Automatic Switched Optical Networks

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Automatic Switched Optical Networks

• "Multi-Layer Network Architecture"

Maarten Vissers Consulting Member of Technical
Staff Lucent Technologies email
mvissers_at_lucent.com
Generalised MPLS Summit, October 2001
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Contents

• Introduction
• Network
• Transport Plane's View
• Control Plane's View
• Traffic Network Engineering
• Interfaces
• Control Plane(s)

This presentation includes animated slides. It is
best viewed in "slide show" mode.
This presentation includes some notes in the
notes pages.
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Introduction

• Automatic Switched Transport Network (ASTN) is
  ITU-T's work item to introduce switching
  capabilities in any layer network
• Requirements are specified in Rec. G.807
  (05/2001)
• Architecture for the "Optical Network" (i.e. OTN,
  SDH/SONET) ? Rec. G.8080 (ex. G.ason)
• Distributed Call and Connection Management (DCM)
  ? Rec. G.7713
• First part is a protocol independent
  specification
• Generalized Automatic Discovery Techniques ? Rec.
  G.7714
• Architecture and specification of data
  communication network (DCN)? Rec. G.7712
• Other recommendations will follow to address
  further aspects of switched networks e.g.
  routing, link resource management
• This presentation focuses on the "multi-layer"
  architecture

Note - ITU-T based terminology is used (Rec.
G.805, G.806, G.ason)
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Network and its "Network Elements"
Note - LOVC and HOVC roles can be played by
several layer networks
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Network - Layer Networks
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Network - Layer NetworksClient/Server
relationships
LOVC and HOVC roles can be played by the layer
networks listed
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Layer Network - Transport Plane's View

• Ports
• Support Links via adaptation to server layer
• Adapt client signals
• Monitor native client signals
• Determine QoS to verify SLAs

• Links
• Represent Bandwidth available to Routing
• Define Topology of layer network
• Addition, Deletion, Sizing

• Fabrics
• Flexibility points
• Not always present
• fixed connections
• Possible restricted connectivity
• e.g. no Wavelength or Time Slot Interchange

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Transport Plane - Ports

• 5 Port Types
• Termination/Monitoring and Adaptation
  functionality
• Spanning single or multiple layer networks
• Monitoring service signal
• Non Intrusive Monitor (NIM)
• Tandem Connection Monitor (TCM)
• Port Management
• Reporting mode
• Connectivity verification
• Error detection
• Protection Switching

To/From USER
To/From USER
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Transport Plane - Connections

• Native
• port B to port B'

• Hybrid
• any other, e.g. B to A', B to C', A to B', ...

• Client
• port A to port A'
• port C to port C'

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Layer Network - Control Plane's View

• SNPs
• Abstraction of CP and TCP CTP and TTP
• Extremity of Sub Networks
• Extremity of Links

• Links
• Represent Bandwidth available to Routing
• Between two SNP Pools
• Define Topology of layer network

• Sub Networks
• Abstract. of specific Char. Information Routing
  Domain
• Fabric is lowest level Sub Network
• Between two or more SNP Pools
• Degenerate SN
• set of fixed connections

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Control Plane - Sub NetworkSub Network
Controllers

• Each sub network has an associated Sub Network
  Controller (SNCr)
• SNCrs within one layer network communicate with
  each other for the purpose of connection control
  (routing)
• SNCrs can be located in 3 different nodes
• network element (NE)
• local processor (LP)
• centralised processor (CP)
• SNCrs of client and server layer networks do not
  communicate with each other
• if communication between a layer network and its
  server layer network is required, it is performed
  via a third component

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Control Plane - Sub NetworkSNCr Hierarchy

• SNCrs within one layer network can be organised
  with peering relationship and/or hierarchical
  relationship

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Control Plane - Sub NetworkSNCr Communications

• All SNCrs in a network communicate via the
  Signalling Communication Network (SCN)
• SCN is a application of the general Data
  Communication Network (DCN)
• SCN is an IP-based transport network
• SCN uses Routers and Router functions within
  Transport NEs
• SCN has build in protection switching
• Backup connections between SNCrs must be present
  to guarantee restoration performance when e.g. a
  cable is cut
• MPLS may be deployed to implement protected
  connections in the SCN
• MPLS OAM (draft Rec. Y.1710/Y.1711)
• MPLS Protection Switching (draft Rec. Y.1720)

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Control Plane - Sub NetworkSNCr Communications
IP/MPLS signalling for DCN/SCN
ODUk signalling
LOVC signalling
HOVC signalling
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Control Plane - (Sub) NetworkCall Controller

• Call Controllers are located at the "edges" of
  the Network
• Call Controllers negotiate call details with the
  User requesting the call
• Once a call is accepted, the Call Controller
  forwards the call request to a Sub Network
  Controller in its layer network
• Call Controllers can be located in a
• network element (NE)
• local processor (LP)
• Call Controllers of client and server layer
  networks do not communicate with each other
• Call Controllers of a layer network do not
  communicate with SNCrs in its client or server
  layer networks

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Control Plane - LinksParallel and Serial
composition

• Parallel composition represents partitions within
  the subnetwork e.g. component links for
• one or more Virtual Private Networks (VPN)
• public network

• shared risk group
• similar propagation delay
• similar administrative cost
• similar server layer protection type
• adaptive or fixed rate

