One document matched: draft-shiomoto-ccamp-mpls-gmpls-interwork-fmwk-00.txt
Network Working Group Kohei Shiomoto(NTT)
Internet Draft Dimitri Papadimitriou(Alcatel)
Proposed Category: Informational Jean-Louis Le Roux(France Telecom)
Expires: April 2006 Deborah Brungard (AT&T)
Eiji Oki(NTT)
Ichiro Inoue(NTT)
October 2005
Framework for IP/MPLS-GMPLS interworking in support of IP/MPLS to
GMPLS migration
draft-shiomoto-ccamp-mpls-gmpls-interwork-fmwk-00.txt
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Abstract
MPLS to GMPLS migration is the process of evolving MPLS-TE-based
control plane to GMPLS-based control plane. An appropriate migration
strategy is selected based on various factors including the service
provider's network deployment plan, customer demand, available
network equipment implementation, etc.
In the course of migration several interworking cases may exist where
MPLS and GMPLS devices or networks must coexist. Such cases may arise
as parts of the network are converted from MPLS protocols to GMPLS
protocols, or may occur if a lower layer network is made GMPLS-
capable (from having no MPLS or GMPLS control plane) in advance of
the migration of the higher layer packet switched layer.
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Since GMPLS signaling and routing protocols are different from the
MPLS protocols, in order for MPLS and GMPLS to interwork, we need
mechanisms to compensate for the difference between MPLS and GMPLS.
This document provides a framework for MPLS and GMPLS interworking to
allow transition from MPLS to GMPLS. We discuss issues, models,
migration scenarios, and requirements. Solutions for MPLS and GMPLS
interworking will be developed in companion documents.
We should note that both MPLS and GMPLS protocols can co-exist as
"ships in the night" without any interworking issue. This document is
mainly addressing interworking to allow transition from MPLS to GMPLS.
Table of Contents
1. Introduction.....................................................3
2. Conventions Used in This Document................................4
3. Motivations for Migration........................................4
4. MPLS to GMPLS migration..........................................4
4.1. Migration models...............................................4
4.1.1. Island model.................................................4
4.1.2. Integrated model.............................................6
4.1.3. Phased model.................................................6
4.2. Migration strategies...........................................7
5. Island model interworking cases..................................8
5.1. MPLS-GMPLS(PSC)-MPLS Islands...................................8
5.2. MPLS-GMPLS(non-PSC)-MPLS Islands...............................8
5.3. GMPLS(PSC)-MPLS-GMPLS(PSC) Islands.............................8
5.4. GMPLS(non-PSC)-MPLS-GMPLS(non-PSC) Islands.....................8
5.5. GMPLS(PSC)-MPLS and MPLS-GMPLS(PSC) Islands....................9
6. Interworking issues between MPLS and GMPLS.......................9
6.1. Control and data plane separation.............................10
6.2. New features..................................................10
6.2.1. Signaling...................................................11
6.2.2. Routing.....................................................12
6.2.3. New mechanisms..............................................13
6.3. Interworking between PSC and non-PSC..........................13
6.3.1. Lack of routing and signaling adjacencies...................13
6.3.2. Control plane resource exhaustion...........................14
6.3.3. TE path computation over the border between MPLS and GMPLS
domains............................................................14
7. History of this document work...................................14
8. Security Considerations.........................................16
9. IANA Considerations.............................................16
10. Full Copyright Statement.......................................17
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11. Intellectual Property..........................................17
12. Acknowledgements...............................................17
13. Authors' Addresses.............................................18
14. References.....................................................18
14.1. Normative References.........................................19
14.2. Informative References.......................................19
1. Introduction
MPLS to GMPLS migration is the process of evolving MPLS-TE-based
control plane to GMPLS-based control plane.
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.
An appropriate migration strategy is selected based on various
factors including the service provider's network deployment plan,
customer demand, available network equipment implementation, etc.
In the course of migration several interworking cases may arise where
MPLS and GMPLS devices or networks must coexist. Such cases may occur
as parts of the network are converted from MPLS protocols to GMPLS
protocols, or may arise if a lower layer network is made GMPLS-
capable (from having no MPLS or GMPLS control plane) in advance of
the migration of the higher layer network.
