Internet DRAFT - draft-ietf-ccamp-gmpls-otn-b100g-applicability
draft-ietf-ccamp-gmpls-otn-b100g-applicability
Internet Engineering Task Force Q. Wang, Ed.
Internet-Draft ZTE Corporation
Intended status: Informational R. Valiveti, Ed.
Expires: 22 May 2023 Infinera Corp
H. Zheng, Ed.
Huawei
H. Helvoort
Hai Gaoming B.V
S. Belotti
Nokia
18 November 2022
Applicability of GMPLS for Beyond 100G Optical Transport Network
draft-ietf-ccamp-gmpls-otn-b100g-applicability-15
Abstract
This document examines the applicability of using existing GMPLS
routing and signalling mechanisms to set up Optical Data Unit-k
(ODUk) Label Switched Paths (LSPs) over Optical Data Unit-Cn (ODUCn)
links as defined in the 2020 version of G.709.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. OTN terminology used in this document . . . . . . . . . . . . 3
3. Overview of the OTUCn/ODUCn in G.709 . . . . . . . . . . . . 5
3.1. OTUCn . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.1. OTUCn-M . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. ODUCn . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Tributary Slot Granularity . . . . . . . . . . . . . . . 8
3.4. Structure of OPUCn MSI with Payload type 0x22 . . . . . . 8
3.5. Client Signal Mappings . . . . . . . . . . . . . . . . . 9
4. GMPLS Implications and Applicability . . . . . . . . . . . . 10
4.1. TE-Link Representation . . . . . . . . . . . . . . . . . 10
4.2. Implications and Applicability for GMPLS Signalling . . . 11
4.3. Implications and Applicability for GMPLS Routing . . . . 12
5. Authors (Full List) . . . . . . . . . . . . . . . . . . . . . 13
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . 15
Appendix A. Possible Future Work . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The current GMPLS routing [RFC7138] and signalling [RFC7139]
extensions support the control of Optical Transport Network (OTN)
signals and capabilities that were defined in the 2012 version of
G.709 [ITU-T_G709_2012].
In 2016 a further version of G.709 was published: [ITU-T_G709_2016].
This version introduced higher rate Optical Transport Unit (OTU) and
Optical Data Unit (ODU) signals, termed OTUCn and ODUCn respectively,
which have a nominal rate of n x 100 Gbit/s. According to the
definition in [ITU-T_G709_2016], OTUCn and ODUCn perform only the
digital section layer role and ODUCn supports only ODUk clients.
This document focuses on the use of existing GMPLS mechanisms to set
up ODUk (e.g., ODUflex) Label Switched Paths (LSPs) over ODUCn links,
independently from how these links have been set up.
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Because [ITU-T_G709_2020] does not introduce any new features to
OTUCn and ODUCn compared to [ITU-T_G709_2016], this document starts
with [ITU-T_G709_2020] by first presenting an overview of the OTUCn
and ODUCn signals, and then analyzing how the current GMPLS routing
and signalling mechanisms can be utilized to set up ODUk (e.g.,
ODUflex) LSPs over ODUCn links.
This document assumes that the reader is familiar with OTN, GMPLS,
and how GMPLS is applied in OTN networks. As such, this document
doesn't provide any background pertaining to OTN networks that
included links with capacities of 100G or less; this background could
be found in documents such as [RFC7062] and [RFC7096]. This document
provides an overview of the dataplane primitives that enable links
with capacities greater than 100G, and analyses the extensions that
would be required in the current GMPLS routing & signaling mechanisms
to support the evolution in OTN networks.
2. OTN terminology used in this document
* FlexO: Flexible OTN information structure. This information
structure is usually with a specific bit rate and frame format,
consisting of overhead and payload, which is used as a group for
the transport of an OTUCn signal.
* LSP: Label Switched Path.
* ODU: Optical Data Unit. An ODU has the frame structure and
overhead, as defined in Figure 12-1 of [ITU-T_G709_2020]. ODUs
can be formed in two ways: a) by encapsulating a single non-OTN
client (such as SONET/SDH, Ethernet) b) multiplexing lower-rate
ODUs. In general, the ODU layer represents the path layer in OTN
networks. The only exception is the ODUCn signal (defined below)
which is defined to be a section layer signal. In the
classification based on bitrates of the ODU signals, ODUs are of
two types: Fixed rate, and flexible rate. Flexible rate ODU(s),
called "ODUFlex" have a rate that is 239/238 times the bit rate of
the client signal it encapsulates.
