2.1. FA-LSP release and setup..................................12 5.2.2. Virtual TE-Link...........................................13
6.2.2. Virtual TE-Link...........................................12 5.3. LSP Attribute inheritance...................................14
6.3. LSP Attribute inheritance...................................14 5.4. Verification of the LSP.....................................14
6.4. Verification of the LSP.....................................14 5.5. Disruption minimization.....................................14
6.5. Disruption minimization.....................................14 5.6. Stability...................................................15
6.6. Stability...................................................14 5.7. Computing paths with and without nested signaling...........16
6.7. Computing paths with and without nested signaling...........15 5.8. Handling single-switching and multi-switching-type-capable
6.8. Handling single-switching and multi-switching type capable nodes............................................................17
nodes............................................................16 5.9. Advertisement of the available adaptation resource..........17
6.9. Advertisement of the available adaptation resource..........16 6. Security Considerations.......................................17
7. Security Considerations.......................................17 7. References....................................................18
8. References....................................................17 7.1. Normative Reference.........................................18
8.1. Normative Reference.........................................17 7.2. Informative References......................................18
8.2. Informative References......................................18 8. Author's Addresses............................................19
9. Author's Addresses............................................18 9. Intellectual Property Considerations..........................20
10. Intellectual Property Considerations.........................19 10. Full Copyright Statement.....................................20
11. Full Copyright Statement.....................................20
1. Introduction 1. Introduction
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
Generalized MPLS (GMPLS) extends MPLS to handle multiple switching Generalized MPLS (GMPLS) extends MPLS to handle multiple switching
technologies: packet switching, layer-two switching, TDM switching, technologies: packet switching, layer-two switching, TDM switching,
wavelength switching, and fiber switching (see [RFC3945]). The wavelength switching, and fiber switching (see [RFC3945]). The
Interface Switching Capability (ISC) concept is introduced for Interface Switching Capability (ISC) concept is introduced for
these switching technologies and is designated as follows: PSC these switching technologies and is designated as follows: PSC
(packet switch capable), L2SC (Layer-2 switch capable), TDM (Time (packet switch capable), L2SC (Layer-2 switch capable), TDM (Time
Division Multiplex capable), LSC (lambda switch capable), and FSC Division Multiplex capable), LSC (lambda switch capable), and FSC
(fiber switch capable). (fiber switch capable).
Service providers may operate networks where multiple different Service providers may operate networks where multiple different
switching technologies exist. The representation, in a GMPLS switching technologies exist. The representation, in a GMPLS
control plane, of a switching technology domain is referred to as a control plane, of a switching technology domain is referred to as a
region [HIER]. region [RFC4206].
A switching type describes the ability of a node to forward data of A switching type describes the ability of a node to forward data of
a particular data plane technology, and uniquely identifies a a particular data plane technology, and uniquely identifies a
network region. A layer describes a data plane switching network region. A layer describes a data plane switching
granularity level (e.g. VC4, VC-12). A data plane layer is granularity level (e.g. VC4, VC-12). A data plane layer is
associated with a region in the control plane (e.g. VC4 associated associated with a region in the control plane (e.g. VC4 associated
to TDM, IP associated to PSC). However, more than one data plane to TDM, IP associated to PSC). However, more than one data plane
layer can be associated to the same region (e.g. both VC4 and VC12 layer can be associated to the same region (e.g. both VC4 and VC12
are associated to TDM). Thus, a control plane region, identified by are associated to TDM). Thus, a control plane region, identified by
its switching type value (e.g. TDM), can itself be sub-divided into its switching type value (e.g. TDM), can itself be sub-divided into
smaller granularity based on the bandwidth that defines the "data smaller granularity based on the bandwidth that defines the "data
plane switching layers" e.g. from VC-11 to VC4-256c. The Interface plane switching layers" e.g. from VC-11 to VC4-256c. The Interface
Switching Capability Descriptor (ISCD) [GMPLS-RTG], identifying the Switching Capability Descriptor (ISCD) [RFC4202], identifying the
interface switching type, the encoding type and the switching interface switching type, the encoding type and the switching
bandwidth granularity, enable the characterization of the bandwidth granularity, enable the characterization of the
associated layers. associated layers.
A network comprising transport nodes with multiple data plane A network comprising transport nodes with multiple data plane
layers of either the same ISC or different ISCs, controlled by a layers of either the same ISC or different ISCs, controlled by a
single GMPLS control plane instance, is called a Multi-Layer single GMPLS control plane instance is called a Multi-Layer Network
Network (MLN). To differentiate a network supporting LSPs of (MLN). To differentiate a network supporting LSPs of different
different switching technologies (ISCs) from a single region switching technologies (ISCs) from a single region network, a
network, a network supporting more than one switching technology is network supporting more than one switching technology is called a
called a Multi-Region Network (MRN). Multi-Region Network (MRN). All MRNs are MLNs, by definition.
MRNs can be categorized according to the distribution of the
switching type values amongst the LSRs:
- Network elements are single switching capable LSRs and
different types of LSRs form the network.
- Network elements are multi-switching capable LSRs i.e. nodes
hosting at least more than one switching capability. Multi-
switching capable LSRs are further
classified as "simplex" and "hybrid" nodes (see Section 4.2).
- Any combination of the above two elements. A network composed
of both single and multi-switching capable LSRs.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006 MLNs can be categorized according to the distribution of the ISCD
values amongst the LSRs:
- Each LSR may support just one ISCD, and the MLN may be comprised
of LSRs that support different ISCDs. Such LSRs are known as
single-switching-type-capable LSRs.
- Each LSR may support more than one ISCD at the same time so that
the network containing these LSR is an MLN. Such LSRs are known
as multi-switching-type-capable LSRs, and can be further
classified as either "simplex" or "hybrid" nodes as defined in
Section 4.2.
- The MLN may be constructed from any combination of single-
switching-type-capable LSRs and multi-switching-type-capable
LSRs.
Since GMPLS provides a comprehensive framework for the control of Since GMPLS provides a comprehensive framework for the control of
different switching capabilities, a single GMPLS instance may be different switching capabilities, a single GMPLS instance may be
used to control the MRNs/MLNs enabling rapid service provisioning used to control the MLN enabling rapid service provisioning and
and efficient traffic engineering across all switching capabilities. efficient traffic engineering across all switching capabilities. In
In such networks, TE Links are consolidated into a single Traffic such networks, TE Links are consolidated into a single Traffic
Engineering Database (TED). Since this TED contains the information Engineering Database (TED). Since this TED contains the information
relative to all the different regions/layers existing in the relative to all the different regions and layers existing in the
network, a path across multiple regions/layers can be computed network, a path across multiple regions or layers can be computed
using this TED. Thus optimization of network resources can be using this TED. Thus optimization of network resources can be
achieved across multiple regions/layers. achieved across the whole MLN.
Consider, for example, a MRN consisting of IP/MPLS routers and TDM Consider, for example, a MRN consisting of packet-switch capable
cross-connects. Assume that a packet LSP is routed between source routers and TDM cross-connects. Assume that a packet LSP is routed
and destination IP/MPLS routers, and that the LSP can be routed between source and destination packet-switchi capable routers, and
across the PSC-region (i.e. utilizing only resources of the IP/MPLS that the LSP can be routed across the PSC-region (i.e. utilizing
level topology). If the performance objective for the LSP is not only resources of the packet region topology). If the performance
satisfied, new TE links may be created between the IP/MPLS routers objective for the LSP is not satisfied, new TE links may be created
across the TDM-region (for example, VC-12 links) and the LSP can be between the packet-switch capable routers across the TDM-region
routed over those links. Further, even if the LSP can be (for example, VC-12 links) and the LSP can be routed over those TE
successfully established across the PSC-region, TDM hierarchical links. Further, even if the LSP can be successfully established
LSPs across the TDM region between the IP/MPLS routers may be across the PSC-region, TDM hierarchical LSPs across the TDM region
established and used if doing so enables meeting an operator's between the packet-switch capable routers may be established and
objectives on network resources available (e.g. link bandwidth, and used if doing so is necessary to meet the operator's objectives for
adaptation port between regions) across the multiple regions. The network resources availability (e.g., link bandwidth, or adaptation
same considerations hold when VC4 LSPs are provisioned to provide ports between regions) across the regions. The same considerations
extra flexibility for the VC12 and/or VC11 layers in a MLN. 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- This document describes the requirements to support multi-
region/multi-layer networks. There is no intention to specify region/multi-layer networks. There is no intention to specify
solution specific elements in this document. The applicability of solution-specific elements in this document. The applicability of
existing GMPLS protocols and any protocol extensions to the MRN/MLN existing GMPLS protocols and any protocol extensions to the MRN/MLN
will be addressed in separate documents [MRN-EVAL]. will be addressed in separate documents [MRN-EVAL].
