NM Information Interworking. NM Information Transparently Transmitted by a Third-Party Equipment. The NM Information of the Third-Party Equipment is Transparently Transmitted, страница 3

7.3  OSI over DCC(TP4)

7.3.1  Background

Generally, Data Communication Channel (DCC) is adopted to transmit information of administration and maintenance (OAM) among SDH equipment. But due to historical reasons, the protocol stacks for DCC communication used by vendors are not fully compatible with each other. As a result, extra overhead or resources are occupied for the transparent transmission of DCC information over the hybrid networking involving various vendors.

Some SDH/SONET network vendors have adopted the OSI protocol stacks for DCC communication. OptiX OSN products support the OSI over DCC features providing following advantages:

n  Satisfy the requirement for interworking of current network without additional extra overhead and service resources.

n  Simplify the networking structure.

n  Save network resources for users.

7.3.2  OSI Protocol Framework

OSI over DCC adopts standard OSI protocol framework with its data link layer (DLL) and physical layer supporting Ethernet and DCC. When the two protocols applied at physical layer and DLL are completely compatible with other equipment, Huawei protocol can be interconnected with that of other vendors at network layer. See Figure 7-6.

OSI over DCC supports dynamic routing protocol IS-IS.

Figure 7-6 Framework of OSI protocol stack

7.3.3  Application and Features

Main Features are listed below:

n  Adopt standard OSI protocol stacks to simplify network management and facilitate the compatibility with equipment of other vendors.

n  Adopt OSI forwarding function of protocol stacks without additional expenses and service paths.

n  Support flexible networking, and facilitate use.

n  Enable easy upgrading and excellent compatibility.

7.3.4  Networking and Service Capability

At present, the OptiX OSI over DCC only manages this equipment directly through OSI DCN. Several networking modes are as follows:

n  Manage OptiX directly through OSI DCN layer 3 routing function.

n  Manage OptiX network through OSI protocol stacks layer 3 routing function of other vendors’ equipment.

n  Manage equipment with OSI protocol stacks of other vendors through the routing function of OptiX network OSI protocol stacks.

The management information can be forwarded through Ethernet (ISO 802.3) and or optical interfaces in the case of interconnection between OptiX and other equipment. The protocol of physical layer protocol should be fully compatible with that of link layer precisely when the optical interfaces are interconnected. In this case, you must confirm relevant parameters and perform actual interconnection test before putting them into use.

n  For the direct management on OptiX directly through OSI DCN. See Figure 7-8.

Figure 7-7 Direct management on OptiX through OSI DCN

n  Manage OptiX equipment through OSI network of other vendors’ equipment. See Figure 7-9.

Figure 7-8 Manage OptiX equipment through OSI network of other vendors’ equipment

n  Manage other vendors’ equipments through OptiX network. See Figure 7-10.

Figure 7-9 Manage other vendors’ equipment through OptiX network

7.3.5  Advantages and Disadvantages

Advantages of OSI over DCC:

n  Require no extra DCN channels.

n  Compared with the physical layer, the network layer provides multiple transparent transmission channels of management information. Therefore, transparent transmission at network layer is more flexible and not restricted by hybrid networking.

n  The network layer is independent from the implementation of physical channel. The processing on physical channel is not standardized, whereas interworking is easily implemented at the network layer due to the standard protocol.

n  Support automatic rerouting function to protect information administration channel.

Disadvantages of OSI over DCC:

n  Equipment applied in data transmission process must support the same protocol at the network layer.

n  Communication performance of equipment provided by different vendors may be affected.