Internet Draft Dimitri Papadimitriou
Martin Vigoureux
Intended Status: Standards Track Alcatel-Lucent
Expiration Date: June 10 2010 Kohei Shiomoto
Creation Date: December 11 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-10.txt
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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.
Table of Contents
Abstract......................................................2
Table of Contents.............................................2
1. Introduction...............................................3
2. Summary of the Requirements and Evaluation.................4
3. Interface adjustment capability descriptor (IACD)..........5
3.1. Overview..............................................5
3.2. Interface Adjustment Capability Descriptor (IACD).....6
4. Multi-Region Signaling.....................................9
4.1. XRO Subobject Encoding...............................11
5. Virtual TE link...........................................12
5.1. Edge-to-edge Association.............................13
5.2. Soft Forwarding Adjacency (Soft FA)..................16
6. Backward Compatibility....................................18
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7. Security Considerations...................................18
8. IANA Considerations.......................................19
8.1 RSVP..................................................19
8.2 OSPF..................................................20
8.3 IS-IS.................................................21
9. References................................................21
9.1 Normative References..................................21
9.2 Informative References................................23
Acknowledgments..............................................23
Author's Addresses...........................................24
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],
[RFC4206], and [RFC5307].
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
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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 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
[RFC5212]. These requirements are evaluated against GMPLS
protocols in [RFC5339] 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 [RFC5339], 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 [RFC5339]:
o GMPLS routing extensions for the advertisement of the
internal adjustment capability of hybrid nodes. See Section
3.2.2 of [RFC5339].
o GMPLS signaling extensions for constrained multi-region
signaling (Switching Capability inclusion/exclusion). See
Section 3.2.1 of [RFC5339]. An additional eXclude Route
object (XRO) Label subobject is also defined since absent
from [RFC4874].
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 [RFC5339].
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o GMPLS routing and signaling extensions for graceful TE-link
deletion. See Section 3.1.1.3 of [RFC5339].
The first three requirements are addressed in Sections 3, 4,
and 5 of this document, respectively. The fourth requirement is
addressed in [GMPLS-RR] with additional context provided by
[GR-TELINK].
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 [RFC5212]. 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 theuse 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,
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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 the
information to take into account when performing multi-region
path computation. This concept enables a node to discriminate
the remote 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 capability of discriminating the
(internal) adjustment capability from the (interface) switching
capability by defining an Interface Adjustment Capability
Descriptor (IACD).
A more detailed problem statement can be found in [RFC5339].
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 [RFC4201], [RFC4203].
The receiving LSR uses its Link State Database to determine the
IACD(s) of the far-end of the link. Different Interface
Adjustment Capabilities at two ends of a TE link are allowed.
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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 associated to
the Lower Encoding field (byte 2). The value of the Lower
Switching Capability field MUST be set to the value of
Switching Capability of the ISCD sub-TLV advertized for
this TE Link. If multiple ISCD sub-TLVs are advertized
for that TE link, the Lower Switching Capability (SC)
value MUST be set to the value of SC to which the
adjustment capacity is associated.
Lower Encoding (byte 2) - 8 bits
Contains one of the LSP Encoding Type values specified
in Section 3.1.1 of [RFC3471] and updates.
Upper Switching Capability (SC) field (byte 3) - 8 bits
Indicates the Upper Switching capability. The Upper
Switching Capability field MUST be set to one of the
values defined in [RFC4202].
Upper Encoding (byte 4) - 8 bits
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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].
The bandwidth values provide an indication of the resources
still available to perform insertion/extraction for a given
adjustment at a given priority (resource pool concept: set of
shareable available resources that can be assigned
dynamically).
Multiple IACD sub-TLVs MAY be present within a given TE Link
TLV.
The presence of the IACD sub-TLV as part of the TE Link TLV
does not modify the format/messaging and the processing
associated to the ISCD sub-TLV defined in [RFC4203].
3.2.2 IS-IS
In IS-IS, the IACD sub-TLV is an optional sub-TLV of the
Extended IS Reachability TLV (see [RFC5305]) with Type 24 (to
be assigned by IANA).
The IACD sub-TLV format is defined as follows:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjustment Capability-specific information |
| (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields of the IACD sub-TLV have the same processing and
interpretation rules as defined in Section 3.2.1.
Multiple IACD sub-TLVs MAY be present within a given extended
IS reachability TLV.
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 sub-TLV defined in [RFC5307].
4. Multi-Region Signaling
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.
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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
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
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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. XRO 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. It also
complements the subobjects defined in [RFC4874] with a Label
subobject (Type 3).
4.1.1 SC Subobject Encoding
XRO Subobject Type 35: 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
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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.
The Switching Capability subobject 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).
4.1.2 Label Subobject Encoding
XRO Subobject Type 3: Label Subobject
The encoding of the Label XRO Subobject is identical to the
Label ERO Subobject defined in [RFC3473] with the exception of
the L bit. For the Label XRO Subobject, the L bit is defined
as:
L
0 indicates that the attribute specified MUST be
excluded.
1 indicates that the attribute specified SHOULD be
avoided.
Label subobjects MUST follow the numbered or unnumbered
interface sub-objects to which they refer, and, when present,
MUST also follow the Switching Capability sub-object.
When XRO label sub-objects are following the Switching
Capability sub-object, the corresponding label values MUST be
compatible 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 [RFC5212]. 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
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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 throughthe 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 the procedures
defined in [RFC4206] to make the virtual TE link "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.
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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.
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 //
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| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 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.
