Network Working Group Kohei Shiomoto(NTT)
Internet Draft Dimitri Papadimitriou(Alcatel)
Proposed Category: Informational Jean-Louis Le Roux(France Telecom)
Expires: October 2006 Deborah Brungard (AT&T)
Kenji Kumaki (KDDI)
Zafar Ali (Cisco)
Eiji Oki(NTT)
Ichiro Inoue(NTT)
Tomohiro Otani (KDDI)
April 2006
Framework for MPLS-TE to GMPLS migration
draft-ietf-ccamp-mpls-gmpls-interwork-fmwk-01.txt
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Abstract
The migration from Multiprotocol Label Switching (MPLS) Traffic
Engineering (TE) to Generalized MPLS (GMPLS) is the process of
evolving an MPLS-TE control plane to a GMPLS control plane. An
appropriate migration strategy can be selected based on various
factors including the service provider's network deployment plan,
customer demand, and operational policy.
This document presents several migration models and strategies for
migrating from MPLS-TE to GMPLS and notes that in the course of
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migration MPLS-TE and GMPLS devices or networks may coexist which may
require interworking between MPLS-TE and GMPLS protocols. The
applicability? of the interworking that is required is discussed as
it appears to influence the choice of a migration strategy.
Table of Contents
1. Introduction...................................................3
2. Conventions Used in This Document..............................3
3. Motivations for Migration......................................4
4. MPLS to GMPLS Migration Models.................................5
4.1. Island model..............................................5
4.1.1. Balanced Islands.....................................6
4.1.2. Unbalanced Islands...................................6
4.2. Integrated model..........................................7
4.3. Phased model..............................................8
5. Migration Strategies and Solutions.............................9
5.1. Solutions Toolkit.........................................9
5.1.1. Layered Networks....................................10
- The overlay model preserves strict separation of routing
information between network layers. This is suitable for the
balanced island model and there is no requirement to handle
routing interworking. Signaling interworking is still required
as described for the peer model. The overlay model requires
the establishment of control plane connectivity for the higher
layer across the lower layer...............................10
5.1.2. Routing Interworking................................11
5.1.3. Signaling Interworking..............................12
6. Manageability Considerations..................................13
6.1. Control of Function and Policy...........................13
6.2. Information and Data Models..............................14
6.3. Liveness Detection and Monitoring........................14
6.4. Verifying Correct Operation..............................14
6.5. Requirements on Other Protocols and Functional Components14
6.6. Impact on Network Operation..............................15
6.7. Other Considerations.....................................15
7. Security Considerations.......................................15
8. Recommendations for Migration.................................16
9. IANA Considerations...........................................16
10. Full Copyright Statement.....................................16
11. Intellectual Property........................................16
12. Acknowledgements.............................................17
13. Authors' Addresses...........................................18
14. References...................................................19
14.1. Normative References....................................19
14.2. Informative References..................................20
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1. Introduction
Multiprotocol Label Switching Traffic Engineering (MPLS-TE) to
Generalized MPLS (GMPLS) migration is the process of evolving an
MPLS-TE-based control plane to a GMPLS-based control plane. The
network under consideration is, therefore, a packet-switching network.
There are several motivations for such migration and they focus
mainly on the desire to take advantage of new features and functions
that have been added to the GMPLS protocols but which are not present
in MPLS-TE.
Although an appropriate migration strategy can be selected based on
various factors including the service provider's network deployment
plan, customer demand, deployed network equipments, operational
policy, etc., the transition mechanisms used should also provide
consistent operation of GMPLS networks while minimizing the impact on
the operation of existing MPLS-TE networks.
In the course of migration MPLS-TE and GMPLS devices or networks may
need to coexist. Such cases may occur as parts of the network are
migrated from MPLS-TE protocols to GMPLS protocols. Additionally, as
part of the preparation for migrating a packet-switching network from
MPLS-TE to GMPLS, it may be desirable to first migrate a lower-layer
network from having control plane to using a GMPLS control plane, and
this can also lead to the need for MPLS-TE/GMPLS interworking.
This document describes several migration strategies and shows the
interworking scenarios that arise during migration, and examines the
implications for network deployments and for protocol usage. Since
GMPLS signaling and routing protocols are different from the MPLS-TE
control protocols, interworking between MPLS-TE and GMPLS networks or
network elements needs mechanisms to compensate for the differences.
