Internet Engineering Task Force (IETF) G. Bernstein, Ed.

Internet Engineering Task Force (IETF) G. Bernstein, Ed.
Request for Comments: 7579 Grotto Networking
Category: Standards Track Y. Lee, Ed.
ISSN: 2070-1721 D. Li
Huawei
W. Imajuku
NTT
J. Han
Huawei
June 2015

General Network Element Constraint Encoding
for GMPLS-Controlled Networks

Abstract

Generalized Multiprotocol Label Switching (GMPLS) can be used to
control a wide variety of technologies. In some of these
technologies, network elements and links may impose additional
routing constraints such as asymmetric switch connectivity, non-local
label assignment, and label range limitations on links.

This document provides efficient, protocol-agnostic encodings for
general information elements representing connectivity and label
constraints as well as label availability. It is intended that
protocol-specific documents will reference this memo to describe how
information is carried for specific uses.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7579.

Bernstein, et al. Standards Track [Page 1]

RFC 7579 General Network Element Constraint Encoding June 2015

Copyright Notice

Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction ....................................................3
1.1. Node Switching Asymmetry Constraints .......................3
1.2. Non-local Label Assignment Constraints .....................4
1.3. Conventions Used in This Document ..........................4
2. Encoding ........................................................4
2.1. Connectivity Matrix Field ..................................5
2.2. Port Label Restrictions Field ..............................6
2.2.1. SIMPLE_LABEL ........................................8
2.2.2. CHANNEL_COUNT .......................................8
2.2.3. LABEL_RANGE .........................................9
2.2.4. SIMPLE_LABEL & CHANNEL_COUNT ........................9
2.2.5. LINK_LABEL_EXCLUSIVITY .............................10
2.3. Link Set Field ............................................10
2.4. Available Labels Field ....................................12
2.5. Shared Backup Labels Field ................................13
2.6. Label Set Field ...........................................14
3. Security Considerations ........................................16
4. IANA Considerations ............................................17
5. References .....................................................17
5.1. Normative References ......................................17
5.2. Informative References ....................................18
Appendix A. Encoding Examples .....................................19
A.1. Link Set Field ............................................19
A.2. Label Set Field ...........................................19
A.3. Connectivity Matrix .......................................20
A.4. Connectivity Matrix with Bidirectional Symmetry ...........24
A.5. Priority Flags in Available/Shared Backup Labels ..........26
Contributors ......................................................27
Authors' Addresses ................................................28

Bernstein, et al. Standards Track [Page 2]

RFC 7579 General Network Element Constraint Encoding June 2015

1. Introduction

Some data-plane technologies that wish to make use of a GMPLS control
plane contain additional constraints on switching capability and
label assignment. In addition, some of these technologies must
perform non-local label assignment based on the nature of the
technology, e.g., wavelength continuity constraint in Wavelength
Switched Optical Networks (WSONs) [RFC6163]. Such constraints can
lead to the requirement for link-by-link label availability in path
computation and label assignment.

This document provides efficient encodings of information needed by
the routing and label assignment process in technologies such as WSON
and are potentially applicable to a wider range of technologies.
Such encodings can be used to extend GMPLS signaling and routing
protocols. In addition, these encodings could be used by other
mechanisms to convey this same information to a path computation
element (PCE).

1.1. Node Switching Asymmetry Constraints

For some network elements, the ability of a signal or packet on a
particular input port to reach a particular output port may be
limited. Additionally, in some network elements (e.g., a simple
multiplexer), the connectivity between some input and output ports
may be fixed. To take into account such constraints during path
computation, we model this aspect of a network element via a
connectivity matrix.

The connectivity matrix (ConnectivityMatrix) represents either the
potential connectivity matrix for asymmetric switches or fixed
connectivity for an asymmetric device such as a multiplexer. Note
that this matrix does not represent any particular internal blocking
behavior but indicates which input ports and labels (e.g.,
wavelengths) could possibly be connected to a particular output port
and label pair. Representing internal state-dependent blocking for a
node is beyond the scope of this document and, due to its highly
implementation-dependent nature, would most likely not be subject to
standardization in the future. The connectivity matrix is a
conceptual M*m by N*n matrix where M represents the number of input
ports (each with m labels) and N the number of output ports (each
with n labels).