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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], [HIER-
BIS]) and numbered FA-LSPs ([RFC4206], [HIER-BIS]).
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 equivalent of the Null service type
specified in [RFC2997].
5.2.1 Pre-Planned LSP Flag
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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).
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Mechanisms for provisioning (pre-planned or not) LSP with 0
bandwidth 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
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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.
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]
Upon approval of this document, IANA is requested to establish
a "Call attributes TLV" registry. The following types should be
defined:
TLV Value Name Reference
--------- ----------------------- ---------
0 Reserved
1 Attributes Flags TLV
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The values should be allocated based on the following
allocation policy as defined in [RFC5226].
Range Registration Procedures
-------- ------------------------
0-32767 RFC
32768-65535 Private Use
Upon approval of this document, IANA is requested to establish
a "Call attributes flags" registry. The following flags should
be defined:
Bit Number 32-bit Value Name Reference
---------- ------------ --------------------- ---------
0 0x80000000 Call Inheritance Flag
1 0x40000000 Pre-Planned LSP Flag
The values should be allocated based on the RFC allocation
policy as defined in [RFC5226].
This document introduces two new subobjects for the
EXCLUDE_ROUTE object [RFC4874], C-Type 1.
Subobject Type Subobject Description
-------------- ---------------------
3 Label
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
----- -------------------------------------------------
25 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
---- ------------------------------------------------- ------
25 Interface Adjustment Capability Descriptor (IACD) Var.
9. References
9.1 Normative References
[RFC2205] Braden, R., et al., "Resource ReSerVation Protocol
(RSVP) -- Version 1 Functional Specification",
RFC 2205, September 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF
Integrated Services", RFC 2210, September 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2997] Bernet, Y., Smith, A., and B. Davie, "Specification
of the Null Service Type", RFC 2997, November 2000.
[RFC3471] Berger, L., et al., "Generalized Multi-Protocol
Label Switching (GMPLS) - Signaling Functional
Description", RFC 3471, January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[RFC3477] Kompella, K., and Y. Rekhter, "Signalling Unnumbered
Links in Resource ReSerVation Protocol - Traffic
Engineering (RSVP-TE)", RFC 3477, January 2003.
[RFC3630] Katz, D., et al., "Traffic Engineering (TE)
Extensions to OSPF Version 2," RFC 3630, September
2003.
[RFC3945] Mannie, E. and al., "Generalized Multi-Protocol
Label Switching (GMPLS) Architecture", RFC 3945,
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October 2004.
[RFC4201] Kompella, K., et al., "Link Bundling in MPLS Traffic
Engineering", RFC 4201, October 2005.
[RFC4202] Kompella, K., Ed., and Rekhter, Y. Ed., "Routing
Extensions in Support of Generalized MPLS", RFC
4202, October 2005.
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF
Extensions in Support of Generalized Multi-Protocol
Label Switching (GMPLS)", RFC 4203, October 2005.
[RFC4206] Kompella, K., and Rekhter, Y., "LSP Hierarchy with
Generalized MPLS TE", RFC4206, October 2005.
[RFC4306] Kaufman, C., Ed., "Internet Key Exchange (IKEv2)
Protocol", RFC 4306, December 2005.
[RFC4606] Mannie, E., and D. Papadimitriou, D., "Generalized
Multi-Protocol Label Switching (GMPLS) Extensions
for Synchronous Optical Network (SONET) and
Synchronous Digital Hierarchy (SDH) Control,
RFC 4606, August 2006.
[RFC5226] Narten, T., Alvestrand, H., "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26, RFC
5226, May 2008.
[RFC5305] Smit, H. and T. Li, "Intermediate System to
Intermediate System (IS-IS) Extensions for Traffic
Engineering (TE)", RFC 5305, October 2008.
[RFC5307] Kompella, K., Ed., and Y. Rekhter, Ed.,
"Intermediate System to Intermediate System (IS-IS)
Extensions in Support of Generalized Multi-Protocol
Label Switching (GMPLS)", RFC 5307, 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.
[RFC4874] Lee, C.Y., et al. "Exclude Routes - Extension to
RSVP-TE," RFC 4874, April 2007.
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[RFC4974] Papadimitriou, D., and Farrel, A., "Generalized MPLS
(GMPLS) RSVP-TE Signaling Extensions in support of
Calls," RFC 4974, August 2007.
9.2 Informative References
[GMPLS-RR] Berger, L., Papadimitriou, D., and JP. Vasseur,
"PathErr Message Triggered MPLS and GMPLS LSP
Reroute", draft-ietf-mpls-gmpls-lsp-reroute, Work
in progress.
[HIER-BIS] Shiomoto, K., and Farrel, A., "Procedures for
Dynamically Signaled Hierarchical Label Switched
Paths", draft-ietf-ccamp-lsp-hierarchy-bis, Work in
progress.
[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.
[MPLS-SEC] Fang, L. Ed., "Security Framework for MPLS and
GMPLS Networks", draft-ietf-mpls-mpls-and-gmpls-
security-framework, Work in progress.
[RFC5212] Shiomoto, K., et al., "Requirements for GMPLS-based
multi-region and multi-layer networks (MRN/MLN)",
RFC5212, July 2008.
[RFC5339] Leroux, J.-L., et al., "Evaluation of existing
GMPLS Protocols against Multi Region and Multi
Layer Networks (MRN/MLN)", RFC 5339, September
2008.
Acknowledgments
The authors would like to thank Mr. Wataru Imajuku for the
discussions on adjustment between regions.
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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
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
D. Papadimitriou Expires June 10, 2010 [Page 23]
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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
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