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New Member

Flooding of a switch

Hi All,

Here is my topology. I'm analysing the MAC address learning process of a switch.

p9.png

Assume that the switch has MAC entries of WS2 and WS4 only. So when i ping WS1 from WS2, since the switch doen't have the WS1 MAC entry it will flood the frame...  but i thought it will flood only on Fa0/1 port and Fa0/3 port but it flooded the frame to Fa0/4 port also, which it should not because already it has the MAC entry of WS4 on Fa0/4. Can someone please explain, why this happened ?

Will the switch assume that device on Fa0/4 might have change and done this flooding on Fa0/4 also or else what is the reason?

Regards,

Chandu

Regards, Chandu
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1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: Flooding of a switch

The switch has no way of knowing what is reachable via fa0/4. It could just be a PC as in your example but it could be another switch with multiple devices connected in which case there would be multiple mac addresses associated with fa0/4.

Because the switch has no way of knowing what is on the end of the link from fa0/4 it has to flood the frame. So the switch will flood the frame to all ports within the same vlan except the port it was received on.

Jon

2 REPLIES
Hall of Fame Super Blue

Re: Flooding of a switch

The switch has no way of knowing what is reachable via fa0/4. It could just be a PC as in your example but it could be another switch with multiple devices connected in which case there would be multiple mac addresses associated with fa0/4.

Because the switch has no way of knowing what is on the end of the link from fa0/4 it has to flood the frame. So the switch will flood the frame to all ports within the same vlan except the port it was received on.

Jon

New Member

Flooding of a switch

Thanks a lot, Jon. Well explained.

Regards,
Chandu

Regards, Chandu
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