GPON FTTH PPPoE login gets disconnected

GPON FTTH PPPoE login will encounter some problems, for example, some Huawei home routers connected to Huawei ONT (HG8546M, HG8245Q2) cannot dial up successfully etc., what’s the reason? In this article, we will describe how to solve these problems.


Problem Description

Trouble Phenomenon? 

There are ten customers D’s ONTs working at bridge mode, PCs connect to Huawei ONT via home routers. The home routers use independent PPPoE accounts for dial up, and result in two phenomena: 

Only the routers under 4 ONTs can dial up successfully, others fail with error code 676, however, it will be successful with company’s public test account. 


Under one Huawei ONT, the two home routers cannot dial up successfully at the same time, one will kick off another if dial up successfully.

Network topology? 


Network topology.png 


Handling Process

Possible reasons 

Huawei OLT/ONT config issue. 

PON optical route problem or traffic congestion. 

Defective hardware of access network equipment. 

Upper-layer network equipment problem. 



1. Succeeded in PPPoE login when testing with PC connected to Huawei ONT (HG8546M, HG8245Q2…) directly. Therefore, the configuration of Huawei OLT (MA5683T/MA5800 X7…) should be no problem. 

2. Succeeded in PPPoE login when testing with one router connected to Huawei ONT (HG8546M, HG8245Q2…), but the router got disconnected when had another home router connected to Huawei ONT (HG8546M, HG8245Q2…) for test. 

3.Checked the MAC addresses learnt by Huawei OLT (MA5683T/MA5800 X7…). Found that the MAC address learnt by Huawei OLT is PC’s MAC. In fact, the PC was not connected at that time. Disconnected the router and checked MAC address again on Huawei OLT (MA5683T/MA5800 X7…). The MAC was gone. So, we determined that the MAC displayed was the home router’s.


MA5600T (config)#display mac-address service-port 2594
     2594 - epon0021-cc67-d7ce dynamic 0 /8 /1 26 - 2458
     MA5600T (config)#undo mac-address mac 0021-cc67-d7ce vlan2458 
     QZ-QZ-QingMeng-MA5600T-2-D(config)#display mac-address service-port 2594 
     Failure: There is not any MAC address 
     MA5600T (config)#display mac-address service-port 2594
   2594 - epon 0021-cc67-d7ce dynamic 0 /8 /1 26 - 2458


4. Checked the configuration of the home routers, found that the auto MAC-clone function was enable on both routers. The cloned MAC address was 0021-cc67-d7ce. Disable the MAC-clone function. The problem was fixed. 

5. Checked other Huawei ONTs whose services were not working, found that all were caused by the MAC-clone function enabled on the routers connected to Huawei ONTs. 

HG8245Q2 front image.jpg


Root Cause

MAC-clone function on router is used for the case when users want to share the account even the carrier has done binding between MAC and account. When MAC-clone is enabled on a router, the router will send out cloned MAC instead of its own MAC in PPPoE packets. By default, this function is disabled. In this example, the problem was caused by the MAC-clone function enabled on some routers. The routers cloned the MAC of PC’s connected to them. This resulted in PPPoE login failure when all cloned MAC were the same. And only one account was allowed to be online under the same ONT.



Disable MAC-clone function on the home routers.


Suggestions and Summary

Countermeasures when faults similar to the case in this presentation happen: 

Check Huawei OLT/ONT config. 

Check the status of relevant equipment. 

Check whether the MAC is learnt properly and correctly. 

Capture packets and analyze the packets if no anomaly found through the previous steps. 


After reading this article, when you encounter these problems, you can follow above steps to check one by one. Finally, I believe that you can solve the problems. If still have problems, please feel free to contact our support team: [email protected] 


Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *