FortiSwitch
FortiSwitch: secure, simple and scalable Ethernet solutions
sachitdas_FTNT
Article Id 409565
Description This article describes the reason for 'FortiLink Switch new peer detected' logs on FortiGate Switch-Controller Event logs.
Scope FortiGate versions 7.4.8, 7.6.3, Managed FortiSwitch v7.6.2/v7.4.7.
Solution

Functionality Impact and Symptoms:

  • 'New peer detected' messages appear in the FortiSwitch event log continuously on the FortiGate. For example:

 

date=2025-08-01 time=04:12:22 eventtime=1756871361886880822 tz="+0200" logid="0115032624" type="event" subtype="switch-controller" level="information" vd="root" logdesc="Fortilink Switch new peer detected" user="Switch-Controller" ui="fortilinkd" name="xxxxx" sn="xxxxx" msg="New peer (S148Fxxxxx) detected on port (port22)"

 

  • FortiLink Topology Display Issue with MCLAG Aggregation Switches. Topology will not show solid inter-switch links. It may show no lines or dotted lines.

 

Trigger Condition: FortiLink setup with FortiSwitch firmware versions 7.6.2 or 7.4.7, and the total number of trunk members (FortiLink + Inter Switch Links + Inter Chassis Link) exceeds 5 on any switch.

 

User Impact: NA (A display issue occurs on the FortiGate; However, data traffic is not affected.)

 

The issue is fixed in FortiGate versions 7.4.9, 7.6.4, and above.

 

For a workaround, contact support for more details.

 

Workarounds:

  • Downgrade the FortiSwitch firmware to versions 7.6.1 or 7.4.6.
  • Or if it is feasible, reduce the total number of trunk member ports to 5 or fewer on the switch.
  • Or change the FortiLink mgmt-mode to https on the affected switch.

 

Note: When switching to HTTPS mode:

  • If the switch is a core switch and fortilink-neighbor-detect is set to 'LLDP', change detect mode to 'fortilink'.
  • Before doing so, verify that the FortiLink trunk (FL) on the switch does not have the 'set static-isl enable' setting.
  • After changing the neighbor detect mode to 'fortilink' on the FortiGate, ensure that the name of the FortiLink trunk on the switch does not include the '-0' suffix.
  • Finally, enable 'set isl-static enable' in that FortiLink trunk (FL).