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119 this document are to be interpreted as described in RFC 2119
[RFC2119]. [RFC2119].
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119 this document are to be interpreted as described in RFC 2119
[RFC2119]. [RFC2119].
3. Positioning 3. Positioning
A multi-region network (MRN) is always a multi-layer network (MLN) A multi-region network (MRN) is always a multi-layer network (MLN)
since the network devices on region boundaries bring together since the network devices on region boundaries bring together
different ISCs. A MLN, however, is not necessarily a MRN since different ISCs. A MLN, however, is not necessarily a MRN since
multiple layers could be fully contained within a single region. multiple layers could be fully contained within a single region.
For example, VC12, VC4, and VC4-4c are different layers of the TDM For example, VC12, VC4, and VC4-4c are different layers of the TDM
region. region.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
3.1. Data plane layers and control plane regions 3.1. Data plane layers and control plane regions
A data plane layer is a collection of network resources capable of A data plane layer is a collection of network resources capable of
terminating and/or switching data traffic of a particular format. terminating and/or switching data traffic of a particular format.
These resources can be used for establishing LSPs or connectionless These resources can be used for establishing LSPs or connectionless
traffic delivery. For example, VC-11 and VC4-64c represent two traffic delivery. For example, VC-11 and VC4-64c represent two
different layers. different layers.
From the control plane viewpoint, an LSP region is defined as a set From the control plane viewpoint, an LSP region is defined as a set
of one or several data plane layers that share the same type of of one or more data plane layers that share the same type of
switching technology, that is, the same switching type. The switching technology, that is, the same switching type. For example,
VC-11 and VC-4 layers are part of the same TDM region. The
currently defined regions are: PSC, L2SC, TDM, LSC, and FSC regions. currently defined regions are: PSC, L2SC, TDM, LSC, and FSC regions.
Hence, an LSP region is a technology domain (identified by the ISC Hence, an LSP region is a technology domain (identified by the ISC
type) for which data plane resources (i.e. data links) are type) for which data plane resources (i.e. data links) are
represented into the control plane as an aggregate of TE represented into the control plane as an aggregate of TE
information associated with a set of links (i.e. TE links). For information associated with a set of links (i.e. TE links). For
example VC-11 and VC4-64c capable TE links are part of the same TDM example VC-11 and VC4-64c capable TE links are part of the same TDM
region. Multiple layers can thus exist in a single region network. region. Multiple layers can thus exist in a single region network.
Note also that the region is a control plane only concept. That is, Note also that the region may produce a distinction within the
layers of the same region share the same switching technology and, control plane. Layers of the same region share the same switching
therefore, need the same set of technology specific signaling technology and, therefore, use the same set of technology-specific
objects. signaling objects within the control plane, but layers from
different regions may use different technology-specific objects or
encodings. This means that there is a control plane discontinuity
when crossing a region boundary.
3.2. Services 3.2. Service layer networks
A service provider's network may be divided into different service A service provider's network may be divided into different service
layers. The customer's network is considered from the provider's layers. The customer's network is considered from the provider's
perspective as the highest service layer. It interfaces to the perspective as the highest service layer. It interfaces to the
highest service layer of the service provider's network. highest service layer of the service provider's network.
Connectivity across the highest service layer of the service Connectivity across the highest service layer of the service
provider's network may be provided with support from successively provider's network may be provided with support from successively
lower service layers. Service layers are realized via a hierarchy lower service layers. Service layers are realized via a hierarchy
of network layers located generally in several regions and commonly of network layers located generally in several regions and commonly
arranged according to the switching capabilities of network devices. arranged according to the switching capabilities of network devices.
For instance some customers purchase Layer 1 (i.e. transport) For instance some customers purchase Layer 1 (i.e. transport)
services from the service provider, some Layer 2 (e.g. ATM), while services from the service provider, some Layer 2 (e.g. ATM), while
others purchase Layer 3 (IP/MPLS) services. The service provider others purchase Layer 3 (IP/MPLS) services. The service provider
realizes the services by a stack of network layers located within realizes the services by a stack of network layers located within
one or more network regions. The network layers are commonly one or more network regions. The network layers are commonly
arranged according to the switching capabilities of the devices in arranged according to the switching capabilities of the devices in
the networks. Thus, a customer network may be provided on top of the networks. Thus, a customer network may be provided on top of
the GMPLS-based multi-region/multi-layer network. For example, a the GMPLS-based multi-region/multi-layer network. For example, a
Layer One service (realized via the network layers of TDM, and/or Layer 1 service (realized via the network layers of TDM, and/or LSC,
LSC, and/or FSC regions) may support a Layer Two network (realized and/or FSC regions) may support a Layer 2 network (realized via ATM
via ATM VP/VC) which may itself support a Layer Three network VP/VC) which may itself support a Layer 3 network (IP/MPLS region).
(IP/MPLS region). The supported data plane relationship is a data- The supported data plane relationship is a data-plane client-server
plane client-server relationship where the lower layer provides a relationship where the lower layer provides a service for the
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006 higher layer using the data links realized in the lower layer.
service for the higher layer using the data links realized in the
lower layer.
Services provided by a GMPLS-based multi-region/multi-layer network Services provided by a GMPLS-based multi-region/multi-layer network
are referred to as "Multi-region/Multi-layer network services". For are referred to as "Multi-region/Multi-layer network services". For
example legacy IP and IP/MPLS networks can be supported on top of example, legacy IP and IP/MPLS networks can be supported on top of
multi-region/multi-layer networks. It has to be emphasized that multi-region/multi-layer networks. It has to be emphasized that
delivery of such diverse services is a strong motivator for the delivery of such diverse services is a strong motivator for the
deployment of multi-region/multi-layer networks. deployment of multi-region/multi-layer networks.
A customer network may be provided on top of a server GMPLS-based
MRN/MLN which is operated by a service provider. For example, a
pure IP and/or an IP/MPLS network can be provided on top of GMPLS-
based packet over optical networks [IW-MIG-FW]. The relationship
between the networks is a client/server relationship and, such
services are referred to as "MRN/MLN services". In this case, the
customer network may form part of the MRN/MLN, or may be partially
separated, for 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 Vertical interaction is defined as the collaborative mechanisms
within a network element that is capable of supporting more than within a network element that is capable of supporting more than
one switching capability and of realizing the client/server one layer and of realizing the client/server relationships between
relationships between them. Protocol exchanges between two network them. Protocol exchanges between two network controllers managing
controllers managing different regions are also a vertical different regions or layers are also a vertical interaction.
interaction. Integration of these interactions as part of the Integration of these interactions as part of the control plane is
control plane is referred to as vertical integration. The latter referred to as vertical integration. Thus, this refers thus to the
refers thus to the collaborative mechanisms within a single control collaborative mechanisms within a single control plane instance
plane instance driving multiple switching capabilities. Such a driving multiple network layers. Such a concept is useful in order
concept is useful in order to construct a framework that to construct a framework that facilitates efficient network
facilitates efficient network resource usage and rapid service resource usage and rapid service provisioning in carrier's networks
provisioning in carrier's networks that are based on multiple that are based on multiple layers, switching technologies, or ISCDs.
switching technologies.
