Internet DRAFT - draft-kunze-g-698-2-management-control-framework
draft-kunze-g-698-2-management-control-framework
Internet Engineering Task Force R.Kunze, Ed.
Internet-Draft Deutsche Telekom AG
Intended status: Informational G.Grammel, Ed.
Expires: September 10, 2012 Juniper Networks
GMG. G.Galimberti, Ed.
Cisco
H.Schmidtke, Ed.
Juniper Networks
March 9, 2012
A framework for Management and Control of G.698.2 optical interface
parameters
draft-kunze-g-698-2-management-control-framework-02
Abstract
This document provides a framework that describes a solution space
for the control and management of optical interfaces parameters
according to the Black Link approach as specified by ITU-T [ITU
G.698.2]. In particular, it examines topological elements and
related network management processes to operate this construct. This
framework is scoped to address the Optical Channel (OCh)-layer
covered by G.698.2. The focus is on enabling the wavelength
provisioning process in a black link approach irrespective on how it
is triggered i.e. by EMS, NMS or GMPLS. This document covers
management as well as control plane considerations in different
management cases of a single channel DWDM interface as defined by
ITU-G.698.2. The purpose is to identify the necessary information
elements and processes to be used by control or management devices
for further processing. Hence wavelength routing and selection
processes as defined e.g. in WSON are beyond the scope of this
document.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on September 10, 2012.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology and Definitions . . . . . . . . . . . . . . . . . 5
3. Solution Space for optical interfaces using a DWDM Black
Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Comparison of approaches for transverse compatibility . . 7
3.1.1. Multivendor DWDM line system with transponders . . . . 7
3.1.2. Black Link Deployments . . . . . . . . . . . . . . . . 9
4. Operational aspects using IUT-T G.698.2 specified single
channel DWDM interfaces . . . . . . . . . . . . . . . . . . . 10
4.1. Bringing into service . . . . . . . . . . . . . . . . . . 10
4.2. Configuration Management . . . . . . . . . . . . . . . . . 11
4.3. In service (performance management) . . . . . . . . . . . 11
4.4. Fault Clearance . . . . . . . . . . . . . . . . . . . . . 11
5. Solutions for managing and controlling the optical
interface within Black Link scenarios . . . . . . . . . . . . 11
5.1. BL Separate Operation and Management Approaches . . . . . 12
5.1.1. Direct connection to the management system . . . . . . 13
5.1.2. Indirect connection to the DWDM management system . . 15
5.2. Control Plane Considerations . . . . . . . . . . . . . . . 16
5.2.1. Considerations using GMPLS UNI . . . . . . . . . . . . 17
6. Requirements for BL deployments . . . . . . . . . . . . . . . 18
6.1. Interoperability Aspects . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 20
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
11.1. Normative References . . . . . . . . . . . . . . . . . . . 21
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11.2. Informative References . . . . . . . . . . . . . . . . . . 22
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1. Introduction
The usage of the Black Link approach in carrier applications (which
include optical amplifiers) adds further networking option for
operators enabling integration of G.698.2 optical interfaces into
routers and other types of client devices.
Carriers deploy their networks today as a combination of transport
and packet infrastructures to ensure high availability and flexible
data transport. Both network technologies are usually managed by
different operational units using different management concepts.
This is the status quo in many carrier networks today. In the case
of a black link deployment, where the optical transport interface
moves into the client device (e.g. , router), it is necessary to
coordinate the management of the optical interface at the client
domain with the optical transport domain. There are different levels
of coordination, which are specified in this framework.
The objective of this document is to provide a framework that
describes the solution space for the control and management of single
channel interfaces as specified by the ITU-T Recommendation G.698.2
[ITU G.698.2]. In particular, it examines topological elements and
related network management measures. From an architectural point of
view, the black link is a set of pre-configured/qualified
unidirectional, single-fiber, network connections between the G.698.2
reference points S and R. The optical transport network is managed
and controlled in order to provide black links of the intended centre
frequencies and the optical interfaces are managed and controlled to
generate signals of the intended centre frequencies and further
parameters as specified in ITU-T Recommendations G.698.2 and G.798.
