Network Working Group Dimitri Papadimitriou
Internet Draft Martin Vigoureux
Intended Status: Proposed Standard Alcatel-Lucent
Expiration Date: September 21, 2009 Kohei Shiomoto
Creation Date: March 22, 2009 NTT
Deborah Brungard
ATT
Jean-Louis Le Roux
France Telecom
Generalized Multi-Protocol Label Switching (GMPLS) Protocol
Extensions for Multi-Layer and Multi-Region Networks (MLN/MRN)
draft-ietf-ccamp-gmpls-mln-extensions-04.txt
Status of this Memo
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Abstract
There are specific requirements for the support of networks
comprising Label Switching Routers (LSR) participating in different
data plane switching layers controlled by a single Generalized Multi
Protocol Label Switching (GMPLS) control plane instance, referred to
as GMPLS Multi-Layer Networks/Multi-Region Networks (MLN/MRN).
This document defines extensions to GMPLS routing and signaling
protocols so as to support the operation of GMPLS Multi-Layer/Multi-
Region Networks. It covers the elements of a single GMPLS control
plane instance controlling multiple LSP regions or layers within a
single TE domain.
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Table of Content
1. Introduction................................................ 2
2. Summary of the Requirements and Evaluation.................. 3
3. Interface adjustment capability descriptor (IACD)........... 3
4. Multi-Region Signaling...................................... 6
5. Virtual TE link............................................. 8
6. Backward Compatibility...................................... 13
7. Security Considerations..................................... 13
8. IANA Considerations Sections................................ 13
9. References.................................................. 14
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 [RFC2119].
In addition the reader is assumed to be familiar with [RFC3945],
[RFC3471], [RFC4201], [RFC4202], [RFC4203], [RFC4205], and [RFC4206].
1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945]
extends MPLS to handle multiple switching technologies: packet
switching (PSC), layer-two switching (L2SC), TDM switching (TDM),
wavelength switching (LSC) and fiber switching (FSC). A GMPLS
switching type (PSC, TDM, etc.) describes the ability of a node to
forward data of a particular data plane technology, and uniquely
identifies a control plane Label Switched Path (LSP) region. LSP
Regions are defined in [RFC4206]. A network comprised of multiple
switching types (e.g. PSC and TDM) controlled by a single GMPLS
control plane instance is called a Multi-Region Network (MRN).
A data plane layer is a collection of network resources capable of
terminating and/or switching data traffic of a particular format.
For example, LSC, TDM VC-11 and TDM VC-4-64c represent three
different layers. A network comprising transport nodes participating
in different data plane switching layers controlled by a single GMPLS
control plane instance is called a Multi-Layer Network (MLN).
The applicability of GMPLS to multiple switching technologies
provides the unified control and operations for both LSP provisioning
and recovery. This document covers the elements of a single GMPLS
control plane instance controlling multiple layers within a given TE
domain. A TE domain is defined as group of Label Switching Routers
(LSR) that enforces a common TE policy. A Control Plane (CP) instance
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can serve one, two or more layers. Other possible approaches such as
having multiple CP instances serving disjoint sets of layers are
outside the scope of this document.
The next sections provide the procedural aspects in terms of routing
and signaling for such environments as well as the extensions
required to instrument GMPLS to provide the capabilities for MLM/MRN
unified control. The rationales and requirements for Multi-Layer/
Region networks are set forth in [MLN-REQ]. These requirements
are evaluated against GMPLS protocols in [MLN-EVAL] and several
areas where GMPLS protocol extensions are required are identified.
This document defines GMPLS routing and signaling extensions so as
to cover GMPLS MLN/MRN requirements.
2. Summary of the Requirements and Evaluation
As identified in [MLN-EVAL], most MLN/MRN requirements rely on
mechanisms and procedures (such as local procedures and policies, or
specific TE mechanisms and algorithms) that are outside the scope of
the GMPLS protocols, and thus do not require any GMPLS protocol
extensions.