This document examines 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 protocols, interworking between MPLS and
GMPLS networks or network elements needs mechanisms to compensate for
the differences. This document provides a framework for MPLS and
GMPLS interworking in support of migration from IP/MPLS to GMPLS by
discussing issues, models, migration scenarios, and requirements.
Solutions for interworking MPLS and GMPLS will be developed in
companion documents.
We should note that both MPLS and GMPLS protocols can co-exist as
"ships in the night" without any interworking issue. This document is
mainly addressing interworking to allow transition from MPLS to GMPLS.
We should also note that MPLS control plane means MPLS-TE control
plane (RSVP-TE, IGP-TE) and not LDP-based control plane. This
document does not address the migration from LDP controlled MPLS
networks to GMPLS RSVP-TE
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2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
In the rest of this document, the term GMPLS includes both PSC and
non-PSC. Otherwise the term "PSC GMPLS" or "non-PSC GMPLS" is
explicitly used.
3. Motivations for Migration
Motivations for migration will vary for different service providers.
This section is only present to provide background so that the
migration discussions may be seen in context. Sections 5 and 6
illustrate the migration models and processes by means of some
example scenarios.
Migration of an MPLS capable LSR to include GMPLS capabilities may be
performed for one or more reasons.
- To add all GMPLS functions to an MPLS PSC network.
- To pick up specific GMPLS features and operate them within an MPLS
PSC network.
- To allow interoperation of equipment with new LSRs that only
support GMPLS.
- To integrate networks that have been under separate administration
and where one network utilizes MPLS and another uses GMPLS.
- 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.
4. MPLS to GMPLS migration
4.1. Migration models
MPLS to GMPLS migration is a process of evolving MPLS-TE-based
control plane to GMPLS-based control plane to GMPLS. Three migration
models are considered as described below. Practically speaking, both
migration models may be deployed at the same time.
4.1.1. Island model
In the island model, "islands" of network nodes operating one
protocol exist within a "sea" of nodes using the other protocol.
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The most obvious example is to consider an island of nodes with GMPLS
capability that is introduced into the legacy network. Such an island
might be composed of newly added network nodes, or might arise from
the upgrade of existing nodes that previously operated MPLS protocols.
Clearly there is no requirement that an island be GMPLS-capable
within an MPLS sea; the opposite is quite possible. That is, there is
a possibility that an island happens to be MPLS-capable within an
GMPLS sea in some cases. Such 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 situation might arise
where the lower-layer network has been migrated and operates GMPLS,
but the packet network still operates MPLS. 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.
Four categories of interworking scenarios are considered: (1) MPLS-
GMPLS-MPLS, (2) GMPLS-MPLS-GMPLS, (3) MPLS-GMPLS and (4) GMPLS-MPLS.
In each case, the interworking behavior is examined based on whether
the GMPLS islands are PSC or non-PSC. These scenarios are considered
further in section 5.
Figure 1 shows an example of the island model for the 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 :
:+---+ +---+ +---+ +---+ +---+ +---+ +---+:
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:|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.
4.1.2. Integrated model
The second 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. Further, existing MPLS devices
are upgraded to support both MPLS and GMPLS. The network continues to
operate providing MPLS services, but where the service can be
provided using only GMPLS functionality it may be routed accordingly
over only such GMPLS-capable devices and achieve a higher level of
functionality by utilizing GMPLS features. Once all devices in the
network are GMPLS-capable, the MPLS protocols may be turned off, and
no new devices need to support MPLS.
In this second model the questions to be addressed concern the co-
existence of the two protocol sets within the network. Actual
interworking is not a concern.
The integrated migration model results in a single network in which
both MPLS-capable and GMPLS-capable LSRs co-exist. Some LSRs will be
capable of only one protocol, and some of both. The migration
strategy here involves introducing GMPLS-capable LSRs into an
existing MPLS-capable network until such time as all LSRs are GMPLS-
capable at which time all MPLS functionality is disabled. Since we
are starting with an MPLS network all devices are PSC and there are
no interworking issues in the data plane. In the control plane the
migration issues concern the separation of MPLS and GMPLS protocols,
and the choice of routes that may be signaled with only one protocol.
