SONET Transmission Products S/DMS TransportNode …npatrick/nortel-sdms-docs/N3RLSQW0.pdf · SONET...

NT7E65DJ 323-1111-150

SONET Transmission Products

S/DMS TransportNode OC-3/OC-12 NE — TBM

System Applications Description

Standard Rel 14 February 2001

What’s inside...

OC-3/OC-12 network element applications

Copyright

1992–2001 Nortel Networks, All Rights Reserved

The information contained herein is the property of Nortel Networks and is strictly confidential. Except as expressly authorized in writing by Nortel Networks, the holder shall keep all information contained herein confidential, shall disclose it only to its employees with a need to know, and shall protect it, in whole or in part, from disclosure and dissemination to third parties with the same degree of care it uses to protect its own confidential information, but with no less than reasonable care. Except as expressly authorized in writing by Nortel Networks, the holder is granted no rights to use the information contained herein.

Nortel Networks and S/DMS TransportNode are trademarks of Nortel Networks. VT100 is a trademark of Digital Equipment Corporation. UNIX is a trademark of X/Open Company Ltd.

Printed in Canada

iii

ContentsAbout this document vReferences in this document v

OC-3/OC-12 network element applications 1-1Access applications 1-1

Applications available now 1-2Applications available in the future 1-2

Point-to-point linear applications 1-3Control shelf 1-4

Add-drop multiplexer linear applications 1-5Add-drop multiplexer single shelf 1-6336-DS1 multishelf terminal 1-7

OC-3 tributaries on OC-12 systems 1-8Linear applications for OC-3 tributaries on the OC-12 TBM shelf 1-9ADM applications for OC-3 tributaries on the OC-12 TBM shelf 1-10

Regenerator application 1-11Network survivability applications 1-12

Route diversity 1-12Bidirectional line-switched rings 1-14Matched nodes on OC-12 rings 1-16

SONET DCC bridge 1-19Provisionable SONET DCC 1-23Reconfigurations 1-24

In-service reconfiguration 1-24Software upgrades 1-25

Hub applications 1-26Carrier serving area hub (future application) 1-26Central office hub (future application) 1-27

System Applications Description 323-1111-150 Rel 14 Standard Feb 2001

iv

Contents

S/DMS TransportNode OC-3/OC-12 NE — TBM Vol 1 323-1111-150 Rel 14 Standard Feb 2001

v

About this documentThis document describes how to use the S/DMS TransportNode products (OC-3, OC-12, and OC-48 network elements) in telecommunications networks. This document covers applications ranging from simple point-to-point systems to sophisticated hub arrangements.

AudienceThis document is for the following members of the operating company:

• strategic planners

• current planners

• provisioners

• transmission standards engineers

References in this documentThis document refers to the following documents:

OC-3/OC-12 TBM• System Description, 323-1111-100

• Software Description, 323-1111-101

• Signal Flow and Protection Switching Descriptions, 323-1111-103

• System Applications Description, 323-1111-150

• Ordering Information, 323-1111-151

• System Expansion Procedures, 323-1111-224

OC-48• System Description, 323-1201-100

• Software Description, 323-1201-101

• Ordering Information, 323-1201-151

• Technical Specifications, 323-1201-180


vi

About this document


1-1

OC-3/OC-12 network element applications 1-

This chapter describes applications of the OC-3/OC-12 network elements (NE) currently available and applications planned for the future.

The need for networking in the interoffice environment originates from the demand for new high-capacity services, and the requirement for effective control and management of services. The present interoffice network structure is based on asynchronous, point-to-point fiber systems that are interconnected at the DS1 and DS3 levels. This network structure requires back-to-back multiplexer configurations and DS1 and DS3 patch panels to physically link the multiplexers and fiber systems. The resulting architecture is built on a rigid interconnection of facilities and does not allow operating companies to effectively manage new services.

Use of fiber in the access or loop network is growing rapidly. Fiber feeders serve carrier serving areas (CSA), buildings, and industrial parks that have customer-located equipment (CLE) installations. The growing demand for DS1 and DS3 services has also triggered the need for fiber.

Access applicationsS/DMS TransportNode products use OC-3/OC-12 network elements for access applications. Networking configurations of the OC-3/OC-12 network elements make them ideal for this environment. Synchronous optical network (SONET) features permit greater flexibility for networking by removing the rigid architectural constraints common to the asynchronous networks previously described. SONET allows greater network survivability, especially with survivable ring and matched node architectures. The current and future OC-3/OC-12 network element applications are listed in the two following subsections. See Software Description, 323-1111-101, for a description of the features available with each configuration of the OC-3/OC-12 network element.

Note: The OC-3/OC-12 network element applications include an extended temperature range capability to meet the requirements of the outside plant environment.


