High CPU usage on Fortiswitches and dhcprd process

[Artur1]

Hello

I have multiple periodicaly CPU usage spikes on all my Fortiswitches connected to Fortigate by Fortilink.

The messeages are:
"[First Event] CPU_SENSOR (53.0%) cleared warning threshold of (85.0%)."

I have checked "diag sys top" and most active process is dhcprd - what is this prosess ? Why it spikes to 99% cpu load ?

Most of my switches are: S148FN-v7.4.2-build801,231207

[ozkanaltas]

Hello @Artur1 ,

When I reviewed the release note for 7.4.2 I saw a known issue about that. If IGMP querier is enabled on your switch you can try a workaround solution. 

987504

High CPU usage occurs on the FS-1xx series when the IGMP querier is enabled and IGMP snooping is disabled.

Workaround: Disable the IGMP querier when IGMP snooping is not being used.

 https://docs.fortinet.com/document/fortiswitch/7.4.2/fortiswitchos-release-notes/700712/known-issues

[Artur1]

thank you

let me understand, what is igmp querier according to igmp snooping ?

i need to have disabled igmp snooping for 2 vlans - chinese ip hdmi trancievers

[ozkanaltas]

Hi @Artur1 ,

IGMP snooping selectively forwards multicast traffic, enhancing network performance. The IGMP snooping querier function ensures proper multicast management by soliciting responses from hosts to build a membership table when there's no router or the router doesn't perform IGMP querying.

If you want to get information about the configuration of IGMP Snooping and query, you can review this document.

https://docs.fortinet.com/document/fortiswitch/7.4.4/fortilink-guide/173274/configuring-igmp-snoopin...