**5.1 OMCI channel analysis**

After the signaling phase is over, the operation, administration and maintenance (OAM) can be transferred using the OMCI channel. In our work, the OMCI procedures begin when the OLT sends a "Get/Set request" message to the ONU. When the ONU receives such a message, it responds with its own "Get/Set" message. In this work, we used a single ONU, see **Table 2**. At this point, the crucial phase of the OMCI analysis is the software image entity type inspection, as the ONU is to be authorized by its own serial number against the database of the OLT (depending on the particular ISP implementation). In the case that the OLT does not have the record of the ONU in the database, the ONU is not allowed to download the software image along with the configuration. On the other hand, if the record is present, the ONU downloads the data. It is important to stress that because the ISPs may offer different transmission speeds, functions, etc., to customers, each customer should have his or her own distinct software image. The software image message responds to the image data transfer used to set the parameters. The message parameters are reported as "inactive" as they are in the initial phase of the file download. The next analyzed message informs about the software image being valid and active. As soon as the ONU has the software image, it is capable of transferring the customer service support data as well as the metadata. To support VoIP telephony, which is a QoS-demanding service, the ONU downloads an additional configuration containing information such as the type of codec, constant bit rate allocation, and T-CONT priority. The next step is to set the parameters for VoIP service. This service is a key service used for the highest priority end units. Their setting corresponds to the priority operation, i.e., T-CONT1, in which a fixed bandwidth must be assigned. In the case of most of the service providers, this value is set to 512 kbit/s. This speed


**81**

**Table 3.**

**Figure 9**.

**Figure 9.**

restored in the downstream direction.

1 1 Remote error indication Sequence number: 3 6 1 Remote error indication Sequence number: 8

59 1 Deactivate ONU-ID Ident superframe counter: 498791449 60 1 Deactivate ONU-ID Ident superframe counter: 498791451

7 1 Dying gasp ONU ID: 1 9 1 Dying gasp ONU ID: 1

*Dying gasp PLOAM message details after the ONU lost power supply.*

**ID ONU-ID Message type**

*Deployment of PON in Europe and Deep Data Analysis of GPON*

must be guaranteed, even though it is considerably higher than the bandwidth of the G.711 codec (64 kbit/s). Successful reception and setting of the VoIP parameters are indicated with the message with ID 381 "Profile version: 00000000." In addition to the previously mentioned OMCI channel procedures that take place on the side of the ONU, there are also procedures on the side of the OLT: channel synchronization, verification, alarm indication, FEC monitoring, and so on, see **Table 2**. In summary, by analyzing the OMCI channel data, we performed active monitoring of the alarms of the distribution network. As seen in the "Get all alarms" message (ID: 400), the end-point ONU has reported a message signaling a failure on the Ethernet port. In the case of OMCI channel measurement, it would be possible to summarize the transferred software image data, ONU data and the VoIP configuration file, see

A special case of the activation process is the message sequencing that can be seen in **Table 3**. This part of the activation is not mandatory for end units but is the last deactivation process aimed at the previously allocated parameters, most often the ONU-ID. This occurs when there is an immediate power outage. In the case of charged capacitors, the end unit sends a "Remote Error Indication" message. The message indicates that the ONU encountered an error. In the context of our experiments, this particular message was sent six times in total. When detecting a certain number of errors, most commonly defined by the manufacturer of the control unit, a "Dying Gasp" message follows. This message is dedicated to informing the control unit about an end unit failure, i.e., the loss of communication. The critical parameter of this message is the ONU-ID. After receiving such a message, the control unit sends the PLOAM message, "Deactivate ONU-ID," that causes this identifier to be released and consequently be reused by another end unit within the activation process. The PLOAM message is sent three times. Other parameters are discarded as internal timers have expired and communication/synchronization has not been

*DOI: http://dx.doi.org/10.5772/intechopen.82679*

*OMCI channel diagram for the analyzed ONU.*

**Table 2.**

*OMCI channel details in the analyzed GPON network.*

*Deployment of PON in Europe and Deep Data Analysis of GPON DOI: http://dx.doi.org/10.5772/intechopen.82679*

**Figure 9.** *OMCI channel diagram for the analyzed ONU.*

*Telecommunication Systems – Principles and Applications of Wireless-Optical Technologies*

