Concept of Automatically switched Optical Network

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Concept of Automatically switched Optical Network
- Rajesh, JTO
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What is ASON? The automatically switched optical
network is a new generation optical transmission
Network.

• Overview
• Recently SDH optical communication system widely
  used an telecommunication in backbone layer,
  metropolitan layer in access layer in transport
  network. SDH offers first protection and
  excellent management performance.
• with the development of telecommunication
  network and increasing user demands some problems
  in SDH systems appear more than more serious such
  as low bandwidth utilize and monotonous
  protection.

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• ASON just come to solve the above problems
• The ASON is an optical transport network
  composed of ASON Network elements. ASON
  performance signaling transmission and switching.
  These NEs can store the topology, routing
  information of the whole network, automatically
  create and remove services through signaling.

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What is ASON / GMPLS
ASON Automatic Switched Optical Network,
Requirements defined by ITU-T. GMPLS Generalized
Multi-Protocol Label Switching, A series
protocols (LMP, RSVP-TE, OSPF) defined by IETF.
NMS
MP (Manage Plane)
NMI
NMI
Network Management Interface
OCC
OCC
CP (Control Plane)
ASON/GMPLS Introduces control plane to ON. Its
the first time to adopt dynamic switching
function. Distributed control plane is the trend.
OCC
NNI
OCC
OCC
E-NNI
UNI control
Connection Control Interface
The purpose of the control plane is to Enhance
Network Reliability and Stability Lower Network
TCO(Total Cost of Ownership) Simplify Network
Operation
CCI
CCI
TP (Transport Plane)
NE
NE
NE
NE
NE
UNI data
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• The Logical Architecture of an ASON can be
  divided into 3 planes
• Transport Plane
• Control Plane
• Management Plane
• The Transport Plane contains a number switches (
  optical or otherwise) responsible for
  transporting user data via connections. These
  switches are connected to each other via PI
  (Physical Interface).

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• The Control Plane is responsible for the actual
  resource and connection management within an ASN
  network. It consists of a series of OCC (Optical
  Connection Controllers), interconnected via NNIs
  ( Network to Network Interfaces).
• These OCCs have the following functions
• Network Topology discovery (Resource discovery)
• Signaling, Routing, Address Assignment
• Connection Set-up/Tear-down
• Connection protection/restoration
• Traffic Engineering
• Wavelength assignment

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• Management Plane is basically a complement plane
  of control plane. It maintain the transport
  plane,
• the control plane and the whole system.
  Its main functions are as follows-
• 1- Performance management
• 2- Fault management
• 3-Configuration management
• 4- Security management

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How does ASON/GMPLS work ?

• Automatic Resource Discovery (LMP)
• Lower OPEX
• Mesh Networking (OSPF)
• Improve resource utilization
• Automatic Restoration (RSVP)
• Enhance reliability

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Where does ASON/GMPLS work
Inter-city Network

• Mesh networking improves resource
  utilization
• Plug play
• Fast expansion and upgrade
• SLAs

Optical Transport Network
Metro/Regional Network
IP Core
Router
Edge layer
ASON node
Internet
Traditional Voice Service
VPN
3GNGN
IPTV
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The Need for ASON

• In an optical network without ASON, when-ever a
  user requires more bandwidth, a new connection
  has to be requested and the service provider has
  to manually plan and configure the route in the
  network.
• This is not only time consuming, but also wastes
  bandwidth when the user economically uses the
  connection.The bandwidth demand is going to
  increse with every momemts IT has become
  precious resource.We have the expectations from
  future optical networks that they will be able
  to efficiently handle resources as quickly as
  possible .

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The Need for ASON

• ASON will be able to fulfill the requirements for
  the newer generation of optical networks such as
• Fast and automatic end-to-end provisioning
• Fast and efficient re-routing
• Support of different clients, but optimized for
  IP
• Dynamic set up of connections
• Support of Optical Virtual Private Networks
  (OVPNs)
• Support of different levels of quality of service
  
• (These requirements are not restricted to optical
  networks and can be applied to any transport
  network (including SDH Networks)

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Perfectly inter-working with traditional SDH
network
Intelligent circuit
Virtual TE-link
NMS T2000
ASON Network
Traditional Network
ASON NE
Traditional NE