* ODUk: Optical Data Unit-k, where k is one of {0, 1, 2, 2e, 3, 4}.
The term ODUk references to an ODU whose bit rate is fully
specified by the index k. The bit rates of the ODUk signal for k
= {0, 1, 2, 2e, 3, 4} are approximately 1.25G, 2.5G, 10G, 10.3G,
40G, 100G respectively.
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* ODUflex: Optical Data Unit - flexible rate. An ODUflex has the
same frame structure as a "generic" ODU, but with rate that is a
fixed multiple of the bitrate of the client signal it
encapsulates. ITU-T defines specific ODUflex containers that are
required to transport specific clients such as 50GE, 200GE, 400GE,
etc.
* ODUC: Optical Data Unit -C; this signal has a bandwidth of
approximately 100G, and is of a slightly higher bit rate than the
fixed rate ODU4 signal. This signal has the format defined in
Figure 12-1 of [ITU-T_G709_2020]. This signal represents the
building block for constructing a higher rate signal called ODUCn
(defined below).
* ODUCn: Optical Data Unit-Cn; Cn indicates the bit rate of
approximately n*100G. This frame structure consists of "n"
interleaved, frame and multi-frame synchronous instances of the
ODUC signal, each of which has the format defined in Figure 12-1
of [ITU-T_G709_2020].
* OPUC: Optical Payload Unit -C; with a payload of approximately
100G. This structure represents the payload area of the ODUC
signal.
* OPUCn: Optical Payload Unit-Cn. Where Cn indicates that the bit
rate is approximately n*100G. This structure represents the
payload area of the ODUCn signal.
* OTUC: Optical Transport Unit -C; with a bandwidth of approximately
100G. This signal forms the building block of the OTUCn signal
defined below, which has a bandwidth of approximately n*100G.
* OTUCn: Fully standardized Optical Transport Unit-Cn. This frame
structure is realized by extending the ODUCn signal with the OTU
layer overhead. The structure of this signal is illustrated in
Figure 11-1 of [ITU-T_G709_2020]. Note that the term "fully
standardized" is defined by ITU-T in
[ITU-T_G709_2020]:Section 6.1.1.
* OTUCn-M: This signal is an extension of the OTUCn signal
introduced above. This signal contains the same amount of
overhead as the OTUCn signal, but contains a reduced amount of
payload area. Specifically, the payload area consists of M 5
Gbit/s tributary slots - where M is less than 20*n, which is the
number of tributary slots in the OTUCn signal.
* OTN: Optical Transport Network.
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* PSI: OPU Payload Structure Indicator. This is a 256-byte signal
that describes the composition of the OPU signal. This field is a
concatenation of the Payload type (PT) and the Multiplex Structure
Indicator (MSI) defined below.
* MSI: Multiplex Structure Indicator. This structure indicates the
grouping of the tributary slots in an OPU payload area that
realizes a client signal which is multiplexed into an OPU. The
individual clients multiplexed into the OPU payload area are
distinguished by the Tributary Port Number (TPN).
* TPN: Tributary Port Number. The tributary port number is used to
indicate the port number of the client signal that is being
transported in one specific tributary slot.
Detailed descriptions of these terms can be found in
[ITU-T_G709_2020].
3. Overview of the OTUCn/ODUCn in G.709
This section provides an overview of OTUCn/ODUCn signals defined in
[ITU-T_G709_2020]. The text in this section is purely descriptive
and is not normative. For a full description of OTUCn/ODUCn signals
please refer to [ITU-T_G709_2020]. In the event of any discrepancy
between this text and [ITU-T_G709_2020], that other document is
definitive.
3.1. OTUCn
In order to carry client signals with rates greater than 100 Gbit/s,
[ITU-T_G709_2020] takes a general and scalable approach that
decouples the rates of OTU signals from the client rate. The new OTU
signal is called OTUCn, and this signal is defined to have a rate of
(approximately) n*100G. The following are the key characteristics of
the OTUCn signal:
* The OTUCn signal contains one ODUCn. The OTUCn and ODUCn signals
perform digital section roles only (see
[ITU-T_G709_2020]:Section 6.1.1)
* The OTUCn signals can be viewed as being formed by interleaving n
synchronous OTUC signals (which are labeled 1, 2, ..., n).