Bernstein, et al. Standards Track [Page 3]

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1.2. Non-local Label Assignment Constraints

If the nature of the equipment involved in a network results in a
requirement for non-local label assignment, we can have constraints
based on limits imposed by the ports themselves and those that are
implied by the current label usage. Note that constraints such as
these only become important when label assignment has a non-local
character. For example, in MPLS, an LSR may have a limited range of
labels available for use on an output port and a set of labels
already in use on that port; these are therefore unavailable for use.
This information, however, does not need to be shared unless there is
some limitation on the LSR's label swapping ability. For example, if
a Time Division Multiplexer (TDM) node lacks the ability to perform
time-slot interchange or a WSON lacks the ability to perform
wavelength conversion, then the label assignment process is not local
to a single node. In this case, it may be advantageous to share the
label assignment constraint information for use in path computation.

Port label restrictions (PortLabelRestriction) model the label
restrictions that the network element (node) and link may impose on a
port. These restrictions tell us what labels may or may not be used
on a link and are intended to be relatively static. More dynamic
information is contained in the information on available labels.
Port label restrictions are specified relative to the port in general
or to a specific connectivity matrix for increased modeling
flexibility. [Switch] gives an example where both switch and fixed
connectivity matrices are used and both types of constraints occur on
the same port.

1.3. 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].

2. Encoding

This section provides encodings for the information elements defined
in [RFC7446] that have applicability to WSON. The encodings are
designed to be suitable for use in the GMPLS routing protocols OSPF
[RFC4203] and IS-IS [RFC5307] and in the PCE Communication Protocol
(PCEP) [RFC5440]. Note that the information distributed in [RFC4203]
and [RFC5307] is arranged via the nesting of sub-TLVs within TLVs;
this document defines elements to be used within such constructs.
Specific constructs of sub-TLVs and the nesting of sub-TLVs of the
information element defined by this document will be defined in the
respective protocol enhancement documents.

Bernstein, et al. Standards Track [Page 4]

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2.1. Connectivity Matrix Field

The Connectivity Matrix Field represents how input ports are
connected to output ports for network elements. The switch and fixed
connectivity matrices can be compactly represented in terms of a
minimal list of input and output port set pairs that have mutual
connectivity. As described in [Switch], such a minimal list
representation leads naturally to a graph representation for path
computation purposes; this representation involves the fewest
additional nodes and links.

The Connectivity Matrix Field is uniquely identified only by the
advertising node. There may be more than one Connectivity Matrix
Field associated with a node as a node can partition the switch
matrix into several sub-matrices. This partitioning is primarily to
limit the size of any individual information element used to
represent the matrix and to enable incremental updates. When the
matrix is partitioned into sub-matrices, each sub-matrix will be
mutually exclusive to one another in representing which ports/labels
are associated with each sub-matrix. This implies that two matrices
will not have the same {src port, src label, dst port, dst label}.

Each sub-matrix is identified via a different Matrix ID that MUST
represent a unique combination of {src port, src label, dst port, dst
label}.

A TLV encoding of this list of link set pairs is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Conn | MatrixID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Set A #1 |
: : :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Set B #1 :
: : :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Link Set Pairs as Needed |
: to Specify Connectivity :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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Where:

Connectivity (Conn) (4 bits) is the device type.

0 - the device is fixed

1 - the device is switched (e.g., Reconfigurable Optical Add/Drop
Multiplexer / Optical Cross-Connect (ROADM/OXC))

MatrixID represents the ID of the connectivity matrix and is an 8-bit
integer. The value of 0xFF is reserved for use with port label
constraints and should not be used to identify a connectivity matrix.

Link Set A #1 and Link Set B #1 together represent a pair of link
sets. See Section 2.3 for a detailed description of the Link Set
Field. There are two permitted combinations for the Link Set Field
parameter "dir" for link set A and B pairs:

o Link Set A dir=input, Link Set B dir=output

In this case, the meaning of the pair of link sets A and B is that
any signal that inputs a link in set A can be potentially switched
out of an output link in set B.

o Link Set A dir=bidirectional, Link Set B dir=bidirectional

In this case, the meaning of the pair of link sets A and B is that
any signal that inputs on the links in set A can potentially
output on a link in set B and any input signal on the links in set
B can potentially output on a link in set A. If link set A is an
input and link set B is an output for a signal, then it implies
that link set A is an output and link set B is an input for that
signal.

See Appendix A for both types of encodings as applied to a ROADM
example.

2.2. Port Label Restrictions Field

The Port Label Restrictions Field tells us what labels may or may not
be used on a link.

