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PPPoE Users Fail to Dial Up Due to Transmission Limitation on the NE40E

Publication Date:  2018-09-26 Views:  403 Downloads:  0

Issue Description

The NE40E functions as an access device, and a large number of PPPoE users give a feedback that the 678 error is displayed on the PC during dialup.

Handling Process

1. Run the trace object mac-address mac-address command to trace the MAC address of the users that encounter the 678 error. It is found that the PADI packet can be received and the PADO packet is sent, indicating that the link is normal.

2. Run the display access-user interface interface-type interface-number command on the interface where the fault occurs. It is found that other users can log in to the interface, indicating that the configuration of the device is normal.

3. The packet header is obtained on the downstream interface of Switch B. It is found that the PADO packet is sent, but the user side does not receive the packet. The packet is discarded during transmission.

4. Check the transmission device. It is found that the minimum transmission unit is set to 64 bytes. The PADO packet length is less than 64 bytes. As a result, the packet is discarded by the transmission device, causing the 678 error on the client.


1. Run the system-view command to enter the system view.

2. Run the sysname host-name command to change the host name of the device. Increase the length of the host name to increase the PADO packet size.

3. You can also modify the minimum transmission unit of the transmission device to rectify the fault.


The PADO packet contains an AC_NAME field, which is filled with the device name of the NE80E/40E. You can change the device name so that the PADO packet meets the minimum transmission unit requirement when passing through the transmission device.