In a strict sense, horizontal interaction is defined as the Horizontal interaction is defined as the protocol exchange between
protocol exchange between network controllers that manage transport network controllers that manage transport nodes within a given
nodes within a given region (i.e. nodes with the same switching layer or region (i.e. nodes with the same switching capability).
capability). For instance, the control plane interaction between For instance, the control plane interaction between two TDM network
two LSC network elements is an example of horizontal interaction. elements switching at OC-48 is an example of horizontal interaction.
GMPLS protocol operations handle horizontal interactions within the GMPLS protocol operations handle horizontal interactions within the
same routing area. The case where the interaction takes place same routing area. The case where the interaction takes place
across a domain boundary, such as between two routing areas within across a domain boundary, such as between two routing areas within
the same network layer, is currently being evaluated as part of the the same network layer, is currently being evaluated as part of the
inter-domain work [Inter-domain], and is referred to as horizontal inter-domain work [Inter-domain], and is referred to as horizontal
integration. Thus horizontal integration refers to the integration. Thus horizontal integration refers to the
collaborative mechanisms between network partitions and/or collaborative mechanisms between network partitions and/or
administrative divisions such as routing areas or autonomous administrative divisions such as routing areas or autonomous
systems. This distinction gets blurred when administrative domains systems.
match layer boundaries. Horizontal interaction is extended to cover
such case. For example, the collaborative mechanisms in place This distinction needs further clarification when administrative
between two lambda switching capable areas relate to horizontal domains match layer boundaries. Horizontal interaction is extended
integration. On the other hand, the collaborative mechanisms in to cover such cases. For example, the collaborative mechanisms in
place in a network that supports IP/MPLS over TDM switching could place between two lambda switching capable areas relate to
be described as vertical and horizontal integration in the case horizontal integration. On the other hand, the collaborative
where each network belongs to a separate area. mechanisms in place in a network that supports IP/MPLS over TDM
switching could be described as vertical and horizontal integration
in the case where each network belongs to a separate routing area.
4. Key concepts of GMPLS-based MLNs and MRNs 4. Key concepts of GMPLS-based MLNs and MRNs
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
A network comprising transport nodes with multiple data plane A network comprising transport nodes with multiple data plane
layers of either the same ISC or different ISCs, controlled by a layers of either the same ISC or different ISCs, controlled by a
single GMPLS control plane instance, is called a Multi-Layer single GMPLS control plane instance, is called a Multi-Layer
Network (MLN). A sub-set of MLNs consists of networks supporting Network (MLN). A sub-set of MLNs consists of networks supporting
LSPs of different switching technologies (ISCs). A network LSPs of different switching technologies (ISCs). A network
supporting more than one switching technology is called a Multi- supporting more than one switching technology is called a Multi-
Region Network (MRN). Region Network (MRN).
4.1. Interface Switching Capability 4.1. Interface Switching Capability
The Interface Switching Capability (ISC) is introduced in GMPLS to The Interface Switching Capability (ISC) is introduced in GMPLS to
support various kinds of switching technology in a unified way support various kinds of switching technology in a unified way
[GMPLS-ROUTING]. An ISC is identified via a switching type. [RFC4202]. An ISC is identified via a switching type.
A switching type (also referred to as the switching capability A switching type (also referred to as the switching capability
types) describes the ability of a node to forward data of a type) describes the ability of a node to forward data of a
particular data plane technology, and uniquely identifies a network particular data plane technology, and uniquely identifies a network
region. The following ISC types (and, hence, regions) are defined: region. The following ISC types (and, hence, regions) are defined:
PSC, L2SC, TDM, LSC, and FSC. Each end of a data link (more PSC, L2SC, TDM, LSC, and FSC. Each end of a data link (more
precisely, each interface connecting a data link to a node) in a precisely, each interface connecting a data link to a node) in a
GMPLS network is associated with an ISC. GMPLS network is associated with an ISC.
The ISC value is advertised as a part of the Interface Switching The ISC value is advertised as a part of the Interface Switching
Capability Descriptor (ISCD) attribute (sub-TLV) of a TE link end Capability Descriptor (ISCD) attribute (sub-TLV) of a TE link end
associated with a particular link interface. Apart from the ISC, associated with a particular link interface [RFC4202]. Apart from
the ISCD contains information, such as the encoding type, the the ISC, the ISCD contains information, including the encoding type,
bandwidth granularity, and the unreserved bandwidth on each of the bandwidth granularity, and the unreserved bandwidth on each of
eight priorities at which LSPs can be established. The ISCD does eight priorities at which LSPs can be established. The ISCD does
not "identify" network layers, it uniquely characterizes not "identify" network layers, it uniquely characterizes
information associated to one or more network layers. information associated to one or more network layers.
TE link end advertisements may contain multiple ISCDs. This can be TE link end advertisements may contain multiple ISCDs. This can be
interpreted as advertising a multi-layer (or multi-switching) TE interpreted as advertising a multi-layer (or multi-switching) TE
link end. link end. That is, the TE link end is present in multiple layers.
4.2. Multiple Interface Switching Capabilities 4.2. Multiple Interface Switching Capabilities
In a MLN, network elements may be single-switching or multi- In an MLN, network elements may be single-switching or multi-
switching type capable nodes. Single-switching type capable nodes switching-type-capable nodes. Single-switching type capable nodes
advertise the same ISC value as part of their ISCD sub-TLV(s) to advertise the same ISC value as part of their ISCD sub-TLV(s) to
describe the termination capabilities of their TE Link(s). This describe the termination capabilities of their TE Link(s). This
case is described in [GMPLS-ROUTING]. case is described in [RFC4202].
Multi-switching capable LSRs are classified as "simplex" and Multi-switching-type-capable LSRs are classified as "simplex" or
"hybrid" nodes. Simplex and Hybrid nodes are categorized according "hybrid" nodes. Simplex and hybrid nodes are categorized according
to the way they advertise these multiple ISCs: to the way they advertise these multiple ISCs:
- A simplex node can terminate links with different switching - A simplex node can terminate links with different switching
capabilities each of them connected to the node by a single link capabilities each of them connected to the node by a single link
interface. So, it advertises several TE Links each with a single interface. So, it advertises several TE Links each with a single
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
ISC value as part of its ISCD sub-TLVs. For example, an LSR with ISC value as part of its ISCD sub-TLVs. For example, an LSR with
PSC and TDM links each of which is connected to the LSR via single PSC and TDM links each of which is connected to the LSR via single
interface. interface.
- A hybrid node can terminate links with different switching - A hybrid node can terminate links with different switching
capabilities terminating on the same interface. So, it advertises capabilities terminating on the same interface. So, it advertises
at least one TE Link containing more than one ISCDs with different at least one TE Link containing more than one ISCDs with different
ISC values. For example, a node comprising of PSC and TDM links, ISC values. For example, a node comprising of PSC and TDM links,
which are interconnected via internal links. The external which are interconnected via internal links. The external
interfaces connected to the node have both PSC and TDM capability. interfaces connected to the node have both PSC and TDM capability.
Additionally TE link advertisements issued by a simplex or a hybrid Additionally TE link advertisements issued by a simplex or a hybrid
node may need to provide information about the node's internal node may need to provide information about the node's internal
adaptation capabilities between the switching technologies adaptation capabilities between the switching technologies
supported. That is, the node's capability to perform layer border supported. That is, the node's capability to perform layer border
node functions. node functions.
4.2.1. Networks with multi-switching capable hybrid nodes 4.2.1. Networks with multi-switching-type-capable hybrid nodes
The network contains at least one hybrid node, zero or more simplex The network contains at least one hybrid node, zero or more simplex
nodes, and a set of single switching capable nodes. nodes, and a set of single-switching-type-capable nodes.
Figure 5a shows an example hybrid node. The hybrid node has two Figure 5a shows an example hybrid node. The hybrid node has two
switching elements (matrices), which support, for instance, TDM and switching elements (matrices), which support, for instance, TDM and
PSC switching respectively. The node terminates two PSC and TDM PSC switching respectively. The node terminates a PSC and a TDM
links (Link1 and Link2 respectively). It also has internal link link (Link1 and Link2 respectively). It also has an internal link
connecting the two swtching elements. connecting the two swtching elements.