The port label restrictions can be encoded as follows. More than one
of these fields may be needed to fully specify a complex port
constraint. When more than one of these fields is present, the
resulting restriction is the union of the restrictions expressed in

Bernstein, et al. Standards Track [Page 6]

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each field. The use of the reserved value of 0xFF for the MatrixID
indicates that a restriction applies to the port and not to a
specific connectivity matrix.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MatrixID | RstType | Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Additional Restriction Parameters per Restriction Type |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where:

MatrixID: either is the value in the corresponding Connectivity
Matrix Field or takes the value 0xFF to indicate the restriction
applies to the port regardless of any connectivity matrix.

RstType (Restriction Type) can take the following values and
meanings:

0: SIMPLE_LABEL (Simple label selective restriction). See
Section 2.2.1 for details.

1: CHANNEL_COUNT (Channel count restriction). See Section 2.2.2
for details.

2: LABEL_RANGE (Label range device with a movable center label and
width). See Section 2.2.3 for details.

3: SIMPLE_LABEL & CHANNEL_COUNT (Combination of SIMPLE_LABEL and
CHANNEL_COUNT restriction. The accompanying label set and
channel count indicate labels permitted on the port and the
maximum number of channels that can be simultaneously used on
the port). See Section 2.2.4 for details.

4: LINK_LABEL_EXCLUSIVITY (A label may be used at most once
amongst a set of specified ports). See Section 2.2.5 for
details.

Switching Cap (Switching Capability) is defined in [RFC4203], and LSP
Encoding Type is defined in [RFC3471]. The combination of these
fields defines the type of labels used in specifying the port label
restrictions as well as the interface type to which these
restrictions apply.

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The Additional Restriction Parameters per RestrictionType field is an
optional field that describes additional restriction parameters for
each RestrictionType pertaining to specific protocols.

2.2.1. SIMPLE_LABEL

In the case of SIMPLE_LABEL, the format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MatrixID | RstType = 0 | Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In this case, the accompanying label set indicates the labels
permitted on the port/matrix.

See Section 2.6 for the definition of label set.

2.2.2. CHANNEL_COUNT

In the case of CHANNEL_COUNT, the format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MatrixID | RstType = 1 |Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MaxNumChannels |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In this case, the accompanying MaxNumChannels indicates the maximum
number of channels (labels) that can be simultaneously used on the
port/matrix.

MaxNumChannels is a 32-bit integer.

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2.2.3. LABEL_RANGE

In the case of LABEL_RANGE, the format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MatrixID | RstType = 2 | Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MaxLabelRange |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

This is a generalization of the waveband device. The MaxLabelRange
indicates the maximum width of the waveband in terms of the channels
spacing given in the Label Set Field. The corresponding label set is
used to indicate the overall tuning range.

MaxLabelRange is a 32-bit integer.

See Section 2.6.2 for an explanation of label range.

2.2.4. SIMPLE_LABEL & CHANNEL_COUNT

In the case of SIMPLE_LABEL & CHANNEL_COUNT, the format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MatrixID | RstType = 3 | Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MaxNumChannels |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In this case, the accompanying label set and MaxNumChannels indicate
labels permitted on the port and the maximum number of labels that
can be simultaneously used on the port.

See Section 2.6 for the definition of label set.

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2.2.5. LINK_LABEL_EXCLUSIVITY

In the case of Link Label Exclusivity, the format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MatrixID | RstType = 4 | Switching Cap | Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Set Field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In this case, the accompanying link set indicates that a label may be
used at most once among the ports in the Link Set Field.

See Section 2.3 for the definition of link set.

2.3. Link Set Field

We will frequently need to describe properties of groups of links.
To do so efficiently, we can make use of a link set concept similar
to the label set concept of [RFC3471]. The Link Set Field is used in
the <ConnectivityMatrix>, which is defined in Section 2.1. The
information carried in a link set 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action |Dir| Format | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: : :
: : :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Identifier N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Action: 8 bits

0 - Inclusive List

Indicates that one or more link identifiers are included in
the link set. Each identifies a separate link that is part of
the set.

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1 - Inclusive Range

Indicates that the link set defines a range of links. It
contains two link identifiers. The first identifier indicates
the start of the range. The second identifier indicates the
end of the range. All links with numeric values between the
bounds are considered to be part of the set. A value of zero
in either position indicates that there is no bound on the
corresponding portion of the range. Note that the Action
field can be set to 0x01 (Inclusive Range) only when the
identifier for unnumbered link is used.

