插入 SFP-H25G-CU2M DAC 后 Catalyst C9300X-24Y 把 FEC 重置为 auto,导致到 FortiGate 的链路断开

发帖人用一根 25G 的 SFP-H25G-CU2M DAC 把 Cisco Catalyst C9300X-24Y 连到一台 FortiGate 防火墙。每次插入这根 DAC,交换机都会记录 '%PLATFORM_PM-6-MODULE_INSERTED: SFP module inserted with interface name Twe1/0/23',紧接着是 '%PLATFORM_PM-6-DIFFERENT_MODULE_INSERTED: Warning: SFP module inserted in to the interface Twe1/0/23 differs from the previously inserted one. The port's fec configuration will be set to the default.'。FEC 设置随即被重置为 auto,而 FortiGate 不支持这个模式,链路始终起不来。用同一种线缆把两台设备各自的端口自环连起来,证实两端都具备 25G 能力;只有跨厂商搭配才会失败。

• 硬件: Cisco Catalyst C9300X-24Y、Fortinet FortiGate 防火墙
• 收发器: SFP-H25G-CU2M
• 封装形式: SFP28、DAC

症状/报错信息:

%PLATFORM_PM-6-MODULE_INSERTED: SFP module inserted with interface name Twe1/0/23
%PLATFORM_PM-6-DIFFERENT_MODULE_INSERTED: Warning: SFP module inserted in to the interface Twe1/0/23 differs from the previously inserted one. The port's fec configuration will be set to the default.
FEC reverts to auto on module insertion
no 25G link to FortiGate