1-2


Applications available nowThe following applications are available:

• point-to-point systems to link high-growth CSAs or broadband/wideband business services to the central office (CO)

• control shelf application to accommodate the operations controller (OPC) when it cannot be placed in a Transport Bandwidth Manager (TBM) shelf handling OC-12 traffic

• OC-3/OC-12 add-drop multiplexer (ADM) single-shelf application to connect the multiple CSAs to the CO

• 336-DS1 multishelf terminal application to enable the OC-12 network element to extract all 336 DS1s from an OC-12 signal

• regenerators for use in interoffice markets

• route diversity used on 1+1 systems that may require a protection path to have a different physical route from the working path

Note: Nortel Networks recommends that no more than four route diverse regenerators be equipped between line terminating equipment (LTE). For applications requiring more than four route diverse regenerators, contact your local or regional Nortel Networks representative.

• OC-12 two-fiber bidirectional line-switched ring (BLSR), used to provide survivable transport of signals in the event of cable cuts and node failures

• matched nodes on OC-12 two-fiber bidirectional line-switched rings (NWK and VTM rings) to provide protected interconnection of rings at the STS-1 level

• SONET data communications channel (DCC) bridge to permit the exchange of operations, administration, maintenance, and provisioning (OAM&P) messages between collocated network elements not connected by fiber

• provisionable SONET DCC to permit the exchange of OAM&P messages between network elements connected by fiber

• in-service upgrades (certain releases and network-element types)

Applications available in the futureThe following applications will be available in future releases:

• CSA hub to concentrate traffic from several CSAs

• CO hub to manage DS1/DS3 traffic from multiple S/DMS TransportNode OC-3/OC-12 systems located in CSA or CLE installations



1-3

Point-to-point linear applicationsAn OC-3/OC-12 point-to-point linear system consists of two terminals that are interconnected through an OC-3/OC-12 optical link in a linear configuration. Each OC-3 terminal provides terminations for DS1, DS3, or STS-1 services, or a combination of these services. Each OC-12 terminal provides terminations for DS1, DS3, STS-1, or OC-3 services, or a combination of these services. A typical example is the connection of a CSA to the CO (see Figure 1-1). The only point-to-point system currently available for OC-3/OC-12 network elements is the 1+1 protection architecture. See Signal Flow and Protection Switching Descriptions, 323-1111-103, for a detailed description of the 1+1 protection scheme.

The OC-3/OC-12 point-to-point system can be applied to lower-growth spans for initial traffic demands. As demand for services increases and broadband services become available, additional OC-3/OC-12 terminal systems can be installed to provide supplementary terminations. As the SONET network evolves, you can upgrade the OC-12 terminal to ADM, ring, or hub configurations. In addition, if the OC-12 capacity become fully used, you can upgrade to the OC-48 network element and use the existing OC-12 network elements as tributary shelves to the OC-48 network element. See Figure 1-2.

Figure 1-1OC-3/OC-12 point-to-point system application

FW-1958 (R8)

DS1DS3

OC-3 or OC-12 DS1DS3

CentralOffice

CarrierServing Area

OC-3 orOC-12

Terminal

OC-3 orOC-12

Terminal

Note: OC-3 tributaries can only be inserted into OC-12 shelves.

OC-3 OC-3

STS-1 STS-1


1-4


Figure 1-2OC-12 TBM connected to the OC-48 network element

FW-0345 (OC12 R13)

Control shelfThe TBM control shelf provides a location for an OPC if the OPC cannot reside in a TBM shelf handling OC-3/OC-12 traffic. The most common use of the control shelf is in ring systems and in OC-3 tributary applications. You can equip an OPC in a terminal, linear, or ring ADM shelf, but placing an OPC in these shelves reduces the number of circuit pack locations available for tributary termination.

DS1

OC-12Terminal

OC-12Terminal

CentralOffice

OC-48OC-48

TerminalOC-48

Terminal

DS3

CentralOffice

DS3

OC-3

STS-1

OC-12

STS-1

DS1

DS3

DS3

OC-3

STS-1

OC-12

STS-1

OC-12



1-5

Add-drop multiplexer linear applicationsThe OC-3/OC-12 TBM ADM network elements provide an interface between two full duplex transport (OC-3, OC-12) optical signals and one or more full duplex tributary signals (DS1, DS3, STS-1, OC-3) at an intermediate point in a linear network (see Figure 1-3). Nonterminated tributary signals are passed through, without regeneration of the signal format or modification to the original bit stream, for transmission to other network elements in the network. Tributary signals that are accessed by the ADM are added (inserted into the OC-3/OC-12 signal) and dropped (extracted from the OC-3/OC-12 signal).

Note: Insert OC-3 tributaries only into OC-12 shelves.

A TBM ADM network element uses four optical interface cards (two primary and two secondary).

You can install any number of TBM ADM network elements in a linear network between two TBM terminal network elements as long as you respect the limits of the operations controller (OPC) span of control. For more information on the limits of the OPC span of control, see the section on the SONET DCC bridge, page 1-19.

For more information on the OC-3/OC-12 ADM applications, see System Description, 323-1111-100.

Figure 1-3OC-3/OC-12 ADM application

FW-0510.1 (tribs R8)

CentralOffice 1

CentralOffice 3

DS3

CentralOffice 2

DS1

OC-3/OC-12Terminal

OC-3/OC-12Terminal

OC-3/OC-12ADM

OC-3OC-12

OC-3OC-12

Note: OC-3 tributaries can only be inserted into OC-12 shelves.