* Each of the OTUC instances has the same overhead as the standard
OTUk signal in [ITU-T_G709_2020]. Note that the OTUC signal
doesn't include the FEC columns illustrated in
[ITU-T_G709_2020]:Figure 11-1. The OTUC signal includes an ODUC.
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* The OTUC signal has a slightly higher rate compared to the OTU4
signal (without FEC); this is to ensure that the OPUC payload area
can carry an ODU4 signal.
* The combined signal OTUCn has n instances of OTUC overhead, and n
instances of ODUC overhead.
The OTUCn, ODUCn and OPUCn signal structures are presented in a
(physical) interface independent manner, by means of n OTUC, ODUC and
OPUC instances that are marked #1 to #n.
OTUCn interfaces can be categorized as follows, based on the type of
peer network element:
* inter-domain interfaces: These types of interfaces are used for
connecting OTN edge nodes to (a) client equipment (e.g. routers)
or (b) hand-off points from other OTN networks. ITU-T
Recommendation [ITU-T_G709.1] specifies a flexible interoperable
short-reach OTN interface over which an OTUCn (n >=1) is
transferred, using bonded Flexible OTN information structure
(FlexO) interfaces which belong to a FlexO group.
* intra-domain interfaces: In these cases, the OTUCn is transported
using a proprietary (vendor specific) encapsulation, FEC etc. It
is also possible to transport OTUCn for intra-domain links using
FlexO.
3.1.1. OTUCn-M
The standard OTUCn signal has the same rate as that of the ODUCn
signal. This implies that the OTUCn signal can only be transported
over wavelength groups which have a total capacity of multiples of
(approximately) 100G. Modern optical interfaces support a variety of
bit rates per wavelength, depending on the reach requirements for the
optical path. If the total rate of the ODUk LSPs planned to be
carried over an ODUCn link is smaller than n*100G, it is possible to
"crunch" the OTUCn not to transmit the unused tributary slots. ITU-T
supports the notion of a reduced rate OTUCn signal, termed the OTUCn-
M. The OTUCn-M signal is derived from the OTUCn signal by retaining
all the n instances of overhead (one per OTUC instance) but with only
M (M is less than 20*n) OPUCn tributary slots available to carry ODUk
LSPs.
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3.2. ODUCn
The ODUCn signal defined in [ITU-T_G709_2020] can be viewed as being
formed by the appropriate interleaving of content from n ODUC signal
instances. The ODUC frames have the same structure as a standard ODU
in the sense that it has the same overhead and payload areas, but has
a higher rate since its payload area can embed an ODU4 signal.
The ODUCn is a multiplex section ODU signal, and is mapped into an
OTUCn signal which provides the regenerator section layer. In some
scenarios, the ODUCn, and OTUCn signals will be co-terminated, i.e.
they will have identical source/sink locations (see Figure 1). In
this figure, the term "OTN Switch" has the same meaning as that used
in [RFC7138]:Section 3. [ITU-T_G709_2020] allows for the ODUCn
signal to pass through one or more digital regenerator nodes (shown
as Nodes B, C in Figure 2) which will terminate the OTUCn layer, but
will pass the regenerated (but otherwise untouched) ODUCn towards a
different OTUCn interface where a fresh OTUCn layer will be
initiated. This process is termed as "ODUCn regeneration" in
[ITU-T_G872]:Section 7.1. In this example, the ODUCn is carried by 3
OTUCn segments.
Specifically, the OPUCn signal flows through these regenerators
unchanged. That is, the set of client signals, their TPNs,
tributary-slot allocation remains unchanged.
+--------+ +--------+
| +-----------+ |
| OTN |-----------| OTN |
| Switch +-----------+ Switch |
| A | | B |
| +-----------+ |
+--------+ +--------+
<--------ODUCn------->
<-------OTUCn------>
Figure 1: ODUCn signal
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+---------+ +--------+ +--------+ +--------+
| +--------+ | | +----------+ |
| OTN |--------| OTN | | OTN |----------| OTN |
| Switch +--------+ Regen +--------+ Regen +----------+ Switch |
| A | | B | | C | | D |
| +--------+ | | +----------+ |
+---------+ +--------+ +--------+ +--------+
<-------------------------ODUCn-------------------------->
<---------------><-----------------><------------------>
OTUCn OTUCn OTUCn
Figure 2: ODUCn signal - multihop
3.3. Tributary Slot Granularity
[ITU-T_G709_2012] introduced the support for 1.25 Gbit/s granular
tributary slots in OPU2, OPU3, and OPU4 signals. [ITU-T_G709_2020]
defined the OPUC with a 5 Gbit/s tributary slot granularity. This
means that the ODUCn signal has 20*n tributary slots (of 5 Gbit/s
capacity). The range of tributary port number (TPN) is 10*n instead
of 20*n, which restricts the maximum client signals that could be
carried over one single ODUC1.
