Title: Automatic Switched Optical Networks
1Automatic 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
2Contents
- 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.
3Introduction
- 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)
4Network and its "Network Elements"
Note - LOVC and HOVC roles can be played by
several layer networks
5Network - Layer Networks
6Network - Layer NetworksClient/Server
relationships
LOVC and HOVC roles can be played by the layer
networks listed
7Layer 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
8Transport 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
9Transport Plane - Connections
- 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'
10Layer 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
11Control 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
12Control Plane - Sub NetworkSNCr Hierarchy
- SNCrs within one layer network can be organised
with peering relationship and/or hierarchical
relationship
13Control 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)
14Control Plane - Sub NetworkSNCr Communications
IP/MPLS signalling for DCN/SCN
ODUk signalling
LOVC signalling
HOVC signalling
15Control 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
16Control 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
17Control 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
18Traffic 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
19Traffic 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
20Network 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
21Network 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
22Network with SNCr's, CallC's and NEC's
23Interfaces - 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
24Interfaces - 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
25Interfaces - 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
26Control 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
27Control 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
28 29Layer Network Overview
30Traffic 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