Optical Routing and Wavelength assignment based on WSON is out of
scope.
Furthermore, support for Fast Fault Detection, to e.g., trigger ODUk
Protection Switching is out of scope of this work. Additionally, the
wavelength ordering process and the process how to determine the
demand for a new wavelength from A to Z is out of scope.
Note that the Control and Management Planes are two separate entities
that are handling the same information in different ways. This
document covers management as well as control plane considerations in
different management cases of single channel DWDM interfaces.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology and Definitions
Current generation WDM netwoks are single vendor networks where the
optical line system and the transponders are tightly integrated. The
Black Link approach changes this situation by introducing a
standardized interface at the level of OCh between the line system
and transponders.
Black Link: The Black Link [ITU G.698.2] allows supporting an optical
transmitter/receiver pair of a single vendor or from different
vendors to provide a single optical channel interface and transport
it over an optical network composed of amplifiers, filters, add-drop
multiplexers which may be from a different vendor. Therefore the
standard defines the ingress and egress parameters for the optical
interfaces at the reference points Ss and Rs. In that case the
optical connection between the two G.968.2 optical interfaces is
referred to as a Black Link. G.698.2 provides an optical interface
specification ensuring the realization of transversely compatible
dense wavelength division multiplexing (DWDM) systems primarily
intended for metro applications which include optical amplifiers and
leads towards a multivendor DWDM optical transmission network.
Single Channel DWDM Interface: The single channel interfaces to DWDM
systems defined in G.698.2, which currently include the following
features: channel frequency spacing: 50 GHz and wider (defined in
[ITU-T G.694.1]); bit rate of single channel: Up to 10 Gbit/s.
Future revisions are expected to include application codes for bit
rates up to 40 Gb/s. Single channel DWDM interfaces to/from other
vendor(s): G.698.2 provides transverse compatibility at the single-
channel point, using a direct wavelength-multiplexing configuration,
for single channel DWDM interfaces to/from other vendors (but not at
the multi-channel point).
Forward error correction (FEC): FEC is a way of improving the
performance of high-capacity optical transmission systems. Employing
FEC in optical transmission systems yields system designs that can
accept relatively large BER (much more than 10-12) in the optical
transmission line (before decoding).
Administrative domain [G.805]: For the purposes of this
Recommendation an administrative domain represents the extent of
resources which belong to a single player such as a network operator,
a service provider or an end-user. Administrative domains of
different players do not overlap amongst themselves.
Intra-domain interface (IaDI) [G.872]: A physical interface within an
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administrative domain.
Inter-domain interface (IrDI) [G.872]: A physical interface that
represents the boundary between two administrative domains.
Management Plane [G.8081]: The management plane performs management
functions for the transport plane, the control plane and the system
as a whole. It also provides coordination between all the planes.
The following management functional areas are performed in the
management plane: performance management; fault management;
configuration management; accounting management and security
management.
Control Plane[G.8081]: The control plane performs neighbour
discovery, call control and connection control functions. Through
signalling, the control plane sets up and releases connections, and
may restore a connection in case of a failure. The control plane
also performs other functions in support of call and connection
control, such as neighbour discovery and routing information
dissemination.
Transponder: A Transponder is a network element that performs O/E/O
(Optical /Electrical/Optical) conversion. In this document it is
referred only transponders with 3R (rather than 2R or 1R
regeneration) as defined in [ITU.G.872].
3. Solution Space for optical interfaces using a DWDM Black Link
The management of optical interfaces using the Black Link approach
deals with aspects related to the management of single-channel
optical interface parameters of physical point-to-point and ring DWDM
applications on single-mode optical fibres.