3.4. Structure of OPUCn MSI with Payload type 0x22
As mentioned above, the OPUCn signal has 20*n 5 Gbit/s tributary
slots (TSs). The OPUCn MSI field has a fixed length of 40*n bytes
and indicates the availability and occupation of each TS. Two bytes
are used for each of the 20*n tributary slots, and each such
information structure has the following format
([ITU-T_G709_2020]:Section 20.4.1):
* The TS availability bit indicates if the tributary slot is
available or unavailable
* The TS occupation bit indicates if the tributary slot is allocated
or unallocated
* The tributary port number (14 bits) of the client signal that is
being carried in this specific TS. A flexible assignment of
tributary port to tributary slots is possible. Numbering of
tributary ports is from 1 to 10*n.
The concatenation of the OPUCn payload type (PT) and the MSI field is
carried over the overhead byte designated as PSI in
[ITU-T_G709_2020]:Figure 15-6.
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3.5. Client Signal Mappings
The approach taken by the ITU-T to map non-OTN client signals to the
appropriate ODU containers is as follows:
* All client signals are mapped into an ODUj, or ODUk (e.g.,
ODUflex) as specified in clause 17 of [ITU-T_G709_2020].
* The terms ODUj & ODUk are used in a multiplexing scenario, with
ODUj being a low-order ODU which is multiplexed into ODUk, a high-
order ODU. As Figure 3 illustrates, the ODUCn is also a high-
order ODU into which other ODUs can be multiplexed; the ODUCn
itself cannot be multiplexed into any higher rate ODU signal; it
is defined to be a section level signal.
* ODUflex signals are low-order signals only. If the ODUflex
entities have rates of 100G or less, they can be transported over
either an ODUk (k=1..4) or an ODUCn. For ODUflex connections with
rates greater than 100G, ODUCn is required.
* ODU Virtual Concatenation has been deprecated. This simplifies
the network, and the supporting hardware since multiple different
mappings for the same client are no longer necessary. Note that
legacy implementations that transported sub-100G clients using ODU
VCAT shall continue to be supported.
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Clients (e.g. SONET/SDH, Ethernet)
| | | | | |
| | | | | |
| | | | | |
+---+---+---+----+ | | |
| OPUj | | | |
+----------------+ | | |
| ODUj | | | |
+----------------+----------------------+---+---+----------+
| |
| OPUk |
+----------------------------------------------------------+
| |
| ODUk k in {0,1,2,2e,3,4,flex}|
+-------------------------+-----+--------------------------+
| | | |
| OTUk, OTUk-SC, OTUk-V | | OPUCn |
+-------------------------+ +--------------------------+
| |
| ODUCn |
+--------------------------+
| |
| OTUCn |
+--------------------------+
Figure 3: Digital Structure of OTN interfaces (from G.709:Figure 6-1)
4. GMPLS Implications and Applicability
4.1. TE-Link Representation
Section 3 of RFC7138 describes how to represent G.709 OTUk/ODUk with
TE-Links in GMPLS. In the same manner, OTUCn links can also be
represented as TE-links. Figure 4 below provides an illustration of
a one-hop OTUCn TE link.
+----------+ +---------+
| OTN | | OTN |
| Switch +-------------------+ Switch |
| A | | B |
+----------+ +---------+
|<---------OTUCn Link---------->|
|<---------TE-Link------------->|
Figure 4: OTUCn TE-Links
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It is possible to create TE-links that span more than one hop by
creating forward adjacencies (FA) between non-adjacent nodes (see
Figure 5). In this illustration, the nodes B and C are performing
the ODUCn regeneration function described in
[ITU-T_G872]:Section 7.1, and are not electrically switching the
ODUCn signal from one interface to another. As in the one-hop case,
Multiple-hop TE-links advertise the ODU switching capability.