The two switching elements are internally interconnected in such a The two switching elements are internally interconnected in such a
way that it is possible to terminate some of the resources of, say, way that it is possible to terminate some of the resources of, say,
Link2 and provide through them adaptation for PSC traffic Link2 and provide adaptation for PSC traffic received/sent over the
received/sent over the PSC interface (#b). This situation is PSC interface (#b). This situation is modeled in GMPLS by
modeled in GMPLS by connecting the local end of Link2 to the TDM connecting the local end of Link2 to the TDM switching element via
switching element via an additional interface realizing the an additional interface realizing the termination/adaptation
termination/adaptation function. Two ways are possible to set up function. Two ways are possible to set up PSC LSPs. Available
PSC LSPs. Available resource advertisement e.g. Unreserved and resource advertisement e.g. Unreserved and Min/Max LSP Bandwidth
Min/Max LSP Bandwidth should cover both two ways. should cover both two ways.
Network element Network element
............................. .............................
: -------- : : -------- :
: | PSC | : : | PSC | :
Link1 -------------<->--|#a | : Link1 -------------<->--|#a | :
: +--<->---|#b | : : +--<->---|#b | :
: | -------- : : | -------- :
TDM : | ---------- : TDM : | ---------- :
+PSC : +--<->--|#c TDM | : +PSC : +--<->--|#c TDM | :
Link2 ------------<->--|#d | : Link2 ------------<->--|#d | :
: ---------- : : ---------- :
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
:............................ :............................
Figure 5a. Hybrid node. Figure 5a. 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 are In GMPLS-based multi-region/multi-layer networks, TE Links are
consolidated into a single Traffic Engineering Database (TED). consolidated into a single Traffic Engineering Database (TED) for
Since this TED contains the information relative to all the layers use by the single control plane instance. Since this TED contains
of all regions in the network, a path across multiple layers the information relative to all the layers of all regions in the
(possibly crossing multiple regions) can be computed using the network, a path across multiple layers (possibly crossing multiple
information in this TED. Thus optimization of network resources regions) can be computed using the information in this TED. Thus
across the multiple layers of the same region and multiple regions optimization of network resources across the multiple layers of the
can be achieved. same region and across multiple regions can be achieved.
These concepts allow for the operation of one network layer over These concepts allow for the operation of one network layer over
the topology (that is, TE links) provided by other network layer(s) the topology (that is, TE links) provided by other network layers
(for example, the use of a lower layer LSC LSP carrying PSC LSPs). (for example, the use of a lower layer LSC LSP carrying PSC LSPs).
In turn, a greater degree of control and inter-working can be In turn, a greater degree of control and inter-working can be
achieved, including (but not limited too): achieved, including (but not limited too):
- dynamic establishment of Forwarding Adjacency LSPs (see Section - dynamic establishment of Forwarding Adjacency LSPs (see Section
4.3.3) 4.3.3)
- 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 Note that in a multi-layer/multi-region network that includes
multi-switching type capable nodes, an explicit route used to multi-switching-type-capable nodes, an explicit route used to
establish an end-to-end LSP can specify nodes that belong to establish an end-to-end LSP can specify nodes that belong to
different layers or regions. In this case, a mechanism to control different layers or regions. In this case, a mechanism to control
the dynamic creation of FA LSPs may be required. the dynamic creation of FA LSPs may be required.
There is a full spectrum of options to control how FA LSPs are There is a full spectrum of options to control how FA LSPs are
dynamically established. It can be subject to the control of a dynamically established. The process can be subject to the control
policy, which may be set by a management component, and which may of a policy, which may be set by a management component, and which
require that the management plane is consulted at the time that the may require that the management plane is consulted at the time that
FA LSP is established. Alternatively, the FA LSP can be established the FA LSP is established. Alternatively, the FA LSP can be
at the request of the control plane without any management control. established at the request of the control plane without any
management control.
4.3.1. Triggered signaling 4.3.1. Triggered signaling
When an LSP crosses the boundary from an upper to a lower layer, it When an LSP crosses the boundary from an upper to a lower layer, it
may be nested into a lower layer FA LSP that crosses the lower may be nested into a lower layer FA LSP that crosses the lower
layer. From signaling perspective, there are two alternatives to layer. From a signaling perspective, there are two alternatives to
establish lower layer FA LSP: static and dynamic. Decision will be establish the lower layer FA LSP: static (pre-provisioned) and
made either by the operator or automatically using features like dynamic (triggered). Pre-provisioned FA-LSP will be initiated
TE auto-mesh, for instance. If such a lower layer LSP does not either by the operator or automatically using features like TE
already exist, the LSP may be established dynamically. Such a auto-mesh [AUTO-MESH]. If such a lower layer LSP does not already
mechanism is referred to as "triggered signaling". exist, the LSP may be established dynamically. Such a mechanism is
referred to as "triggered signaling".
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
4.3.2. FA-LSP 4.3.2. FA-LSP
Once an LSP is created across a layer, it can be used as a data Once an LSP is created across a layer, it can be used as a data
link in an upper layer. link in an upper layer.
Furthermore, it can be advertised as a TE-link, allowing other Furthermore, it can be advertised as a TE-link, allowing other
nodes to consider the LSP as a TE link for their path computation nodes to consider the LSP as a TE link for their path computation
[HIER]. An LSP created either statically or dynamically by one [RFC4206]. An LSP created either statically or dynamically by one
instance of the control plane and advertised as a TE link into the instance of the control plane and advertised as a TE link into the
same instance of the control plane is called a FA-LSP. The TE-link same instance of the control plane is called a Forwarding adjacency
associated to an FA-LSP is called an FA. An FA has the special LSP (FA-LSP). The TE-link as which the FA-LSP is advertised is
characteristic of not requiring a routing adjacency (peering) called an FA. An FA has the special characteristic of not requiring
between its ends yet still guaranteeing control plane connectivity a routing adjacency (peering) between its end points yet still
between the FA-LSP ends based on a signaling adjacency. A FA is a guaranteeing control plane connectivity between the FA-LSP end
useful and powerful tool for improving the scalability of GMPLS points based on a signaling adjacency. A FA is a useful and
Traffic Engineering (TE) capable networks. 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) The aggregation of LSPs enables the creation of a vertical (nested)
LSP Hierarchy. A set of FA-LSPs across or within a lower layer can LSP Hierarchy. A set of FA-LSPs across or within a lower layer can
be used during path selection by a higher layer LSP. Likewise, the be used during path selection by a higher layer LSP. Likewise, the
higher layer LSPs may be carried over dynamic data links realized higher layer LSPs may be carried over dynamic data links realized
via LSPs (just as they are carried over any "regular" static data via LSPs (just as they are carried over any "regular" static data
links). This process requires the nesting of LSPs through a links). This process requires the nesting of LSPs through a
hierarchical process [HIER]. The TED contains a set of LSP hierarchical process [RFC4206]. The TED contains a set of LSP
advertisements from different layers that are identified by the advertisements from different layers that are identified by the
ISCD contained within the TE link advertisement associated with the ISCD contained within the TE link advertisement associated with the
LSP [GMPLS-ROUTING]. LSP [RFC4202].
If a lower layer LSP is not advertised as an FA, it can still be
used 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.
4.3.3. Virtual network topology (VNT) 4.3.3. Virtual network topology (VNT)
A set of one or more of lower-layer LSPs provides information for A set of one or more of lower-layer LSPs provides information for
efficient path handling in upper-layer(s) of the MLN, or, in other efficient path handling in upper-layer(s) of the MLN, or, in other
words, provides a virtual network topology to the upper-layers. For words, provides a virtual network topology (VNT) to the upper-
instance, a set of LSPs, each of which is supported by an LSC LSP, layers. For instance, a set of LSPs, each of which is supported by
provides a virtual network topology to the layers of a PSC region, an LSC LSP, provides a virtual network topology to the layers of a
assuming that the PSC region is connected to the LSC region. Note PSC region, assuming that the PSC region is connected to the LSC
that a single lower-layer LSP is a special case of VNT. The virtual region. Note that a single lower-layer LSP is a special case of the
network topology is configured by setting up or tearing down the VNT. The virtual network topology is configured by setting up or
LSC LSPs. By using GMPLS signaling and routing protocols, the tearing down the lower layer LSPs. By using GMPLS signaling and
virtual network topology can be adapted to traffic demands. routing protocols, the virtual network topology can be adapted to
traffic demands.