The Black Link approach allows the direct connection of a wide
variety of equipments using a DWDM link, for example:
a. A digital cross-connect with multiple optical interfaces,
supplied by a different vendor from the line system
b. Multiple optical client devices, each from a different vendor,
supplying one channel each
c. A combination of the above
Table 1 provides a list of BL management tasks regarding the
configuration of optical parameters.
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+---------------------------------------+---------+----+----+---+---+
| Task | Domain | a | b | c | d |
+---------------------------------------+---------+----+----+---+---+
| determination of centre frequency | optical | R | R | R | R |
| configuration of centre frequency at | client | NR | NR | R | R |
| optical IF | | | | | |
| path computation of wavelength | optical | NR | NR | R | R |
| routing of wavelength | optical | NR | NR | R | R |
| wavelength setup across optical | optical | ? | ? | R | R |
| network | | | | | |
| detection of wavelength fault | client | R | R | R | R |
| fault isolation, identification of | optical | NR | R | R | R |
| root failure | | | | | |
| repair actions within optical network | optical | R | R | R | R |
| protection switching of wavelength | optical | NR | NR | R | R |
| restoration of wavelength | optical | NR | NR | R | R |
+---------------------------------------+---------+----+----+---+---+
Note: R = relevant, NR = not relevant
Table 1: List of tasks related to BL management
Furthermore the following deployment cases will be considered:
a. Passive WDM
b. P2P WDM systems
c. WDM systems with OADMs
d. Transparent optical networks supporting specific IPoWDM
functions, interfaces, protocols etc.
Case a) is added for illustration only, since passive WDM is
specified in ITU-T Recommendations G.695 and G.698.1.
Case b) and case c)are motivated by the usage of legacy equipment
using the traditional connection as described in Figure 1combined
with the BL approach.
3.1. Comparison of approaches for transverse compatibility
3.1.1. Multivendor DWDM line system with transponders
As illustrated in Figure 1, for this approach interoperability is
achieved via the use of optical transponders providing OEO (allowing
conversion to appropriate parameters). The optical interfaces
labelled "single channel non-DWDM interfaces from other vendor(s)"
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and "Single channel non DWDM interfaces to/from other vendor(s)" can
then be any short reach standardized optical interface that both
vendors support, such as those found in [ITU-T G.957] [ITU-T G.691],
[ITU-T G.693], [ITU-T G.959.1], etc.
IrDI IaDI
| |
. .
| +----------------------------|---+
. | + WDM Domain + . |
| | |\ /| | |
+------+ . | | \ |\ / | . | +------+
| TX/ |-->--+---+--T/-|OM|----|/-------|OD|--+-\T+------->--| RX/ |
| RX |--<--+---+--T/-| |----- /|-----| |--.-\T+-------<--| TX |
+------+ | | | / \| \ | | | +------+
. | |/ \| . |
| | + + | |
. +----------------------------.---+
| |
TX/RX = Single channel non-DWDM interfaces
T/ = Transponder
OM = Optical Mux
OD = Optical Demux
Figure 1: Inter and Intra-Domain Interface Identification
In the scenario of Figure 1 the administrative domain is defined by
the Interdomain Interface (IrDI). This interface terminates the DWDM
domain. The line side is characterized by the IaDI. This interface
specifies the internal parameter set of the optical administrative
domain. In the case of black link deployment this interface moves
into the client devices and extends the optical and administrative
domain towards the client node. ITU-T G.698.2 specifies the
parameter set for a certain set of applications.
This document elaborates only the IaDI Interface as specified in
ITU-T G.698.2 as transversely compatible and multi-vendor interface
within one administrative domain controlled by the network operator.
This administrative domain can contain several vendor domains (vendor
A for the DWDM sub-network, and vendors B1 and B2 at the transmitter
and receiver terminal side).
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3.1.2. Black Link Deployments
In case of a Black Link deployment as shown in Figure 2, through the
use of the single channel DWDM interfaces defined in [ITU G.698.2],
multi-vendor interconnection can also be achieved while removing the
need for one short reach transmitter and receiver pair per channel
(eliminating the transponders).