+--------+ +--------+ +--------+ +---------+
| OTN | | OTN | | OTN | | OTN |
| Switch |<------->| regen |<-------->| regen |<------->| Switch |
| A | OTUCn | B | OTUCn | C | OTUCn | D |
+--------+ Link +--------+ Link +--------+ Link +---------+
|<-------------------- ODUCn Link -------------------->|
|<---------------------- TE-Link --------------------->|
Figure 5: Multiple-hop ODUCn TE-Link
The two endpoints of a TE-Link are configured with the supported
resource information, which may include whether the TE-Link is
supported by an ODUCn or an ODUk or an OTUk, as well as the link
attribute information (e.g., slot granularity, list of available
tributary slot).
4.2. Implications and Applicability for GMPLS Signalling
Once the ODUCn TE-Link is configured, the GMPLS mechanisms defined in
[RFC7139] can be reused to set up ODUk/ODUflex LSPs with no changes.
As the resource on the ODUCn link which can be seen by the client
ODUk/ODUflex is a set of 5 Gbit/s slots, the label defined in
[RFC7139] is able to accommodate the requirement of the setup of
ODUk/ODUflex over ODUCn link. In [RFC7139], the OTN-TDM
GENERALIZED_LABEL object is used to indicate how the lower order (LO)
ODUj signal is multiplexed into the higher order (HO) ODUk link. In
a similar manner, the OTN-TDM GENERALIZED_LABEL object is used to
indicate how the ODUk signal is multiplexed into the ODUCn link. The
ODUk Signal Type is indicated by Traffic Parameters. The IF_ID
RSVP_HOP object provides a pointer to the interface associated with
TE-Link and therefore the two nodes terminating the TE-link know (by
internal/local configuration) the attributes of the ODUCn TE Link.
Since the TPN defined in [ITU-T_G709_2020] for an ODUCn link has 14
bits, while this field in [RFC7139] only has 12 bits, some extension
work will eventually be needed. Given that a 12-bit TPN field can
support ODUCn links with up to n=400 (i.e. 40Tbit/s links), this need
is not urgent.
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An example is given in Figure 6 to illustrate the label format
defined in [RFC7139] for multiplexing ODU4 onto ODUC10. One ODUC10
has 200 5 Gbit/s slots, and twenty of them are allocated to the ODU4.
With this label encoding, only 20 out of the 200 bits mask are non-
zero, and is very inefficient. The inefficiency grows for larger
values of "n" and an optimized label format may be desirable.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TPN = 3 | Reserved | Length = 200 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0 0 0 0 0| Padding Bits(0) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Label format
4.3. Implications and Applicability for GMPLS Routing
For routing, it is deemed that no extension to current mechanisms
defined in [RFC7138] is needed. Because, once an ODUCn link is up,
the resources that need to be advertised are the resources that are
exposed by this ODUCn link and the multiplexing hierarchy on this
link. Since the ODUCn link is the lowest layer of the ODU
multiplexing hierarchy involving multiple ODU layers, and there is a
1:1 correspondence with the OTUCn signal, there is no need to
explicitly define a new value to represent the ODUCn signal type in
the OSPF-TE routing protocol.
The OSPF-TE extension defined in section 4 of [RFC7138] can be reused
to advertise the resource information on the ODUCn link to help
finish the setup of ODUk/ODUflex.
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5. Authors (Full List)
Qilei Wang (editor)
ZTE
Nanjing, China
Email: wang.qilei@zte.com.cn
Radha Valiveti (editor)
Infinera Corp
Sunnyvale, CA, USA
Email: rvaliveti@infinera.com
Haomian Zheng (editor)
Huawei
CN
EMail: zhenghaomian@huawei.com
Huub van Helvoort
Hai Gaoming B.V
EMail: huubatwork@gmail.com
Sergio Belotti
Nokia
EMail: sergio.belotti@nokia.com
6. Contributors
Iftekhar Hussain, Infinera Corp, Sunnyvale, CA, USA,
IHussain@infinera.com
Daniele Ceccarelli, Ericsson, daniele.ceccarelli@ericsson.com
Rajan Rao, Infinera Corp, Sunnyvale, USA, rrao@infinera.com
Fatai Zhang, Huawei,zhangfatai@huawei.com
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Italo Busi, Huawei,italo.busi@huawei.com
Dieter Beller, Nokia, Dieter.Beller@nokia.com
Yuanbin Zhang, ZTE, Beiing, zhang.yuanbin@zte.com.cn
Zafar Ali, Cisco Systems, zali@cisco.com
Daniel King, d.king@lancaster.ac.uk
Manoj Kumar, Cisco Systems, manojk2@cisco.com
Antonello Bonfanti, Cisco Systems, abonfant@cisco.com
Yuji Tochio, Fujitsu, tochio@fujitsu.com
7. IANA Considerations
This memo includes no request to IANA.