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Control Plane - LinksParallel and Serial
composition

• Serial composition represents link connections
  through
• non-switched subnetwork
• switched third party subnetworks providing nailed
  up soft permanent connections between SNPs at
  edges

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Traffic Network Engineering

• Traffic engineering (TE)
• Put the traffic where the bandwidth is
• (Sub-)second/minute time scale
• Network Engineering (NwE)
• Put the bandwidth where the traffic is or is soon
  expected to be
• 15 minute/hour/day/week time scale
• Network Planning (NP)
• Put the equipment, fibers and bandwidth where the
  traffic is expected to be in the future
• Month/quarter/year time scale

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Traffic Engineering (TE)

• The process concerned with optimally routing of
  signals over existing links in a layer network
• More specific Optimally assigning available
  bandwidth to requests (to the network) for
  bandwidth.
• It is an intra layer network process
• TE process in each layer network
• discovers the links created by network planning
  and engineering
• advertises the links and their bandwidth
  utilisation
• manages (set-up, release, modify) connections in
  the layer network i.e. processes incoming calls
  for native and client connections
• restores high grade connections on signal fail
  or signal degrade of the connection
• It is implemented by the Sub Network Controllers
  within the layer network

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Network Engineering

• The process concerned with optimally selecting
  topology and bandwidth in a layer network, based
  on
• (pro-active) traffic demands expected between any
  two locations in the network and
• (re-active) the actual traffic demand
• It is an inter layer network process
• NwE process in each layer network
• advertises the nodes and their ports within the
  layer network
• monitors the layer network and determines if/when
  a new (topological) link should be added or an
  existing link should be modified or released,
  based on the network provider's policy
• determines best set of connections between ports
  in the layer network
• requests those connections to be set up by its
  server layer networks i.e. generates outgoing
  calls for client connections
• It is implemented by the (distributed) Network
  Engineering Controllers (NEC) within the layer
  network

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Network Planning

• The process concerned with optimally selecting
  equipment, fiber medium and bandwidth based on
• expected traffic growth, also taking into account
  inherent uncertainties
• service levels (availability, service delivery
  times)
• total network cost (capex and opex)
• NP process is a multi layer network process
• Physical fiber infrastructure and topology
• Logical architecture and topology
• hierarchical levels
• ring / mesh / star
• granularity
• It is implemented by off-line planning algorithms
  and tools
• quantitatively evaluate alternatives
• dimensioning
• cost calculations, business modelling

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Network with SNCr's, CallC's and NEC's
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Interfaces - Types

• Interior Network Node Interface (I-NNI)
• within operators administrative domain
• supports set up and control of connections across
  ASON network
• presents full topology/routing information
• Exterior Network Node Interface (E-NNI)
• between operator administrative domains
• between I-NNI areas within operator's admin
  domain (scalability)
• supports set up and control of connections across
  ASON network
• presents reachability and summarized address
  information
• User to Network Interface (UNI)
• between user and network domains
• supports call requests from User
• Layer Network Interface ? also a UNI
• between client and server layer networks
• supports call request from client layer's network
  engineering controller

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Interfaces - Layer Networks Links

• Each component link in a layer network has an
  associated Interface type (I-NNI, E-NNI, UNI)
• One link with multiple component links may have
  multiple interface types associated
• e.g. 1 component link with UNI, and 3 components
  link with I-NNI
• A physical interface may encompass multiple layer
  networks
• e.g. STM-4 interface may support HOVC and LOVC
  layer networks
• A link in one of the layer networks in the
  physical interface is independent of a link in
  one of the other layer networks in the physical
  interface
• e.g. HOVC link may be a UNI and LOVC link may be
  a E-NNI

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Interfaces - Layer Networks LinksExample
LOVC PN
LOVC Link
LOVC VPN 1
UNI
I-NNI
LOVC VPN 2
I-NNI
STM-N Physical Interface
HOVC Link
PC
HOVC PN
HOVC Permanent Connection non-switched
UNI
I-NNI
Component Link
HOVC VPN
PN Public Network VPN Virtual Private Network
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Control Plane(s) - 1 or N

• How many control planes are present in an ASON
  network?
• Just a matter of semantics...
• 1 control plane with N TE instances (1 per layer
  network)
• N control planes (1 per layer network) with 1 TE
  instance per control plane
• i.e. do you prefer to wrap the box, or do you
  prefer to wrap each piece within the box
  individually

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Control Plane(s) - Implementation

• The ASON specification is a functional
  specification
• Multiple implementation are envisaged to concur
  in the network e.g. components in an
  implementation
• are identical to components in functional
  specification
• encompass multiple components in functional
  specification
• Control plane implementations targeted for small
  networks may "integrate" functional components
• Control plane implementations targeted for large
  networks may follow more closely the functional
  components structure
• One size doesn't fit all

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• THANK YOU

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Layer Network Overview
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Traffic EngineeringSNCr functions
0..N
Policing Agent
0..N
1..N
Policing Agent
Neighbour Discovery
Route Table Construction
Route Table Construction
Neighbour Discovery
0..N
Link Resource Manager
0..N
Link Resource Manager
Route Table
Route Table
Route Table Update
0..N
0..N
Connection Admission Control
Connection Admission Control
Connection Controller
Connection Controller
Connection Point Status
SubNetwork Controller
Protocol Controller