Figure 2 shows a set of reference points, for the linear "black-link"
approach, for single-channel connection (Ss and Rs) between
transmitters (Tx) and receivers (Rx). Here the DWDM network elements
include an optical multiplexer (OM) and an optical demultiplexer (OD)
(which are used as a pair with the peer element), one or more optical
amplifiers and may also include one or more OADMs.
|==================== Black Link =======================|
+-------------------------------------------------+
Ss | DWDM Network Elements | Rs
+---+ | | | \ / | | | +---+
Tx L1----|->| \ +------+ +------+ / |--|--->Rx L1
+---+ | | | | | +------+ | | | | | +---+
+---+ | | | | | | | | | | | | +---+
Tx L2----|->| OM |-|>|------|->| OADM |--|------|->| OD |--|--->Rx L2
+---+ | | | | | | | | | | | | +---+
+---+ | | | | | +------+ | | | | | +---+
Tx L3----|->| / | DWDM | | ^ | DWDM | \ |--|--->Rx L3
+---+ | | / | Link +----|--|----+ Link | \ | | +---+
+-----------+ | | +----------+
+--+ +--+
| |
v |
+---+ +---+
RxLx TxLx
+---+ +---+
Ss = Reference point at the DWDM network element tributary output
Rs = Reference point at the DWDM network element tributary input
Lx = Lambda x
OM = Optical Mux
OD = Optical Demux
OADM = Optical Add Drop Mux
Linear black link as per ITU-T G.698.2
Figure 2: Linear Black Link
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In Figure 2, if the administrative domain consists of several domains
(e.g. A for a DWDM network supporting the Black Link, B1 for the
DWDM Tx, and B2 for the DWDM Rx), it is typical that there will be a
separate Element Management Systems (EMS) will be used for each
vendor domain (e.g. EMS-a for domain A, EMS-b1 for domain B1, and
EMS-b2 for domain B2). Each EMS may have a common standard north
bound management interface to a Network Management System (NMS),
allowing consistent end-to-end management of the connection.
To facilitate consistent end-to-end network management, the north
bound management interface from the EMS to the NMS should be
consistent (frome a management information point of view) with the
standard protocol-neutral (or protocol-specific) information model
used in the EMS south bound management interface to its subtending
NEs (TX and/or RX). The [Black-Link-MIB] defines such a protocol-
specific information using SNMP/SMI.
4. Operational aspects using IUT-T G.698.2 specified single channel
DWDM interfaces
A Comparison of the Black Link with the traditional operation
scenarios provides an insight of similarities and distinctions in
operation and management. The following four use cases provide an
overview about operation and maintenance processes.
4.1. Bringing into service
It is necessary to differentiate between two operational issues for
setting up a light path (a Black Link connection is specific in
having defined maximum impairments) within an operational network.
The first step is the preparation of the connection if no optical
signal is applied. Therefore it is necessary to define the path of
the connection.
The second step is to setup the Black Link connection. This is done
using the NMS of the optical transport network. From the operation
point of view the task is similar in a Black Link scenario and in a
traditional WDM environment. The Black Link connection is measured
by using BER tester which use optical interfaces according to
G.698.2. These measurements are carried out in accordance with ITU-T
Recommendation M.xxxx. When needed further Black Link connections
for resilience are brought into service in the same way.
If the optical interface moves into a client device some of changes
from the operational point of view have to be considered. The centre
frequency of the Black Link connections was determined by the setup
process. The optical interfaces at both terminals are set to the
centre frequency of the Black Link connection before interconnected
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with the dedicated ports of the WDM network. Optical monitoring is
activated in the WDM network after the terminals are interconnected
with the dedicated ports in order to monitor the status of the Black
Link connection. The monitor functions of the optical interfaces at
the terminals are also activated in order to monitor the end to end
connection.
Furthermore it should be possible to automate this last step. After
connecting the client device towards the first control plane managed
transport node a control connection may e.g. be automatically
established using LMP to exchange configuration information.