Note that MPLS-TE and GMPLS protocols can co-exist as "ships in the
night" without any interworking issue.
Also note that, in this document, the term "MPLS" is used to refer to
MPLS-TE protocols only ([RFC3209], [RFC3630], [RFC3473]) and excludes
other MPLS protocols such as the Label Distribution Protocol (LDP).TE
functionalities of MPLS could be migrated to GMPLS-TE, but non-TE
functionalities could not.
2. Conventions Used in This Document
This is not a requirements document, nevertheless the key words
"MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
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"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document
are to be interpreted as described in RFC 2119 [RFC2119] in order to
clarify the recommendations that are made.
In the rest of this document, the term "GMPLS" includes both packet
switching capable (PSC) and non-PSC. Otherwise the term "PSC GMPLS"
or "non-PSC GMPLS" is explicitly used.
In general, the term "MPLS" is used to indicate MPLS traffic
engineering (MPLS-TE). If non-TE MPLS is intended, it is explicitly
indicated.
The reader is assumed to be familiar with the terminology introduced
in [RFC3945].
3. Motivations for Migration
Motivations for migration will vary for different service providers.
This section is only presented to provide background so that the
migration discussions may be seen in the context. Sections 4 and 5
illustrate the migration models and processes with possible examples.
Migration of an MPLS-capable LSR to include GMPLS capabilities may be
performed for one or more reasons, including, no exhaustively:
o To add all GMPLS capabilities to an existing MPLS network.
o To add a GMPLS network without upgrading existing MPLS PSC LSRs.
o To pick up specific GMPLS features and operate them within an MPLS
PSC network.
o To allow existing MPLS-capable LSRs to interoperate with new LSRs
that only support GMPLS.
o To integrate multiple networks managed by separate administrative
organizations, which independently utilize MPLS or GMPLS.
o To build integrated PSC and non-PSC networks where the non-PSC
networks can only be controlled by GMPLS since MPLS does not
operate in non-PSC networks.
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It must be understood that the ultimate objective of migration from
MPLS to GMPLS is that all LSRs and the entire network end up running
GMPLS protocols. During this process various interim situations may
exist giving rise to the interworking situations described in this
document. Those interim situations may persist for considerable
periods of time, but the ultimate objective is not to preserve these
situations, and for the purpose of this document, they should be
considered as temporary.
4. MPLS to GMPLS Migration Models
Three migration models are described below. Multiple migration models
may co-exists in the same network.
4.1. Island model
In the island model, "islands" of network nodes operating one
protocol exist within a "sea" of nodes using the other protocol.
The most obvious example is to consider an island of GMPLS-capable
nodes which is introduced into a legacy MPLS network. Such an island
might be composed of newly added GMPLS network nodes, or might arise
from the upgrade of existing nodes that previously operated MPLS
protocols. The opposite is also quite possible. That is, there is a
possibility that an island happens to be MPLS-capable within a GMPLS
sea. Such a situation might arise in the later stages of migration,
when all but a few islands of MPLS-capable nodes have been upgraded
to GMPLS.
It is also possible that a lower-layer, manually-provisioned network
(for example, a TDM network) supports an MPLS PSC network. During the
process of migrating both networks to GMPLS, the lower-layer network
might be migrated first. This would appear as a GMPLS island within
an MPLS sea.
Lastly, it is possible to consider individual nodes as islands. That
is, it would be possible to upgrade or insert an individual GMPLS-
capable node within an MPLS network, and to treat that GMPLS node as
an island.
Over time, collections of MPLS devices are replaced or upgraded to
create new GMPLS islands or to extend existing ones, and distinct
GMPLS islands may be joined together until the whole network is
GMPLS-capable.
From a migration/interworking point of view, we need to examine how
these islands are positioned and how LSPs run between the islands.
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Four categories of interworking scenarios are considered: (1) MPLS-
GMPLS-MPLS, (2) GMPLS-MPLS-GMPLS, (3) MPLS-GMPLS and (4) GMPLS-MPLS.
In case 1 the interworking behavior is examined based on whether the
GMPLS islands are PSC or non-PSC.
Figure 1 shows an example of the island model for MPLS-GMPLS-MPLS
interworking. The model consists of a transit GMPLS island in an MPLS
sea. The nodes at the boundary of the GMPLS island (G1, G2, G5, and
G6) are referred to as "island border nodes". If the GMPLS island was
non-PSC, all nodes except the island border nodes in the GMPLS-based
transit island (G3 and G4) would be non-PSC devices, i.e., optical
equipment (TDM, LSC, and FSC).