Four areas for extensions of GMPLS protocols and procedures have been
identified in [MLN-EVAL]:
o GMPLS routing extensions for the advertisement of the internal
adjustment capability of hybrid nodes. See Section 3.2.2 of [MLN-
EVAL].
o GMPLS signaling extensions for constrained multi-region signaling
(Switching Capability inclusion/exclusion). See Section 3.2.1 of
[MLN-EVAL].
o GMPLS signaling extensions for the setup/deletion of Virtual TE-
links (as well as exact trigger for its actual provisioning). See
Section 3.1.1.2 of [MLN-EVAL].
o GMPLS routing and signaling extensions for graceful TE-link
deletion (covered in [GR-TELINK]). See Section 3.1.1.3 of [MLN-
EVAL].
The first three requirements are addressed in Sections 3, 4, and 5 of
this document, respectively. The fourth requirement is addressed in
[GR-TELINK]. Companion documents address GMPLS OAM (see [GMPLS OAM])
aspects that have been identified in [MLN-EVAL].
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3. Interface adjustment capability descriptor (IACD)
In the MRN context, nodes that have at least one interface that
supports more than one switching capability are called Hybrid nodes
[MLN-REQ]. The logical composition of a hybrid node contains at least
two distinct switching elements that are interconnected by "internal
links" to provide adjustment between the supported switching
capabilities. These internal links have finite capacities that must
be taken into account when computing the path of a multi-region
TE-LSP.
The advertisement of the internal adjustment capability is required
as it provides critical information when performing multi-region path
computation.
3.1 Overview
In an MRN environment, some LSRs could contain multiple switching
capabilities such as PSC and TDM, or PSC and LSC, all under the
control of a single GMPLS instance,
These nodes, hosting multiple Interface Switching Capabilities (ISC)
[RFC4202], are required to hold and advertise resource information on
link states and topology, just like other nodes (hosting a single
ISC). They may also have to consider some portions of internal node
resources use to terminate hierarchical LSPs, since in circuit-
switching technologies (such as TDM, LSC, and FSC) LSPs require the
use of resources allocated in a discrete manner (as pre-determined by
the switching type). For example, a node with PSC+LSC hierarchical
switching capability can switch a lambda LSP, but cannot terminate
the Lambda LSP if there is no available (i.e., not already in use)
adjustment capability between the LSC and the PSC switching
components. Another example occurs when L2SC (Ethernet) switching can
be adapted in LAPS X.86 and GFP for instance before reaching the TDM
switching matrix. Similar circumstances can occur, if a switching
fabric that supports both PSC and L2SC functionalities is assembled
with LSC interfaces enabling "lambda" encoding. In the switching
fabric, some interfaces can terminate Lambda LSPs and perform frame
(or cell) switching whilst other interfaces can terminate Lambda LSPs
and perform packet switching.
Therefore, within multi-region networks, the advertisement of the
so-called adjustment capability to terminate LSPs (not the interface
capability since the latter can be inferred from the bandwidth
available for each switching capability) provides critical
information to take into account when performing multi-region path
computation. This concept enables a node to discriminate the remote
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nodes (and thus allows their selection during path computation) with
respect to their adjustment capability e.g. to terminate LSPs at the
PSC or LSC level.
Hence, we introduce the idea of discriminating the (internal)
adjustment capability from the (interface) switching capability by
considering an Interface Adjustment Capability Descriptor (IACD).
A more detailed problem statement can be found in [MLN-EVAL].
3.2 Interface Adjustment Capability Descriptor (IACD)
The interface adjustment capability descriptor (IACD) provides the
information for the forwarding/switching) only capability.
Note that the addition of the IACD as a TE link attribute does not
modify the format of the Interface Switching Capability Descriptor
(ISCD) defined in [RFC4202], and does not change how the ISCD sub-
TLV is carried in the routing protocols or how it is processed
when it is received [RFC4203], [RFC4205].
3.2.1 OSPF
In OSPF, the IACD sub-TLV is defined as an optional sub-TLV of the TE
Link TLV (Type 2, see [RFC3630]), with Type 24 (to be assigned by
IANA) and variable length.
