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sachitdas_FTNT
Staff
Staff
January 29, 2026

Technical Tip: FortiLink Type L4

  • January 29, 2026
  • 0 replies
  • 406 views
Description This article describes the meaning of FortiLink Type L4.
Scope FortiGate managing FortiSwitches version 7.4.x and above.
Solution

Consider FortiLink 802.3ad aggregate interface connected directly to FortiSwitches.

 

topology.png

 

Under FortiGate GUI -> Managed FortiSwitches -> List View -> FortiLink Type Column shows as L4 by default.

 

L4.png

 

L4 refers to the Frame Distribution/Hashing Algorithm used in FortiLink 802.3ad aggregate interface.

config system interface

 

algorithm.png

 

FGT# # diagnose netlink aggregate list
List of 802.3ad link aggregation interfaces:
1 name fortilink status up algorithm L4 lacp-mode active