Transcript Control plane - E

This teaching material is a part of e-Photon/ONe Master study
in Optical Communications and Networks
Course and module:
Optical Core Networks
ASON, ASTN and GMPLS basics
Author(s):
Piero Castoldi, Scuola Superiore Sant’Anna, [email protected]
This tutorial is licensed under the Creative Commons
creativecommons.org/licenses/by-nc-sa/3.0/
http://www.e-photon-one.org
Outline
• ASON/ASTN architecture



Data plane
Control plane
Management plane
• GMPLS – Introduction
• GMPLS Protocol suite



Routing protocol
Signaling protocol
Link Management protocol
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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ASON/ASTN
Data Plane
Management Plane
Control Plane
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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ASON/ASTN architecture
•
It comprises Data Plane, Management Plane and Control Plane
Management
Plane (MP)
NMS = Network
Management System
EMS = Element
Management System
CLIENT = Client network
OXC = Optical Cross
Connect
NMI-A = Network
Management Interface
(ASON)
NMI-T = Network
Management Interface
(Transport)
UNI-C = User to
Network Interface
(Control)
UNI-T =User to
Network Interface
(Transport))
NMS
Corba/Q3
EMS
NMI-T
(TL-1, SNMP, Q3)
Control plane (CP)
UNI-C
UNI-C
CCI
UNI-T
CLIENT
OXC
OXC
CLIENT
UNI-T
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
OXC
Data plane (DP)
OXCRevision:
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Data plane - Basics
•
•
•
•
•
•
Pure transport of data
In electrical networks it is strictly coupled with the control plane (e.g.
router)
Nodes: “network elements” that may terminate lightpaths or cannot
“read” data flowing (e.g. OXC in transparent networks)
Links: bundle of fibers (typically) that may support WDM transmission
ASON data plane is a special case of ASTN data plane (ASTN may
include electrical transmission at the “data plane” level)
Reference:


ITU-T Rec. G.8080/Y.1304, Architecture for Automatically switched optical
network (ASON), November 2001.
ITU-T Rec. G.807/Y.1302, Requirements for automatic switched transport
networks (ASTN), July 2001.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Data plane
Network Structure and Terminology
C3
C9
Node or
Network Element (NE)
C2
C4
C10
C1
End
system
A
C8
C6
C7
B3
B2
Subnetwork A
B4
B1
Link
B7
Network
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
B8
B6
Subnetwork B
Revision:
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End
system
Z
Data plane
Connection Structure and Terminology
C3
C9
Link Connection
C2
C4
End
system
A
Subnetwork
connection
C10
C1
C8
C6
C7
B3
B2
Subnetwork
connection
B4
B1
B8
B6
B7
Network connection
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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End
system
Z
Control plane and management plane
Motivation
• The purpose of the management and control plane for
optical networks is to provide for the efficient delivery
of highly available, highly reliable communication
services.
• These services consist of a variety of different types of
connections between end users of the optical network.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Network Management definition
Network management is a service that employs a variety of
tools, applications, and devices to assist human network
managers in the control and maintenance of a network.
Network management includes the deployment, integration
and coordination of the hardware, software and human elements
to monitor, test, poll, configure, analyze, evaluate the network
resources to meet the real-time, operational performance and
QoS requirements at a reasonable cost.
The combination of hardware and software used to monitor
and administer a network is called Network Management
System (NMS)
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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Layered Network Management
NMS
Core
EMS
O3
EMS 1
O9
O2
EMS 2
O4
O10
O1
O8
O6
M5
O7
M4
M1
M2
Core Network
M6
M3
Metro SubNetwork 2
Metro SubNetwork 1
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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How do we manage all this?
Divide and Conquer!
• Multiple layers of management