If tunable interfaces are used in the Black Link scenario it would be
possible to define a series of backup wavelength routes for
restoration that could be tested and stored in backup profile. In
fault cases this wavelength routes can be used to recover the
service.
4.2. Configuration Management
tbd.
4.3. In service (performance management)
tbd.
4.4. Fault Clearance
tbd.
5. Solutions for managing and controlling the optical interface within
Black Link scenarios
Operation and management of WDM systems is traditionally seen as a
homogenous group of tasks that could be carried out best when a
single management system or an umbrella management system is used.
Currently each WDM vendor provides an Element Management System (EMS)
that also administers the wavelengths.
Therefore from the operational point of view in a pure Black Link or
in a mixed setup with transponders there are the following approaches
will be considered to manage and operate optical interfaces.
1. Separate operation and management of client device and the
transport network
a. Direct link between the client device and the management
system of the optical network (e.g. EMS, NMS)
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b. Indirect link to the management system of the optical network
using a protocol between the client device and the directly
connected WDM system node to exchange management information with
the optical domain
2. Common operation and management of client device and the
Transport network
The first option keeps the status quo in large carrier networks as
mentioned above. In that case it must be ensured that the full FCAPS
Management (Fault, Configuration, Accounting, Performance and
Security) capabilities are supported. This means from the management
staff point of view nothing changes. The transceiver/receiver
optical interface will be part of the optical management domain and
will be managed from the transport management staff.
The second solution addresses the case where underlying WDM transport
network is mainly used to interconnect a homogeneous set of client
nodes (e.g. IP routers or digital crossconnects). Since the service
creation and restoration could be done by to higher layers (e.g.
IP), this may lead to more efficient network operation and a higher
level of integration.
5.1. BL Separate Operation and Management Approaches
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5.1.1. Direct connection to the management system
As depicted in Figure 3 (case 1a) one possibility to manage the
optical interface within the client domain is a direct connection to
the management system of the optical domain. This ensures
manageability as usual.
+-----+
| NMS |
|_____|
/_____/
|
|
|
+---+---+
+----->+ EMS |
/ | |
/ +-------+
/ | MI
SNMP / | DCN Network
--------------------+-------------------------------
/ +------+-----------------------+
/ | +| WDM Domain + |
/ | |\ /| |
+---+--+ | | \ |\ / | | +------+
| CL |-/C------+--- -|OM|----|/-------|OD|--- +-------/C-| CL |
| |-/C------+--- -| |----- /|-----| |----+-------/C-| |
+------+ | | / \| \ | | +------+
| |/ \| |
| + + |
+------------------------------+
CL = Client Device
/C = G.698.2 Optical Interface
OM = Optical Mux
OD = Optical Demux
EMS = Element Management System
MI= Management Interface
Figure 3: Connecting G.698.2 optical interfaces to the Transport
Management system
The exchange of management information between client device and the
management system assumes that some form of a direct management
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communication link exists between the client device and the DWDM
management system (e.g. EMS). This may be an Ethernet Link or a DCN
connection (management communication channel MCC).
It must be ensured that the optical network interface can be managed
in a standardized way to enable interoperable solutions between
different optical interface vendors and vendors of the optical
network management application. RFC 3591 [RFC3591] defines managed
objects for the optical interface type but needs further extension to
cover the optical parameters required by this framework document.
Therefore an extension to this MIB for the optical interface has been
drafted in [Black-Link-MIB]. In that case SNMP is used to exchange
data between the client device and the management system of the WDM
domain.
Note that a software update of the optical interface components of
the client nodes must not lead obligatory to an update of the
software of the EMS and vice versa.
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5.1.2. Indirect connection to the DWDM management system
The alternative as shown in Figure 4 can be used in cases where a
more integrated relationship between transport node (e.g. OM or OD)
and client device is aspired. In that case a combination of control
plane features and manual management will be used.
