After Flexlink Active link down, why other PC or network devices can send ARP packet?

[mhiyoshi]

Hello all

I have a question about basic Flexlink. I appreciate any related information.

Here is the network topology below.

#############################################################################

                                           (FlexLink-Backup) *capture data after active link down

1812J-F0-----G1/0/5-3750X-G1/0/2-----G1/0/2-2960S-2-G1/0/3------
                                         |                                                                         |
                                         |                                                                         |
                                    G1/0/1-----------G1/0/1-2960S-1-G1/0/3-----------
                                           (FlexLink-Active)

1812J-F0_MAC:0000.0000.1111

#############################################################################

Please look at the above topology, if I execute shutdown command on 3750X-G1/0/1 then

 G1/0/2 can take over the link, this is normal specification on Basic Flexlink.

However I can not recognize why other device for example in this case Cisco1812J can send 

ARP packet to the MAC address 01:00:0c:cd:cd;cd as STP-UPlinkfast.

Please see the attache capture data.

*This topology condition is No MAC address move update transmit./receive command.

[mhiyoshi]

I am sorry for this discussion, I think my understanding about Flexlink is incorrect,

because Catalyst Switch configred Flexlink can send dummy multicast packet after active link failure, so other device such PC , other switch can not send any ARP packet and also they can not detect any link failure in this case.

Thank you very much.

Best Regards,

Masanobu Hiyoshi