Dir: Directionality of the link set (2 bits)

0 - bidirectional

1 - input

2 - output

In optical networks, we think in terms of unidirectional and
bidirectional links. For example, label restrictions or
connectivity may be different for an input port than for its
"companion" output port, if one exists. Note that "interfaces"
such as those discussed in the Interfaces MIB [RFC2863] are
assumed to be bidirectional. This also applies to the links
advertised in various link state routing protocols.

Format: The format of the link identifier (6 bits)

0 - Link Local Identifier

Indicates that the links in the link set are identified by
link local identifiers. All link local identifiers are
supplied in the context of the advertising node.

1 - Local Interface IPv4 Address

Indicates that the links in the link set are identified by
Local Interface IPv4 Address.

2 - Local Interface IPv6 Address

Indicates that the links in the link set are identified by
Local Interface IPv6 Address.

Others - Reserved for future use

Bernstein, et al. Standards Track [Page 11]

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Note that all link identifiers in the same list must be of the
same type.

Length: 16 bits

This field indicates the total length in bytes of the Link Set
Field.

Link Identifier: length is dependent on the link format

The link identifier represents the port that is being described
either for connectivity or for label restrictions. This can be
the link local identifier of GMPLS routing [RFC4202], GMPLS OSPF
routing [RFC4203], and IS-IS GMPLS routing [RFC5307]. The use of
the link local identifier format can result in more compact
encodings when the assignments are done in a reasonable fashion.

2.4. Available Labels Field

The Available Labels Field consists of priority flags and a single
variable-length Label Set Field 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PRI | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where:

PRI (Priority Flags, 8 bits): A bitmap used to indicate which
priorities are being advertised. The bitmap is in ascending order,
with the leftmost bit representing priority level 0 (i.e., the
highest) and the rightmost bit representing priority level 7 (i.e.,
the lowest). A bit MUST be set (1) corresponding to each priority
represented in the sub-TLV and MUST NOT be set (0) when the
corresponding priority is not represented. If a label is available
at priority M, it MUST be advertised available at each priority N <
M. At least one priority level MUST be advertised.

The PRI field indicates the availability of the labels for use in
Label Switched Path (LSP) setup and preemption as described in
[RFC3209].

Bernstein, et al. Standards Track [Page 12]

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When a label is advertised as available for priorities 0, 1, ... M,
it may be used by any LSP of priority N <= M. When a label is in use
by an LSP of priority M, it may be used by an LSP of priority N < M
if LSP preemption is supported.

When a label was initially advertised as available for priorities 0,
1, ... M and once a label is used for an LSP at a priority, say N
(N<=M), then this label is advertised as available for 0, ... N-1.

Note that the Label Set Field is defined in Section 2.6. See
Appendix A.5 for illustrative examples.

2.5. Shared Backup Labels Field

The Shared Backup Labels Field consists of priority flags and a
single variable-length Label Set Field 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PRI | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Where:

PRI (Priority Flags, 8 bits): A bitmap used to indicate which
priorities are being advertised. The bitmap is in ascending order,
with the leftmost bit representing priority level 0 (i.e., the
highest) and the rightmost bit representing priority level 7 (i.e.,
the lowest). A bit MUST be set (1) corresponding to each priority
represented in the sub-TLV and MUST NOT be set (0) when the
corresponding priority is not represented. If a label is available
at priority M, it MUST be advertised available at each priority N <
M. At least one priority level MUST be advertised.

The same LSP setup and preemption rules specified in Section 2.4
apply here.

Note that Label Set Field is defined in Section 2.6. See
Appendix A.5 for illustrative examples.

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2.6. Label Set Field

The Label Set Field is used within the Available Labels Field or the
Shared Backup Labels Field, defined in Sections 2.4 and 2.5,
respectively. It is also used within SIMPLE_LABEL, LABEL_RANGE, or
SIMPLE_LABEL & CHANNEL_COUNT, defined in Sections 2.2.1, 2.2.3, and
2.2.4, respectively.