Reconfiguration of the virtual network topology may be triggered by Reconfiguration of the virtual network topology may be triggered by
traffic demand change, topology configuration change, signaling traffic demand changes, topology configuration changes, signaling
request from the upper layer, and network failure. For instance, by requests from the upper layer, and network failures. For instance,
reconfiguring the virtual network topology according to the traffic by reconfiguring the virtual network topology according to the
demand between source and destination node pairs, network traffic demand between source and destination node pairs, network
performance factors, such as maximum link utilization and residual performance factors, such as maximum link utilization and residual
capacity of the network, can be optimized [MAMLTE]. Reconfiguration capacity of the network, can be optimized [MAMLTE]. Reconfiguration
is performed by computing the new VNT from the traffic demand is performed by computing the new VNT from the traffic demand
matrix and optionally from the current VNT. Exact details are matrix and optionally from the current VNT. Exact details are
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
outside the scope of this document. However, this method may be outside the scope of this document. However, this method may be
tailored according to the Service Provider's policy regarding tailored according to the service provider's policy regarding
network performance and quality of service (delay, loss/disruption, network performance and quality of service (delay, loss/disruption,
utilization, residual capacity, reliability). utilization, residual capacity, reliability).
5. Service networks provided over MRN/MLN 5.Requirements
A customer network may be provided on top of a server MRN/MLN
network (such as a transport network) which is operated by a
service provider. For example legacy IP or IP/MPLS networks can be
provided on top of GMPLS packet or optical networks [IW-MIG-FW].
The relationship between the networks is a client/server
relationship and, such services are referred to as "MRN/MLN
services".
The customer network may be provided either as part of the MRN/MLN
or in a separate network instance distinct from the MRN/MLN. There
could also be an administrative boundary between the customer
network and the MRN/MLN operated by the service provider. All
requirements described in this document SHOULD be applicable if
there is an administrative boundary between the customer network
and the MRN/MLN operated by service provider.
Impact on the customer network design, operation, and
administration SHOULD be minimized. For instance, the design for
address assignment and IGP area division should be kept independent
from the underlying MRN/MLN.
The MRN/MLN SHOULD provide mechanisms to allow an administrative
boundary between the customer network and the MRN/MLN.
6. Requirements
6.1. Scalability 5.1. Scalability
The MRN/MLN relies on a unified traffic engineering and routing The MRN/MLN relies on a unified traffic engineering and routing
model. The TED in each LSR is populated with TE-links from all model. The TED in each LSR is populated with TE-links from all
layers of all regions. This may lead to a huge amount of layers of all regions. This may lead to a huge amount of
information that has to be flooded and stored within the network. information that has to be flooded and stored within the network.
Furthermore, path computation times, which may be of great Furthermore, path computation times, which may be of great
importance during restoration, will depend on the size of the TED. importance during restoration, will depend on the size of the TED.
Thus MRN/MLN routing mechanisms MUST be designed to scale well with Thus MRN/MLN routing mechanisms MUST be designed to scale well with
an increase of any of the following: an increase of any of the following:
skipping to change at page 11, line 50 skipping to change at page 12, line 4
The MRN/MLN relies on a unified traffic engineering and routing The MRN/MLN relies on a unified traffic engineering and routing
model. The TED in each LSR is populated with TE-links from all model. The TED in each LSR is populated with TE-links from all
layers of all regions. This may lead to a huge amount of layers of all regions. This may lead to a huge amount of
information that has to be flooded and stored within the network. information that has to be flooded and stored within the network.
Furthermore, path computation times, which may be of great Furthermore, path computation times, which may be of great
importance during restoration, will depend on the size of the TED. importance during restoration, will depend on the size of the TED.
Thus MRN/MLN routing mechanisms MUST be designed to scale well with Thus MRN/MLN routing mechanisms MUST be designed to scale well with
an increase of any of the following: an increase of any of the following:
- Number of nodes - Number of nodes
- Number of TE-links (including FA-LSPs) - Number of TE-links (including FA-LSPs)
- Number of LSPs - Number of LSPs
- Number of regions and layers - Number of regions and layers
- Number of ISCDs per TE-link. - Number of ISCDs per TE-link.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006 Further, design of the routing protocols MUST NOT prevent TE
information filtering based on ISCDs. Signaling protocol SHOULD be
able to operate on partial TE information.
6.2. LSP resource utilization 5.2. LSP resource utilization
It MUST be possible to utilize network resources efficiently. It MUST be possible to utilize network resources efficiently.
Particularly, resource usage in all layers SHOULD be optimized as a Particularly, resource usage in all layers SHOULD be optimized as a
whole (i.e. across all layers), in a coordinated manner, (ie taking whole (i.e., across all layers), in a coordinated manner, (i.e.,
all layers into account). The number of lower-layer LSPs carrying taking all layers into account). The number of lower-layer LSPs
upper-layer LSPs SHOULD be minimized as much as possible (Note that carrying upper-layer LSPs SHOULD be minimized (Note that multiple
multiple LSPs may be used for load balance) . Unneccesary lower- LSPs MAY be used for load balancing). Unneccesary lower-layer LSPs,
layer LSPs SHOULD be avoided. which would not carry any traffic by rerouting the traffic over it
to alternative lower-layer LSPs, SHOULD be avoided.
6.2.1. FA-LSP release and setup 5.2.1. FA-LSP release and setup
Statistical multiplexing can only be employed in PSC and L2SC Statistical multiplexing can only be employed in PSC and L2SC
regions. A PSC or L2SC LSP may or may not consume the maximum regions. A PSC or L2SC LSP may or may not consume the maximum
reservable bandwidth of the FA LSP that carries it. On the other reservable bandwidth of the FA LSP that carries it. On the other
hand, a TDM, or LSC LSP always consumes a fixed amount of bandwidth hand, a TDM, or LSC LSP always consumes a fixed amount of bandwidth
as long as it exists (and is fully instantiated) because as long as it exists (and is fully instantiated) because
statistical multiplexing is not available. statistical multiplexing is not available.
If there is low traffic demand, some FA LSPs, which do not carry If there is low traffic demand, some FA LSPs that do not carry any
any LSP may be released so that resources are released. Note that LSP MAY be released so that lower-layer resources are released.
if a small fraction of the available bandwidth is still under use, Note that if a small fraction of the available bandwidth of an FA-
the nested LSPs can also be re-routed optionally using the make- LSP is still in use, the nested LSPs can also be re-routed to other
before-break technique. Alternatively, the FA LSPs may be retained FA-LSPs (optionally using the make-before-break technique) to
for future usage. Release or retention of underutilized FA LSPs is complete free up the FA-LSP. Alternatively, the FA LSPs MAY be
a policy decision. 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 As part of the re-optimization process, the solution MUST allow
rerouting of FA LSPs while keeping interface identifiers of rerouting of an FA LSP while keeping interface identifiers of
corresponding TE links unchanged. corresponding TE links unchanged. Further, this process MUST be
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 Additional FA LSPs MAY also be created based on policy, which might
consider residual resources and the change of traffic demand across consider residual resources and the change of traffic demand across
the region. By creating the new FA LSPs, the network performance the region. By creating the new FA LSPs, the network performance
such as maximum residual capacity may increase. such as maximum residual capacity may increase.
As the number of FA LSPs grows, the residual resource may decrease. As the number of FA LSPs grows, the residual resource may decrease.
In this case, re-optimization of FA LSPs MAY be invoked according In this case, re-optimization of FA LSPs MAY be invoked according
the policy. to policy.