+-----+
| NMS |
|_____|
/_____/
|
|
|
+---+---+
| EMS |
| |
+-------+
| MI
|
|
LMP +------+-----------------------+
+------------+---+ +| + |
| | | |\ /| |
+---+--+ | +-+ \ |\ / | | +------+
| CL |-/C------+--- -|OM|----|/-------|OD|--- +-------/C-| CL |
| |-/C------+--- -| |----- /|-----| |----+-------/C-| |
+------+ | | / \| \ | | +------+
| |/ \| |
| + + |
+------------------------------+
CL = Client Device
/C = G.698.2 optical Interface
OM = Optical Mux
OD = Optical Demux
EMS= Element Management System
MI= Management Interface
Figure 4: Direct connection between peer node and first optical
network node
For information exchange between the client node and the direct
connected node of the optical transport network LMP as specified in
RFC 4209 [RFC4209] can (should) be used. This extension of LMP may
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be used between a peer node and an adjacent optical network node as
depicted in Figure 4.
Recently LMP based on RFC 4209 does not yet support the transmission
of configuration data (information). This functionality has to be
added to the existing extensions of the protocol. The use of LMP-WDM
assumes that some form of a control channel exists between the client
node and the WDM equipment. This may be a dedicated lambda, an
Ethernet Link, or other signaling communication channel (SCC).
5.2. Control Plane Considerations
The concept of black link equally applies to management and control
plane mechanisms. The general GMPLS control Plane for wavelength
switched optical networks is work under definition in the scope of
WSON.One important aspect of the BL is the fact that it includes the
wavelength that is supported by the given link. Thus a BL can
logically be considered as a fiber that is transparent only for a
single wavelength. In other words, the wavelength becomes a
characteristic of the link itself. Nevertheless the procedure to
light up the fiber may vary depending on the BL implementation.
Since the implementation of the BL itself is unknown a priori,
different sequences to light up wavelength need to be considered:
1. Transponders first, transponder tuning: The transmitter is
switched on and the BL is immediately transparent to its
wavelength. This requires the transmitter to carefully tune
power and frequency not overload the line system or to create
transients.
2. Transponder first, OLS tuning: The transmitter is switched on
first and can immediately go to the max power allowed since the
OLS performs the power tuning. This leads to an intermediate
state where the receiver doesn not receive a valid signal while
the transmitter is sending out one. Alarm suppression mechanisms
shall be employed to overcome that condition.
3. OLS first, Transponder tuning: At first the OLS is tuned to be
transparent for a given wavelength, then transponders need to be
tuned up. Since the OLS in general requires the presence of a
wavelength to fine-tune it is internal facilities there may be a
period of time where a valid signal is transmitted but the
receiver is unable to detect it. This equally need to be covered
by alarm suppression mechanisms.
4. OLS first, OLS tuning: The OLS is programmed to be transparent
for a given Wavelength, then the transponders need to be switched
on and further power tuning takes place. The sequencing of
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enabling the link needs to be covered as well.
The preferred way to address these in a Control Plane enabled network
is neighbour discovery including exchange of link characteristics and
link property correlation. The general mechanisms are covered in
RFC4209 [LMP-WDM] and RFC 4204[LMP] which provides the necessary
protocol framework to exchange those characteristics between client
and black link. LMP-WDM is not intended for exchanging routing or
signalling information but covers:
Control channel manangement
Link property correlation
Link verification
Fault Manangement
Extensions to LMP/LMP-WDM covering the code points of the BL
definition are needed. Additionally when client and server side are
managed by different operational entities, Link state exchange is
required to align the management systems.
5.2.1. Considerations using GMPLS UNI
The deployment of G.698.2 optical interfaces is leading to some
functional changes related to the control plane models and has
therefore some impact on the existing interfaces especially in the
case of an overlay model where the edge node requests resources from
the core node and the edges node do not participate in the routing
protocol instance that runs among the core nodes. RFC 4208 [RFC4208]
defines the GMPLS UNI that will be used between edge and core node.