DS3DS1

OC-3

DS3DS1

OC-3

STS-1 STS-1

STS-1

OC-3


1-6


Add-drop multiplexer single shelfThe OC-3 or OC-12 ADM configuration is a 1+1 protected system with integrated optics for two directions of transmission (for example, east and west). The ADM route can contain multiple ADMs allowing traffic to be accessed at all intermediate sites along the route. A typical application for an OC-12 ADM is the interconnection of multiple CSAs along a feeder route, see Figure 1-4. The CO terminates 28 DS1 and 3 DS3 signals from CSA 1, and 28 DS1 and 2 DS3 signals from CSA 2 (a total of 56 DS1 and 5 DS3 signals).

You can extend the ADM route to include new CSAs beyond CSA 2. To upgrade the CSA 2 terminal, in service to the ADM configuration, add the appropriate optics to an existing terminal and upgrade the shelf software. For more information on extending a linear ADM chain, see System Expansion Procedures II, 323-1111-225.

Figure 1-4OC-12 ADM single-shelf application

FW-0015 (tribs)

OC-12

OC-12Terminal

OC-12Terminal

CentralOffice

CarrierServing Area

2

56 DS1

5 DS3

OC-12OC-12

Add-dropMultiplex

CarrierServing Area

1

28 DS13 DS3 28 DS1

2 DS3

2 OC-31 OC-3



1-7

336-DS1 multishelf terminalAn OC-12 signal can carry 336 DS1 signals. A DS1 mapper provides access to 14 DS1 signals. An OC-12 TBM terminal network element can house 12 DS1 mappers, therefore, the maximum number of DS1s that can be interfaced by an OC-12 shelf is 168 (multiply 14 by 12 for a total of 168). To extract the full 336 DS1 signals from an OC-12, two collocated OC-12 TBM shelves are required (see Figure 1-5).

The shelf that terminates the OC-12 from the remote network element is configured as an ADM and interfaces 168 DS1 signals from 6 STS-1 signals. The remaining 6 STS-1 signals pass through to the second shelf. The second shelf is configured as a terminal and can contain the OPC. This shelf also interfaces 168 DS1 signals from 6 STS-1 signals and is connected to the ADM by means of an STS-12 signal.

The ADM shelf contains a pair (working and protection) of OC-12 optical interface circuit packs in the primary position and a pair (working and protection) of OC-12 intra-office optical interface circuit packs in the secondary position. The terminal shelf contains a pair (working and protection) of OC-12 intra-office optical interface circuit packs in the primary position.

Figure 1-5336-DS1 multishelf application

FW-0510.2 (OC12 R13)

CentralOffice 2

OC-12ADM

OC-12Terminal

OC-12168DS1

168DS1

CentralOffice 1

OC-12ADM

OC-12Terminal

168DS1

168DS1

OC-12intra-officeinterface

OC-12intra-officeinterface

336 DS1 336 DS1CNet CNet

Note: The CNet cable is optional.


1-8


OC-3 tributaries on OC-12 systemsThe OC-3 tributary provides an optical tributary interface for OC-12 TBM terminal, linear ADM, and ring ADM configurations, allowing customer-premises equipment (CPE) such as an asynchronous transfer mode (ATM) switch or OC-3 TBM shelves to connect with an OC-12 TBM shelf. OC-3 tributaries on OC-12 systems (see Figure 1-6) are ideal for high-capacity spans on backbone routes. OC-3 tributaries provide the flexibility to handle either DS1, DS3, STS-1 traffic, or mixed DS1/DS3/STS-1 traffic. You can terminate as many as four OC-3 tributaries from four different OC-3 TBM shelves on an OC-12 shelf configured for this application.

Note: Transport Services Shelf (TSS) configurations are not supported. For RadioNode applications, use TBM shelves.

Figure 1-6OC-12 system with OC-3 tributaries

FW-2448(R8)

OC-3 #1OC-3 #2OC-3 #3OC-3 #4

TBMshelf

OC-12

OC-12

••• TBM

shelf

OC-12

OC-12DS1 #1•••

DS1 #n

OC-3 #1OC-3 #2

STS-1 or DS3 #1

STS-1 or DS3 #n



1-9

Linear applications for OC-3 tributaries on the OC-12 TBM shelfIn software releases where OC-3 tributaries were not supported, STS-1 connections were added and dropped at either DS1 or DS3 tributaries supported by the OC-12 TBM shelf. OC-3 tributaries software allows STS-1 connections to be added and dropped into any of the three STS-1 channels carried on the OC-3 tributary circuit pack.

User interface changes to the Connection Manager tool allow the user to specify an OC-3 tributary circuit pack as the add/drop point to an end-to-end connection. The Connection Manager tool recognizes which slots of the TBM shelf are provisioned with OC-3 tributaries and not DS1, DS3, or STS-1 tributaries.

OC-3 tributary circuit packs operate in a 1+1 nonrevertive protection mode. Working and protection circuit packs occupy adjacent slots in the shelf.