The IACD sub-TLV format is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lower SC |Lower Encoding | Upper SC |Upper Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 6 |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjustment Capability-specific information |
| (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Lower Switching Capability (SC) field (byte 1) - 8 bits
Indicates the lower switching capability for the lower
Encoding field (byte 2) as defined for the ISCD sub-TLV.
Lower Encoding (byte 2) - 8 bits
Contains one of the values specified in Section 3.1.1 of
[RFC3473] and updates.
Upper Switching Capability (SC) field (byte 3) - 8 bits
Indicates the upper switching capability.
Upper Encoding (byte 4) - 8 bits
Set to the encoding of the available adjustment capacity and to
0xFF when the corresponding SC value has no access to the wire,
i.e., there is no ISC sub-TLV for this upper switching
capability. The adjustment capacity is the set of resources
associated to the upper switching capability.
The Adjustment Capability-specific information - variable
This field is defined so as to leave the possibility for
future addition of technology-specific information associated
to the adjustment capability.
Other fields MUST be processed as specified in [RFC4202] and
[RFC4203].
Multiple IACD sub-TLVs MAY be present within a given TE Link TLV
and the bandwidth simply provides an indication of resources still
available to perform insertion/ extraction for a given adjustment
(pool concept).
The presence of the IACD sub-TLV as part of the TE Link TLV does not
modify format/messaging and processing associated to the ISCD defined
in [RFC4203].
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3.2.2 IS-IS
In IS-IS, the IACD sub-TLV is an optional sub-TLV of the Extended IS
Reachability TLV (see [RFC3784]) with Type 24 (to be assigned by
IANA).
The IACD sub-TLV format is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Switching Cap | Encoding | Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjustment Capability-specific information |
| (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where the fields have the same processing and interpretation rules as
for Section 3.2.1.
Multiple IACD sub-TLVs MAY be present within a given extended IS
reachability TLV and the bandwidth simply provides an indication of
resources still available to perform insertion/ extraction for a
given adjustment (pool concept).
The presence of the IACD sub-TLV as part of the extended IS
reachability TLV does not modify format/messaging and processing
associated to the ISCD defined in [RFC4205].
4. Multi-Region Signaling
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Section 6.2 of [RFC4206] specifies that when a region boundary node
receives a Path message, the node determines whether or not it is at
the edge of an LSP region with respect to the ERO carried in the
message. If the node is at the edge of a region, it must then
determine the other edge of the region with respect to the ERO,
using the IGP database. The node then extracts from the ERO the
sub-sequence of hops from itself to the other end of the region.
The node then compares the sub-sequence of hops with all existing FA-
LSPs originated by the node:
o If a match is found, that FA-LSP has enough unreserved bandwidth
for the LSP being signaled, and the G-PID of the FA-LSP is
compatible with the G-PID of the LSP being signaled, the node uses
that FA-LSP as follows. The Path message for the original LSP is
sent to the egress of the FA-LSP. The PHOP in the message is the
address of the node at the head-end of the FA-LSP. Before sending
the Path message, the ERO in that message is adjusted by removing
the subsequence of the ERO that lies in the FA-LSP, and replacing
it with just the end point of the FA-LSP.
o If no existing FA-LSP is found, the node sets up a new FA-LSP.
That is, it initiates a new LSP setup just for the FA-LSP.
Note: compatible G-PID implies that traffic can be processed by
both ends of the FA-LSP without dropping traffic after its
establishment.
Applying the procedure of [RFC4206], in a MRN environment MAY lead to
setup single-hop FA-LSPs between each pair of nodes. Therefore,
considering that the path computation is able to take into account
richness of information with regard to the SC available on given
nodes belonging to the path, it is consistent to provide enough
signaling information to indicate the SC to be used and over which
link. Particularly, in case a TE link has multiple SCs advertised as
part of its ISCD sub-TLVs, an ERO does not provide a mechanism to
select a particular SC.
