Troubleshooting Tip: Split port on FortiSwitch-1024E and FortiSwitch-T1024E does not pass any traffic using a breakout cable

[Adolfo_Z_H]

Description

This article describes that adding a split 40G into 4 x 10G  or a 100G to 25x 4 on FortiSwitch-1024E / FortiSwitch-T1024E using a breakout cable does not pass any traffic.

Splits ports seem to be always on ALARM STATE and besides physical status is up, no traffic can be observed on the port.

Scope

FortiSwitch-1024E and FortiSwitch-T1024E.

Solution

This is a known issue and can be solved using v7.2.6 and v7.4.2 before attempting to configure a split port.

Be advised on this kind of breakout cable, all lanes share the same SFP module, so if any cables are disconnected, the module will show an alarm status.

ST1E24TF23000XXX # get switch modules summary


  Portname State Type DMI Transceiver RX Vendor Part Number Serial Number
  __________ _______ _______ ___ ____________ ___ ________________ ________________ ______________

  port25.1 ALARM QSFP+ Y 40G-Base-SR4 N/A +Fortinet FTL410QE4CFTN UXXXXXX
  port25.2 ALARM QSFP+ Y 40G-Base-SR4 N/A +Fortinet FTL410QE4CFTN UXXXXXX
  port25.3 ALARM QSFP+ Y 40G-Base-SR4 N/A +Fortinet FTL410QE4CFTN UXXXXXX
  port25.4 ALARM QSFP+ Y 40G-Base-SR4 N/A +Fortinet FTL410QE4CFTN UXXXXXX

This is the expected behavior, ALARM status should be cleared when all cables are properly connected to a peer equipment.

Related document:

Configuring FortiSwitch split ports (phy-mode) in FortiLink mode