................. .......................... ..................
: MPLS : : GMPLS : : MPLS :
:+---+ +---+ +----+ +---+ +----+ +---+ +---+:
:|R1 |__|R11|___| G1 |_________|G3 |________| G5 |___|R31|__|R3 |:
:+---+ +---+ +----+ +-+-+ +----+ +---+ +---+:
: ________/ : : _______/ | _____ / : : ________/ :
: / : : / | / : : / :
:+---+ +---+ +----+ +-+-+ +----+ +---+ +---+:
:|R2 |__|R21|___| G2 |_________|G4 |________| G6 |___|R41|__|R4 |:
:+---+ +---+ +----+ +---+ +----+ +---+ +---+:
:................: :........................: :................:
|<-------------------------------------------------------->|
e2e LSP
Figure 1 Example of the island model for MPLS-GMPLS-MPLS interworking.
4.1.1. Balanced Islands
In the MPLS-GMPLS-MPLS and GMPLS-MPLS-GMPLS cases, LSPs start and end
using the same protocols. Available strategies include:
- tunneling the signaling across the island network using LSP
nesting or stitching (only with GMPLS-PSC)
- protocol interworking or mapping (only with GMPLS-PSC)
4.1.2. Unbalanced Islands
As just mentioned, there are two island interworking models
consisting of abutting islands. GMPLS(PSC)-MPLS and MPLS-GMPLS(PSC)
islands cases are likely to arise where the migration strategy is not
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based on a core infrastructure, but has edge nodes (ingress or
egress) located in islands of different capabilities.
In this case, an LSP starts or ends in a GMPLS (PSC) island and
correspondingly ends or starts in an MPLS island. This mode of
operation can only be addressed using protocol interworking or
mapping. Figure 2 shows the reference model for this migration
scenario. Head-end and tail-end LSR are in distinct control plane
clouds.
............................ .............................
: MPLS : : GMPLS (PSC) :
:+---+ +---+ +----+ +---+ +---+:
:|R1 |________|R11|_______| G1 |________|G3 |________|G5 |:
:+---+ +---+ +----+ +-+-+ +---+:
: ______/ | _____/ : : ______/ | ______/ :
: / | / : : / | / :
:+---+ +---+ +----+ +-+-+ +---+:
:|R2 |________|R21|_______| G2 |________|G4 |________|G6 |:
:+---+ +---+ +----+ +---+ +---+:
:..........................: :...........................:
|<-------------------------------------------------->|
e2e LSP
Figure 2 GMPLS-MPLS interworking model.
It is important to underline that this scenario is also impacted by
the directionality of the LSP, and the direction in which the LSP is
established.
4.2. Integrated model
The second migration model involves a more integrated migration
strategy. New devices that are capable of operating both MPLS and
GMPLS protocols are introduced into the MPLS network.
In the island model, a GMPLS-capable device does not support the MPLS
protocols except border nodes , while in the integrated model there
are two types of node present during migration:
- those that support MPLS only (legacy nodes)
- those that support MPLS and GMPLS.
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In the island model only island border nodes may support both MPLS
and GMPLS while in the integrated model all GMPLS LSRs also support
MPLS.
That is, in integrated model, existing MPLS devices are upgraded to
support both MPLS and GMPLS. The network continues to provide MPLS
services, and also offers GMPLS services. So, where one end point of
a service is a legacy MPLS node, the service is supported using MPLS
protocols. Similarly, where the selected path between end points
traverses a legacy node that is not GMPLS-capable, MPLS protocols are
used. But where the service can be provided using only GMPLS-capable
nodes, it may be routed accordingly and can achieve a higher level of
functionality by utilizing GMPLS features.
Once all devices in the network are GMPLS-capable, the MPLS specific
protocol elements may be turned off, and no new devices need to
support these elements.
In this model, the questions to be addressed concern the co-existence
of the two protocol sets within the network. Actual interworking is
not a concern.
4.3. Phased model
The phased model introduces GMPLS features and protocol elements into
an MPLS network one by one. For example, some object or sub-object
(such as the ERO label sub-object, [RFC3473]) might be introduced
into the signaling used by LSRs that are otherwise MPLS-capable. This
would produce a kind of hybrid LSR.