• Hybrid Network of ASON network and traditional
  MSP-Ring
• Unified NMS of ASON NE and legacy NE
• E2E service pointclick provisioning between
  traditional and ASON NE by Unified NMS
• The timeslot of ASON NE can be configured as
  static circuit
• Supports virtual TE-link

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Supported optical transport services

• Permanent OCh- Permanent connection is a service
  
• connection computed before hand and created
  through NM.
• The traditional SDH connections are permanent
  connection.
• Switched OCh-Switched connection is a service
  connection requested by a terminal user like
  Router and then created in the ASON control plane
  through signaling at the UNI
• Soft Permanent connection -.setup from the
  management system using routing capabilities
  embedded in the network. It requires routing and
  signaling at the NNI to establish the connection.
• Optical Virtual private Network
• Lamda trunking

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• Resource Reservation
• The time slot created with ASON Services
  are managed by the ASON software and cannot be
  used by the any software to create permanent
  connection.
• Level Switching Path (LSP)
• The LSP is the path of ASON services
  passing through in ASON to create ASON services
  is to crate LSPs.
• Control Channel (CC)
• Control channels are created and
  maintained between adjacent nodes by link
  management protocols (LMP). Control channels
  divided into two types-
• In fiber Control Channel- Usage DCC channel (D4
  to D12) and can be discovered automatically.
• Out of fiber Control Channel- Usage the Ethernet
  link and need manual configuration.

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High Reliability Control Plane control channel
backup
In-Band (D-byte)
DmDn
DmDn
DmDn
DmDn
DmDn
NMS
DmDn
DmDn
DmDn
Out-of-Band (DCN)

• Supports in-band (D-byte) and/or out-of-band
  control channel.
• Provides 11 stand-by for control channels when
  both in-band and out-of-band are deployed.
• The working channel will switch to the backup one
  in case of working channel failure.

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• Control Link- Controls links are detected and
  maintained by OSPF protocol. All ASON NEs get
  the control topology of the network.
• Traffic Engineering Link (T E Link)- T E Link is
  the traffic engineering link. The ASON, NEs sends
  its bandwidth information to other ASON NEs
  through the T E Link to provide for data route
  computation.
• Rerouting -rerouting is means of resuming
  services .when an LSP is disconnected, the source
  node queries and finds a best route to resume
  services.
• Rerouting Lockout -rerouting is not required
  after failure of LSP in some cases then we need
  rerouting lockout
• Rerouting Priority -when several LSPs have the
  same source node reroute simultaneously ,the LSP
  of higher priority reroutes first and has more
  possibility to reroute successfully.

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• Shared risk link group (SR LG) -fibers in the
  same optical cable have the same risks, when the
  cable is cut ,all fibers are cut. therefore ASON
  services should not be rerouted to another link
  that has the same risk.

Topology Auto-Discovery

• Control Topology Auto-Discovery -after the
  fibers in an ASON network are connected
  correctly ,each ASON NE discovers control links
  automatically through OSPF and floods its own
  control link to the whole network.
• Service Topology Auto -Discovery -After an ASON
  NE creates a control channel between neighbors
  NEs through LMP,TE link verification can be
  started. Each ASON NE floods its own TE links
  to the whole network through OSPF-TE. Each NE
  then gets the network wide TE links. this is
  network wise service Topology.

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Control topology auto-discovery
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Service topology auto-discovery
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End-To-End Configuration

• The ASON supports both SDH permanent connections
  and end-to-end
• ASON services. To configure an ASON service, we
  only need to
• specify its source node, sink node, bandwidth
  requirement and
• protection level. Service routing and cross
  connection at intermediate
• nodes are all automatically completed by the
  network.
• As compared with the service configuration of the
  SDH network, it fully utilizes the routing and
  signaling functions of ASON NEs and thus it is
  convenient to configure the service.

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Provide Multiple levels of service SLA
Index Diamond Gold Silver Copper Iron
Service level
Protection scheme Permanent 11 Protection 1 1 Protection Restoration 1 1 Protection Virtual Ring Protection Virtual Ring Protection Restoration Dynamic Restoration Pre-Calculating Restoration Shared Mesh Restoration None None
Description Provide permanent protection for service when network resource is utilizable Performs as protection most of the time, if protection is invalid, restoration works Real-time restoration of service, no need of standby resource - -
Index Protection time lt50ms Protection timelt50ms Restoration timelt2s Restoration timelt2s - -
BW Utilization low Medium High Very high Highest
Revenue Very high High Medium low Lowest
Reference only , according to different
networks fibers cuts , the time is different
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• Different kinds of service for different
  customers needs.
• Protection and restoration combine for multi
  failures,
• improves the reliability
• Supports High and Low Restoration Priority
• Hitless interchanging on line between SLAs