In order to limit the modifications to existing RSVP-TE procedures
([RFC3473] and referenced), this document defines a new sub-object of
the eXclude Route Object (XRO), see [RFC4874], called the Switching
Capability sub-object. This sub-object enables (when desired) the
explicit identification of at least one switching capability to be
excluded from the resource selection process described above.
Including this sub-object as part of the XRO that explicitly
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indicates which SCs have to be excluded (before initiating the
procedure described here above) over a specified TE link, solves the
ambiguous choice among SCs that are potentially used along a given
path and give the possibility to optimize resource usage on a multi-
region basis. Note that implicit SC inclusion is easily supported by
explicitly excluding other SCs (e.g. to include LSC, it is required
to exclude PSC, L2SC, TDM and FSC).
The approach followed here is to concentrate exclusions in XRO and
inclusions in ERO. Indeed, the ERO specifies the topological
characteristics of the path to be signaled. Usage of EXRS subobjects
would also lead in the exclusion over certain portions of the LSP
during the FA-LSP setup. Thus, it is more suited to extend generality
of the elements to the excluded in the XRO but also prevent complex
consistency checks but also transpositions between EXRS and XRO at
FA-LSP head-ends.
4.1 SC Subobject Encoding
The contents of an EXCLUDE_ROUTE object defined in [RFC4874] are a
series of variable-length data items called subobjects. This document
defines the Switching Capability (SC) subobject of the XRO (Type 35),
its encoding and processing.
Subobject Type TBD: Switching Capability
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Attribute | Switching Cap |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L
0 indicates that the attribute specified MUST be excluded
1 indicates that the attribute specified SHOULD be avoided
Attribute
0 reserved value
1 indicates that the specified SC should be excluded or
avoided with respect to the preceding numbered (Type 1 or
Type 2) or unnumbered interface (Type) subobject
Switching Cap (8-bits)
Switching Capability value to be excluded.
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This sub-object must follow the set of one or more numbered or
unnumbered interface sub-objects to which this sub-object refers. In
case, of loose hop ERO subobject, the XRO sub-object must precede the
loose-hop sub-object identifying the tail-end node/interface of the
traversed region(s).
Furthermore, it is expected, when label sub-object are following
numbered or unnumbered interface sub-objects, that the label value is
compliant with the SC capability to be explicitly excluded.
5. Virtual TE link
A virtual TE link is defined as a TE link between two upper layer
nodes that is not associated with a fully provisioned FA-LSP in a
lower layer [MLN-REQ]. A virtual TE link is advertised as any TE
link, following the rules in [RFC4206] defined for fully provisioned
TE links. A virtual TE link represents thus the potentiality to setup
an FA-LSP in the lower layer to support the TE link that has been
advertised. In particular, the flooding scope of a virtual TE link is
within an IGP area, as is the case for any TE link.
Two techniques can be used for the setup, operation, and maintenance
of virtual TE links. The corresponding GMPLS protocols extensions are
described in this section. The procedures described in this section
complement those defined in [RFC4206] and [HIER-BIS].
5.1 Edge-to-edge Association
This approach, that does not require state maintenance on transit
LSRs, relies on extensions to the GMPLS RSVP-TE Call procedure (see
[RFC4974]).
This technique consists of exchanging identification and TE
attributes information directly between TE link end points through
the establishment of a call between terminating LSRs. These TE link
end-points correspond to the LSP head-end and tail-end points of the
LSPs that will be established. The end-points MUST belong to the same
(LSP) region.
Once the call is established the resulting association populates the
local Traffic Engineering DataBase (TEDB) and the resulting virtual
TE link is advertised as any other TE link. The latter can then be
used to attract traffic. When an upper layer/region LSP tries to make
use of this virtual TE link, one or more FA LSPs MUST be established
using procedures defined in [RFC4206] to make the virtual TE link
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"real" and allow it to carry traffic by nesting the upper
layer/region LSP.
In order to distinguish usage of such call from the call and
associated procedures defined in [RFC4974], a CALL ATTRIBUTES object
is introduced.