Management functionality in each network element and support on
each communications link
Element management system (EMS): Manages a subnetwork of
the network elements (e.g., OLTs, OADMs, OXCs, etc)
EMSs have communication interfaces (and software agents) to
communicate with.
EMSs in a network are interconnected with a data communication
network (e.g., the OSC can be used for that).
Network management system (NMS): talks to the EMSs to get the
overall view of the network.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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OTN’s Embedded Management Functionality
Questions
How do we know if we are receiving a good
signal?
How do we know if we are receiving the right
signal
What should I send downstream if I don’t
receive a good signal?
OTN
Management
capability
Continuity
supervision

Loss of continuity detection
Connectivity
supervision

Trail trace identification
Maintenance
information

Forward defect indication

Backward defect indication

Backward quality
indication

Performance monitoring

Tandem connection
monitoring
Protection
control

Automatic protection
switching protocol
Management
communications

Reserving part of an optical
support channel for
management and control
communications.
How do I know if the receiver can hear me?
Mechanism or Process
How well can they hear me?
What’s the bit error rate of the received signal?
Signal quality
supervision
In what part of the network did these errors
occur?
How can I control switch over to redundant
transport systems in a timely manner.
How can I communicate with remote
equipment for management and control
purposes?
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Management plane - Information model
• EMSs operate on information models (IM).
• IMs are usually implemented in an object oriented language,
since they have an object-oriented representation themselves.
• Inheritance plays an important role.
• Connection trails are IMs for example that can represent
lightpaths.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Management plane - Management protocols (1)
• Most management systems are master-slave based with “get”
and “set” operations over IMs.
• Additionally, messages can be slave initiated (exception
reports, or alarms, traps)
• The most well-known IP based management protocol is SNMP.
The IM in SNMP is called MIB (management information base)
• Yet most carriers still rely on TL-1 (Transaction Language-1).
TL-1 is a simple ASCII command language.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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Management plane - Management protocols (2)
• The most common management framework is: TMN
(Telecommunications Management Network).
• TMN’s hierarchical management protocol is called: CMIP
(Common Management Information Protocol). CMIP runs over
OSI but has also been defined for TCP/IP.
• In order to be able to manage a network with equipment from
various vendors, a common interface is needed. CORBA
(common object request broker) can be used to enable
communication of software agents.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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ASON/ASTN
Control Plane
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Need for the control plane
A few unanswered questions…
• Inventory and resource management


Neighbor discovery: How do I know who is on the other end of a link?
Global topology dissemination, i.e. how do I know what equipment is in
my network? (Links and switching nodes)
• Dynamic provisioning

Connection request, path calculation, connection establishment: how do
I control (set up and tear down) lots of connections efficiently?
Previously manually configured!
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Control Plane
• It is a parallel network devoted to the transport of routing and signalling
messages (e.g. adjacencies information exchange)
• Each data plane element has a control plane controller
Functional tasks:
• Automatic Neighbor Discovery

Allows a node to determine the identity of each neighboring node and the set of links
that connect them.
• Topology and resource status dissemination

Allows every node to automatically discover the complete network topology and
resources
• Signaling for Connection Provisioning

Allows the establishment and teardown of a path from one end of the connection
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Management and control
• Management systems have significant functionality not addressed in
the control plane

For example performance monitoring
• New control plane functionality supplements but does not replace
important management functions.


Management systems can make use of discovered neighbor and topology
information
Parts of connection processing can be off loaded to the control system.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Networks used by MP and CP
• So-called “Data Communication Network” (DCN)


A means for the nodes to communicate for executing control
and management protocols
Maybe a completely separate communications network, or use
in-band dedicated channels, or a combination of the two…
• Administrative Framework


