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Carriers Service Framework and
Associated UNI Requirements
Yong Xue
[email protected]
UUNET/WorldCom
12/15/2000
49th IETF
Document and Authors
Internet-Draft: <draft-many-carrier-framework-uni-00.txt>
Yong Xue , Daniel Awduche
Monica Lazer, John Strand, Jennifer Yates
Larry McAdams
Olga Aparicio, Roderick Dottin
Rahul Aggarwal
12/15/2000
49th IETF
UUNET/WorldCom
AT&T
Cisco
Cable & Wireless
Redback Networks
About This Document




Contains the carrier optical service framework and
major requirements developed by OIF Carrier Study
Group
These requirements have been used to guide OIF
UNI1.0 development and liaisoned to T1X1.5 and
ITU SG 13 as input to ITU G.Ason development.
Still a work-in-progress document. Addressing issues
of most concern in carriers community and not meant
to be complete and comprehensive at this stage.
Cover more than just IP client
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Carriers Major Concerns
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Viable optical business and service models
UNI and optical connection requirements
Network reference models and support
Security is a big concern: resource and access control
Control plane functions w.r.t UNI
Scalability
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Carriers Objectives
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Promote a standardized optical control plane with its associated
interfaces and protocols to achieve multi-vendor/multi-carrier
interoperability.
Provide rapid automatic end-to-end provisioning of optical
connection across one or more optical networks.
Support different service and business models including
“branded” services, bandwidth-on-demand services , and Optical
VPN (OVPN).
Support multiple different client signal types, including IP, ATM,
PDH PL, SONET/SDH, and transparent signals
Promote policy-based call acceptance, peering policies and
access/resource control.
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Carriers Objectives
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Support the scalability both at node and network level: several
thousands of ports per node and hundreds of switch nodes per
network.
Provide restoration, diverse routing and other Qos features
within the control plane on a per-service-path basis.
Reduce the need and cost for carrier developed OSS software
development
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Optical Network
Optical Lightpath
ED
Sub-rate
Connections
ED
ONE
ONE
Optical Service Path
ONE
ONE
ED
ED
ONE
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: Client Edge Device
: Optical Network Element
Sub-rate
Connections
ONE-SR
Optical Lightpath:
Optical Service Path
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: ONE-to-ONE
: ED-to-ED
Optical Network
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Major Components
 Optical Network Elements (ONE): OXC, OADM
 User Edge Device (UED): IP Router, ATM, FR, SONET
 Sub-networks
 DWDM Optical Line System (OLS)
Network Access Methods
 Cross-office (co-located)
 Inter-office (remote)
 Via third-party carrier
Abstract Model: A set of ingress/egress ports and a well-defined
set of p2p optical connection services.
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Basic Optical Service Models
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Provisioned Bandwidth Service (PBS)
 “Point and click” and static near-real-time provisioning through
management interface (via NMS or OSS)
 Client/Server relationship between clients and optical network
 Customer has no network visibility and depends on network
intelligence.
Bandwidth on Demand Service (BODS)
 Signaled connection request via UNI
 Dynamic and real-time provisioning in seconds or sub-seconds
 Customer has no, limited or full network visibility depending
upon interconnecting and control model used
 Rely on network or client intelligence based on the
interconnecting and control model used
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Basic Optical Service Models
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Optical Virtual Private Network (OVPN)
 Customers contract for specific set network resources such as
link bandwidth, wavelength, and/or optical connection ports.
 Closed User Group (CUS) and virtual network
 Optical connection can be based on signaled or static
provisioning
 Customer may have limited visibility and control of contracted
network resources
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Optical Connection Services
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Service Definition:
 A fixed bandwidth connection between an ingress port and
an egress port across the optical transport network.
Optical Connection Behavior Defined by its Attributes:
 identification-based: unique connection ID, contract ID, user
group ID, source and destination identifiers (address, port,
channel and sub-channel)
 characteristics-based: framing ( type, bandwidth,
transparency, directionality), priority, protection (1+1, 1:n,
unprotected, etc.), scheduling and service level.