5.1.1 CALL_ATTRIBUTES Object
The CALL_ATTRIBUTES object is used to signal attributes required in
support of a call, or to indicate the nature or use of a call. It is
modeled on the LSP-ATTRIBUTES object defined in [RFC5420]. The
CALL_ATTRIBUTES object may also be used to report call operational
state on a Notify message.
The CALL_ATTRIBUTES object class is 201 (TBD by IANA) of the form
11bbbbbb. This C-Num value (see [RFC2205], Section 3.10) ensures that
LSRs that do not recognize the object pass it on transparently.
One C-Type is defined, C-Type = 1 for CALL Attributes. This object is
OPTIONAL and MAY be placed on Notify messages to convey additional
information about the desired attributes of the call.
CALL_ATTRIBUTES class = 201, C-Type = 1
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attributes TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Attributes TLVs are encoded as described in Section 5.1.3.
5.1.2 Processing
If an egress (or intermediate) LSR does not support the object, it
forwards it unexamined and unchanged. This facilitates the exchange
of attributes across legacy networks that do not support this new
object.
5.1.3 Attributes TLVs
Attributes carried by the CALL_ATTRIBUTES object are encoded within
TLVs. One or more TLVs MAY be present in each object.
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There are no ordering rules for TLVs, and no interpretation should be
placed on the order in which TLVs are received.
Each TLV is encoded as follows.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Value //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
The identifier of the TLV.
Length
Indicates the total length of the TLV in octets. That is, the
combined length of the Type, Length, and Value fields, i.e.,
four plus the length of the Value field in octets.
The entire TLV MUST be padded with between zero and three
trailing zeros to make it four-octet aligned. The Length field
does not count any padding.
Value
The data field for the TLV padded as described above.
5.1.4 Attributes Flags TLV
The TLV Type 1 indicates the Attributes Flags TLV. Other TLV types
MAY be defined in the future with type values assigned by IANA (see
Section 8). The Attributes Flags TLV may be present in a
CALL_ATTRIBUTES object.
The Attribute Flags TLV value field is an array of units of 32 flags
numbered from the most significant bit as bit zero. The Length field
for this TLV is therefore always a multiple of 4 bytes, regardless of
the number of bits carried and no padding is required.
Unassigned bits are considered as reserved and MUST be set to zero on
transmission by the originator of the object. Bits not contained in
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the TLV MUST be assumed to be set to zero. If the TLV is absent
either because it is not contained in the CALL_ATTRIBUTES object or
because this object is itself absent, all processing MUST be
performed as though the bits were present and set to zero. That is to
say, assigned bits that are not present either because the TLV is
deliberately foreshortened or because the TLV is not included MUST be
treated as though they are present and are set to zero.
5.1.5 Call Inheritance Flag
This document introduces a specific flag (most significant bit (msb)
position bit 0) of the Attributes Flags TLV, to indicate that the
association initiated between the end-points belonging to a call
results into a (virtual) TE link advertisement.
The Call Inheritance Flag MUST be set to 1 in order to indicate that
the established association is to be translated into a TE link
advertisement. The value of this flag SHALL by default be set to 1.
Setting this flag to 0 results in a hidden TE link or in deleting the
corresponding TE link advertisement (by setting the corresponding
Opaque LSA Age to MaxAge) if the association had been established
with this flag set to 1. In the latter case, the corresponding FA-LSP
SHOULD also be torn down to prevent unused resources.
The Notify message used for establishing the association is defined
as per [RFC4974]. Additionally, the Notify message must carry an
LSP_TUNNEL_INTERFACE_ID Object, that allows identifying unnumbered
FA-LSPs ([RFC3477], [RFC4206]) and numbered FA-LSPs ([RFC4206]).
5.2. Soft Forwarding Adjacency (Soft FA)
The Soft Forwarding Adjacency (Soft FA) approach consists of setting
up the FA LSP at the control plane level without actually committing
resources in the data plane. This means that the corresponding LSP
exists only in the control plane domain. Once such FA is established
the corresponding TE link can be advertised following the procedures
described in [RFC4206].