This approach may appear simpler to implement as one is able to
quickly and easily pick up key new functions without needing to
upgrade the whole protocol implementation. It is most likely to be
used where there is a desire to rapidly implement a particular
function within a network without the necessity to install and test
the full GMPLS function.
Interoperability concerns are exacerbated by this migration model,
unless all LSRs in the network are updated simultaneously and there
is a clear understanding of which subset of features are to be
included in the hybrid LSRs. Interworking between a hybrid LSR and an
unchanged MPLS LSR would put the hybrid in the role of a GMPLS LSR as
described in the previous sections and puts the hybrid in the role of
an MPLS LSR. The potential for different hybrids within the network
will complicate matters considerably.
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5. Migration Strategies and Solutions
An appropriate migration strategy is selected by a network operator
based on factors including the service provider's network deployment
plan, customer demand, existing network equipment, operational policy,
support from its vendors, etc.
For PSC networks, the migration strategy involves the selection
between the models described in the previous section. The choice will
depend upon the final objective (full GMPLS capability, partial
upgrade to include specific GMPLS features, or no change to existing
IP/MPLS networks), and upon the immediate objectives (full, phased,
or staged upgrade).
For PSC networks serviced by non-PSC networks, two basic migration
strategies can be considered. In the first strategy, the non-PSC
network is made GMPLS-capable first and then the PSC network is
migrated to GMPLS. This might arise when, in order to expand the
network capacity, GMPLS-based non-PSC sub-networks are introduced
into or underneath the legacy MPLS-based networks. Subsequently, the
legacy MPLS-based PSC network is migrated to be GMPLS-capable as
described in the previous paragraph. Finally the entire network,
including both PSC and non-PSC nodes, may be controlled by GMPLS.
The second strategy for PSC and non-PSC networks is to migrate from
the PSC network to GMPLS first and then enable GMPLS within the non-
PSC network. The PSC network is migrated as described before, and
when the entire PSC network is completely converted to GMPLS, GMPLS-
based non-PSC devices and networks may be introduced without any
issues of interworking between MPLS and GMPLS.
These migration strategies and the migration models described in the
previous section are not necessarily mutually exclusive. Mixtures of
all strategies and models could be applied. The migration models and
strategies selected will give rise to one or more of the interworking
cases described in the following section.
5.1. Solutions Toolkit
As described in the previous sections, an essential part of a
migration and deployment strategy is how the MPLS and GMPLS or hybrid
LSRs interwork. This section sets out some of the alternatives for
achieving interworking between MPLS and GMPLS, and points out some of
the issues that need to be addressed if the alternatives are adopted.
This document does not describe solutions to these issues.
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Note that it is possible to consider upgrading the routing and
signaling capabilities of LSRs from MPLS to GMPLS separately.
5.1.1. Layered Networks
In the balanced island model, LSP tunnels [RFC4206] is a solution to
carry the end-to-end LSPs across islands of incompatible nodes.
Network layering is often used to separate domains of different data
plane technology. It can also be used to separate domains of
different control plane technology (such as MPLS and GMPLS protocols),
and the solutions developed for multiple data plane technologies can
be usefully applied to this situation [RFC3945], [RFC4206], and
[INTER-DOM]. [MLN-REQ] gives a discussion of the requirements for
multi-layered networks.
The GMPLS architecture [RFC3945] identifies three architectural
models for supporting multi-layer GMPLS networks, and these models
may be applied to the separation of MPLS and GMPLS control plane
islands.
- In the peer model, both MPLS and GMPLS nodes run the same routing
instance, and routing advertisements from within islands of one
level of protocol support are distributed to the whole network.
This is achievable only as described in section 5.1.2 either by
direct distribution or by mapping of parameters.
Signaling in the peer model may result in contiguous LSPs,
stitched LSPs (only for GMPLS PSC), or nested LSPs. If the network
islands are non-PSC then the techniques of [MLN] may be applied,
and these techniques may be extrapolated to networks where all
nodes are PSC, but where there is a difference in signaling
protocols.
- The overlay model preserves strict separation of routing
information between network layers. This is suitable for the
balanced island model and there is no requirement to handle
routing interworking. Even though the overlay model preserves
separation of signaling information between network layers, there
may be some interaction in signaling between network layers.
The overlay model requires the establishment of control plane
connectivity for the higher layer across the lower layer.
