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OSN 500 550 580 V100R008C50 Commissioning and Configuration Guide 02

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Basic Concepts

Basic Concepts

CES: By using the PWE3 technology, PWE3 packet headers are added to TDM traffic to create circuit emulation services (CES). PWE3 packet headers carry the frame format information, alarm information, signaling information, and synchronization and timing information of the TDM traffic. The encapsulated PW packets are transmitted over the MPLS tunnel on the PSN. After being decapsulated at the PW egress, the TDM circuit switched service traffic is re-created. On a packet switching network, the transmit and receive ends of a CES service maintain clock synchronization by means of adaptive clock recovery (ACR).

Emulation Mode

The OptiX NG-SDH series equipment supports two types of CES services: structure-aware TDM circuit emulation service over packet switched network (CESoPSN) CES and structure-agnostic TDM over packet (SAToP) CES.

In the case of CESoPSN CES:

  • The equipment senses the frame format, frame alignment mode, and timeslot information in the TDM circuit.
  • The equipment processes the overheads and extracts the payloads in TDM frames. Then, the equipment loads timeslots to the packet payload in a certain sequence. As a result, the services in each timeslot are fixed and visible in packets.

In the case of SAToP CES:

  • The equipment does not sense any format in the TDM signal. Instead, it considers TDM signals as bit flows at a constant rate, and therefore the entire bandwidth of TDM signals is emulated.
  • The overheads and payloads in TDM signals are transparently transmitted.

Service Types

The OptiX OSN 580 supports CES services of only the UNI-NNI type.

As shown in Figure 3-57, CES services of the UNI-NNI type are configured on OptiX OSN 580 devices.
  • CES service devices receive TDM services from client-side devices through E1 ports or optical ports.
  • An NE converts services between a packet board and a TDM board through virtual ports on an EM10 board.
  • CES PWs are created between NEs to emulate end-to-end TDM services.
Figure 3-57  CES services of the UNI-NNI type

Updated: 2019-01-21

Document ID: EDOC1100020976

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