There are two techniques to setup Soft FAs:
o The first one consists in setting up the FA LSP by precluding
resource commitment during its establishment. These are known as
pre-planned LSPs.
o The second technique consists in making use of path provisioned
LSPs only. In this case, there is no associated resource demand
during the LSP establishment. This can be considered as the RSVP-TE
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equivalent of the Null service type specified in [RFC2997].
5.2.1 Pre-Planned LSP Flag
The LSP ATTRIBUTES object and Attributes Flags TLV are defined in
[RFC5420]. The present document defines a new flag, the Pre-Planned
LSP flag, in the existing Attributes Flags TLV (numbered as Type 1).
The position of this flag is TBD in accordance with IANA assignment.
This flag, part of the Attributes Flags TLV, follows general
processing of [RFC5420] for LSP_REQUIRED_ATTRIBUTE object. That is,
LSRs that do not recognize the object reject the LSP setup
effectively saying that they do not support the attributes requested.
Indeed, the newly defined attribute requires examination at all
transit LSRs along the LSP being established.
The Pre-Planned LSP flag can take one of the following values:
o When set to 0 this means that the LSP MUST be fully provisioned.
Absence of this flag (hence corresponding TLV) is therefore
compliant with the signaling message processing per [RFC3473])
o When set to 1 this means that the LSP MUST be provisioned in the
control plane only.
If an LSP is established with the Pre-Planned flag set to 1, no
resources are committed at the data plane level.
The operation of committing data plane resources occurs by re-
signaling the same LSP with the Pre-Planned flag set to 0. It is
RECOMMENDED that no other modifications are made to other RSVP
objects during this operation. That is each intermediate node,
processing a flag transiting from 1 to 0 shall only be concerned with
the commitment of data plane resources and no other modification of
the LSP properties and/or attributes.
If an LSP is established with the Pre-Planned flag set to 0, it MAY
be re-signaled by setting the flag to 1.
5.2.2 Path Provisioned LSPs
There is a difference in between an LSP that is established with 0
bandwidth (path provisioning) and an LSP that is established with a
certain bandwidth value not committed at the data plane level (i.e.
pre-planned LSP).
Mechanisms for provisioning (pre-planned or not) LSP with 0 bandwidth
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is straightforward for PSC the SENDER_TSPEC/FLOWSPEC, the Peak Data
Rate field of Int-Serv objects, see [RFC2210], is set to 0. For L2SC
LSP, the CIR, EIR, CBS, and EBS must be set of 0 in the Type 2 sub-
TLV of the Ethernet Bandwidth Profile TLV. In these cases, upon LSP
resource commitment, actual traffic parameter values are used to
perform corresponding resource reservation.
However, mechanisms for provisioning (pre-planned or not) TDM or LSC
LSP with 0 bandwidth is currently not possible because the exchanged
label value is tightly coupled with resource allocation during LSP
signaling (see e.g. [RFC4606] for SDH/SONET LSP). For TDM and LSC
LSP, a NULL Label value is used to prevent resource allocation at the
data plane level. In these cases, upon LSP resource commitment,
actual label value exchange is performed to commit allocation of
timeslots/wavelengths.
6. Backward Compatibility
New objects and procedures defined in this document are running
within a given TE domain, defined as group of LSRs that enforces a
common TE policy. Thus, the extensions defined in this document are
expected to run in the context of a consistent TE policy.
Specification of a consistent TE policy is outside the scope of this
document.
In such TE domains, we distinguish between edge LSRs and intermediate
LSRs. Edge LSRs must be able to process Call Attribute as defined in
Section 5.1 if this is the method selected for creating edge-to-edge
associations. In that domain, intermediate LSRs are by definition
transparent to the Call processing.
In case the Soft FA method is used for the creation of virtual TE
links, edge and intermediate LSRs must support processing of the LSP
ATTRIBUTE object per Section 5.2.