The general format for a label set is given below. This format uses
the Action concept from [RFC3471] with an additional Action to define
a "bitmap" type of label set. Labels are variable in length.
Action-specific fields are defined in Sections 2.6.1, 2.6.2, and
2.6.3.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action| Num Labels = N | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base Label |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Action-specific fields) |
| . . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Action:

0 - Inclusive List

1 - Exclusive List

2 - Inclusive Range

3 - Exclusive Range

4 - Bitmap Set

Num Labels is generally the number of labels. It has a specific
meaning depending on the Action value. See Sections 2.6.1, 2.6.2,
and 2.6.3 for details. Num Labels is a 12-bit integer.

Length is the length in bytes of the entire Label Set Field.

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2.6.1. Inclusive/Exclusive Label Lists

For inclusive/exclusive lists (Action = 0 or 1), the wavelength set
format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 or 1 | Num Labels = 2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label #1 |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label #N |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Label #1 is the first label to be included/excluded, and Label #N is
the last label to be included/excluded. Num Labels MUST match
with N.

2.6.2. Inclusive/Exclusive Label Ranges

For inclusive/exclusive ranges (Action = 2 or 3), the label set
format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|2 or 3 | Num Labels | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Start Label |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| End Label |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Note that Start Label is the first label in the range to be
included/excluded, and End Label is the last label in the same range.
Num Labels MUST be two.

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2.6.3. Bitmap Label Set

For bitmap sets (Action = 4), the label set format is:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4 | Num Labels | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Base Label |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bitmap Word #1 (Lowest numerical labels) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bitmap Word #N (Highest numerical labels) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

In this case, Num Labels tells us the number of labels represented by
the bitmap. Each bit in the bitmap represents a particular label
with a value of 1/0 indicating whether or not the label is in the
set. Bit position zero represents the lowest label and corresponds
to the base label, while each succeeding bit position represents the
next label logically above the previous.

The size of the bitmap is Num Labels bits, but the bitmap is padded
out to a full multiple of 32 bits so that the field is a multiple of
four bytes. Bits that do not represent labels SHOULD be set to zero
and MUST be ignored.

3. Security Considerations

This document defines protocol-independent encodings for WSON
information and does not introduce any security issues.

However, other documents that make use of these encodings within
protocol extensions need to consider the issues and risks associated
with inspection, interception, modification, or spoofing of any of
this information. It is expected that any such documents will
describe the necessary security measures to provide adequate
protection. A general discussion on security in GMPLS networks can
be found in [RFC5920].

Bernstein, et al. Standards Track [Page 16]

RFC 7579 General Network Element Constraint Encoding June 2015

4. IANA Considerations

This document provides general protocol-independent information
encodings. There is no IANA allocation request for the information
elements defined in this document. IANA allocation requests will be
addressed in protocol-specific documents based on the encodings
defined here.

5. References

5.1. Normative References

[G.694.1] ITU-T, "Spectral grids for WDM applications: DWDM
frequency grid", ITU-T Recommendation G.694.1, February
2012.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group
MIB", RFC 2863, DOI 10.17487/RFC2863, June 2000,
<http://www.rfc-editor.org/info/rfc2863>.

[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>.

[RFC3471] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description",
RFC 3471, DOI 10.17487/RFC3471, January 2003,
<http://www.rfc-editor.org/info/rfc3471>.

[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
Extensions in Support of Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 4202, DOI 10.17487/RFC4202,
October 2005, <http://www.rfc-editor.org/info/rfc4202>.

[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005,
<http://www.rfc-editor.org/info/rfc4203>.

Bernstein, et al. Standards Track [Page 17]

RFC 7579 General Network Element Constraint Encoding June 2015

[RFC5307] Kompella, K., Ed., and Y. Rekhter, Ed., "IS-IS Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
<http://www.rfc-editor.org/info/rfc5307>.

[RFC6205] Otani, T., Ed., and D. Li, Ed., "Generalized Labels for
Lambda-Switch-Capable (LSC) Label Switching Routers",
RFC 6205, DOI 10.17487/RFC6205, March 2011,
<http://www.rfc-editor.org/info/rfc6205>.

5.2. Informative References

[RFC5440] Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.

[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<http://www.rfc-editor.org/info/rfc5920>.

[RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
"Framework for GMPLS and Path Computation Element (PCE)
Control of Wavelength Switched Optical Networks (WSONs)",
RFC 6163, DOI 10.17487/RFC6163, April 2011,
<http://www.rfc-editor.org/info/rfc6163>.