In case of a black link deployment additional functionalities are
needed to setup a connection.
It is necessary to differentiate between topology/signalling
information and configuration parameters that are needed to setup a
wavelength path. RSVP-TE could be used for the signalling and the
reservation of the wavelength path. But there are additional
information needed before RSVP-TE can start the signalling process.
There are three possibilities to proceed:
a. Using RSVP-TE only for the signalling and LMP as described above
to exchange information to configure the optical interface within
the edge node or
b. RSVP-TE will be used to transport additional information
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c. Leaking IGP information instead of exchanging this information
needed from the optical network to the edge node (overlay will be
transformed to a border-peer model)
Furthermore following issues should be addressed:
a) The Communication between peering edge nodes using an out of band
control channel. The two nodes have to exchange their optical
capabilities. An extended version of LMP is needed to exchange FEC
Modulation scheme,etc. that must be the same. It would be helpful to
define some common profiles that will be supported. Only if the
profiles match with both interface capabilities it is possible start
signalling.
b) Due to the bidirectional wavelength path that must be setup it is
obligatory that the upstream edge node inserts a wavelength value
into the path message for the wavelength path towards the upstream
node itself. But in the case of an overlay model the client device
may not have fullinformation which wavelength must/should be
selectedand this information must be exchanged between the edge and
the core node.
...additional points
6. Requirements for BL deployments
This section raises requirements from the carrier perspective and
will be removed in a separate requirements draft if necessary.
6.1. Interoperability Aspects
For carrier network deployments, interoperability is a key
requirement. Today it is state-of-the-art to interconnect e.g.
client devices from different vendors via a WDM transport system
using short-reach, grey interfaces. Applying the Black Link (BL)
concept, client devices (e.g. routers) are now directly connected via
transport interfaces which must be interoperable to each other.
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A progressive approach addressing interoperability is shown in
Figure 5.According to the concept of ITU-T G.698.2 the black link,
the single channel (coloured) Tx and the Rx can be provided different
vendors. The single-channel reference points Ss and Rs indicate the
demarcation between the Tx/Rx and the black link, and the set of
optical parameters refers to these reference points according to
G.698.2. However, G.698.2 does not give any insight into the client
equipment (CL), e.g. routers or switches, containing the optical
transmitters and receivers.This is a valid topic which is subject of
other standards and multi-source agreement (MSAs) describing
electrical interfaces, mechanical properties and environmental
conditions. Such topics are out of the scope of this document.
<========= Black Link =========>
+---------------------------+
| Black Link |
+-----------+ | + + | +-----------+
|CL #1 | -+---|\ /|---+- | CL #2 |
| +------+-+ | | \ +-------+ / | | +-+------+ |
| -+-| Tx | | | | | | | | | | Rx |-+- |
| -+-| +--+-+---|OM|-- OADM |--|OD|---+-+--+ |-+- |
| -+-| | Ss | | | | | | | | RS | |-+- |
| +------+-+ | | / +-------+ \ | | +-+------+ |
| | -+---|/ \|---+- | |
| | | + + | | |
+-----------+ | | +-----------+
+---------------------------+
CL = Client Device
OM = Optical Mux
OD = Optical Demux
Figure 5: Interoperability aspects
7. Acknowledgements
The author would like to thank Ulrich Drafz for the very good
teamwork during the last years and the initial thoughts related to
the packet optical integration. Furthermore the author would like to
thank all people involved within Deutsche Telekom for the support and
fruitful discussions.
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8. IANA Considerations
This memo includes no request to IANA.
9. Security Considerations
The architecture and solution space in scope of this framework
imposes no additional requirements to the security models already
defined in RFC5920 for packet/optical networks using GMPLS, covering
also Control Plane and Management interfaces. Respective security
mechanisms of the components and protocols, e.g. LMP security
models, can be applied unchanged.
As this framework is focusing on the single operator use case, the
security concerns can be relaxed to a subset compared to a setup
where information is exchanged between external parties and over
external interfaces.