- The augmented model allows limited routing exchange from the lower
layer network to the higher layer network. Generally speaking,
this assumes that the border nodes provide some form of filtering,
mapping or aggregation of routing information advertised from the
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lower layer network. This architectural model can also be used for
balanced island model migrations. Signaling interworking is
required as described for the peer model.
- The border peer architecture model is defined in [MPLS-OVER-GMPLS].
This is a modification of the augmented model where the layer
border routers have visibility into both layers, but no routing
information is otherwise exchanged between models. This
architectural model is particularly suited to the MPLS-GMPLS-MPLS
island model for PSC and non-PSC GMPLS islands. Signaling
interworking is required as described for the peer model.
5.1.2. Routing Interworking
Migration strategies may necessitate some interworking between MPLS
and GMPLS routing protocols. GMPLS extends the TE information
advertised by the IGPs to include non-PSC information and extended
PSC information. Because the GMPLS information is provided as
additional TLVs that are carried along with the MPLS information,
MPLS LSRs are able to "see" all GMPLS LSRs as though they were MPLS
PSC LSRs. They will also see other GMPLS information, but will ignore
it, flooding it transparently across the MPLS network for use by
other GMPLS LSRs.
- Routing separation is achieved in the overlay, and border peer
models. This is convenient since only the border nodes need to be
aware of the different protocol variants, and no mapping is
required. It is suitable to the MPLS-GMPLS-MPLS and GMPLS-MPLS-
GMPLS island migration models.
- Direct distribution involves the flooding of MPLS routing
information into a GMPLS network, and GMPLS routing information
into an MPLS network. The border nodes make no attempt to filter
the information. This mode of operation relies on the fact that
MPLS routers will ignore, but continue to flood, GMPLS routing
information that they do not understand. The presence of
additional GMPLS routing information will not interfere with the
way that MPLS LSRs select routes, and although this is not a
problem in a PSC-only network, it could cause problems in a peer
architecture network that includes non-PSC nodes as the MPLS nodes
are not capable of determining the switching types of the other
LSRs and will attempt to signal end-to-end LSPs assuming all LSRs
to be PSC. This fact would require island border nodes to take
triggered action to set up tunnels across islands of different
switching capabilities.
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GMPLS LSRs might be impacted by the absence of GMPLS-specific
information in advertisements initiated by MPLS LSRs. Specific
procedures might be required to ensure consistent behavior by
GMPLS nodes. If this issue is addressed, then direct distribution
can be used in all migration models (except the overlay and border
peer architectural models where the problem does not arise).
- Protocol mapping converts routing advertisements so that they can
be received in one protocol and transmitted in the other. For
example, a GMPLS routing advertisement could have all of its
GMPLS-specific information removed and could be flooded as an MPLS
advertisement. This mode of interworking would require careful
standardization of the correct behavior especially where an MPLS
advertisement requires default values of GMPLS-specific fields to
be generated before the advertisement can be flooded further.
There is also considerable risk of confusion in closely meshed
networks where many LSRs have MPLS and GMPLS capable interfaces.
This option for routing interworking during migration is NOT
RECOMMENDED for any migration model.
- Ships in the night refers to a mode of operation where both MPLS
and GMPLS routing protocol variants are operated in the same
network at the same time as separate routing protocol instances.
The two instances are independent and are used to create routing
adjacencies between LSRs of the same type. This mode of operation
may be appropriate to the integrated migration model.
5.1.3. Signaling Interworking
Signaling protocols are used to establish LSPs and are the principal
concern for interworking during migration. Issues of compatibility
arise because of simple changes in the encodings and codepoints used
by MPLS and GMPLS signaling, but also because of changes in function
levels provided by MPLS and GMPLS.
- Tunneling and stitching (GMPLS-PSC case) mechanisms are a good way
to avoid any requirement for direct protocol interworking during
migration in the island model because protocol elements are
transported transparently across migration islands without being
inspected. However, care may be needed to achieve functional
mapping in these modes of operation since one set of features must
be carried across a network designed to support a different set of
features. In general, this is easily achieved for the MPLS-GMPLS-
MPLS model, but may be hard to achieve in the GMPLS-MPLS-GMPLS
model for example, when end-to-end bidirectional LSPs are
requested since the MPLS island does not support bidirectional
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LSPs.
Note that tunneling and stitching are not available in unbalanced
island models because in these cases the LSP end points use
different protocol variants.