STS-3c supportThe signals received by the OC-3 tributaries can be either individual STS-1 signals, or a single STS-3c signal providing a 155 Mbit/s interface for applications such as asynchronous transfer mode (ATM).

Connection services on the OPC and network element support STS-1 and STS-3c connections.

Note: To support incoming STS-3c traffic, provision STS-1 connections on adjacent channels (STS-1 channels 1 to 3, 4 to 6, 7 to 9, or 10 to 12) using the existing Connection Manager tool. See Figure 1-7 for the correct connection of STS-3c signals within an STS-12 payload.


1-10


Figure 1-7Connection of STS-3c signals within an STS-12

FW-2449

ADM applications for OC-3 tributaries on the OC-12 TBM shelfFigure 1-8 shows OC-3 tributaries on an OC-12 ADM shelf. The use of OC-12/STS-12 connections to other TBM shelves allows the system to handle DS1, DS3, and STS-1 traffic as well as mixed DS1/DS3/STS-1 traffic.

Figure 1-8OC-12 ADM application (DS1/DS3/STS-1 traffic)

FW-2304 (TBM R8)

STS-3c #1123

456

789

101112

123

456

789

101112

STS-3c #2

STS-3c #3

STS-3c #4

STS-12 STS-12

OC-12TBM

OC-12

OC-3TBM

OC-3

OC-12ADM

OC-3TBM

OC-3

OC-3TBM

OC-3

OC-12OC-12TBM

OC-3TBM

OC-3

DS1/3,STS-1

DS1/3,STS-1

DS1/3,STS-1

DS1/3,STS-1

DS1/3,STS-1

DS1/3,STS-1

DS1/3,STS-1



1-11

Regenerator applicationThe OC-12 regenerator shelf regenerates the optical signal between OC-12 terminals, linear ADM and ring ADM shelves, and extends the optical route. The distance achievable between network elements depends on the characteristics of the optical link. With the OC-12 interfaces, a system gain of 29.0 dB is typically achievable between regenerators using 1310 nm optics. Regenerator nodes do not process signals or extract the tributaries. Regenerator nodes provide access to SONET overhead and section-level performance monitoring.

Note: OC-12 TBM regenerators are supported for OC-12 route diverse systems only. The regenerator handles only one of the optics channels from the terminal end (either the working or standby channel).

Figure 1-9 illustrates a typical configuration using terminals and regenerators in a point-to-point linear system. The regenerators provide the same function between add-drop multiplexer (ADM) nodes in rings and in linear systems.

Figure 1-9OC-12 regenerator application (point-to-point linear system shown)

FW-0019.1 (TBM)

Working channel/fiber

Protection channel/fiber(diverse path)

OC-12Regenerator

DS1

DS3 OC-12Terminal

OC-12Terminal

DS1

DS3

OC-12Regenerator

OC-12Regenerator


1-12


Network survivability applications Transport network survivability is a major concern to telephone companies operating high-capacity fiber networks. S/DMS TransportNode products are provided with a number of protection applications to prevent the loss of traffic in the event of node or fiber failure. In linear systems, route diversity provides protection in the event of fiber breaks. In a bidirectional line-switched ring, ring topologies provides this protection.

Route diversityOC-3/OC-12 network element configurations support route-diversity protection (see Figure 1-10). These configurations are based on a 1+1 point-to-point OC-3/OC-12 system in which the working and protection fibers are routed separately. Traffic is transmitted along both the working and protection fibers. The two diverse routes can support a different number of regenerators.

By routing the working fiber on a different physical cable from the protection fiber, the traffic is fully protected against cable cuts as well as equipment failures. When a working fiber is cut, the terminal automatically switches to receive transmission from the protection path. With route diversity, the OAM&P communications are protected from node failures and cable cuts.

In Figure 1-10, a fiber cut between the OC-12 terminal (1) and the OC-12 regenerator (5) on the working path causes the traffic and OAM&P communications to reroute to the OC-12 regenerators (2) and (3), then to the OC-12 terminal (4). Traffic reroutes using the protection channel (diverse path). OAM&P communications between the OC-12 terminal (1) and the OC-12 regenerator (5) are restored using regenerators (2), (3), and the OC-12 terminal (4).

A node failure at the OC-12 regenerator (5) on the working path causes traffic and OAM&P communications to reroute to the OC-12 regenerators (2) (3), then to the OC-12 terminal (4). Traffic reroutes using the protection channel.

Note: OC-12 regenerators are currently supported for OC-12 route diverse systems only. Nortel Networks recommends that no more than four route diverse regenerators be equipped between line terminating equipment (LTE). For applications requiring more than four route diverse regenerators, contact your local or regional Nortel Networks representative.