8. Security Considerations
This document analyzed the applicability of protocol extensions in
[RFC7138] and [RFC7139] for use in the 2020 version of G.709 [ITU-
T_G709_2020] and found that no new extensions are needed. Therefore,
this document introduced no new security considerations to the
existing signaling and routing protocols beyond those already
described in [RFC7138] and [RFC7139]. Please refer to [RFC7138] and
[RFC7139] for further details of the specific security measures.
Additionally, [RFC5920] addresses the security aspects that are
relevant in the context of GMPLS.
9. References
9.1. Normative References
[ITU-T_G709_2020]
ITU-T, "ITU-T G.709: Optical Transport Network Interfaces;
06/2020", June 2020.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<https://www.rfc-editor.org/info/rfc5920>.
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[RFC7138] Ceccarelli, D., Ed., Zhang, F., Belotti, S., Rao, R., and
J. Drake, "Traffic Engineering Extensions to OSPF for
GMPLS Control of Evolving G.709 Optical Transport
Networks", RFC 7138, DOI 10.17487/RFC7138, March 2014,
<https://www.rfc-editor.org/info/rfc7138>.
[RFC7139] Zhang, F., Ed., Zhang, G., Belotti, S., Ceccarelli, D.,
and K. Pithewan, "GMPLS Signaling Extensions for Control
of Evolving G.709 Optical Transport Networks", RFC 7139,
DOI 10.17487/RFC7139, March 2014,
<https://www.rfc-editor.org/info/rfc7139>.
9.2. Informative References
[ITU-T_G709.1]
ITU-T, "ITU-T G.709.1: Flexible OTN short-reach interface;
2018", 2018.
[ITU-T_G709_2012]
ITU-T, "ITU-T G.709: Optical Transport Network Interfaces;
02/2012", February 2012.
[ITU-T_G709_2016]
ITU-T, "ITU-T G.709: Optical Transport Network Interfaces;
07/2016", July 2016.
[ITU-T_G872]
ITU-T, "ITU-T G.872: Architecture of Optical Transport
Networks; 12/2019", December 2019.
[RFC7062] Zhang, F., Ed., Li, D., Li, H., Belotti, S., and D.
Ceccarelli, "Framework for GMPLS and PCE Control of G.709
Optical Transport Networks", RFC 7062,
DOI 10.17487/RFC7062, November 2013,
<https://www.rfc-editor.org/info/rfc7062>.
[RFC7096] Belotti, S., Ed., Grandi, P., Ceccarelli, D., Ed.,
Caviglia, D., Zhang, F., and D. Li, "Evaluation of
Existing GMPLS Encoding against G.709v3 Optical Transport
Networks (OTNs)", RFC 7096, DOI 10.17487/RFC7096, January
2014, <https://www.rfc-editor.org/info/rfc7096>.
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Appendix A. Possible Future Work
As noted in Section Section 4.2, the GMPLS TPN field in Section 6.1
of [RFC7139] is only 12 bits whereas an ODUCn link could require up
to 14 bits. Although the need is not urgent, future work could
extend the TPN field in GMPLS to use the Reserved bits immediately
adjacent. This would need to be done in a backward compatible way.
Section Section 4.2 further notes that the current encoding of GMPLS
labels can be inefficient for larger values of n in ODUCn. Future
work might examine a more compact, yet generalized label encoding to
address this issue should it be felt, after analysis of the
operational aspects, that the current encoding is causing problems.
Introduction of a new label encoding would need to be done using a
new LSP Encoding Type / G-PID pairing to ensure correct
interoperability.
Authors' Addresses
Qilei Wang (editor)
ZTE Corporation
Nanjing
China
Email: wang.qilei@zte.com.cn
Radha Valiveti (editor)
Infinera Corp
Sunnyvale
USA
Email: rvaliveti@infinera.com
Haomian Zheng (editor)
Huawei
China
Email: zhenghaomian@huawei.com
Huub van Helvoort
Hai Gaoming B.V
Almere
Netherlands
Email: huubatwork@gmail.com
Sergio Belotti
Nokia
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Email: sergio.belotti@nokia.com
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