Any solution MUST include measures to protect against network Any solution MUST include measures to protect against network
destabilization caused by the rapid set up and tear down of LSPs as destabilization caused by the rapid set up and tear down of LSPs as
traffic demand varies near a threshold. traffic demand varies near a threshold.
6.2.2. Virtual TE-Link 5.2.2. Virtual TE-Link
It may be considered disadvantageous to fully instantiate (i.e. It may be considered disadvantageous to fully instantiate (i.e.
pre-provision) the set of lower layer LSPs since this may reserve pre-provision) the set of lower layer LSPs that provide the VNT
bandwidth that could be used for other LSPs in the absence of the since this might reserve bandwidth that could be used for other
upper-layer traffic. LSPs in the absence of the upper-layer traffic.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
However, in order to provision upper-layer LSPs across the lower- However, in order to allow path computation of upper-layer LSPs
layer, the LSPs MAY still be advertised into the upper-layer as across the lower-layer, the lower-layer LSPs MAY be advertised into
though they had been fully established. Such TE links that the upper-layer as though they had been fully established, but
represent the possibility of an underlying LSP are termed "virtual without actually establishing them. Such TE links that represent
TE-link". Note that this is not a mandatory (MUST) requirement the possibility of an underlying LSP are termed "virtual TE-link".
since even if there are no LSPs advertised to the higher layer, it It is an implementation choice at a boundary node whether to create
is possible to route an upper layer LSP into a lower layer based on virtual TE-links, and the choice if available MUST be under the
the lower layer's TE-links and making assumptions that proper control of operator policy. Note that there is no requirement to
hierarchical LSPs in the lower layer will be dynamically created as support the creation of virtual TE-links, since real TE-links (with
needed. 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, If an upper-layer LSP that makes use of a virtual TE-Link is set up,
the underlying LSP MUST be immediately signaled in the lower layer the underlying LSP MUST be immediately signaled in the lower layer.
if it has not been established.
If virtual TE-Links are used in place of pre-established LSPs, the If virtual TE-Links are used in place of pre-established LSPs, the
TE links across the upper-layer can remain stable using pre- TE-links across the upper-layer can remain stable using pre-
computed paths while wastage of bandwidth within the lower-layer computed paths while wastage of bandwidth within the lower-layer
and unnecessary reservation of adaptation ports at the border nodes and unnecessary reservation of adaptation ports at the border nodes
can be avoided. can be avoided.
The concept of VNT can be extended to allow the virtual TE-links to The concept of the VNT can be extended to allow the virtual TE-
form part of the VNT. The combination of the fully provisioned TE- links to form part of the VNT. The combination of the fully
links and the virtual TE-links defines the VNT across the lower provisioned TE-links and the virtual TE-links defines the VNT
layer. provided by the lower layer.
The solution SHOULD provide operations to facilitate the build-up The solution SHOULD provide operations to facilitate the build-up
of such virtual TE-links, taking into account the (forecast) of such virtual TE-links, taking into account the (forecast)
traffic demand and available resource in the lower-layer. traffic demand and available resource in the lower-layer.
Virtual TE-links MAY be modified dynamically (by adding or removing Virtual TE-links MAY be modified dynamically (by adding or removing
virtual TE links) according to the change of the (forecast) traffic virtual TE links, or chancing their capacity) according to the
demand and the available resource in the lower-layer. change of the (forecast) traffic demand and the available resource
in the lower-layer.
Any solution MUST include measures to protect against network Any solution MUST include measures to protect against network
destabilization caused by the rapid changes in the virtual network destabilization caused by the rapid changes in the virtual network
topology as traffic demand varies near a threshold. topology as traffic demand varies near a threshold.
The VNT can be changed by setting up and/or tearing down virtual TE The VNT can be changed by setting up and/or tearing down virtual TE
links as well as by modifying real links (i.e. the fully links as well as by modifying real links (i.e. the fully
provisioned LSPs). provisioned LSPs).
The maximum number of virtual TE links that can be configured The maximum number of virtual TE links that can be defined SHOULD
SHOULD be well-engineered. be configurable.
How to design the VNT and how to manage it are out of scope of this How to design the VNT and how to manage it are out of scope of this
document and will be treated in a companion document on solution. document.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
6.3. LSP Attribute inheritance 5.3. LSP Attribute inheritance
TE-Link parameters SHOULD be inherited from the parameters of the TE-Link parameters SHOULD be inherited from the parameters of the
LSP that provides the TE link, and so from the TE links in the LSP that provides the TE-link, and so from the TE-links in the
lower layer that are traversed by the LSP. lower layer that are traversed by the LSP.
These include: These include:
- Interface Switching Capability - Interface Switching Capability
- TE metric - TE metric
- Maximum LSP bandwidth per priority level - Maximum LSP bandwidth per priority level
- Unreserved bandwidth for all priority levels - Unreserved bandwidth for all priority levels
- Maximum Reservable bandwidth - Maximum Reservable bandwidth
- Protection attribute - Protection attribute
- Minimum LSP bandwidth (depending on the Switching Capability) - Minimum LSP bandwidth (depending on the Switching Capability)
Inheritance rules MUST be applied based on specific policies. Inheritance rules MUST be applied based on specific policies.
Particular attention should be given to the inheritance of TE Particular attention should be given to the inheritance of TE
metric (which may be other than a strict sum of the metrics of the metric (which may be other than a strict sum of the metrics of the
component TE links at the lower layer) and protection attributes. component TE links at the lower layer) and protection attributes.
6.4. Verification of the LSP 5.4. Verification of the LSP
When the LSP is created, it SHOULD be verified that it has been
established before it can be used by an upper layer LSP. Note, this
is not within the GMPLS capability scope for non-PSC interfaces.
6.5. Disruption minimization When a lower layer LSP is established for use as a data link by a
higher layer, the LSP MAY be verified for correct connectivity and
data integrity. Such mechanisms are data technology-specific and
are beyond the scope of this document, but may be coordinated
through the GMPLS control plane.
5.5. Disruption minimization
When reconfiguring the VNT according to a change in traffic demand, When reconfiguring the VNT according to a change in traffic demand,
the upper-layer LSP might be disrupted. Such disruption MUST be the upper-layer LSP might be disrupted. Such disruption to the
minimized. upper layers MUST be minimized.
When residual resource decreases to a certain level, some LSPs MAY When residual resource decreases to a certain level, some lower
be released according to local or network policies. There is a layer LSPs MAY be released according to local or network policies.
trade-off between minimizing the amount of resource reserved in the There is a trade-off between minimizing the amount of resource
lower layer LSPs and disrupting higher layer traffic (i.e. moving reserved in the lower layer and disrupting higher layer traffic
the traffic to other TE-LSPs so that some LSPs can be released). (i.e. moving the traffic to other TE-LSPs so that some LSPs can be
Such traffic disruption MAY be allowed but MUST be under the released). Such traffic disruption MAY be allowed but MUST be under
control of policy that can be configured by the operator. Any the control of policy that can be configured by the operator. Any
repositioning of traffic MUST be as non-disruptive as possible (for repositioning of traffic MUST be as non-disruptive as possible (for
example, using make-before-break). example, using make-before-break).
6.6. Stability 5.6. Stability
The path computation is dependent on the network topology and Path computation is dependent on the network topology and
associated link state. The path computation stability of an upper associated link state. The path computation stability of an upper
layer may be impaired if the VNT changes frequently and/or if the layer may be impaired if the VNT changes frequently and/or if the
status and TE parameters (TE metric for instance) of links in the status and TE parameters (TE metric for instance) of links in the
virtual network topology changes frequently. virtual network topology changes frequently.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
In this context, robustness of the VNT is defined as the capability In this context, robustness of the VNT is defined as the capability
to smooth changes that may occur and avoid their propagation into to smooth changes that may occur and avoid their propagation into
higher layers. Changes of the VNT may be caused by the creation higher layers. Changes of the VNT may be caused by the creation,
and/or deletion of several LSPs. deletion, or modification of several LSPs.