1-13

Figure 1-101+1 route-diversity protection

FW-0019 (TBM)



OC-12OC-12

OC-12Regenerator

(2) (3)

(5)

DS1

DS3 OC-3Terminal

(1) OC-3


OC-3

OC-3Terminal

(2) DS1

DS3


DS1

DS3 OC-12Terminal

(1)

OC-12Terminal

(4) DS1

DS3

OC-12Regenerator

OC-12Regenerator

OC-12 applications only

OC-3 or OC-12 applications


1-14


Bidirectional line-switched rings Two types of OC-12 two-fiber bidirectional line-switched rings (BLSR) are available: the VTM ring and the NWK ring. In a VTM ring, the primary transport interface circuit packs in each ring ADM are OC-12 VTM circuit packs, which support VT bandwidth management (VTM). In an NWK ring, the primary transport interface circuit packs are OC-12 networking interface circuit packs, which do not support VTM.

Note: In releases of this document prior to Release 11, OC-12 NWK rings were referred to as OC-12 TA-1230 rings.

In a bidirectional line-switched ring, the ring ADM nodes are arranged in a closed fiber loop. Adjacent ring ADM nodes are interconnected by two fibers, one for each direction of transmission (see Figure 1-11). The ring configuration can be used in access, intra-LATA, small city, and interoffice periphery applications. The standard allows a maximum of 16 ADM nodes for each ring.

Figure 1-11OC-12 bidirectional line-switched ring

FW-1414

Each fiber carries 6 STS-1 channels of working traffic (STS-1 time slots 1 to 6) and 6 STS-1 channels of protection traffic (STS-1 time slots 7 to 12) to provide shared protection. During normal operation, traffic is carried in both directions on the working channel time slots. In Figure 1-11, traffic traveling from node A to node C by way of node B is carried on any of the working time

6 Working STS-1s/6 Protection STS-1son each fiber

Node A

OC-12NetworkElement

Node B

Node CNode D

OC-12NetworkElement

OC-12NetworkElement

OC-12NetworkElement

Add-droptributaries

Add-droptributaries

Add-droptributaries

Add-droptributaries


OC-3/OC-12 network element applications 1-15

slots (STS-1s 1 to 6) during normal operation. When protection against a failure is required, the affected connections are automatically reassigned to the reserved protection time slots in the opposite direction. If a node or line failure occurs at node B, traffic switches to the protection time slots (STS-1 time slots 7 to 12) on the second fiber to travel the opposite way around the ring to node C by way of node D.

The use of facilities in the ring is maximized because line switching means that only time slots on the spans required to complete a route from origin to destination are assigned to a particular connection. The same time slots on unused spans can be used for other connections. For example, if a connection requires STS-1s 2 and 3 from nodes A to B, STS-1s 2 and 3 are available for other connections on lines B to D, D to C, and C to A.

Note: Any point-to-point connection can use two possible routes, one in each direction around the ring. To maximize the capacity of the ring, assign connections to follow the shortest possible route through the fewest spans.

One ring contains multiple spans. The maximum STS-1 capacity of the ring is the number of spans multiplied by 6. In a VTM ring, each STS-1 can carry 28 DS1 signals or a single DS3 signal. In an NWK ring, each STS-1 can carry 28 DS1s, a single DS3, or a single STS-1 signal within a higher rate SONET tributary, such as an OC-3/OC-12/STS-12. You can configure a maximum of 16 ADMs in a single ring network. If the capacity of one ring is exhausted, you can overlay another ring on the first (each ADM node of the second ring can be collocated with the nodes of the first). These rings can be interconnected by a control network for control purposes.

One OPC span of control supports multiple rings or a mixture of ring and linear systems. The number of rings that can be shared over a span of control is limited by the number of nodes on the ring (maximum 16) and the response-time performance required by the customer.

Note 1: For linear and ring system mixes in the same OPC span of control or under the control of the same OPC, all network elements must run the same software.

Note 2: You can use regenerators in either NWK or VTM rings.

NWK ringIn a NWK ring, all network elements must contain OC-12 networking interfaces. None of the elements can contain OC-12 VTM circuit packs.

In a NWK ring, you can specify connections at the STS-1 or STS-3c levels. You cannot specify connections at the VT level, as you can in a VTM ring. In each span of the NWK ring, the working traffic occupies six STS-1 channels, each of which can carry 28 DS1 signals, a single DS3, or a single STS-1 signal.


1-16 OC-3/OC-12 network element applications

For synchronization, each NWK ring ADM contains ESI cards. In at least one of the NWK ring ADMs, the ESI connect to an external timing source such as a building integrated timing supply (BITS). Each of the other NWK ring ADMs is line-timed. Each line-timed ring ADM takes its timing reference from the incoming OC-12 signal. In each of the line-timed ring ADMs, the ESI cards filter the timing references carried by the incoming OC-12 signal, and provide a 51.84 MHz/s timing reference to the OC-12 networking interfaces.

In each NWK ring ADM, five circuit packs provide ring protection (protection against facility failures and node failures). The five circuit packs are the two OC-12 networking interfaces, the two ring loopback circuit packs, and the overhead bridge circuit pack.

VTM ringIn a VTM ring, all network elements must contain OC-12 VTM circuit packs. None of the network elements can contain OC-12 networking interfaces.

In a VTM ring, you can specify connections at the VT level as well as the STS-1 and STS-3c levels. The ability to perform VT bandwidth management (VTM) allows for efficient use of the facilities around the ring. In each span of the VTM ring, the working traffic occupies six STS-1 channels, each of which can carry 28 DS1 signals, or a single DS3 signal.