7. Security Considerations
This document does not introduce any new security consideration from
the ones already detailed in [MPLS-SEC] that describes the MPLS and
GMPLS security threats, the related defensive techniques, and the
mechanisms for detection and reporting. Indeed, the applicability of
the proposed GMPLS extensions is limited to single TE domain. Such a
domain is under the authority of a single administrative entity. In
this context, multiple switching layers comprised within such TE
domain are under the control of a single GMPLS control plane
instance.
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Nevertheless, Call initiation, as depicted in section 5.1, MUST
strictly remain under control of the TE domain administrator. To
prevent any abuse of Call setup, edge nodes MUST ensure isolation of
their call controller (i.e. the latter is not reachable via external
TE domains). To further prevent man-in-the-middle attack, security
associations MUST be established between edge nodes initiating and
terminating calls. For this purpose, IKE [RFC4306] MUST be used for
performing mutual authentication and establishing and maintaining
these security associations.
8. IANA Considerations
8.1 RSVP
IANA has made the following assignments in the "Class Names, Class
Numbers, and Class Types" section of the "RSVP PARAMETERS" registry
located at http://www.iana.org/assignments/rsvp-parameters.
This document introduces a new class named CALL_ATTRIBUTES has been
created in the 11bbbbbb range (201) with the following definition:
Class Number Class Name Reference
------------ ----------------------- ---------
201 CALL ATTRIBUTES [This I-D]
Class Type (C-Type):
1 Call Attributes [This.I-D]
This document introduces a new subobject for the EXCLUDE_ROUTE object
[RFC4874], C-Type 1.
Subobject Type Subobject Description
-------------- ---------------------
35 Switching Capability (SC)
8.2 OSPF
IANA maintains Open Shortest Path First (OSPF) Traffic Engineering
TLVs Registries included below for Top level Types in TE LSAs and
Types for sub-TLVs of TE Link TLV (Value 2).
This document defines the following sub-TLV of TE Link TLV (Value 2)
Value Sub-TLV
----- -------------------------------------------------
24 Interface Adjustment Capability Descriptor (IACD)
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8.3 IS-IS
This document defines the following new sub-TLV type of top-level TLV
22 that need to be reflected in the ISIS sub-TLV registry for TLV 22:
Type Description Length
---- ------------------------------------------------- ------
24 Interface Adjustment Capability Descriptor (IACD) Variable
9. References
9.1 Normative References
[HIER-BIS] Shiomoto, K., and Farrel, A., "Procedures for Dynamically
Signaled Hierarchical Label Switched Paths", draft-ietf
ccamp-lsp-hierarchy-bis, Work in progress.
[RFC2205] Braden, R., et al., "Resource ReSerVation Protocol
(RSVP) -- Version 1 Functional Specification",
RFC2205, September 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF
Integrated Services", RFC2210, September 1997.
[RFC3471] Berger, L., et al., "Generalized Multi-Protocol Label
Switching (GMPLS) - Signaling Functional Description",
RFC3471, January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC3473, January 2003.
[RFC3630] Katz, D., et al., "Traffic Engineering (TE) Extensions to
OSPF Version 2," RFC3630, September 2003.
[RFC3784] Smit, H. and T. Li, "Intermediate System to
Intermediate System (IS-IS) Extensions for Traffic
Engineering (TE)", RFC3784, June 2004.
[RFC3945] Mannie, E. and al., "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC3945, October 2004.
[RFC4201] Kompella, K., et al., "Link Bundling in MPLS Traffic
Engineering", RFC4201, October 2005.
D. Papadimitriou Expires September 21, 2009 [Page 17]
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[RFC4202] Kompella, K., Ed., and Rekhter, Y. Ed., "Routing
Extensions in Support of Generalized MPLS", RFC4202,
October 2005.
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC4203, October 2005.
[RFC4205] Kompella, K., Ed., and Y. Rekhter, Ed., "Intermediate
System to Intermediate System (IS-IS) Extensions in
Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC4205, October 2005.
[RFC4206] Kompella, K., and Rekhter, Y., "LSP Hierarchy with
Generalized MPLS TE", RFC4206, October 2005.