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DIAMOND SERVICE (PLATINUM SERVICE)
Diamond services have the best protection
ability. When there are enough resources in the
network, Diamond services provide a permanent
11 protection ASON/GMPLS based restoration.
Diamond services are applicable to voice and
data services, VIP private Line, such as
Banking, Security and Aviation.
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Diamond Service Permanent 11 Protection
NMS
Working Path
Protection Path

• Any change of resource will be indicated on the
  NMS immediately
• Provide permanent protection for service when
  network resource is utilizable
• The highest quality private-line solution
  99.9999

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Diamond Service - 11ProtectionRestoration
NMS
Working Path
Protection Path

• Any change of resource will be indicated on the
  NMS immediately
• Provide once 50ms protection and multi
  restoration, Anti multi fiber-failures

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Diamond Service - 11 Protection
NMS
Working Path
Protection Path

• Any change of resource will be indicated on the
  NMS immediately
• Provide 50ms protection for once fiber-failure

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GOLD SERVICE
Gold services are applicable to voice and
significant data services. Compared with diamond
services, gold services have greater bandwidth
utilization. When a fiber on the path of a gold
service is cut, the ASON triggers MSP switching
to protect the service at first. If the multiplex
section protection fails, The ASON triggers
rerouting to restore the service.
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Gold Service Virtual Ring Protection
Restoration
NMS
Virtual Ring
Protection Route
Restoration Route
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Gold Service Virtual Ring Protection
Restoration

• When the first fiber cut happens, virtual ring
  will perform protection(lt50ms)
• When the second fiber cut happens to the same
  virtual ring, service will be restored in 2
  seconds.
• Provide once 50ms protection and multi
  restoration, Anti multi fiber-failures
• Any change of resource will be indicated on the
  NMS immediately

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SILVER SERVICE
Silver services, the revertive time is hundreds
of milliseconds to several seconds. The silver
level Service is suitable for those data or
internet services that have low real-time
requirement. Silver services are also called
rerouting services. When an LSP failure, the ASON
triggers rerouting to restore the service. If
there are not enough resources, service may be
interrupted.
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Silver Service No Dedicated Resource is Needed

• When service is fall down, it will be restored to
  the new route. Service rerouting can be set as
  Revertible or Non-revertible.
• All restoration service can be treat as High or
  Low priority,
• When resource is limited, High priority
  service is guaranteed to be reroute
• Rerouting can be locked / unlocked.
• Improves the bandwidth utilization dramatically
  and provide controlled networking

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Silver Service Pre-Calculating/Preplan
Restoration
MDS6600
Preplan path
iManager T2000
Rerouting according to the preplan path
preplan path
original path
rerouting path

• Controllable and predictable circuit resource
  managing

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Silver Service Shared Mesh Restoration
iManager T2000
MDS6600
shared restoration resource
Bandwidth Resource Reserved Path
VC4
Rerouting according to the reserved path
Insure service restoration 100 successfully
reserved path
original path
rerouting path

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Silver Service Shared Mesh Restoration

• The pre-defined path will be dispatched to nodes
  through the T2000 after simulating by MDS6600

• The pre-defined path will be dispatched to nodes
  through the
• T2000 after simulating by MDS6600.
• The overlapped timeslot resources can share by
  multiple
• reserved routes

• Ensure the success of 100 of rerouting and
  guarantee the
• reliability of rerouting for key services

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COPPER SERVICE
The copper services are seldom used. Generally,
temporary services, such as the abrupt services
in holidays, are configured as copper services.
Copper services are also called non-protection
services. If an LSP fails, services do not
reroute and are interrupted.
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IRON SERVICE
The iron services are also seldom used.
Generally, temporary services are configured as
iron services. For example, when service volume
soars, during holidays, the services can be
configured as iron services to fully use the
bandwidth resources.
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Best Effort Rerouting When No Many Directions
Bandwidth availability is improved by reusing
part of the original route
Other Route
Original Route

• When there are not so many directions, Best
  effort rerouting can succeed in finding a route
  to go, so that network reliability is enhanced

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Thanks for patiently viewing
Thanks
ALTTC
OFC Faculty
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