Creation and deletion of LSPs MAY be triggered by adjacent layers Creation, deletion and modification of LSPs MAY be triggered by
or through operational actions to meet traffic demand change, adjacent layers or through operational actions to meet traffic
topology change, signaling request from the upper layer, and demand changes, topology changes, signaling requests from the upper
network failure. Routing robustness SHOULD be traded with layer, and network failures. Routing robustness SHOULD be traded
adaptability with respect to the change of incoming traffic with adaptability with respect to the change of incoming traffic
requests. requests.
A full mesh of LSPs MAY be created between every pair of border A full mesh of LSPs MAY be created between every pair of border
nodes of the PSC region. The merit of a full mesh of PSC TE-LSPs is nodes of the higher layer. The merit of a full mesh of PSC TE-LSPs
that it provides stability to the PSC-level routing. That is, the is that it provides stability to the higher layer routing. That is,
forwarding table of an PSC-LSR is not impacted by re-routing the TED or forwarding table used in the higher layer of an PSC-LSR
changes within the lower-layer (e.g., TDM layer). Further, there is is not impacted by routing changes within the lower-layer (e.g.,
always full PSC reachability and immediate access to bandwidth to TDM layer). Further, there is always full PSC reachability and
support PSC LSPs. But it also has significant drawbacks, since it immediate access to bandwidth to support LSPs in the higher layer.
requires the maintenance of n^2 RSVP-TE sessions, which may be But it also has significant drawbacks, since it requires the
quite CPU and memory consuming (scalability impact). Also this may maintenance of n^2 RSVP-TE sessions, which may be quite CPU and
lead to significant bandwidth wasting if LSP with a certain amount memory consuming (scalability impact). Also this may lead to
of reserved bandwidth is used. significant bandwidth wastage if LSPs with a certain amount of
Note that the use of virtual TE-links solves the bandwidth wasting reserved bandwidth are used.
Note that the use of virtual TE-links solves the bandwidth wastage
issue, and may reduce the control plane overload. issue, and may reduce the control plane overload.
6.7. Computing paths with and without nested signaling 5.7. Computing paths with and without nested signaling
Path computation MAY take into account LSP region and layer Path computation MAY take into account LSP region and layer
boundaries when computing a path for an LSP. For example, path boundaries when computing a path for an LSP. For example, path
computation MAY restrict the path taken by an LSP to only the links computation MAY restrict the path taken by an LSP to only the links
whose interface switching capability is PSC. whose interface switching capability is PSC.
Interface switching capability is used as a constraint in computing Interface switching capability is used as a constraint in path
the path. A TDM-LSP is routed over the topology composed of TE computation. For example, a TDM-LSP is routed over the topology
links of the same TDM layer. In calculating the path for the LSP, composed of TE links of the same TDM layer. In calculating the path
the TE database MAY be filtered to include only links where both for the LSP, the TED MAY be filtered to include only links where
end include requested LSP switching type. In this way hierarchical both end include requested LSP switching type. In this way
routing is done by using a TE database filtered with respect to hierarchical routing is done by using a TED filtered with respect
switching capability (that is, with respect to particular layer). to switching capability (that is, with respect to particular layer).
If triggered signaling is allowed, the path computation mechanism If triggered signaling is allowed, the path computation mechanism
MAY produce a route containing multiple layers/ regions. The path MAY produce a route containing multiple layers/regions. The path is
is computed over the multiple layers/regions even if the path is computed over the multiple layers/regions even if the path is not
not "connected" in the same layer as the endpoints of the path "connected" in the same layer as the endpoints of the path exist.
exist. Note that here we assume that triggered signaling will be Note that here we assume that triggered signaling will be invoked
invoked to make the path "connected", when the upper-layer to make the path "connected", when the upper-layer signaling
signaling request arrives at the boundary node. request arrives at the boundary node.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006 The upper-layer signaling request may contain an ERO that includes
only hops in the upper layer, in which case the boundary node is
responsible for triggered creating of the lower-layer FA-LSP using
a path of its choice, or for the selection of any available lower
layer LSP as a data link for the higher layer. This mechanism is
appropriate for environments where the TED is filtered in the
higher layer, where separate routing instances are used per layer,
or where administrative policies prevent the higher layer from
specifying paths through the lower layer.
The upper-layer signaling request may contain a loose ERO, and the Obviously, if the lower layer LSP has been advertised as a TE link
boundary node is responsible for creation of the lower-layer FA-LSP. (virtual or real) into the higher layer, then the higher layer
When the boundary node receives the signaling setup request and signaling request may contain the TE link identifier and so
determines that it has to expand the loose ERO content by creating indicate the lower layer resources to be used. But in this case,
the lower-layer FA-LSP, it will create the lower layer FA-LSP the path of the lower layer LSP can be dynamically changed by the
accordingly. Once the lower-layer LSP is established, the ERO lower layer at any time.
contents for the upper-layer signaling setup request are expanded
to include the lower-layer FA-LSP and signaling setup for the
upper-layer LSP are carried in-band of the lower-layer LSP.
The upper-layer signaling request may contain a strict ERO Alternatively, the upper-layer signaling request may contain an ERO
specifying the lower layer FA-LSP route. In this case, the boundary specifying the lower layer FA-LSP route. In this case, the boundary
node is responsible for decision as to which it should use the path node is responsible for decision as to which it should use the path
contained in the strict ERO or it should re-compute the path within contained in the strict ERO or it should re-compute the path within
in the lower-layer. in the lower-layer.
Even in case the lower-layer FA-LSPs are already established, a Even in case the lower-layer FA-LSPs are already established, a
signaling request may also be encoded as loose ERO. In this signaling request may also be encoded as loose ERO. In this
situation, it is up to the boundary node to decide whether it 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 should a new lower-layer FA-LSP or it should use the existing
lower-layer FA-LSPs. lower-layer FA-LSPs.
We should note that the lower-layer FA-LSP can be advertised just The lower-layer FA-LSP can be advertised just as an FA-LSP in the
as an FA-LSP in the upper-layer or an IGP adjacency can be brought upper-layer or an IGP adjacency can be brought up on the lower-
up on the lower-layer FA-LSP. layer FA-LSP.
6.8. Handling single-switching and multi-switching type capable 5.8. Handling single-switching and multi-switching-type-capable
nodes nodes
The MRN/MLN can consist of single-switching type capable and multi- The MRN/MLN can consist of single-switching-type-capable and multi-
switching type capable nodes. The path computation mechanism in the switching-type-capable nodes. The path computation mechanism in the
MLN SHOULD be able to compute paths consisting of any combination MLN SHOULD be able to compute paths consisting of any combination
of such nodes. of such nodes.
Both single switching capable and multi-switching (simplex or Both single-switching-type-capable and multi-switching-type-capable
hybrid) capable nodes could play the role of layer boundary. (simplex or hybrid) nodes could play the role of layer boundary.
MRN/MLN Path computation SHOULD handle TE topologies built of any MRN/MLN Path computation SHOULD handle TE topologies built of any
combination of single switching, simplex and hybrid nodes combination of nodes
6.9. Advertisement of the available adaptation resource 5.9. Advertisement of the available adaptation resource
A hybrid node SHOULD maintain resources and advertise the resource A hybrid node SHOULD maintain resources and advertise the resource
information on its internal links, the links required for vertical information on its internal links, the links required for vertical
(layer) integration. Likewise, path computation elements SHOULD be (layer) integration. Likewise, path computation elements SHOULD be
prepared to use the availability of termination/adaptation prepared to use the availability of termination/adaptation
resources as a constraint in MRN/MLN path computations to reduce resources as a constraint in MRN/MLN path computations to reduce
the higher layer LSP setup blocking probability because of the lack the higher layer LSP setup blocking probability because of the lack
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
of necessary termination/ adaptation resources in the lower of necessary termination/ adaptation resources in the lower
layer(s). layer(s).
The advertisement of the adaptation capability to terminate LSPs of The advertisement of the adaptation capability to terminate LSPs of
lower-region and forward traffic in the upper-region is REQUIRED, lower-region and forward traffic in the upper-region is REQUIRED,
as it provides critical information when performing multi-region as it provides critical information when performing multi-region
path computation. path computation.