4.1.3. 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
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(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 their whole protocol implementation.
The interoperability concerns (LABEL REQUEST and LABEL object, for
instance, when speaking about RSVP-TE signaling) are exacerbated by
this migration model unless all LSRs in the network are updated
simultaneously. 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, while interworking between a hybrid LSR and
a GMPLS LSR puts the hybrid in the role of an MPLS LSR. The potential
for different hybrids within the network only serves to complicate
matters considerably. Thus the piecemeal migration from MPLS to GMPLS
is NOT RECOMMENDED.
4.2. Migration strategies
An appropriate migration strategy is selected based on various
factors including the service provider's network deployment plan,
customer demand, available network equipment, 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 or partial
upgrade to include specific GMPLS features), and upon the immediate
objectives (phased upgrade or staged upgrades).
For PSC networks supported 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 where, 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 is controlled by GMPLS.
The second strategy for PSC and non-PSC networks is to migrate 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.
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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. Island model interworking cases
5.1. MPLS-GMPLS(PSC)-MPLS Islands
The migration of an MPLS-based packet network to become a GMPLS
(PSC)-based network may be performed to provide GMPLS-based advanced
features in the network or to facilitate interworking with GMPLS-
based optical core network.
The migration may give rise to islands of GMPLS support within a sea
of MPLS nodes such that an end-to-end LSP begins and ends on MPLS-
capable LSRs. The GMPLS PSC island may be used to "hide" islands of
GMPLS non-PSC functionality that are completely contained within the
GMPLS PSC islands. This would protect the MPLS LSRs from having to be
aware of non-PSC technologies.
5.2. MPLS-GMPLS(non-PSC)-MPLS Islands
The introduction of a GMPLS-based controlled optical core network to
increase the capacity of a MPLS packet network is an example that may
give rise to this scenario. Until the MPLS network is upgraded to be
GMPLS-capable, the MPLS and GMPLS networks must interwork. The
interworking challenges may be reduced by wrapping the non-PSC GMPLS
island entirely within a GMPLS PSC island as described in the
previous section.
5.3. GMPLS(PSC)-MPLS-GMPLS(PSC) Islands
This case might arise as the result of installing new GMPLS-capable
islands around a legacy MPLS network, or as the result of controlled
migration of some islands to become GMPLS-capable.
5.4. GMPLS(non-PSC)-MPLS-GMPLS(non-PSC) Islands
This case is out of scope for this document. Since the MPLS island is
necessarily packet capable (i.e. PSC), this scenario requires that
non-PSC LSPs are carried across a PSC network. Such a situation does
not arise through simple control plane migration although the
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interworking scenario might occur for other reasons and be supported,
for example, by pseudowires.
5.5. GMPLS(PSC)-MPLS and MPLS-GMPLS(PSC) Islands
This case is likely to arise where the migration strategy is not
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. Some signaling and
routing conversion is required on island border LSRs. Figure 2 shows
the reference model for this migration scenario. Head-end and Tail-
end LSR are in distinct control plane clouds.
Since both islands are PSC there is no data plane conversion at the
island boundaries. However, from a control plane point of view this
model may prove challenging because the protocols must share or
convert information between the islands rather than tunnel it across
an island.
................. .................................
: MPLS : : GMPLS (PSC) :
:+---+ +---+ +---+ +---+ +---+:
:|R1 |__|R11|___|G1 |__________|G3 |__________|G5 |:
:+---+ +---+ +---+ +-+-+ +---+:
: ______ _/ : : ________/ | ________/ :
: / : : / | / :
:+---+ +---+ +---+ +-+-+ +---+:
:|R2 |__|R21|___|G2 |__________|G4 |__________|G6 |:
:+---+ +---+ +---+ +---+ +---+:
:................: :...............................:
|<------------------------------------------->|
e2e LSP
Figure 2: GMPLS-MPLS interworking model.
It is also important to underline that this scenario is also impacted
by the directionality of the LSP establishment. Indeed, a
unidirectional packet LSP from R1 to G5 is more easily accommodated
at G1 than a bi-directional PSC LSP from G5 to R1.
