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DCC Solution for SONET/SDH Systems White Paper

Version 1.0, October 2003

DCC Solutions for SONET/SDH Systems

Version 1.0 October 2003

Page 1 of 1 Opencon Systems, Inc. Proprietary Information. Unauthorized Distribution is Prohibited.

DCC Solution for SONET/SDH Systems White Paper

Version 1.0, October 2003

COPYRIGHT This material is the property of OpenCon Systems, Inc. Unauthorized distribution is prohibited Copyright 2003 OpenCon Systems, Inc. All Rights Reserved

Page 2 of 2 Opencon Systems, Inc. Proprietary Information. Unauthorized Distribution is Prohibited.

DCC Solution for SONET/SDH Systems White Paper

Version 1.0, October 2003

Table of Contents1. 2. 3. 4. 5.5.1 4.1. 5.2

OVERVIEW SONET/SDH DATA COMMUNICATION CHANNEL SONET/SDH DCC PROTOCOL STACKS DCC SUBSYSTEM REQUIREMENTS DCC NETWORK CONFIGURATIONSEnd-to-End OSI-7 Layer Communication TCP-IP to OSI-7 Mediation IP Tunneling

4 6 7 12 1414 15 17

6. 7. 8.

OCS DCC PACKAGE REFERENCES ABBREVIATIONS

19 20 21

Page 3 of 3 Opencon Systems, Inc. Proprietary Information. Unauthorized Distribution is Prohibited.

DCC Solution for SONET/SDH Systems White Paper

Version 1.0, October 2003

1. OverviewEach SONET/SDH frame includes two Data Communication Channels (DCC) called Section DCC and Line DCC for transporting management messages between NEs and between NEs and Management systems. These in-band data communication channels enable service providers Operation Support Systems (OSS) to manage SONET/SDH Network Elements (NE) without the need for an expensive outof-band data communication network. SONET/SDH is the most widely used transport technology in carriers network today and deployment of SONET/SDH based network equipment continues to grow as carriers extend the reach of fiber from central offices to business locations. As the size of SONET/SDH networks grow and as carriers start deploying systems from different vendors, managing these networks have become increasingly difficult and complicated. To reduce the cost and complexity of managing these networks, carriers rely on embedded Data Communication Channels (DCC) within a SONET/SDH frame and expect vendors to provide equipments that are interoperable with the SONET equipments that are already deployed in their networks. To ensure interoperability with the equipment deployed in the network, SONET/SDH vendors have to support DCC standards such as Telcordias GR-253 and ITU G.7712. Telcordias GR-253-CORE standard defines the interfaces and the communication protocols required for transporting information over DCC. The following is a summary of Telcordia requirements pertaining to DCC: Communication interfaces:: (a) Data Communication Channel, X.25 interface (b) Local Communication Network (LCN) OSI 7-layer Protocol Stacks SONET-specific Naming Resolution Protocol: Terminal IDentification (TID) Address Resolution Protocol (TARP) Network Management Protocols: Transaction Language-1 (TL-1) or Common Management Information Protocol (CMIP) Generic File Management System

With the explosive growth of packet-based traffic in the service providers network, the SONET/SDH equipment vendors have started to incorporate packet network interfaces such as Ethernet into their equipment to transport packet-based traffic over SONET/SDH network. Unlike circuit switched traffic, packet switched traffic is bursty in nature and requires IP based signaling protocols to dynamically set up and tear down payload paths between the NEs in the network. SONET/SDH network elements that support packet interfaces are generally managed by IP based protocols such as SNMP and HTTP. To manage these types of next generation SONET/SDH network elements, the embedded DCC channel has to carry IP based management messages and has to interoperate at the DCC level with legacy network elements that are capable of transporting OSI-based messages through DCC. To address this interoperability problem at the DCC level, ITU G.7712 has defined the following three DCC network domains:

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DCC Solution for SONET/SDH Systems White Paper OSI DCC network IP DCC OSI+IP DCC network

Version 1.0, October 2003

IP Tunneling is one of the methods recommended by ITU G.7712 for tunneling IP traffic through the OSI based DCN network. In the following subsections, we will illustrate how IP Tunneling method can be used to integrate next generation SONET/SDH systems with the legacy network elements. OCS standards-based, off-the-shelf DCC System Solution shortens the DCC implementation time and is designed to provide DCC interoperability with equipment from leading SONET/SDH equipment vendors such as Fujitsu, Lucent and Nortel. OCS offers two standards-based DCC packages that can be used by equipment vendors to quickly implement an interoperable DCC solution in their equipments. These two DCC packages include support for full OSI 7-Layer Stack and an OSI three layer stack (also referred to as Short Stack). Both full stack and short stack versions support IP Tunneling as per G.7712 recommendations. OCS solution is designed to be hardware and operating system independent and can be easily ported to most hardware/software platforms.