The mechanism SHOULD cover the case where the upper-layer links The mechanism SHOULD cover the case where the upper-layer links
which are directly connected to upper-layer switching element and which are directly connected to upper-layer switching element and
the ones which are connected through internal links between upper- the ones which are connected through internal links between upper-
layer element and lower-layer element coexist (See section 4.2.1). layer element and lower-layer element coexist (See section 4.2.1).
7. Security Considerations 6. Security Considerations
The current version of this document does not introduce any new The current version of this document does not introduce any new
security considerations as it only lists a set of requirements. In security considerations as it only lists a set of requirements. In
the future versions, new security requirements may be added. the future versions, new security requirements may be added.
8. References 7. References
8.1. Normative Reference 7.1. Normative Reference
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC 2119,
March 1997.
[RFC3979] Bradner, S., "Intellectual Property Rights in IETF [RFC3979] Bradner, S., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3979, March 2005. Technology", BCP 79, RFC 3979, March 2005.
[GMPLS-ROUTING] K.Kompella and Y.Rekhter, "Routing Extensions in [RFC4202] K.Kompella and Y.Rekhter, "Routing Extensions in
Support of Generalized Multi-Protocol Label Support of Generalized Multi-Protocol Label
Switching," draft-ietf-ccamp-gmpls-routing-09.txt, Switching (GMPLS)," RFC4202, October 2005.
October 2003 (work in progress).
[Inter-domain] A.Farrel, J-P. Vasseur, and A.Ayyangar, "A [Inter-domain] A.Farrel, J-P. Vasseur, and A.Ayyangar, "A
framework for inter-domain MPLS traffic framework for inter-domain MPLS traffic
engineering," draft-ietf-ccamp-inter-domain- engineering," draft-ietf-ccamp-inter-domain-
framework, work in progress. framework, work in progress.
[HIER] K.Kompella and Y.Rekhter, "LSP hierarchy with [RFC4206] K.Kompella and Y.Rekhter, "Label Switched Paths (LSP)
generalized MPLS TE," draft-ietf-mpls-lsp-hierarchy- Hierarchy with Generalized Multi-Protocol Label
08.txt, work in progress, Sept. 2002. Switching (GMPLS) Traffic Engineering (TE),"
RFC4206, Oct. 2005.
[STITCH] Ayyangar, A. and Vasseur, JP., "Label Switched Path [STITCH] Ayyangar, A. and Vasseur, JP., "Label Switched Path
Stitching with Generalized MPLS Traffic Engineering", Stitching with Generalized MPLS Traffic Engineering",
draft-ietf-ccamp-lsp-stitching, work in progress. draft-ietf-ccamp-lsp-stitching, work in progress.
[LMP] J. Lang, "Link management protocol (LMP)," draft- ietf- [RFC4204] J. Lang, "Link management protocol (LMP)," RFC4204,
ccamp-lmp-10.txt (work in progress), October 2003. October 2005.
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
[RFC3945] E.Mannie (Ed.), "Generalized Multi-Protocol Label [RFC3945] E.Mannie (Ed.), "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3945, October Switching (GMPLS) Architecture", RFC 3945, October
2004. 2004.
8.2. Informative References 7.2. Informative References
[MAMLTE] K. Shiomoto et al., "Multi-area multi-layer traffic [MAMLTE] K. Shiomoto et al., "Multi-area multi-layer traffic
engineering using hierarchical LSPs in GMPLS engineering using hierarchical LSPs in GMPLS
networks", draft-shiomoto-multiarea-te, work in networks", draft-shiomoto-multiarea-te, work in
progress. progress.
[MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou, D., [MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou, D.,
Shiomoto, K., Vigoureux, M.,"Evaluation of existing Shiomoto, K., Vigoureux, M.,"Evaluation of existing
GMPLS Protocols against Multi Layer and Multi Region GMPLS Protocols against Multi Layer and Multi Region
Networks (MLN/MRN)", draft-leroux-ccamp-gmpls-mrn- Networks (MLN/MRN)", draft-leroux-ccamp-gmpls-mrn-
eval, work in progress. eval, work in progress.
[IW-MIG-FW] Shiomoto, K., Papadimitriou, D., Le Roux, J.L., [IW-MIG-FW] Shiomoto, K., Papadimitriou, D., Le Roux, J.L.,
Brungard, D., Oki, E., Inoue, I., " Framework for Brungard, D., Oki, E., Inoue, I., " Framework for
IP/MPLS-GMPLS interworking in support of IP/MPLS to IP/MPLS-GMPLS interworking in support of IP/MPLS to
GMPLS migration ", draft-shiomoto-ccamp-mpls-gmpls- GMPLS migration ", draft-ietf-ccamp-mpls-gmpls-
interwork-fmwk-00.txt, work in progress. interwork-fmwk-00.txt, work in progress.
9. Author's Addresses [AUTO-MESH] Vasseur, JP., Le Roux, JL., et al., "Routing
extensions for discovery of Multiprotocol (MPLS)
Label Switch Router (LSR) Traffic Engineering (TE)
mesh membership", draft-ietf-ccamp-automesh, work in
progress.
8. Author's 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 Alcatel
Francis Wellensplein 1, Francis Wellensplein 1,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Phone : +32 3 240 8491 Phone : +32 3 240 8491
Email: dimitri.papadimitriou@alcatel.be Email: dimitri.papadimitriou@alcatel.be
Jean-Louis Le Roux Jean-Louis Le Roux
France Telecom R&D, France Telecom R&D,
Av Pierre Marzin, Av Pierre Marzin,
22300 Lannion, France 22300 Lannion, France
Email: jeanlouis.leroux@francetelecom.com Email: jeanlouis.leroux@orange-ft.com
Martin Vigoureux Martin Vigoureux
Alcatel Alcatel
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
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
Email: martin.vigoureux@alcatel.fr Email: martin.vigoureux@alcatel.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
Contributors Contributors
skipping to change at page 19, line 29 skipping to change at page 20, line 16
Phone: +81 422 59 3441 Email: oki.eiji@lab.ntt.co.jp Phone: +81 422 59 3441 Email: oki.eiji@lab.ntt.co.jp
Ichiro Inoue (NTT Network Service Systems Laboratories) Ichiro Inoue (NTT Network Service Systems Laboratories)
3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan 3-9-11 Midori-cho, Musashino-shi, Tokyo 180-8585, Japan
Phone: +81 422 59 3441 Email: ichiro.inoue@lab.ntt.co.jp Phone: +81 422 59 3441 Email: ichiro.inoue@lab.ntt.co.jp
Emmanuel Dotaro (Alcatel) Emmanuel Dotaro (Alcatel)
Route de Nozay, 91461 Marcoussis cedex, France Route de Nozay, 91461 Marcoussis cedex, France
Phone : +33 1 6963 4723 Email: emmanuel.dotaro@alcatel.fr Phone : +33 1 6963 4723 Email: emmanuel.dotaro@alcatel.fr
10. Intellectual Property Considerations 9. Intellectual Property Considerations
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that rights might or might not be available; nor does it represent that
it has made any independent effort to identify any such rights. it has made any independent effort to identify any such rights.
Information on the procedures with respect to rights in RFC Information on the procedures with respect to rights in RFC
documents can be found in BCP 78 and BCP 79. documents can be found in BCP 78 and BCP 79.
skipping to change at page 20, line 4 skipping to change at page 20, line 43
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
The IETF has been notified by Tellabs Operations, Inc. of The IETF has been notified by Tellabs Operations, Inc. of
intellectual property rights claimed in regard to some or all of intellectual property rights claimed in regard to some or all of
the specification contained in this document. For more information, the specification contained in this document. For more information,
draft-ietf-ccamp-gmpls-mln-reqs-00.txt January 2006
see http://www.ietf.org/ietf/IPR/tellabs-ipr-draft-shiomoto-ccamp- see http://www.ietf.org/ietf/IPR/tellabs-ipr-draft-shiomoto-ccamp-
gmpls-mrn-reqs.txt gmpls-mrn-reqs.txt
11. Full Copyright Statement 10. Full Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT
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