[RFC7446] Lee, Y., Ed., Bernstein, G., Ed., Li, D., and W. Imajuku,
"Routing and Wavelength Assignment Information Model for
Wavelength Switched Optical Networks", RFC 7446,
DOI 10.17487/RFC7446, February 2015,
<http://www.rfc-editor.org/info/rfc7446>.

[Switch] Bernstein, G., Lee, Y., Gavler, A., and J. Martensson,
"Modeling WDM Wavelength Switching Systems for Use in
GMPLS and Automated Path Computation", Journal of Optical
Communications and Networking, Volume 1, Issue 1,
pp. 187-195, June 2009.

Bernstein, et al. Standards Track [Page 18]

RFC 7579 General Network Element Constraint Encoding June 2015

Appendix A. Encoding Examples

This appendix contains examples of the general encoding extensions
applied to some simple ROADM network elements and links.

A.1. Link Set Field

Suppose that we wish to describe a set of input ports that have link
local identifiers numbered 3 through 42. In the Link Set Field, we
set Action = 1 to denote an inclusive range, Dir = 1 to denote input
links, and Format = 0 to denote link local identifiers. Thus, we
have:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |0 1|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #42 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.2. Label Set Field

In this example, we use a 40-channel C-Band Dense Wavelength Division
Multiplexing (DWDM) system with 100 GHz spacing with lowest frequency
192.0 THz (1561.4 nm) and highest frequency 195.9 THz (1530.3 nm).
These frequencies correspond to n = -11 and n = 28, respectively.
Now suppose the following channels are available:

Frequency (THz) n Value bitmap position
--------------------------------------------------
192.0 -11 0
192.5 -6 5
193.1 0 11
193.9 8 19
194.0 9 20
195.2 21 32
195.8 27 38

Bernstein, et al. Standards Track [Page 19]

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Using the label format defined in [RFC6205], with the Grid value set
to indicate an ITU-T A/2 [G.694.1] DWDM grid and C.S. set to indicate
100 GHz, this lambda bitmap set would then be 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 4 | Num Labels = 40 | Length = 16 bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = -11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 0 1 0| Not used in 40 Channel system (all zeros) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

To encode this same set as an inclusive list, we would have:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Num Labels = 7 | Length = 32 bytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = -11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = -6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = -0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = 9 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = 21 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n for lowest frequency = 27 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

A.3. Connectivity Matrix

Suppose we have a typical 2-degree 40-channel ROADM. In addition to
its two line side ports, it has 80 add and 80 drop ports. The figure
below illustrates how a typical 2-degree ROADM system that works with
bidirectional fiber pairs is a highly asymmetrical system composed of
two unidirectional ROADM subsystems.

Bernstein, et al. Standards Track [Page 20]

RFC 7579 General Network Element Constraint Encoding June 2015

(Tributary) Ports #3-#42
Input added to Output dropped from
West Line Output East Line Input
vvvvv ^^^^^
| |||.| | |||.|
+-----| |||.|--------| |||.|------+
| +----------------------+ |
| | | |
Output | | Unidirectional ROADM | | Input
-----------------+ | | +--------------
<=====================| |===================<
-----------------+ +----------------------+ +--------------
| |
Port #1 | | Port #2
(West Line Side) | |(East Line Side)
-----------------+ +----------------------+ +--------------
>=====================| |===================>
-----------------+ | Unidirectional ROADM | +--------------
Input | | | | Output
| | _ | |
| +----------------------+ |
+-----| |||.|--------| |||.|------+
| |||.| | |||.|
vvvvv ^^^^^
(Tributary) Ports #43-#82
Output dropped from Input added to
West Line Input East Line Output

Referring to the figure above, we see that the Input direction of
ports #3-#42 (add ports) can only connect to the output on port #1
while the Input side of port #2 (line side) can only connect to the
output on ports #3-#42 (drop) and to the output on port #1 (pass
through). Similarly, the input direction of ports #43-#82 can only
connect to the output on port #2 (line) while the input direction of
port #1 can only connect to the output on ports #43-#82 (drop) or
port #2 (pass through). We can now represent this potential
connectivity matrix as follows. This representation uses only 29
32-bit words.