Concerning the access control to Management interfaces, security
issues can be generally addressed by authentification techniques
providing origin verification, integrity and confidentiality.
Additionally, access to Management interfaces can be physically or
logically isolated, by configuring them to be only accessible out-of-
band, through a system that is physically or logically separated from
the rest of the network infrastructure. In case where management
interfaces are accessible in-band at the client device or within the
optical transport netork domain, filtering or firewalling techniques
can be used to restrict unauthorized in-band traffic. Authentication
techniques may be additionally used in all cases.
10. Contributors
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Arnold Mattheus
Deutsche Telekom
Darmstadt
Germany
email arnold.Mattheus@telekom.de
Manuel Paul
Deutsche Telekom
Berlin
Germany
email Manuel.Paul@telekom.de
Josef Roese
Deutsche Telekom
Darmstadt
Germany
email j.roese@telekom.de
Frank Luennemann
Deutsche Telekom
Muenster
Germany
email Frank.Luennemann@telekom.de
11. References
11.1. Normative References
[ITU G.698.2] International Telecommunications Union, "Amplified
multichannel dense wavelength division multiplexing
applications with single channel optical
interfaces", ITU-T Recommendation G.698.2,
November 2009.
[ITU.G.872] International Telecommunications Union,
"Architecture of optical transport networks", ITU-
T Recommendation G.872, November 2001.
[ITU.G709] International Telecommunications Union, "Interface
for the Optical Transport Network (OTN)", ITU-
T Recommendation G.709, March 2003.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3591] Lam, H-K., Stewart, M., and A. Huynh, "Definitions
of Managed Objects for the Optical Interface Type",
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RFC 3591, September 2003.
[RFC4204] Lang, J., "Link Management Protocol (LMP)",
RFC 4204, October 2005.
[RFC4209] Fredette, A. and J. Lang, "Link Management Protocol
(LMP) for Dense Wavelength Division Multiplexing
(DWDM) Optical Line Systems", RFC 4209,
October 2005.
11.2. Informative References
[Black-Link-MIB] Internet Engineering Task Force, "A SNMP MIB to
manage black-link optical interface parameters of
DWDM applications", draft-galimbe-kunze-g-698-2-
snmp-mib draft-galimbe-kunze-g-698-2-snmp-mib,
July 2011.
[ITU-T G.691] ITU-T, "Optical interfaces for single channel
STM-64 and other SDH systems with optical
amplifiers", ITU-T Recommendation ITU-T G.691,
2008.
[ITU-T G.693] ITU-T, "Optical interfaces for intra-office
systems", ITU-T Recommendation ITU-T G.693, 2009.
[ITU-T G.8081] ITU-T, "Terms and definitions for Automatically
Switched Optical Networks (ASON)", ITU-T
Recommendation G.8081", ITU-T Recommendation ITU-T
G.8081, September 2010.
[ITU-T G.957] ITU-T, "Optical interfaces for equipments and
systems relating to the synchronous digital
hierarchy", ITU-T Recommendation ITU-T G.957, 2006.
[ITU-T G.959.1] ITU-T, "Optical transport network physical layer
interfaces", ITU-T Recommendation ITU-T G.959.1,
2009.
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Authors' Addresses
Ruediger Kunze (editor)
Deutsche Telekom AG
Berlin, 10589
DE
Phone: +49 30 3497 3152
EMail: ruediger.kunze@telekom.de
Gert Grammel (editor)
Juniper Networks
ddddd
dddd, 1234
US
Phone: +1 45552
EMail: ggrammel@juniper.net
Gabriele Galimberti (editor)
Cisco
Via Philips,12
20052 - Monza
Italy
Phone: +390392091462
EMail: ggalimbe@cisco.com
Hans-Juergen Schmidtke (editor)
Juniper Networks
dddd, 1234
US
Phone: +1 45552
EMail: hschmidtke@juniper.net
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