For synchronization in a VTM ring, use ESI cards only in ring ADMs to be connected to external timing sources. Each of the other ring ADMs is line-timed. Each line-timed ring ADM takes its timing reference from the incoming OC-12 signal. However, none of the line-timed VTM ring ADMs contains ESI cards, because the OC-12 VTM circuit packs filter the timing references.

Note: Use synchronization-status messaging in rings using line time to ensure network robustness.

In each VTM ring ADM, two OC-12 VTM circuit packs provide ring protection. The functionality of the ring loopback circuit packs and the overhead bridge circuit pack is built into the VTM optics.

Matched nodes on OC-12 ringsThe matched-node feature provides a means to interconnect two rings in a survivable manner (two paths are provisioned between the rings). This feature allows you to interconnect OC12 NWK or VTM bidirectional line-switched rings (BLSR) to OC-12 or OC-48 rings. This feature also allows you to interconnect OC-3, OC-12 or OC-48 unidirectional path-switched rings (UPSR), if the interconnecting ring complies with matched-node standards.



Only SONET STS-1 tributaries are supported as the physical means to support the two paths interconnecting the adjacent rings with OC-12 matched-node connections. These two links between the rings have path-switched protection on a 1:1 revertive basis at the STS level. All STS-1 connections on OC-12 systems are bidirectional, including the STS-1 inter-ring connections.

The two paths are interconnected to the adjacent ring via two ADM nodes of the ring. These two nodes are referred to as the primary and secondary nodes (see Figure 1-12). Although all inter-ring connections are bidirectional, only one direction is shown in the illustration for clarity.

The ADM node serving as the broadcast point (the primary gateway node), drops the signal over the tributary to the matching node in the adjoining ring. At the same time, the node sends the same signal on a passthrough connection to the secondary node over the OC12 transport optic (drop and continue).

The portion of the signal that continues on the OC-12 optics can use either working or protection bandwidth. If the signal uses working bandwidth, the protection scheme is called a drop-and-continue on working (DCW). If the signal uses protection bandwidth, the protection scheme is called a drop-and-continue on protection (DCP). DCP is available only on VTM rings.

The secondary node in the first ring drops the signal over a tributary to its matching node in the adjacent ring (in the same manner as on the primary segment). From the matching node, the signal passes over the transport optics of the second ring to the node receiving the primary signal. This node, which acts as the decision point, selects either the primary feed (normal operation) or the secondary feed (protected operation) according to the condition of the primary and secondary signals. If the secondary signal fails or both the primary and secondary signals fail, the primary path remains selected. The primary feed is the preferred feed.



Figure 1-12Matched nodes in OC-12 NWK rings (STS connections spanning multiple rings)

FW-26697

Source

Service access point

Secondary feed

Secondary feed

Primary feed

Secondary feed

Broadcastpoint

Broadcastpoint

Primary feed

Secondary feed

Legend:= Inter-ring STS path

= Fibers not used by the STS path

Note: For clarity, only one direction of the STS path is shown.

Ring A(3 ADM nodes)

Ring B(6 ADM nodes)

Ring C(4 ADM nodes)

Endnode

Destination

Decisionpoint

Secondarynode

Primarynode

(selectornode)

Primaryto

primary(same-

siderouting)

Primaryto

secondary(opposite-

siderouting)

Decisionpoint

Secondarynode

Primarynode

(selectornode)

Primary feed

Secondary feed

Intermediate(passthrough)

node



SONET DCC bridge The SONET data communications channel (DCC) bridge feature permits OC-3/OC-12 TBM networks to exchange OAM&P messages. The bridge also allows OC-3/OC-12 TBM and OC-48 networks that are not connected by fiber but have network elements located at the same site, to exchange OAM&P messages. A system uses the control network LAN to send SONET DCC messages to another system.

Note: The SONET DCC bridge carries only the OAM&P messages contained in the SONET section overhead. The SONET DCC bridge does not carry voice or data services such as DS1/DS3 or orderwire.

Figure 1-13 shows an example configuration of two independent networks, each containing a primary OPC and a backup OPC and OC-3/OC-12 terminal network elements. A VT100 terminal monitors each system at one end. These systems can be either two TBMs, two TSSs, or one TBM and one TSS.

Figure 1-14 shows the two collocated terminals (from the example given in Figure 1-13) linked together using a control network. A single VT100 terminal can now monitor both networks, one primary OPC, and one backup OPC.

You can use more than one SONET DCC bridge simultaneously between systems. However, the number of network elements managed by a pair of OPCs (their span of control) is restricted to 34 (24 LTEs and 10 regenerators). If performance statistics are collected at the OPC for reporting through Transaction Language 1 (TL1), then the maximum number of line-terminating equipment (LTEs) in a span of control is either 24 or the number that contains up to 2016 DS1 circuits, whichever is the smaller. If performance statistics are not collected at the OPC for reporting through TL1, the maximum number of LTEs in a span of control is 24.