Uniform addressing scheme for controlled entities
Policy enforcement pertaining to provisioning and restoration
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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Control Plane technology standards
Standard Bodies and Organizations
Charter: Global Telecom Architecture and
Standards
Member Organizations:
• Global Service Providers
• PTTs, ILECs, IXCs
• Telecom equipment vendors
• Governments
Charter: Evolution of the
Internet (IP) Architecture
Charter: Development of Optical
Networking Products and Services
Active Participants:
• ISPs
• Service Provider IP Divisions
• IP/Ethernet Vendors
Member Organizations:
• PTTs, ISPs, ILECs, IXCs
• Optical Networking Vendors
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Charter: Network Management
Over 350 members including
• Service providers
• Equipment vendors
• Software vendors
Revision:
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ITU-T, International Telecommunications Union –
Telecommunications Sector
• Defines architectures and models
• Architecture, Requirements, Models
•
•
•
G.807: Requirements for ASTN
G.8080: ASON Architecture
G.7712: Data Communication Network Arch.
• Discovery
•
•
G.7714: General process and model
G.7714.1: Discovery for SONET/SDH and Optical Transport Network (OTN)
• Signaling:
•
•
G.7713: Distributed Connection Management model
G.7713.1, G.7713.2, G.7713.3 Signaling protocols
• Routing
•
•
G.7715: Routing architecture and requirements
G.7715.1: Link state routing requirements
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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IETF, Internet Engineering Task Force
• Extends MPLS/IP protocols based on generalized interface requirements
• Architecture


GMPLS Architecture (draft)
Generalized Multi-Protocol Label Switching Architectural Extensions
• Link Management

Link Management Protocol (draft)
• Signaling
•
•
•
RFC 3471: GMPLS Signaling Functional Spec.
RFC 3473: GMPLS-RSVP-TE
RFC 3472: GMPLS-CR-LDP
• Routing
•
GMPLS extensions for OSPF-TE (draft)
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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OIF, Optical Internetworking Forum
• Focuses on application of IETF protocols in an overlay model
• Generates implementation agreements
• Signaling/Interface Standards




UNI version 1.0 release 2
External intra-carrier NNI 1.0 (signaling)
Security specifications for the above.
In progress routing
• Interoperability Events!
• Physical Layer Standards

A very successful set of inter-chip specifications (not in our scope here).
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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TMF, Telemanagement Forum
• An number of activities beyond our scope…
• MTNM (Multi Technology Network Management)




Business Agreement - TMF513 (requirements)
Information Agreement - TMF608 (technology independent info
models for management purpose)
Solution Sets - TMF814 (CORBA), XML to come
Currently working on management of control plane
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
25 (53 )
GMPLS
Generalized Multiprotocol
Label Switching
Introduction
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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MPLS Network
Label Switching Routers
Edge Label Switching
Routers
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
GMPLS Rationale
• Need some control plane for OXCs
• Similarities between optical channels and traffic engineered LSPs suggest to
use MPLS principles for OXCs
• MPLS control plane is standard and IP-centric and the label switching concept
is very powerful
• Support traffic engineering functions
• Idea of MPLS can be extended to more than just streams of packets.
• Therefore, a concept has been developed called “Generalized MPLS”
• Interoperability among diverse devices (routers, switches, ADMs, OXCs etc.)
• Provide standards based, multi-vendor interoperability within an optical
transport network
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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LSR/OXC and LSP/lambda commonalities
• LSR/OXC:

Data plane driven by a switching table
LSR: (input interface, ingress label)  (output interface, egress label)
• OXC: (input interface, ingress )  (output interface, egress )
•

Switching independent of switching unit payload
LSR & OXC switch based on Label or Lambda
• do label swapping in MPLS, while do not need to recognise packet
boundaries or process packet headers in the case of OXC
•
• LSP/lambda:
unidirectional and point-to-point
Same label/lambda cannot be allocated twice on an interface

Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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From MPLS to GMPLS
Use case example
• Each switching element (OXC) is the equivalent of
a LSR
• Lightpaths are considered the equivalent of LSPs
• Wavelengths and switch ports are considered
equivalent to labels and router ports
• Optical circuit provisioning similar to MPLS traffic
engineering via Explicit routing
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Network
Lambda
Switching
Router
OLSR
Lambda
Switching
Router
Lambda Switching
Edge Router
Lambda Switching
Edge Router
Lambda
Switching
Router
Lambda
Switching
Router
Lambda
Switching
Router
MPL(ambda)S Domain
Lambda Switching
Edge Router
Fiber with WDM
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Optical Label Switch Router (OLSR)
IP Routing and
Signaling
IP Routing and
Signaling
OXC
DWDM
DWDM
OCP
• tightly-coupled OCP and OXC creates an Optical Label Switch Router
• runs IP and MPLS protocols - MPLaS, GMPLS
• switches at Fiber and Lambda Level
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Three classes of OXCs
F-OXC
WR-OXC
WT-OXC
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Fiber-to-fiber
Wavelength
routing
Wavelength
translating
Revision:
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GMPLS: General features
• MPLS has been extended to include other LSR types whose forwarding decisions are not
based on packets rather are times slots, wavelengths or physical port numbers.
• Hence the notion of LSP has been generalized to:
FSC (fiber switch capable) LSP,
 LSC (Lambda Switch Capable) LSP,
 TDM LSP.

• LSP must start and end on LSR of the same type
• New forms of labels are required (also called generalized label) characterized by (see also
next slide):
link protection type,
 LSP encoding,
 LSP payload.

Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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G-MPLS Label Request
• Example shown is carried in RSVP PATH message
• Link Prot. (Protection) Type
• desired protection scheme of link
• e.g. 1+1, 1:N, ring, etc.
• LSP Encoding Type
• encoding of LSP
• e.g. GE, Lambda, SONET, etc.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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G-MPLS Label
• Example shown is carried in RSVP RESV message
• Link ID
• identifies which component link (out of several possible) that label
will be allocated on
• Label
• different formats for fiber, waveband, lambda, TDM and packet
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Some G-MPLS Label Formats
SDH
Wavelength
Waveband
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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Interfaces in a GMPLS LSR (1)
• Packet switch capable (PSC) interfaces

They recognize IP packets, ATM cells, Frame Relay frames,
Ethernet frames, MPLS frames and can do the forwarding
based on the content of the packet/cell header
• Time division multiplex capable (TDM) interfaces

They forward data based on the data’s time slot that
repeats in a frame. This interface is used in SONET/SDH
cross connects
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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Interfaces in a GMPLS LSR (2)
• Lambda (wavelength) switch capable (LSC) interfaces

They forward data from an incoming wavelength to an
outgoing wavelength. This interface is used in OXCs.
• Fiber switch capable (FSC) interfaces

They forward data from one or more incoming fibers to one
(or more) outgoing fibers. They are used in an OXC that
can operate at the level of one or more fibers.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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GMPLS Issues & Resolutions(1)
•
Data forwarding is now not limited to that of merely
packet forwarding.
• The general solution must be able to retain the
simplicity of forwarding using a label for a variety of
devices that switch in time or wavelength, or space
(physical ports).
=> Generalized Label
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Issues & Resolutions(2)
• Not every type of network is capable of looking into the contents of
the received data and of extracting a label.
• For instance, packet networks are able to parse the headers of the
packets, check the label, and carry out decisions for the output
interface (forwarding path) that they have to use.
• This is not the case for TDM or optical networks. The equipments
in these types of networks are not designed to have the ability to
examine the content of the data that is fed into them.
=> Allows the data plane & control plane to be physically or logically
separated.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Issues & Resolutions(3)
• Unlike packet networks, in TDM, LSC, and FSC interfaces, bandwidth
allocation for an LSP can be performed only in discrete units.
• For example, a packet-based network may have flows of 1 Mbps to 10
or 100 Mbps.
• However, an optical network will use links that have fixed bandwidths:
optical carrier (OC)-3, OC-12, OC-48, etc. When a 10 Mbps LSP is
initiated by a PSC device and must be carried by optical connections
with fixed bandwidths-e.g., an OC-12 line-it would not make sense to
allocate an entire 622M line for a 10M flow.
=> Hierarchical LSPs
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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GMPLS Issues & Resolutions(4)
• Scalability is an important issue in designing large networks to
accommodate changes in the network quickly and gracefully.
• The resources that must be managed in a TDM or optical network
are expected to be much larger in scope than in a packet-based
network.
• For optical networks, it is expected that hundreds to thousands of
wavelengths (lambdas) will be transporting user data on hundreds
of fibers.
=> Forwarding Adjacency - LSP (FA), i.e. a TE link between two
GMPLS nodes whose path transits zero or more (G)MPLS nodes.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Issues & Resolutions(5)
• Configuring the switching fabric in electronic or
optical switches may be a time-consuming
process.
• Latency in setting up an LSP within these types of
networks could have a cumulative delaying effect
in setting up an end-to-end flow.
=> Suggested Label & Bidirectional LSP
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Issues & Resolutions(6)
•
SONET/SDH networks have the inherent ability to perform a
fast switchover from a failed path to a working one (50
milliseconds).
• GMPLS' control plane must be able to accommodate this and
other levels of protection granularity.
• It also needs to provide restoration of failed paths via static
(pre-allocated) or dynamic reroute, depending on the required
class of service (CoS).
=> Reliability - Fault Management
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
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GMPLS Control plane
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Protocol Suite
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Protocol Suite
• Consists of a family of three different kinds of
protocols:
Routing protocol with traffic engineering extensions
 Signaling protocol with traffic engineering extensions
 Link Management protocol

Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Protocol Suite
Routing protocol
•
uses link-state routing protocol between switches to report on link status,
characteristics & constraints

•
•
•
note, below the IP layer
can do path determination with routing protocol or using explicit routing
can use OSPF or IS-IS with TE extensions. Most vendors use OSPF-TE
Routing protocols for the auto-discovery of network topology, advertise
resource availability (e.g., bandwidth or protection type). The major
enhancements are:
1.
2.
3.
Advertising link-protection type
Implementing derived links (forwarding adjacency) for improved scalability
Route discovery for back-up path
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
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GMPLS Protocol Suite
Signaling protocol (1)
• Extended the signaling (RSVP-TE, CR-LDP) to accommodate the
characteristics of TDM/SONET & WDM optical networks.

most vendors use RSVP-TE
• Signaling protocols for the establishment of traffic-engineered
generalized LSPs. The major enhancements are as follows:
1.
2.
3.
4.
Label exchange to include non-packet networks (generalized labels)
Signaling for the establishment of a back-up path (protection Information)
Expediting label assignment via suggested label
Waveband switching support - set of contiguous wavelengths switched
together
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
50 (53 )
GMPLS Protocol Suite
Signaling protocol (2)
• Now CR-LDP or RSVP-TE can be used to request
these new “labels”.




Request a fiber over which to send the packet.
Request the wavelength within the fiber.
Request the timeslot within the wavelength.
Request an MPLS LSP.
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
51 (53 )
GMPLS Protocol Suite
Link Management Protocol (1)
• A new protocol, Link Management Protocol (LMP)
has been introduced to manage and maintain the
health of the control and data planes between two
neighboring nodes.
• LMP runs between data-plane-adjacent nodes and it
is link-technology independent
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
52 (53 )
GMPLS Protocol Suite
Link Management Protocol (2)
• Link Management Protocol does
1.
2.
3.
4.
Control-Channel Management: Established by negotiating link
parameters (e.g., frequency in sending keep-alive messages) and
ensuring the health of a link (hello protocol)
Link-Connectivity Verification: Ensures the physical connectivity of the
link between the neighboring nodes using a PING - like test message
Link-Property Correlation: Identification of the link properties of the
adjacent nodes (e.g., protection mechanism)
Fault Isolation: Isolates a single or multiple faults in the optical domain
Authors: Piero Castoldi
Course: Optical Core Networks
Module: ASON-ASTN-GMPLS basics
Revision:
11/2/2008
53 (53 )