6. Interworking issues between MPLS and GMPLS
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Issues of MPLS and GMPLS interworking stem from the difference
between MPLS and GMPLS protocols and architecture. These issues are
categorized into four groups:
(1) control and data plane separation,
(2) new features introduced by GMPLS,
(3) new methods introduced by GMPLS, and
(4) interworking between PSC and non-PSC.
Note that a GMPLS PSC island may be treated in the same way as an
island of non-PSC LSRs, and much can be gained by applying the
techniques described in section 6.4 to the other scenarios described
here.
6.1. Control and data plane separation
In MPLS, the control plane traffic (signaling and routing) is carried
in-band with data. This means that there is fate sharing between a
data link and the control traffic on the link. The control plane
keep-alive techniques can be used to detect some data plane failures.
TDM, LSC, FSC networks do not recognize packet delineation, so in-
band control channels cannot be terminated, and GMPLS must support
dedicated control channels (separated from the data channels). In
GMPLS, the control channel can be logically or physically separated
(i.e., in-fiber out-of-band or out-of-fiber out-of-bound) from the
data channel depending on the capabilities of the network devices and
the operational requirements.
The GMPLS control plane, which is designed to carry the control
packets, offers the possibility to use dedicated control channels
that must not be used to carry data. This is particularly important
when the control channels are of low capacity and are not designed to
carry user traffic.
Since GMPLS introduces a separation between control and data channels,
control traffic may use different channels than the data traffic, and
this requires new routing and signaling protocol elements (e.g.
identification of data channels within the control plane).
6.2. New features
New features introduced by GMPLS and not available in MPLS include
bidirectional LSPs, label suggestion, label restriction, graceful
restart, and graceful teardown, as well as GMPLS's support of
networks with multiple switching capabilities (see [RFC3945]).
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6.2.1. Signaling
GMPLS RSVP-TE signaling ([RFC3471]) introduces new RSVP-TE objects,
and their associated procedures, that are not processed/generated by
MPLS LSRs. Clearly an MPLS LSR cannot be expected to originate LSPs
that use these objects and will, therefore, not have access to the
additional GMPLS functions. However, the new RSVP-TE objects listed
below will need to be handled in interworking scenarios where the LSP
ingress and/or egress is GMPLS-capable, and MPLS LSRs are required to
process the signaling messages:
o The (Generalized) Label Request object (new C-Type), used to
identify the LSP encoding type, the switching type and the
generalized protocol ID (G-PID) associated with the LSP.
o The (Generalized) Label object (new C-Type)
o The IF_ID RSVP_HOP objects, IF_ID ERROR_SPEC objects, and IF_ID
ERO/RRO subobjects that handle the Control plane/Data plane
separation in GMPLS network.
o The Suggested Label Object, used to reduce LSP setup delays.
o The Label Set Object, used to restrict label allocation to a set
of labels, (particularly useful for wavelength conversion
incapable nodes)
o The Upstream Label Object, used for bi-directional LSP setup
o The Restart Cap object, used for graceful restart.
o The Admin Status object, used for LSP administration, and
particularly for graceful LSP teardown.
o The Recovery Label object used for Graceful Restart
o The Notify Request object used to solicit notification of errors
and events.
Future GMPLS extensions are likely to add further new objects.
Some of these objects can be passed transparently by MPLS LSRs to
carry them across MPLS islands because their C-Nums are of the form
11bbbbbb, but others will cause an MPLS LSR to reject the message
that carries them because their C-Nums are of the form 0bbbbbbb.
Even when objects are inherited from MPLS by GMPLS they can be
expected to cause problems. For example, the Label object in GMPLS
uses a new C-Type to indicate Generalized LabelE This C-Type is
unknown to MPLS LSRs which will reject any message carrying it.
GMPLS also introduces new message flags and fields (including new
sub-objects and TLVs) that will have no meaning to MPLS LSRs. This
data will normally be forwarded untouched by transit MPLS LSRs, but
they cannot be expected to act on it.
Also GMPLS introduces two new messages, the Notify message, and the
RecoveryPath message that are not supported by MPLS nodes.