After the signaling phase is over, the operation, administration and maintenance (OAM) can be transferred using the OMCI channel. In our work, the OMCI procedures begin when the OLT sends a "Get/Set request" message to the ONU. When the ONU receives such a message, it responds with its own "Get/Set" message. In this work, we used a single ONU, see **Table 2**. At this point, the crucial phase of the OMCI analysis is the software image entity type inspection, as the ONU is to be authorized by its own serial number against the database of the OLT (depending on the particular ISP implementation). In the case that the OLT does not have the record of the ONU in the database, the ONU is not allowed to download the software image along with the configuration. On the other hand, if the record is present, the ONU downloads the data. It is important to stress that because the ISPs may offer different transmission speeds, functions, etc., to customers, each customer should have his or her own distinct software image. The software image message responds to the image data transfer used to set the parameters. The message parameters are reported as "inactive" as they are in the initial phase of the file download. The next analyzed message informs about the software image being valid and active. As soon as the ONU has the software image, it is capable of transferring the customer service support data as well as the metadata. To support VoIP telephony, which is a QoS-demanding service, the ONU downloads an additional configuration containing information such as the type of codec, constant bit rate allocation, and T-CONT priority. The next step is to set the parameters for VoIP service. This service is a key service used for the highest priority end units. Their setting corresponds to the priority operation, i.e., T-CONT1, in which a fixed bandwidth must be assigned. In the case of most of the service providers, this value is set to 512 kbit/s. This speed

**ID Type Entity** 367 Get TCI priority: 1 ONU

370 Get TCI priority: 1 Software

373 Get response Is committed: committed; is active: active; is valid: valid Software

378 Get VOIP configuration state VOIP config

381 Get response Profile version: 00000000 VOIP config

OMCI alarms received on ME—physical path termination point ETHERNET UNI, instance—257, LAN-LOS No carrier at the

V3R016C00S917T; is committed: uncommitted; is active:

ONU

image

image

data

data

VOIP config data

ONU DATA

ONU DATA

Software image

368 Get response TCI priority: 1; result reason: command processed successfully;

371 Get response Result reason: command processed successfully; version:

379 Get response VOIP configuration state inactive: configuration retrieval has

inactive; is valid: valid

not been attempted

Ethernet UNI.

*OMCI channel details in the analyzed GPON network.*

vendor id: ZTEG

**5.1 OMCI channel analysis**

**80**

**Table 2.**

400 Get all alarms

401 Get all alarms response must be guaranteed, even though it is considerably higher than the bandwidth of the G.711 codec (64 kbit/s). Successful reception and setting of the VoIP parameters are indicated with the message with ID 381 "Profile version: 00000000." In addition to the previously mentioned OMCI channel procedures that take place on the side of the ONU, there are also procedures on the side of the OLT: channel synchronization, verification, alarm indication, FEC monitoring, and so on, see **Table 2**. In summary, by analyzing the OMCI channel data, we performed active monitoring of the alarms of the distribution network. As seen in the "Get all alarms" message (ID: 400), the end-point ONU has reported a message signaling a failure on the Ethernet port.

In the case of OMCI channel measurement, it would be possible to summarize the transferred software image data, ONU data and the VoIP configuration file, see **Figure 9**.

A special case of the activation process is the message sequencing that can be seen in **Table 3**. This part of the activation is not mandatory for end units but is the last deactivation process aimed at the previously allocated parameters, most often the ONU-ID. This occurs when there is an immediate power outage. In the case of charged capacitors, the end unit sends a "Remote Error Indication" message. The message indicates that the ONU encountered an error. In the context of our experiments, this particular message was sent six times in total. When detecting a certain number of errors, most commonly defined by the manufacturer of the control unit, a "Dying Gasp" message follows. This message is dedicated to informing the control unit about an end unit failure, i.e., the loss of communication. The critical parameter of this message is the ONU-ID. After receiving such a message, the control unit sends the PLOAM message, "Deactivate ONU-ID," that causes this identifier to be released and consequently be reused by another end unit within the activation process. The PLOAM message is sent three times. Other parameters are discarded as internal timers have expired and communication/synchronization has not been restored in the downstream direction.


**Table 3.** *Dying gasp PLOAM message details after the ONU lost power supply.*
