As shown in the attachment, two ME60s worked in load sharing mode. PPPoE sessions were terminated on Eth-trunk3 and Eth-trunk4 on each BRAS. The customer migrated PPPoE users from Eth-trunk3 and Eth-trunk4 to 10G links 3/0/0 and 3/0/1. After the migration, some PPPoE users who use third-party modems failed to go online.
Possible causes included:
1. Configurations were incorrect.
2. BRASs' processing mechanism had a bug.
3. Third-party modems had problems.
To address the issue, Huawei performed the following operations and observed the following information:
1. Checked the configuration and found that the configuration was correct.
2. Verified that the BRAS processing mechanism was normal.
3. Asked the customer to configure port mirroring on the BRAS and UA5000 to capture packets. According to the captured packets, the third-party modem transmitted four PADR packets upon receiving four PADO packets and did not respond to the BRAS during LCP negotiation. ME60 transmitted PADT packets after failing to receive responses for three times and released sessions.
Third-party modems did not comply with RFC standards.
Replaced third-party modems.