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6.2.1.1 Bi-directional LSP
GMPLS provides bidirectional LSP setup - a single signaling session
manages the bidirectional LSP, and forward and reverse data paths
follow the same route in the GMPLS network. There is no equivalent in
MPLS networks, forward and backward LSPs must be created in different
signaling sessions - the route taken by those LSPs may be different
from each other, and their sessions are treated differently from each
other. Common routes and fate sharing require additional, higher-
level coordination in MPLS.
If MPLS and GMPLS networks are inter-connected, bidirectional LSPs
from the GMPLS network need to be carried in the MPLS network.
Note that this issue arises only in the cases where an LSP is
originated by GMPLS-capable LSRs. In other words, it applies only to
the GMPLS-MPLS-GMPLS island model and to the island migration model.
In the MPLS-GMPLS-MPLS and MPLS-GMPLS models, the ingress LSR is
unaware of the concept of a bidirectional LSP and cannot attempt the
service even if it could find some way to request it through the
network. In the case of GMPLS-MPLS, a similar issue exists because
the egress MPLS-capable LSR is unaware of the concept of
bidirectional LSPs and cannot initiate a return LSP.
Note that the island border LSRs will bear the responsibility for
achieving the bidirectional service across the central MPLS island.
6.2.2. Routing
TE-link information is advertised by the IGP using TE extensions.
This allows LSRs to collect topology information for the whole TE
network and to store it in the traffic-engineering database (TED).
Traffic-engineered explicit routes are calculated using the network
graphs derived from the TED.
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 extensions to the MPLS information, MPLS
LSRs are able to "see" GMPLS LSRs as though they were PSC LSRs. They
will also see other GMPLS information, but will ignore it, passing it
transparently across the MPLS network for use by other GMPLS LSRs.
This means that MPLS LSRs may use the combination of MPLS information
advertised by MPLS LSRs and a restricted subset of the information
advertised by GMPLS LSRs to compute a traffic-engineered explicit
route across a mixed network. However, it is likely that a path
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computation component in an MPLS network will only be aware of MPLS
TE information and will not understand concepts such as switching
capability type. This may mean that an incorrect path will be
computed for an e2e LSP from one MPLS island to another across a
GMPLS island if different switching capabilities exist.
6.2.3. New mechanisms
GMPLS also provides several features in a distinct manner from MPLS.
For instance local protection is provided using different mechanisms
in MPLS (see [RFC4090]) and GMPLS (see [SEGMENT-RECOVERY]). Local
protection of island border nodes may be a particular problem.
6.3. Interworking between PSC and non-PSC
Three issues of interworking between MPLS-based packet networks and
GMPLS-based optical transport network result from the fact that
control and data planes are separated in GMPLS-based optical
transport networks. These three issues are:
(a) Lack of routing and signaling adjacencies,
(b) Control plane resource exhaustion, and
(c) TE path computation over the border between MPLS and GMPLS
domains.
There are several architectural alternatives for interworking between
packet network and optical transport network: overlay, peer and
augmented models [RFC3945]. Impacts of each issue on each model are
different.
These issues are explained using an example network shown in Figure 3.
................. .............................. ..................
: Ingress MPLS : : GMPLS-based optical : : Egress MPLS :
:+---+ +---+ +---+ +---+ +---+ +---+ +---+:
:|R1 |__|R11|___|G1 |__________|G3 |__________|G5 |___|R31|__|R3 |:
:+---+ +---+ +---+ +-+-+ +---+ +---+ +---+:
: ________/ : : ________/ | ________/ : : ________/ :
: / : : / | / : : / :
:+---+ +---+ +---+ +-+-+ +---+ +---+ +---+:
:|R2 |__|R21|___|G2 |__________|G4 |__________|G6 |___|R41|__|R4 |:
:+---+ +---+ +---+ +---+ +---+ +---+ +---+:
:................: :...........................: :................:
Figure 3: Interworking of MPLS-TE networks and GMPLS-based optical
transport networks.
