automatically switched optical network

Automatic Switched Optical Network

2nd WDM Hungarian Workshop Budapest, March 27th 2001

Automatic Switched Optical Networks: functionality and architectural components

Roberto ClementeGiuseppe Ferraris

2nd WDM Hungarian Workshop Budapest, March 27th 2001 [email protected]

Optical transport network evolution

è Transparent transport of different optical clientsè Interconnection of different administrative domainsèOptical channel networking and protectionèPerformance monitoring and alarm supervisionèNetwork management

OTNOTNWDMWDM

Main functionality provided by an OTN

Point-to-point systems

yesterdayyesterday

Pre-OTN: OADM ring and point-to-point

systems

todaytoday

Meshed/ring networksInterconnection of

OTN domains

tomorrowtomorrow

Introduction


New requirements for OTN4Fast and automatic end-to-end provisioning4Fast and efficient re-routing4Support of different clients, but optimized for IP4Dynamic set up of connections4Support of Optical Virtual Private Networks (OVPNs)4Support of different levels of quality of service

Automatically Switched Optical Network (ASON)Automatically Switched Optical Network (ASON)More generally, the same requirements can be

applied to any transport network (SDH too)Automatically Switched Transport Networks (ASTN)Automatically Switched Transport Networks (ASTN)

Introduction


An example of SLAWhy ASON?

4 I need to permanently connect my sites (“always on” connection)…

4 I need other connections based on my traffic demands (per usage connections…)


Optical Transport Network

Node ANode B

Node C

“Always on” connectionsPermanent connections

Client equipment are connected to the transport network

The transport network operator sets up the “always on” connections


Without ASON, when traffic grows…Why ASON?


Node ANode B

Node C

WarningToo many packets to

node B

Traffic Traffic grows…grows…


…the customer analyses traffic reports…

Why ASON?


Node ANode B

Node C

A new connection to B is needed


…he contacts the network provider…Why ASON?


Node ANode B

Node C

Connect ports Am and Bn A customer request…


…the job order moves on…Why ASON?


Node ANode B

Node C

Connect ports Am and Bn


…the operator looks for a route…Why ASON?


Node ANode B

Node C

What route?


Why ASON?

Node ANode B

Node C

…the operator looks for a route…What route?


Why ASON?

Node ANode B

Node C

…the route is found


…the route is found and the network is re-configured…

Why ASON?

Node ANode B

Node C


…the new connection is operational!Why ASON?


Node ANode B

Node C


Node ANode B

Node C

With ASON…Why ASON?

Signaling between transport equipment for network discovery

Each network element knows the network topology


…when traffic grows…Why ASON?


Node ANode B

Node C

WarningToo many packets to

node B

Traffic Traffic grows…grows…


…connection-request through the UNI…Why ASON?


Node ANode B

Node C

Connection set up request (A,2,B,4…)

User NetworkInterface

The client equipment request the establishment

of a new connection…

The client equipment request the establishment

of a new connection…


…connection-request is sent…Why ASON?

Node ANode B

Node C

Connection set up request (W,i,X,j,Y,k,…)

…and sends a connection setup request…

…and sends a connection setup request…


…setup request is acknowledged…Why ASON?

Node ANode B

Node C

Setup acknowledgment (W,i,X,j,Y,k,…)

…each switching matrix is configured and the

connection is established

…each switching matrix is configured and the

connection is established


…the new connection is established!Why ASON?


Node ANode B

Node C


Generic requirements for an ASON

4Dynamic and fast provisioning of OCh connections through the optical network

4Different OCh services with different quality degrees

4Client-independent solution4Automate the rules of enforcing SLA

Generic requirements


Two alternative approaches for switched OChs

44Client server (overlay) modelClient server (overlay) modelThe client network (IP, ATM, …) or customer device requests resources (OCh connections) to the optical network (server), but has no knowledge about its internal structure

l ITU G.ASON “Automatic Switched Optical Network”l OIFl ODSIl IETF G-MPLS “Generalized Multi Protocol Label Switching”

