EPON Failure Case study. Based on introducing the basic concepts and principles of EPON. This article adopts the judgment and handling methods of some common EPON faults summarized in the work. As well as the two fault handling situations, encountered this year, and makes a simple analysis for maintenance reference.

Here are the articles to explain, A Case study on EPON Failure

Technical personnel must not only have theoretical knowledge of the three networks but also have rich practical experience. This article summarizes some common EPON fault judgment and handling methods. As well as the handling process of the two EPON failures encountered, and introduces them for reference by technical personnel.

Introduction to EPON

EPON adopts a point-to-multipoint structure and passive optical fiber transmission to provide various services on Ethernet. EPON technology is based on the passive optical network architecture, and defines a new physical layer (mainly optical interface) specification and extended Ethernet data link layer protocol applied to the EPON system to achieve TDM access of Ethernet frames in point-to-multipoint PON.

In addition, EPON also defines an operation, maintenance, and management (OAM) mechanism to achieve the necessary operation management and maintenance functions. And to separate the signals of multiple users coming and going on the same optical fiber. The following two multiplexing technologies stand used. The downlink data stream adopts broadcast technology and the uplink data stream adopts TDMA technology.

At the data link layer, the function of the multipoint MAC control protocol (MPCP) is to realize point-to-point simulation in a point-to-multipoint EPON system, support multiple MAC client layer entities in point-to-multipoint, and support control functions for additional MACS. MPCP mainly handles the discovery and registration of ONUS, the allocation of uplink transmission resources between multiple ONUS, dynamic bandwidth allocation, and the reporting of the local congestion status of statistical ONUS. Continue the essay on the EPON Failure Case study.

EPON fault handling process

  1. A single fault stands mainly accepted by the 112 fault stations.
  2. When the maintenance personnel finds that it is an ONU failure, replace the ONU, and report the MAC address of the ONU to the computer room, and the computer room will do the data configuration.
  3. When the maintenance personnel finds that it is a power failure, notify the property personnel to repair the power supply in time.
  4. When the maintenance personnel finds that the optical path is faulty, notify the computer room personnel. And cooperate with the computer room personnel to find out the fault point, and confirm that the optical cable stands interrupted. Also, notify the optical cable maintenance personnel to repair the optical cable.
  5. When the maintenance personnel finds that the ONU is normal and one of the services is abnormal, notify the computer room personnel to check the configuration of a certain service data.
  6. When the same business failure stands found in a large area. The computer room personnel check the configuration of certain business data.

Common causes of failure

  1. The service of a certain port of the ONU is not normal. User terminal or external line failure, such as external line disconnection, mixed line; user computer system failure; computer network card failure; user account failure; fault type data configuration failure can also determine based on broadband dialing error code, such as VLAN configuration error; number terminal number error; number permission error.
  2. The entire ONU business is not regular. ONU failure, such as power failure; ONU damage; optical path interruption.
  3. The business failure of the user of the whole board. PON board failure, such as PON board damage; PON board data configuration error; PON board hanging.
  4. The whole frame of user business failure. Uplink port failure; main control board failure; upper equipment failure; network attack.

Case analysis of EPON Failure Case study

Case 1:

(1) Fault phenomenon

After the power failure in the cell and the incoming call. All broadband dial-up connections of all users in the cell prompted error 678 and could not connect; voice and digital TV services were normal.

(2) Fault handling process
  1. In the broadband billing management system, the user account check, no abnormalities stand found, and the user account data problem stands eliminated.
  2. The ONU failure has not been restored after restarting, and the M24E board hanging and ONU hanging problems stand eliminated.
  3. Log into OLT to check that the ONU display under each PON port is normal.
  4. Log into the ONU to check that the data configuration is normal and the business board status is normal.
  5. After logging into ONU, the PINGOLT management IP address and PINGDNS address are available, but PINGBAS is not available. Contact the information center to check the BAS data.
  6. The information center personnel requested to change the SVLAN. Since the users of this cell and other cell users share the gei_0/6/2 uplink port, no changes have been made, only the ONU data has been redone, and the fault has not been ruled out.
  7. After using the reset-cardstatno13 command to reset the No. 13 EPFC board, network users under the board can log in normally.
(3) Analysis of the cause of the failure
  1. The failure was due to a power failure in the community, and many onuses stood registered to the OLT at the same time after the call, causing the EPFC board to hang.
  2. Since there has been no large number of network outages and failures caused by EPFC hanging, the attention mainly focused on the ONU and network data configuration and routing during processing, resulting in a long troubleshooting time.
  3. After this troubleshooting is over, logging in to the ONU still cannot ping the BAS, delete the static route 172 in the ONU.30.0.0255.255.0.0172.30.250.1.
  4. After that, it can ping, but a voice gateway cannot add if the route does not add when configuring the ONU data.
  5. The error “DB: error record not exist” will appear, and the ONU voice protocol will show a BREAK after deleting the static route for some time, and the voice service will be interrupted.

Case 2:

(1) Fault phenomenon

The voice service of the newly installed ONU equipment in the cell failed to register on the Soft switch MGC. While the network and TV services were normal.

(2) Fault handling process
  1. Compare the version of the new device with the old device is the same;
  2. Check the configuration of the soft switch cell bearer network switch and no problems exist found. The PINGMGC registered address from the ONU device is accessible.;
  3. Whether it is related to the IP address used by the device, delete one of the old ONU device configurations, add the same configuration to the new device, and still fail to register;
  4. Check the configuration of the MGC firewall and all the IP addresses used stand released;
  5. Clean up the resource usage of MGC, the fault is still there;
  6. Through the packet capture analysis, the registration information sent by ONU is uploaded. But MGC has not received the registration information;
  7. There is a main switch in the bearer network, which is a Boda switch. Because the manufacturer did not leave a password, it cannot view. It may be a failure caused by its configuration.;
  8. The manufacturer’s engineers came to the site to make changes to the configuration policy of this switch and restarted some MGC services for troubleshooting.
(3) Analysis and summary of the cause of the failure
  1. The community initially installed one ONU device in each building and reserved an IP address for the second ONU. Before installing the second device, the NGN bearer network was adjusted several times. And the configuration of the reserved IP address was not considered. This failure occurred.
  2. The reasons for the failure of the voice gateway registration are. A. Voice gateway version matching and configuration problems; B. bearer network configuration problems; C. MGC gateway resource and configuration problems; D. hardware connection problems.

The fault can certainly eliminate by checking one by one.

Finishing mentions

EPON access method is currently the ideal way for comprehensive community access. And its application will become more and more extensive. EPON Failure Case study. How to maintain it well is to go through a long-term accumulation process. As long as you carefully summarize the cause of each failure and do a good job of daily maintenance and maintenance. The maintenance of the EPON network will become easy and fast. And the quality of service of the EPON network can also improve.

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A Case study on EPON Failure; Photo by Sammyayot254 on Unsplash.

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