Page 5 of 5 Opencon Systems, Inc. Proprietary Information. Unauthorized Distribution is Prohibited.

DCC Solution for SONET/SDH Systems White Paper

Version 1.0, October 2003

2. SONET/SDH Data Communication ChannelSection DCC is based on three (3) bytes embedded in the SONET frame. These bytes are termed D1, D2 and D3 in the transport overhead of the Synchronous Transport Signal 1 (STS-1) frame. Figure 1 shows the structure of the STS-1 frame.1 byte A1 B1 D1 H1 B2 D4 D7 D10 S1/Z1 1 byte A2 E1 D2 H2 K1 D5 D8 D11 M0 or M1/Z2 1 byte J0/Z0 F1 D3 H3 K2 D6 D9 D12 E2 87 columns

STS-1 payload capacity (9 87 bytes)

Transport Overhead

Figure 1: STS-1 Frame Structure There are 27 bytes in the transport overhead part of the STS-1 frame. They provide many features for standard-based SONET equipment such as Automatic Protection Switching (APS). Bytes D1, D2 and D3 provide the Section Data Communication Channel for message-based administration, monitoring, alarm maintenance and other communication needs. The Section DCC bandwidth is 192 Kbit/s between each pair of SONET section termination equipment. Any SONET equipment that can extract these 3 bytes from the STS-1 frame overhead and process them is considered to support a DCC interface. Bytes D4 through D12 form another embedded data communication channel within SONET/SDH frame and are referred to as Line DCC. The bandwidth of Line DCC is 576 Kbit/s. Most of the SONET equipment vendors extract and process only SDCC overhead bytes.

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DCC Solution for SONET/SDH Systems White Paper

Version 1.0, October 2003

3. SONET/SDH DCC Protocol StacksIn order to exchange SONET/SDH network management information between OSSs and SONET/SDH NEs, a standards based management framework is needed. Telcordia has defined in GR-253-CORE standards, a network management architecture for exchanging SONET/SDH operations messages. In practice, SONET/SDH operations communications architectures will vary depending on deployment configurations and applications supported by the network. Figure 2, shows an example of the SONET /SDH Operations Communications Architecture.

NMS-1

NMS-2

Data Communications Network EMS LAN HUB GNE ADM GNE

ADM

SONET/SDH Ring Terminal ADM ADM Terminal

Terminal Terminal GNE: Gateway NE ADM: Add-drop Multiplexer Terminal EMS: Element Management System

Terminal

NMS: Network Management System

Figure 2: Example SONET/SDH Network Figure 2, shows the SONET/SDH network that includes SONET/SDH Add-drop multiplexers (ADM) and Terminals. As illustrated in the Figure, the network management systems use wide area Data Communication Network (e.g., X.25) to manage elements in the SONET/SDH network. Figure 2, also illustrates the configuration where two network elements communicate with each other via an intra-site Local Area Network (LAN). Figure 3, illustrates the protocol stacks for the X.25 DCN, the DCC and the intra-site LAN. In all three cases, it is assumed that OSI based protocols are used for communication.

Page 7 of 7 Opencon Systems, Inc. Proprietary Information. Unauthorized Distribution is Prohibited.

DCC Solution for SONET/SDH Systems White PaperStack A: OS (X.25 DCN) TL1 CMISE ROSE ACSE ASN.1/BER Kernel/Full Duplex TP4 CLNP X.25 LAPBEIA-232-D V.35

Version 1.0, October 2003 Stack B: NE (DCC)TL1 CMISE ROSE ACSE Stack C: NE (LAN) TL1 CMISE ROSE ACSE ASN.1/BER Kernel/Full Duplex TP4 CLNP ES-IS IS-IS LLC1 CSMA/CDAUI 10BASE2 10BASE-T

Application

Pre sentationSession Transport

Network Data Link Physical

ASN.1/BER Kernel/Full Duplex TP4 CLNP ES-IS IS-IS LAPDDCC

Figure 3: Protocol Components of OSI-7 layer DCC On top of these three stacks are the TL-1 and Common Management Information Service Element (CMISE) management applications. In this example, both TL-1 and CMISE applications are implemented on top of OSI-7 protocols.v

TL-1 is easily the most widely used protocol in telecommunication management today. Most telecommunication elements in North America today are managed using TL-1. TL-1 was designed to be a human readable machine language for craft operators and operations personnel. In the 1980s, Telcordia adopted TL-1 as the network element management protocol for their Network Monitoring and Analysis (NMA) system. NM