Figure 1-13Example of two independent networks with network elements located in the same office

FW-0536 (OC12 tribs R8)

PrimaryOPC

Legend:

OC-12Term

OC-12Term

OC-12Term

OC-12Term

DS1, DS3,or STS-1

Network 1(TBM or TSS)

VT100-compatibleterminal

Network 2(TBM only)

PrimaryOPC


Operations ControllerOPC =

OC-3

OC-3 OC-3

OC-3

Central Office

DS1, DS3,or STS-1

DS1, DS3,or STS-1

DS1, DS3,or STS-1



Figure 1-14Two transmission spans bridged by a control network

FW-0537 (TBM tribs R8)

In the case of OC-12/STS-12 tributaries, the SONET DCC can be carried by either of the following:

• SONET DCC bridge for collocated TBM shelves

• OC-12/STS-12 DCC into Quadrant IV (not for route diverse or ring systems)

If the OC-12 TBM shelves are collocated and the number of network elements does not exceed ten, the control network bridge provides a simple means of providing DCC connectivity in the network (see Figure 1-15).

With the use of the control network bridge and the SONET DCC over OC-48 links, TBM shelves in several locations can be part of the same span of control. In Figure 1-15, two spans of control are shown: one for the OC-48 network elements and one for the OC-12 TBM network elements.

Note: Despite the separate spans of control, remote login functionality exists between the OC-12 TBM and the OC-48 network elements.

BackupOPC

SONETDCC

bridge

CNetcable

PrimaryOPC

Legend:CNet =DCC =OPC =

SONET =

Control NetworkData Communication ChannelOperations ControllerSynchronous Optical Network

OC-12Term

OC-12Term

OC-12Term

OC-12Term

DS1, DS3,or STS-1

Network 1(TBM or TSS)


Network 2(TBM only)

OC-3

OC-3

OC-3

Central Office

DS1, DS3,or STS-1

OC-3

DS1, DS3,or STS-1

DS1, DS3,or STS-1



Figure 1-15Data communications connectivity with CNet bridging

FW-2306

If the system is non-route diverse 1+1 or configured for 1:N (OC-48) protection switching, the SONET DCC is carried on the OC-12/STS-12 signal terminated on the fourth quadrant of the OC-48 shelf. If the number of OC-12 and OC-48 TransportNode network elements located in an office exceeds the limitations of the control network (more than ten network elements), data communications to all TransportNode network elements can be provided through a combination of SONET DCC (through Quadrant IV) and the control network (see Figure 1-16).

TBM OC-48 TBMOC-48

TBM span-of-control

OC-48 span-of-controlCNetCNet

P1 B1P2 B2



Figure 1-16Data communications with CNet and SONET DCC

FW-2307 OC12 (R13)

Provisionable SONET DCCThe provisionable SONET data communications channel (DCC) permits OAM&P messages to be exchanged between network elements that are connected by fiber. The SONET DCC is essential for downloading software, upgrading, and maintaining an association to the network element.

SONET DCCs can be enabled or disabled on both the transport and tributary optical interfaces. This is for mid-span meet scenarios in which security may be a concern or if there are incompatibilities when equipment is connected to another manufacturer’s equipment.

When a transport optical interface, OC-3 or OC-12, is provisioned, the SONET DCC for that line is automatically added, that is, enabled. When the tributary optical interface OC-3 is provisioned, the SONET DCC for that line is disabled.

SONET DCC

CNet

TBM

TBM

TBM

TBM

OC-48

I

II

III

IV

= indicates OC-12

Legend:



ReconfigurationsThe OC-3/OC-12 TBM network elements support in-service reconfiguration and software upgrades to permit SONET networks to evolve easily, and thus provide greater service flexibility. Change Application Procedures (CAP) are available from Nortel Networks for all supported configuration and software upgrades.

In-service reconfigurationThis section describes upgrades for linear systems and NWK rings, as well as tributary upgrades.

Reconfiguring linear ADM chains by adding or deleting a nodeLinear-to-linear reconfigurations convert existing point-to-point terminal systems to linear ADM configurations. Linear-to-linear upgrades also modify linear ADM configurations.

Reconfiguring linear systems to NWK ringsYou can upgrade a linear system to an NWK-type two-fiber bidirectional line-switched ring (BLSR). You can perform in-service upgrades of linear systems to NWK ring systems on the following linear configurations:

• linear ADM

• point-to-point terminal

• back-to-back point-to-point terminal

Reconfiguring NWK rings to VTM ringsYou can upgrade a NWK ring system to a VTM ring system. You reconfigure the entire ring network element by network element.

Reconfiguring tributariesTributary reconfigurations include the addition of DS1 and DS3 tributaries, and changes to the mix of DS1 and DS3 tributaries. Tributary reconfigurations also include

• STS-1 tributaries on the OC-3 shelf

• STS-1 and protected and unprotected OC-3 tributaries on the OC-12 terminal, ADM, and ring ADM shelves

• changes to the mix of DS1/DS3/STS-1/ OC-3



Software upgradesSoftware upgrades to the latest release are available. You can upgrade BLSR rings with the matched-node feature (NWK or VTM BLSRs).To upgrade from one software release to another with a linear-to-linear or ring-to-ring upgrade, only a software upgrade is required. To reconfigure from linear to ring, upgrade the software first (linear to linear), then reconfigure to a ring.