- Protocol mapping is the conversion of signaling messages between
MPLS and GMPLS variants. This mechanism requires careful
documentation of the protocol fields and how they are mapped, but
is relatively simple in the MPLS-GMPLS unbalanced island model.
However, the MPLS-GMPLS island model may manifest as the GMPLS-
MPLS model for LSPs signaled in the opposite direction and this
will lead to considerable complications for providing GMPLS
services over the MPLS island and for terminating those services
at an egress LSR that is not GMPLS-capable. Further, in balanced
island models, and in particular where there are multiple small
(individual node) islands, the repeated conversion of signaling
parameters may lead to loss of information or mis-requests.
- Ships in the night could be used in the integrated migration model
to allow MPLS-capable LSRs to establish LSPs using MPLS signaling
protocols and GMPLS LSRs to establish LSPs using GMPLS signaling
protocols. LSRs that can handle both sets of protocols could play
a part in either case, but no conversion of protocols would be
applied.
6. Manageability Considerations
Attention should be given during migration planning to how the
network will be managed during and after migration. For example, will
the LSRs of different protocol capabilities be managed separately or
as a whole. This is most clear in the Island Model where it is
possible to consider managing islands of one capability separately
from the surrounding sea. In the case of islands that have different
switching capabilities, it is possible that the islands already had
different management in place before the migration: the resultant
migrated network may seek to merge the management or to preserve it.
6.1. Control of Function and Policy
The most important control to be applied is at the moment of
changeover between different levels of protocol support. Such a
change may be made dynamically or during a period of network
maintenance.
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Where island boundaries exist, it must be possible to manage the
relationships between protocols and to indicate which interfaces
support which protocols on a border LSR. Further, island borders are
a natural place to apply policy, and management should allow
configuration of such policies.
6.2. Information and Data Models
No special information or data models are required to support
migration, but note that migration in the control plane implies
migration from MPLS management tools to GMPLS management tools.
During migration, therefore, it may be necessary for LSRs and
management applications to support both MPLS and GMPLS variants of
management data.
The GMPLS MIB modules are designed to allow support of the MPLS
protocols and build on the MPLS MIB modules through extensions and
augmentations. This may make it possible to migrate management
applications ahead of the LSRs that they manage.
6.3. Liveness Detection and Monitoring
Migration will not imposes additional issues for OAM above those that
already exist for inter-domain OAM and for OAM across multiple
switching capabilities.
Note, however, that if a flat PSC MPLS network is migrated using the
island model, and is treated as a layered network using tunnels to
connect across GMPLS islands, then requirements for a multi-layer OAM
technique may be introduced into what was previously defined in the
flat OAM problem-space. The OAM framework of MPLS/GMPLS interworking
may be described in more detail in a later version.
6.4. Verifying Correct Operation
The concerns for verifying correct operation (and in particular
correct connectivity) are the same as for liveness detection and
monitoring. Principally, the process of migration may introduce
tunneling or stitching into what was previously a flat network.
6.5. Requirements on Other Protocols and Functional Components
No particular requirements are introduced on other protocols. As it
has been observed, the management components may need to migrate in
step with the control plane components, but this does not impact the
management protocols, just the data that they carry.
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It should also be observed that providing signaling and routing
connectivity across a migration island in support of a layered
architecture may require the use of protocol tunnels (such as GRE)
between island border nodes. Such tunnels may impose additional
configuration requirements at the border nodes.
6.6. Impact on Network Operation
The process of migration is likely to have significant impact on
network operation while migration is in progress. The main objective
of migration planning should be to reduce the impact on network
operation and on the services perceived by the network users.
To this end, planners should consider reducing the number of
migration steps that they perform, and minimizing the number of
migration islands that are created.
A network manager may prefer the island model especially when
migration will extend over a significant operational period because
it allows the different network islands to be administered as
separate management domains. This is particularly the case in the
overlay and augmented network models where the details of the
protocol islands remain hidden from the surrounding LSRs.
6.7. Other Considerations
A migration strategy may also imply moving an MPLS state to a GMPLS
state for an in-service LSP. This may arise once all of the LSRs
along the path of the LSP have been updated to be both MPLS and
GMPLS-capable. Signaling mechanisms to achieve the replacement of an
MPLS LSP with a GMPLS LSP without disrupting traffic exist through
make-before-break procedures [RFC3209] and [RFC3473], and should be
carefully managed under operator control.
