What will a switch do when

[mikegrous]

There is an arp entry..But no port for the cooresponding MAC address?

#sho ip arp 10.200.0.14

Protocol  Address          Age (min)  Hardware Addr   Type   Interface

Internet  10.200.0.14             4   001d.45e2.8d43  ARPA   Vlan200

Rack20-L3-3750-12#sho mac add dy | i 8d43

[Reza Sharifi]

is 10.200.0.14 connected directly to this switch?

[mikegrous]

yes. Over a directly connected VLAN

[Richard Burts]

If a frame comes into the switch to be forwarded and the switch does not have an entry for the MAC in its mac-address table then the switch will flood the frame to every port in that vlan except for the port on which it arrived.

HTH

Rick

[mikegrous]

thats what i thought. So the dest MAC would be a broadcast MAC. The return traffic would then populate the MAC table.

[Richard Burts]

Just to be clear - the destination mac is not a broadcast, but the forwarding activity is the same as if it were a broadcast. The technical name for it is unicast flooding. And yes, the response traffic source mac address should be used to build an entry in the mac-address table.

HTH

Rick

[mikegrous]

Got it thank you.

[Richard Burts]

I am glad that we were able to help to clarify the expected behavior. If you are satisfied with the responses perhaps you can mark this question as answered?

HTH

Rick