In-service single-stage software upgrades to Release 13 are supported from the following software releases:

• Release 9.01

• Release 10.03

• Release 11.2

Software upgrades to other releases listed are also supported, but in multiple stages. The software must be upgraded first to Release 9.01, 10.03, or 11.2, then upgraded to Release 13.

Use the appropriate procedure in System Expansion Procedures I, 323-1111-224, or System Expansion Procedures II, 323-1111-225 for all changes or upgrades to the system configuration or software. For more information, contact your Nortel Networks support group.



Hub applicationsYou can configure the OC-12 network element to act as a multipoint optical hub to support several optical links. Two hub applications are considered for access: a CSA hub and a CO hub.

With the CSA hub, an OC-12 network element located in the access network (often a CSA site) concentrates small-capacity fiber routes, from multiple locations, onto a single OC-12 facility homing to the CO.

The CO hub terminates multiple low-capacity access fibers (three DS3s or equivalent) at the CO onto a single OC-12 network element system.

Carrier serving area hub (future application)Figure 1-17 shows a typical OC-12 network element CSA hub. From the 3 DS3 and 140 DS1 tributaries terminating at the CO, 56 DS1 tributaries are from CSA 1, 1 DS3 and 56 DS1 tributaries from CSA 2, and 2 DS3 and 28 DS1 tributaries from CSA 3.

The CSA hub in Figure 1-17 is used at CSA 1 to terminate local traffic and concentrate traffic from CSA 2 and CSA 3 onto a single OC-12 for transmission to a CO. The system uses underfilled OC-12 rates (a maximum STS-3 bandwidth) to transmit between the hub and remote CSAs. The CSA hub uses internal STS-1 facility management to route traffic between the optical interfaces, eliminating the need for back-to-back terminals. Additionally, the hub is OAM&P transparent; once the required equipment is in place at a remote CSA (for example, CSA 2), you can perform all operations remotely from the CO.

Note: The two carrier serving areas CSA 2 (NE 2) and CSA 3 (NE 3), cannot be in the same span of control as CSA 1 (NE 1).



Figure 1-17 OC-12 CSA hub application

FW-0016

Central office hub (future application)Currently, CSAs and CLEs are typically connected to the CO in a star configuration using point-to-point systems. When using fiber systems in the access network, the traffic carried by each system usually consists of only a few DS1 tributaries. Each fiber terminal at the CO end is underused. The hub configuration provides a means of concentrating independent terminals, at the CO, into a single terminal with multiple optical interfaces.

Figure 1-18 shows a typical application for an OC-12 CO hub. In this example, the CO concentrates traffic from two CLE sites. Traffic from the access network is output by way of OC-12 terminals with partially filled (a maximum STS-3 bandwidth) OC-12 links. The OC-12 CO hub consolidates low-filled OC-12 signals up to the maximum capacity of an STS-12. At the CO, the OC-12 hub consists of two shelves: one to house the two fiber terminations from CLEs 1 and 2, and another to terminate the 56 DS1 tributaries as well as to connect with an OC-48 interoffice terminal. The OC-48 terminal serves as the transport for all services passed through a CO.

Note: The two carrier serving areas CSA 2 (NE 2) and CSA 3 (NE 3) cannot be in the same span of control as CSA 1 (NE 1).

OC-3

OC-12Terminal

OC-3Terminal

CentralOffice 56 DS11 DS3

140 DS13 DS3

OC-12OC-12Hub

56 DS1

OC-3Terminal

28 DS12 DS3

OC-3

Carrier-Serving Area 2 (NE 2)





Figure 1-18 OC-12 network element CO hub application

FW-0017 (OC12 R13)

56 DS11 DS3

CentralOffice

56 DS1

28 DS12 DS3

Interoffice Access

3 DS328 DS1

OC-3

OC-3

OC-12Interconnect

OC-12

Hub

OC-3Terminal

OC-3Terminal

OC-48

FW-0017

Customer-locatedequipment 1 (NE 1)

Customer-locatedequipment 2 (NE 2)


SONET Transmission Products

S/DMS TransportNode OC-3/OC-12 NE — TBM System Applications Description

Copyright 1992–2001 Nortel Networks, All Rights Reserved

The information contained herein is the property of Nortel Networks and is strictly confidential. Except as expressly authorized in writing by Nortel Networks, the holder shall keep all information contained herein confidential, shall disclose it only to its employees with a need to know, and shall protect it, in whole or in part, from disclosure and dissemination to third parties with the same degree of care it uses to protect its own confidential information, but with no less than reasonable care. Except as expressly authorized in writing by Nortel Networks, the holder is granted no rights to use the information contained herein.

Nortel Networks and S/DMS TransportNode are trademarks of Nortel Networks. VT100 is a trademark of Digital Equipment Corporation. UNIX is a trademark of X/Open Company Ltd.

323-1111-150 Rel 14 StandardFebruary 2001Printed in Canada

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