7. Security Considerations
Security and confidentiality is often applied (and attacked) at
administrative boundaries. Some of the models described in this
document introduce such boundaries, for example between MPLS and
GMPLS islands. These boundaries offer the possibility of applying or
modifying the security as one might when crossing an IGP area or AS
boundary, even though these island boundaries might lie within an IGP
area or AS.
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No changes are proposed to the security procedures built into MPLS
and GMPLS signaling and routing. GMPLS signaling and routing inherit
their security mechanisms from MPLS signaling and routing without any
changes. Hence, there will be no issues with security in interworking
scenarios. Further, since the MPLS and GMPLS signaling and routing
security is provided on a hop-by-hop basis, and since all signaling
and routing exchanges described in this document for use between any
pair of LSRs are based on either MPLS or GMPLS, there are no changes
necessary to the security procedures.
8. IANA Considerations
This informational framework document makes no requests for IANA
action.
9. Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
10. Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
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.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
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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, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
11. Acknowledgements
The authors are grateful to Daisaku Shimazaki for discussion during
initial work on this document. The authors are grateful to Dean Cheng
for his valuable comments.
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12. Authors' Addresses
Kohei Shiomoto, Editor
NTT
Midori 3-9-11
Musashino, Tokyo 180-8585, Japan
Phone: +81 422 59 4402
Email: shiomoto.kohei@lab.ntt.co.jp
Dimitri Papadimitriou
Alcatel
Francis Wellensplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 240 8491
Email: dimitri.papadimitriou@alcatel.be
Jean-Louis Le Roux
France Telecom
av Pierre Marzin 22300
Lannion, France
Phone: +33 2 96 05 30 20
Email: jeanlouis.leroux@orange-ft.com
Deborah Brungard
AT&T
Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA
Phone: +1 732 420 1573
Email: dbrungard@att.com
Kenji Kumaki
KDDI Corporation
Garden Air Tower
Iidabashi, Chiyoda-ku,
Tokyo 102-8460, JAPAN
Phone: +81-3-6678-3103
Email: ke-kumaki@kddi.com
Zafar Alli
Cisco Systems, Inc.
EMail: zali@cisco.com
Eiji Oki
NTT
Midori 3-9-11
Musashino, Tokyo 180-8585, Japan
Phone: +81 422 59 3441
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Email: oki.eiji@lab.ntt.co.jp
Ichiro Inoue
NTT
Midori 3-9-11
Musashino, Tokyo 180-8585, Japan
Phone: +81 422 59 3441
Email: inoue.ichiro.lab.ntt.co.jp
Tomohiro Otani
KDDI Laboratories
Email: otani@kddilabs.jp
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," BCP 14, IETF RFC 2119, March 1997.
[RFC4090] Pan, P., Swallow, G. and A. Atlas, "Fast Reroute Extensions
to RSVP-TE for LSP Tunnels", RFC 4090, May 2005.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
Architecture", RFC 3945, October 2004.
[SEGMENT-RECOVERY]Berger, L., "GMPLS Based Segment Recovery", draft-
ietf-ccamp-gmpls-segment-recovery, work in progress.
[E2E-RECOVERY] Lang, J. P., Rekhter, Y., Papadimitriou, D. (Editors),
" RSVP-TE Extensions in support of End-to-End Generalized
Multi-Protocol Label Switching (GMPLS)-based Recovery",
draft-ietf-ccamp-gmpls-recovery-e2e-signaling, work in
progress.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions ", RFC 3473, January 2003.
[TE-NODE-CAPS] Vasseur, Le Roux, editors " IGP Routing Protocol
Extensions for Discovery of Traffic Engineering Node Capabilities",
draft-ietf-ccamp-te-node-cap, work in progress.
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13.2. Informative References
[MLN-REQ] Shiomoto, K., Papadimitriou, D., Le Roux, J.L., Vigoureux,
M., Brungard, D., "Requirements for GMPLS-based multi-
region and multi-layer networks (MRN/MLN)", draft-ietf-
ccamp-gmpls-mln-reqs, work in progress.
[RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP)
Hierarchy with Generalized Multi-Protocol Label Switching
(GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.
[STITCH] Ayyangar, A., Vasseur, JP. "Label Switched Path Stitching
with Generalized MPLS Traffic Engineering", draft-ietf-
ccamp-lsp-stitching, work in progress.
Shiomoto Expires April 23, 2007 [Page 20]