[RFC5420] Farrel, A., et al., "Encoding of Attributes for
Multiprotocol Label Switching (MPLS) Label Switched Path
(LSP) Establishment Using Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE)", RFC 5420, February 2009.
[RFC4428] Papadimitriou, D., et al. "Analysis of Generalized Multi-
Protocol Label Switching (GMPLS)-based Recovery
Mechanisms (including Protection and Restoration)",
RFC4428, March 2006.
[RFC4874] Lee, C.Y., et al. "Exclude Routes - Extension to RSVP-TE,"
RFC4874, April 2007.
[RFC4974] Papadimitriou, D., and Farrel, A., "Generalized MPLS
(GMPLS) RSVP-TE Signaling Extensions in support of Calls,"
RFC4974, August 2007.
9.2 Informative References
[GR-TELINK] Ali, Z., et al., "Graceful Shutdown in MPLS and
Generalized MPLS Traffic Engineering Networks", draft-
ietf-ccamp-mpls-graceful-shutdown, Work in progress.
[MLN-EVAL] Leroux, J.-L., et al., "Evaluation of existing GMPLS
Protocols against Multi Region and Multi Layer Networks
(MRN/MLN)", RFC 5339, September 2008.
[MLN-REQ] Shiomoto, K., et al., "Requirements for GMPLS-based
multi-region and multi-layer networks (MRN/MLN)",
RFC5212, July 2008.
D. Papadimitriou Expires September 21, 2009 [Page 18]
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[MPLS-SEC] Fang, L. Ed., "Security Framework for MPLS and GMPLS
Networks", draft-ietf-mpls-mpls-and-gmpls-security-
framework-03.txt, Work in progress.
[MLRT] Imajuku, W., et al., "Multilayer routing using multilayer
switch capable LSRs", draft-imajuku-ml-routing-02.txt,
Work in Progress.
Acknowledgments
The authors would like to thank Mr. Wataru Imajuku for the
discussions on adjustment between regions [MLRT].
Author's Addresses
Dimitri Papadimitriou
Alcatel-Lucent Bell
Copernicuslaan 50
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
E-mail: dimitri.papadimitriou@alcatel-lucent.be
Martin Vigoureux
Alcatel-Lucent
Route de Villejust
91620 Nozay, France
Tel : +33 1 30 77 26 69
Email: martin.vigoureux@alcatel-lucent.fr
Kohei Shiomoto
NTT
3-9-11 Midori-cho
Musashino-shi, Tokyo 180-8585, Japan
Phone: +81 422 59 4402
Email: shiomoto.kohei@lab.ntt.co.jp
Deborah Brungard
ATT
Rm. D1-3C22 - 200 S. Laurel Ave.
Middletown, NJ 07748, USA
Phone: +1 732 420 1573
Email: dbrungard@att.com
Jean-Louis Le Roux
France Telecom
Avenue Pierre Marzin
22300 Lannion, France
D. Papadimitriou Expires September 21, 2009 [Page 19]
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Phone: +33 (0)2 96 05 30 20
Email: jean-louis.leroux@rd.francetelecom.com
Contributors
Eiji Oki
NTT Network Service Systems Laboratories
3-9-11 Midori-cho
Musashino-shi, Tokyo 180-8585, Japan
Phone : +81 422 59 3441
Email: oki.eiji@lab.ntt.co.jp
Ichiro Inoue
NTT Network Service Systems Laboratories
3-9-11 Midori-cho
Musashino-shi, Tokyo 180-8585, Japan
Phone : +81 422 59 6076
Email: ichiro.inoue@lab.ntt.co.jp
Emmanuel Dotaro
Alcatel-Lucent France
Route de Villejust
91620 Nozay, France
Phone : +33 1 6963 4723
Email: emmanuel.dotaro@alcatel-lucent.fr
Gert Grammel
Alcatel-Lucent SEL
Lorenzstrasse, 10
70435 Stuttgart, Germany
Email: gert.grammel@alcatel-lucent.de
D. Papadimitriou Expires September 21, 2009 [Page 20]
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D. Papadimitriou Expires September 21, 2009 [Page 22]