 Routing-based: diversity
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Optical Connection Services
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Optical Connection Operations
 Requests to create, delete, modify and query an optical
connection
 Only non-destructive attribute modification is allowed.
 A status code should be returned for each operation request.
 Same functions should be available via management
interface
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Service Requirements
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Service Type and Granularity
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SONET/SDH: STS-n/STM-m
 OC-48/STM-16 & OC-192/STM-64
 OC-768/STM-256
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Ethernet: 1Gb/s E, 10Gb/s E (LAN and WAN mode)
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PDH: DS1/E1, DS3/E3, …
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Other Choices
 Sub-rates multiplexed interfaces (both channelized and
concatenated)
 G.709 digital wrapper,
 selectable rates interfaces,
 composite interfaces
Interface Type vs. Service Type
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Service Requirements
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Addressing Schema
 Separation of client network and optical network address
space
 Provisioning based on the client address or names, including
IP, NSAP and E.164
 Address resolution and address translation service should be
provided by the optical network.
Qos Service Mapping from SLA Contract
 Service provider has flexibility to map different class of
services (COS) to its own set of priority, protection,
restoration parameters.
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Sub-Rate Service Framework
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Wavelength (Lambda) switching at DWMD channel rate ( OC48/STM-16 and up) in optical domain.
Sub-Rate:
 switched at less than 2.5Gb/s switching in the electrical
domain
 Sub-rate extension to UNI: UNI-SR
 Separate process for ONE-SR
ONE-SR
 Multiplexing/demultiplexing
 Mapping and adaptation
 Possible implementation: separate box or software process
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Sub-Rate Service Framework
Optical Service Path
Optical Lightpath
ONE
ONE-SR
ED
(STSmN,
STM-N,
VC-K,
VT-X)
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UNISR
UNI
>= 10 Gb/s
<= 2.5 Gb/s
<= 2.5 Gb/s
Granularity
<=2.5 Gb/s
>= 2.5 Gb/s
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Granularity
>=2.5 Gb/s
Network Reference Model
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An Optical Network Can be Decomposed into Three Logical Network
Planes
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User Data Plane (U-Plane)
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Control Plane (C-Plane)
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Management Plane (M-Plane)
Each Logical Network Plane Consists of
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A plane-specific set of networking functions
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A transport network
Optical Networking Function
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optical connection routing
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optical connection switching
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optical connection multiplexing/demultiplexing
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optical connection protection and restoration
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Carrier Network Reference Model
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Consists of one or more sub-networks
 With equipment from single or multiple vendors
 With equipment based on single or multiple technologies
Interfaces Reference Points
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User-Network Interface (UNI) and Network-Network Interface
(NNI)
Private vs. Public UNI/NNI: Based on trust relationship between
interconnected optical domains
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Data Service Interface (DSI)
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UNI Sub-rate (UNI-SR)
Inter-carrier vs. Intra-carrier model
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Inter-Carrier Network Model
ED
PUB-UNI
ED
PUB-UNI
PUB-NNI
Carrier A
Optical Network
Carrier B
Optical Network
PUB-UNI
ED
ED
Carrier C
Optical Network
PUB-UNI
PUB-UNI
ED
ED
ED
ED
PUB-UNI/NNI
PRI-UNI/NNI
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PUB-UNI
PUB-NNI
PUB-NNI
PUB-UNI
ED
:Client's Edge Device
:Public UNI/NNI
:Private UNI/NNI
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Intra-Carrier Network Model
ED
PUB-NNI
PUB-UNI
3rd Party
Network
PUB-UNI
Vendor A
Optical network
ED
PUB-UNI
ED
DSI
DSI
PRI-UNI
CED
PRI-NNI
Optical
Sub-Network
PRI-UNI
Optical
Sub-Network
PRI-NNI
CED
PRI-NNI
Optical
Sub-Network
DSI
PUB-UNI
PRI-UNI
CED
ED
PUB-UNI
PUB-UNI
ED
CED
PUB-UNI/NNI
PRI-UNI/NNI
DSI
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DSI
:Client Edge Device
ED
:Carrier Edge Device
:Public UNI/NNI
:Private UNI/NNI
:Data Service Interface (ATM, SONET, etc.)