6.3.1. Lack of routing and signaling adjacencies
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The ingress MPLS and the egress MPLS domains are interconnected via a
GMPLS-based optical network as shown in Fig 3. LSAs in the egress
MPLS domain are not advertised in the ingress MPLS domain unless
routing adjacencies are established between the IP/MPLS domain and
GMPLS domain or unless routing adjacencies are established directly
between IP/MPLS domains (overlay model). Therefore the ingress LSR in
the ingress MPLS domain is not able to find the egress LSR in the
egress MPLS domain. The signaling messages are not passed across the
GMPLS domain between the ingress and the egress MPLS domains unless
the signaling adjacencies are established between the MPLS domain and
the GMPLS domain or directly between MPLS domains (overlay model).
This issue appears in the augmented and the overlay model when there
are no links provided between MPLS domains across the GMPLS domain.
6.3.2. Control plane resource exhaustion
It is a danger that only arises at a PSC LSR that uses an out of band
control channel at the border between MPLS and GMPLS domains. This
issue is already mentioned at the head of section 6.1.
This issue can appear in the peer, the augmented, and the overlay
models depending on how the border node handles the data forwarding
and manages the address space.
6.3.3. TE path computation over the border between MPLS and GMPLS
domains
If the ingress LSR in the ingress MPLS domain does not understand the
GMPLS TE protocols and information elements, it assumes that there is
no available TE-path across the GMPLS domain unless MPLS-compatible
TE LSAs representing the available TE-paths in the GMPLS domain are
advertised into the ingress and egress MPLS domains.
This issue appears in the peer and the augmented models.
A different issue, which has very similar results, appears in the
overlay model. In the overlay model, mechanism to discover
connectivity is out of scope and we need to find connectivity between
IP/MPLS domains across the core GMPLS domain. This issue is referred
to as the "unknown adjacency" problem.
7. History of this document work
This document has been spun off from the internet draft entitled
"IP/MPLS-GMPLS interworking in support of IP/MPLS to GMPLS migration
<draft-oki-ccamp-gmpls-ip-interworking-06.txt>".
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This document provides a framework for IP/MPLS-GMPLS interworking in
support of IP/MPLS to GMPLS migration. Solutions for IP/MPLS-GMPLS
interworking in support of IP/MPLS to GMPLS migration will be
developed in companion documents.
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8. 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.
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 either fully MPLS or fully GMPLS, there are no
changes necessary to the security procedures.
9. IANA Considerations
This information framework document makes no requests for IANA action.
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10. Full Copyright Statement
Copyright (C) The Internet Society (2005).
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.
11. 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
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.
12. Acknowledgements
The authors are grateful to Daisaku Shimazaki for discussion during
initial work on this document.
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13. Authors' Addresses
Kohei Shiomoto
NTT
Midori 3-9-11
Musashino, Tokyo 180-8585, Japan
Phone: +81 422 59 4402
Email: shiomoto.kohei@lab.ntt.co.jp
Eiji Oki
NTT
Midori 3-9-11
Musashino, Tokyo 180-8585, Japan
Phone: +81 422 59 3441
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
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 R&D
av Pierre Marzin 22300
Lannion, France
Phone: +33 2 96 05 30 20
Email: jeanlouis.leroux@francetelecom.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
14. References
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14.1. 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.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description",
RFC 3471, January 2003.
14.2. Informative References
[MRN-REQ] Shiomoto, K., Papadimitriou, D., Le Roux, J.L.,
Vigoureux, M., Brungard, D., "Requirements for GMPLS-
based multi-region and multi-layer networks", draft-
shiomoto-ccamp-gmpls-mrn-reqs, work in progress.
[MRN-SOL] Papadimitriou, D., Vigoureux, M., Shiomoto, K.,
Brungard, D., Le Roux, J.L., "Generalized Multi-
Protocol Label Switching (GMPLS) Protocol Extensions
for Multi-Region Networks (MRN)", draft-
papadimitriou-ccamp-gmpls-mrn-extensions, work in
progress.
[MRN-EVAL] Le Roux, J.L., Brungard, D., Oki, E., Papadimitriou,
D., Shiomoto, K., Vigoureux, M.,"Evaluation of
existing GMPLS Protocols against Multi Layer and Multi
Region Networks (MLN/MRN)", draft-leroux-ccamp-gmpls-
mrn-eval, work in progress.
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