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EARL Table and Uplinkfast - Confusion - Dummy Frames

Hello all,

I have just been looking at the uplinkfast configuration sheets and I read the following..

"As soon as the switch transitions the alternate port to the forwarding state, the switch begins transmitting dummy multicast frames on that port, one for each entry in the local EARL table (except those entries associated with the failed root port). By default, approximately 15 dummy multicast frames are transmitted per 100 milliseconds."

Can I assume from this that the EARL table is not the CAM table, and the switch starts to send out dummy frames for MAC addresses it has on the actual switch interfaces (you know when you do a show mod) and not sending dummy frames for all MAC addresses it has in its cam table for end-user devices?

I am so confused by this point as also, it makes a comparison that if you have more than 500 devices attached to your leaf switch in the IDF, you should look at increasing the "rate station_update_rate" command on your switch.

I read this on page 267 of the book Cisco LAN Switching.

Can anyone please clear up this confusing point on exactly what the switch sends out with these dummy multicast frames?

Kind regards,


  • Other Network Infrastructure Subjects

Re: EARL Table and Uplinkfast - Confusion - Dummy Frames

I think uplink fast will send all the addresses in CAM table as multicast frames.It will not stop with sending just the dynamically learned mac addresses or switch interface addresses.