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[EX] Framing errors increase on MAC SEC enabled interface but no impact to data traffic



Article ID: KB36654 KB Last Updated: 24 May 2021Version: 1.0

When Mac Sec is enabled on an interface and any frames are received other than EAPOL from the ISP, then the frame is dropped and it is reported under Framing errors.


Framing errors increasing on MAC SEC Enabled interface.

root@c02-45> show interfaces xe-0/2/0 extensive | match fram | refresh 20
---(refreshed at 2021-03-01 00:55:06 PST)---
    Errors: 24932, Drops: 0, Framing errors: 24932, Runts: 0,

Note: Data traffic was not affected but there was a continuous increase in framing errors.

When sending frames of unknown protocol type like ethertype Slow Protocols (0x8809), or ethertype Unknown (0x88a7), or anything other than EAPOL towards MAC SEC enabled switches, then Framing errors are observed.


These frames cannot be captured through TCP dump in MAC Sec Enabled switch. When MAC SEC is disabled, the framing errors will stop and the TCP dump will show as follows:

01:53:32.995525  In 00:00:00:00:00:02 > 01:80:c2:00:00:03, ethertype Slow Protocols (0x8809), length 68: LACP version 128 packet not supported

It is expected behavior to drop the traffic other than EAPOL packets. These framing errors are not an indication of physical layer issues, like cables and SFPS.

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