44PeerPeer--toto--peer modelpeer modelThe client is only IP and the control plane of the optical network is integrated with the IP control plane

l IETF G-MPLS “Generalized Multi Protocol Label Switching”

Alternative approaches


ASON architecture (logical view)

Optical switch

Transport plane

PI

OCC Control plane

NNI

CCI

Client equipment (IP router, ATM switch, …)

OCC

Optical switch

PI

UNI

NMI-T

NMI-A

Optical switch

OCC

EM/NM

Management plane

CCI: Connection Control InterfaceNMI-A: Network Management Interface for the ASON Control PlaneNMI-T: Network Management Interface for the Transport NetworkNNI: Network to Network Interface

OCC: Optical Connection ControllerPI: Physical InterfaceUNI: User to Network Interface

ASON is an Optical Transport Network (OTN) capable to ASON is an Optical Transport Network (OTN) capable to switch automatically Optical Channelsswitch automatically Optical Channels

General architecture


Supported optical transport services

44Permanent Permanent OChOCh – setup from the management system by means of the configuration of all the involved equipment (possible today)

44Soft permanentSoft permanent OChOCh – setup from the management system using routing capability embedded in the network; it requires routing and signaling at the NNI to establish connections

44Switched Switched OChOCh – setup by the customer/client layer using signaling at the UNI

44Optical Virtual Private NetworkOptical Virtual Private Network44Lambda Lambda TrunkingTrunking

Optical transport services


Control plane

4It carries signaling messages4It represents the transport infrastructure for

control traffic 4It can be either in-band or out-of-band4Its topology can be different from the transport

network topology

Internet developed protocols seem to be the most likely candidates to accomplish the functions

needed to automate the OTNFASHION still have a short look at other protocols

as well (e.g. PNNI)

Control plane


Basic functionality

4Network topology discovery (resource discovery)

4Signaling, routing, address assignment4Connection set-up/tear-down4Connection protection/restoration4Traffic engineering4Wavelength assignment

Functionality


Network topology discovery

4Control plane topology (signaling or control channel network) and transport network topology can be different

4ASON requires both logical and physical topology information

4The discovery can be done by using currently available IP protocols, like OSPF or MPLS, with some extensions

Topology discovery


Network topology discovery (II)

4Physical topology information refers toèNode addressèPort number (or address)èPort connectivity (to both

end devices and neighbor nodes)

è Inside node interconnection scheme

èNumber of portsèBandwidth of each portèLink ID, fiber ID, trunk IDèTrench IDèGrooming channel ID

4Logical topology information refers toèEnd-to-end path

information like working paths, protection/ /restoration paths

èOptical VPNè Information related to TE

(attributes TE) like available bandwidth, quality of service, policy routing information, …

Topology discovery


Switched OCh Resilience

44ProtectionProtection – resources for an alternative route are reserved before a failure occurs

44RestorationRestoration – resources for an alternative route are not reserved before a failure occurs and are found after a failure has occurred (automatic re-rerouting)

Resilience


Basic operations

44SetSet--up up OChsOChs44Modify Modify OChsOChs44Release Release OChsOChs

Connection provisioning

4Example of parameters associated to the set-up OChs operationèEnd pointsèScheduled serviceèScheduled durationèResilienceèPre-emption (priority)


Provisioning options

4Slow vs. fast4On-demand vs. pre-ordered4Guaranteed vs. best-effort

Connection provisioning


Routing and signaling

Internet developed protocols seem to be the most likely candidates

4Routing protocols based on OSPF (or perhaps IS-IS)

4Constraint-based routing4Signaling protocols based on MPLS (LDP, CR-

LDP, RSVP)

Routing and signaling


Several open issues are addressed

4Adaptation of IP developed protocol to ASON

4Transparency (wavelength conversion, monitoring, management, …)

4Sub-rate bandwidth provisioning and traffic aggregation

4Traffic engineering

Open issues under study


Conclusions

4ASON is client independent and it has its own control plane

4All the information required by the client layer are exchanged through the signaling at the UNI

4The signaling and routing protocols allow fast and automatic configuration of the network for provisioning and re-routing purposes

Conclusions

automatically switched optical network

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