Intra-Carrier Solutions Enabled by the OIF NNI

Erning YeNortel Networks

Reference Network

Metro

E-NNI

E-NNI

E-NNI

E-NNI

E-NNI

E-NNIEMS

EMS

I-NNI

UNI

UNI

Core

Core

Regional

Regional Regional

Metro Metro

Metro

Multiple Control Domains Each domain could be a core, regional, or metro

network. The control inside each domain is independent:• Different signaling control systems (e.g., proxy) with

different protocols (e.g., PNNI, CR-LDP, RSVP, etc.)• Different routing control systems (e.g., centralized or

distributed) with different protocols (e.g., PNNI, OSPF, IS-IS, etc.)

• Different protection and restoration mechanisms.• Different EMS/NMS• Use UNI or NMI to initialize and/or terminate

connection services.• Different addressing scheme and/or space inside

domain. Implementation agreement on E-NNI between domains

provides end-to-end services that are transparent to users.

Sub-network Organization and Routing Areas

Sub-network

E-NNI

Sub-network

Sub-network

Sub-networkE-NNI

Sub-network

RA.1 RA.2

RA.top

RA.2.2RA.2.1

RA.2.2.2RA.2.2.1

RA.2.2.3

NNI Routing – Requirements Accept ITU-T G.7715 routing requirements,

architecture and terminology. Scope of routing area is a consequence of

sub-network organization that is described in G.805 at a given layer.

Subdivision of the network into routing areas where the areas can contain smaller areas. This creates routing levels.

4 levels of routing hierarchy is required by carriers (OIF NNI requirement).

Interoperability between adjacent routing areas is domain-domain routing protocol based on a hierarchical link state protocol.

Sub-network Abstraction and Routing Controller

Abstract nodeCentralized routing control

Abstract TE linksDistributed routing control

Abstract TE linksCentralized routing control

RA.2.2

RA.2.2.1

RA.2.2.2

RA.2.2.3

RC

Abstracted intra-domain link

RC

RCRC

RC

NNI Routing Separation of transport plane and control

plane:• Separated address space for routing controller

and transport nodes• Separated topology for routing controller and

transport nodes Routing control could be centralized or

distributed. Transport sub-network could be abstracted to

be one node or several border nodes with abstract intra-domain links.

Transport routing’s main function is to provide path computation to Connection Management (Control plane). In hierarchical routing, the path is computed at certain routing level.

NNI Signaling

Domain A Domain B Domain C

ClientClientE-NNI E-NNIUNI UNI

SPC Service

SC Service

Call Segment

Network Call Controller

Connection Controller

UNISegment

Sub-networkSegment

Sub-networkSegment

Sub-networkSegment

UNISegment

NNISegment

NNISegment

Call/Connection Separation and Call Segments

Call model is part of ASON architecture (G.8080), G7713 and OIF NNI.

In a multiple control domain environment, the end-to-end call is achieved by concatenating multiple individual UNI, sub-network and NNI call segments.

Each call segment could have multiple connections associated with it (e.g., 1+1 path protection, virtual concatenate connections).

Network call controllers and connection controllers are defined in G.8080 and used in the NNI signaling specification.• NNI call controller is responsible for associating

the call segments of NNI and sub-network• NNI connection controller is responsible for

signaling protocol interoperability

NNI Application – Domain Based Recovery

Call/connection separation and call segmentation by ENNI enables domain based protection and restoration

ENNI can be used to separate rerouting (recovery) domain. Each rerouting domain contains one or more than one call segment (A rerouting domain may contain other rerouting domains).

Each rerouting domain could have its own protection mechanism, e.g., liner protection on ENNI link, APS protection inside one domain, and 1+1 path protection in another domain.

The call controller at ingress ENNI performs redial function in the scope of rerouting domain.

The failure happens in one domain would not cause connection teardown in other domains.

Recovery Example

Client ClientX

E-NNI E-NNI

Client ClientX

E-NNI E-NNI