Problems with rate-limit flood unknown-destmac causing slow traffic

[javfe]

We have detected that some users are experiencing slow traffic, specially while they are uploading files to a shared server (located in the same vlan as the computer or in different vlan). They upload the files both via Windows smb or via sftp. Once they start to upload the files we have detected that after a while the “Unknown-dest-mac flood” counter increases dramatically and the switch reach the rate-limit configured (1000 pps in the UP-LINK port and 120 pps in the users ports) and so it starts to drop packets, causing the slowness in the traffic and uploads.
 

Regards

Javier

[StephanH · Accepted solution]

Hello javfe,I think the categorization is not the problem. You have to check different causes. One if them are the server ports. Here are some other hints:

[javfe]

Hello StephanN,

When downloading from another server or a share with an interface, the same problem occurs. If I configure the port with "rate-limit flood unknown-destmac no-limit" the problem disappears.
Could there be a problem with the categorization of the traffic?

[StephanH]

Hello Javfe,

if you do not know the status, the best way is to check the status, you have to check step by step all possible causes. If you have no access to the server you can disable redundat ports on the switch side, too.

[javfe]

Hello StephanH,

I don’t know the status of the server. 

The first file download is successful. After a few minutes the flood rate exceeded counter starts to increase. If I renew the connection the network, the transfer works correctly until after a few minutes.