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PUB-NNI
ED
Control Plane Architecture
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Control Plane Functions
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Signaling and Routing
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Resource, end-systems and service discovery
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End-to-end auto optical connection provisioning, tear-down, and
management
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Support direct switching cross-connect provisioning for permanent
connection
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Support various optical connection protection and restoration
schema
Control Plane Function Access Support via:
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UNI
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NNI
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NMS/EMS
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UNI Signaling Model
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UNI-C and UNI-N Control Process
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Functional entities for signaling associated with client-side ED and
network-side ONE.
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Tightly-coupled vs. loosely-coupled.
Signaling Methods
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IN-Band:Signaling messages carried over a logical communication
channel embedded in the data-carrying optical link or channel
between UNI-C and UNI-N
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Out-of-Band: Signaling messages carried over a dedicated
communication channel or fiber path separate from the datacarrying optical link or channel between UNI-C and UNI-N
 In-Fiber vs. Out-of-Fiber
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Third-party Signaling: UNI-C is non-ED resident and directly
communicates with UNI-N of ONE on behalf of ED.
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Service and End-System Discovery
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Service Discovery
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Querying and Signaling to ED available services and parameters
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Support automatic service request and provisioning
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Carried by the service discovery protocol
End-System Discovery
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Auto identification between ONE and ED, and between ONEs
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Link connection state discovery
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Auto address registration/de-registration
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Carried by the service discovery protocol
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Exchange of defined set of local topological and identity
information
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Exchanged information accessible via management interface
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Routing Functions and Models
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Routing Function:
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Dissemination and propagation of reachability, resource, and
topological information.
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Optical connection path computation.
Route Generation
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Static configuration
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Route server
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Dynamic learning via routing protocol
Routing Model
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Overlay, Peer and Augmented
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Carriers are very sensitive to routing model selection due to
security and scalability concerns.
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Configurable and enforceable routing control policy should be
supported at UNI/NNI
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Routing Functions and Models
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Overlay Model
 Optical network and client networks are independent routing
domains
 No routing information exchanged at UNI/NNI
 Required support at both private UNI/NNI and Public
UNI/NNI
Peer Model
 Optical network and client networks are integrated routing
domains and running the same routing protocol
 Full or partial routing information exchanged at UNI/NNI
 Support only allowed at private UNI/NNI
 Some possible scaling issues
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Routing Functions and Models
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Augmented Model
 Optical network and client networks are independent routing
domains
 Only client network reachabilty information carried across
optical network and advertised to other clients.
 An inter-domain routing protocol used at UNI/NNI
 May be supported at both private UNI/NNI and public
UNI/NNI
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Routing Constraint Support
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Diversity
 Shared Risk Link Group (SRLG)
 K-out-of N Diversity
 Hierarchical and Geographic Diversity
(Node/Network/Location)
Channel Grouping
 TDM Multiplexed Sub-channels Bundling
 Wavelength Grouping (Waveband)
Edge Compatibility
 Laser Frequency
 Compatible Adaptation Functions
 User/Peer Group
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Security and Access Control
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Trust Relationship Between Network and Clients as Well as
Between Two Networks
 Trusted vs. untrusted relation
 Distinguish between private and public UNI/NNI interfaces at
network demarcation points.
Policy-Based Control
 Configurable and enforceable policy-based access/resource
control at UNI/NNI Interfaces
 Different policy defined at private and public interfaces
Service Request Authentication and Authorization
Network Resources Information Access Control
Firewall between UNI and NNI
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Questions ?
Thanks!
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