Bernstein, et al. Standards Track [Page 21]

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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Conn = 1 | MatrixID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: adds to line
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |0 1|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #42 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |1 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: line to drops
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 1|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |1 0|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #42 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: line to line
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 1|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |1 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: adds to line
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |0 1|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #43 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #82 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |1 0|0 0 0 0 0 0| Length = 8 |

Bernstein, et al. Standards Track [Page 22]

RFC 7579 General Network Element Constraint Encoding June 2015

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: line to drops
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 1|0 0 0 0 0 0|| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |1 0|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #43 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #82 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: line to line
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 1|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |1 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Bernstein, et al. Standards Track [Page 23]

RFC 7579 General Network Element Constraint Encoding June 2015

A.4. Connectivity Matrix with Bidirectional Symmetry

If one has the ability to renumber the ports of the previous example
as shown in the next figure, then we can take advantage of the
bidirectional symmetry and use bidirectional encoding of the
connectivity matrix. Note that we set dir=bidirectional in the Link
Set Fields.

(Tributary)
Ports #3-42 Ports #43-82
West Line Output East Line Input
vvvvv ^^^^^
| |||.| | |||.|
+-----| |||.|--------| |||.|------+
| +----------------------+ |
| | | |
Output | | Unidirectional ROADM | | Input
-----------------+ | | +--------------
<=====================| |===================<
-----------------+ +----------------------+ +--------------
| |
Port #1 | | Port #2
(West Line Side) | |(East Line Side)
-----------------+ +----------------------+ +--------------
>=====================| |===================>
-----------------+ | Unidirectional ROADM | +--------------
Input | | | | Output
| | _ | |
| +----------------------+ |
+-----| |||.|--------| |||.|------+
| |||.| | |||.|
vvvvv ^^^^^
Ports #3-#42 Ports #43-82
Output dropped from Input added to
West Line Input East Line Output

Bernstein, et al. Standards Track [Page 24]

RFC 7579 General Network Element Constraint Encoding June 2015

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Conn = 1 | MatrixID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: Add/Drop #3-42 to Line side #1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |0 0|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #42 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: line #2 to add/drops #43-82
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=1 |0 0|0 0 0 0 0 0| Length = 12 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #43 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #82 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: line to line
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action=0 |0 0|0 0 0 0 0 0| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier = #2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Bernstein, et al. Standards Track [Page 25]

RFC 7579 General Network Element Constraint Encoding June 2015

A.5. Priority Flags in Available/Shared Backup Labels

If one wants to make a set of labels (indicated by Label Set Field
#1) available only for the highest priority level (Priority Level 0)
while allowing a set of labels (indicated by Label Set Field #2) to
be available to all priority levels, the following encoding will
express such need.

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 0 0 0| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field #1 |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 1 1 1 1 1 1 1| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Set Field #2 |
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Bernstein, et al. Standards Track [Page 26]

RFC 7579 General Network Element Constraint Encoding June 2015

Contributors

Diego Caviglia
Ericsson
Via A. Negrone 1/A 16153
Genoa
Italy
Phone: +39 010 600 3736
EMail: [email protected]

Anders Gavler
Acreo AB
Electrum 236
SE - 164 40 Kista
Sweden
EMail: [email protected]

Jonas Martensson
Acreo AB
Electrum 236
SE - 164 40 Kista
Sweden
EMail: [email protected]

Itaru Nishioka
NEC Corp.
1753 Simonumabe
Nakahara-ku, Kawasaki, Kanagawa 211-8666
Japan
Phone: +81 44 396 3287
EMail: [email protected]

Rao Rajan
Infinera
EMail: [email protected]

Giovanni Martinelli
Cisco
EMail: [email protected]

Remi Theillaud
Marben
EMail: [email protected]

Bernstein, et al. Standards Track [Page 27]

RFC 7579 General Network Element Constraint Encoding June 2015

Authors' Addresses

Greg M. Bernstein (editor)
Grotto Networking
Fremont, California
United States
Phone: (510) 573-2237
EMail: [email protected]

Young Lee (editor)
Huawei Technologies
1700 Alma Drive, Suite 100
Plano, TX 75075
United States
Phone: (972) 509-5599 (x2240)
EMail: [email protected]

Dan Li
Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base,
Bantian, Longgang District
Shenzhen 518129
China
Phone: +86-755-28973237
EMail: [email protected]

Wataru Imajuku
NTT Network Innovation Labs
1-1 Hikari-no-oka, Yokosuka, Kanagawa
Japan
Phone: +81-(46) 859-4315
EMail: [email protected]

Jianrui Han
Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base,
Bantian, Longgang District
Shenzhen 518129
China
Phone: +86-755-28972916
EMail: [email protected]

Bernstein, et al. Standards Track [Page 28]