Remote management and supervision of SHDSL devices

Purpose

This chapter describes the remote management of NTUs and SRUs which is controlled by the LTU.

EOC Management Reference Model

The LTU maintains an information database of all attached NTUs and SRUs for the purpose of configuration, performance and fault information retrieval or control by network management. All elements attached to an SHDSL span have to respond to queries made to them from other elements. The database in the LTU is considered the “master database”. Conflicts between the entities in the SHDSL span are resolved in favour of the LTU. For 1643 Access Multiplexer AM/1643 Access Multiplexer Small AMS only communication initiated by the LTU is supported.

The alarm status of the SHDSL devices (NTU and SRUs) that are attached to an SHDSL port on the LTU is polled by the LTU in regular intervals. Polling is realized by means of EOC messages or by a combination of EOC and EOC-ext. messages (see below).

The following figure shows the reference configuration for management purposes:

EOC messages

Management of the SRUs and NTUs is exercised via the Embedded Operations Channel (EOC) in the SDHSL overhead. The capacity of this channel is 20 bits per 6 ms frame or 3333 kbit/s. EOC messages are protected by a CRC16 code, appended in the last two octets of the message.

EOC addressing

The addressing scheme on the EOC can distinguish between the LTU, the NTU and up to 8 SRUs per SHDSL span. At most two SRUs per LTU port are possible. During a discovery phase, the number of SRUs and their addresses are established.

The detailed procedure for address discovery is described in clause 9.5.3 of ITU-T Rec. G.991.2. Note that SRUs can have different addresses in each direction of transmission.

Proprietary messages (EOC-ext.)

In addition to a subset of the G.991.2 (EOC) message set, a number of proprietary messages for remote management of SRUs and NTUs is supported. The reason for this proprietary addition is that the standard message set is only covering the SHDSL aspects of the service, but not the interface towards the enduser, which can be E1, ISDN-PRI, ISDN-LL or E/FE. In the following this additional message set ist called EOC-ext.

When the LTU processes an EOC-ext. message, it is already validated as an EOC message (correct CRC). The LTU only supports EOC-ext. commands and requests in the transmit direction and confirmation and response messages in the receive direction.

EOC management communication

The communication from the LTU to an SRU or an NTU goes through three distinct phases:

• Discovery phase:

  This is the initial phase where the presence of the SHDSL devices (NTU and SRUs) is detected. Additionally the EOC addresses are assigned and distributed.

• Inventory phase:

  This is the secondary phase where the inventory data from a discovered SHDSL device is collected. The LTU can determine the equipment type (SRU, NT2M or NT10ETH). and whether an NTU is already connected to the LTU via another SHDSL port.

• Operational phase:

  This phase is entered after the completion of the inventory phase of an SHDSL device. At the start of the operational phase and automatic configuration download to the NTu or SRU is initiated in case the target was discovered on the port before. Otherwise, the user has to provide a manual command to download the configuration. After that normal alarm and performance monitoring starts. On user request additional reconfiguration requests are possible.

Software download

Attached SHDSL devices that support the EOC-ext. message extension can be provided with new software images remotely from the NE. In the system the image is stored in a non-volatile memory. To initiate the software download a user command is needed. Once the software is successfully downloaded, a reset command needs to be issued to the SHDSL device in order to activate the new software image. Only one SW image for an NTU can be stored in the NE of at most 2 Mbyte.

The 1643 AM/1643 AMS supports the ITM-CIT and Alcatel-Lucent OMS to display a dynamic software download progress indicator per module. This module also indicates the software download percentage for the SHDSL module.

Configuration download

The NE keeps in its MIB a copy of all (managed) configurational settings related to each attached SHDSL device. Upon user request these settings can be downloaded to the target device, causing the device settings to be synchronized with the NE MIB. Automatic download of the configuration happens after a power cycle of an SHDSL device or after an interruption of the link. The NE detects in both cases the same SHDSL device (same serial number etc.) to be present.

In case a new SHDSL device is detected on an LTU SHDSL port (i.e. different serial number etc.), you will be notified by means of a “new device detected” alarm. You then have the option to initiate a configuration download in order to download the configuration of a previously connected SHDSL device to the new SHDSL device (provided the new SHDSL device is of the same type).

Alcatel-Lucent – Proprietary

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