MAC Address learned on multiple VLANs

Created: Jul 30, 2019 17:55:32Latest reply: Jul 31, 2019 09:15:49 234 5 16 0
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is there any explanation why MAC Address is learned on some VLANs?


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All_About_Switch
Official Created Jul 31, 2019 06:00:26 Helpful(0) Helpful(0)

On S series switches (except S1700), MAC addresses are learned based on MAC addresses+VLANs. If multiple VLANs receive packets with the same MAC address, these VLANs will learn the same MAC address.
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Renan_Brasil
Renan_Brasil Created Jul 30, 2019 18:17:08 Helpful(0) Helpful(0)

Hi,

A virtual network (VLAN) operates at layer 2 of the OSI model. By default, Layer 2 devices forward or filter frames by MAC address. Therefore, for a source device to communicate with a layer 2 destination device, MAC learning is required.
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chenhui
chenhui Admin Created Jul 31, 2019 01:21:48 Helpful(0) Helpful(0)

@Mysterious.color Hi,
As in my opinion, switch learns MAC address based on interfaces, rather than VLANs,while the interfaces are bind to different VLANs. Based on these information, the CAM entries generated on the switch.
Switch forwards the traffic based the CAM entries.

In addition, VLAN seperates the broadcast domain, and limit the broadcast traffic spreading in the same VLAN, which would help to reduce the useless traffic on the switch, and the consumption of the hardward, bandwidth
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Popeye_Wang
Popeye_Wang Admin Created Jul 31, 2019 02:42:28 Helpful(0) Helpful(0)

Do you mean that the same mac is learned by different VLANs on different ports? That's MAC address flapping, caused by the network loop.
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All_About_Switch
All_About_Switch Official Created Jul 31, 2019 06:00:26 Helpful(0) Helpful(0)

On S series switches (except S1700), MAC addresses are learned based on MAC addresses+VLANs. If multiple VLANs receive packets with the same MAC address, these VLANs will learn the same MAC address.
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  • convention:

Mysterious.color
Mysterious.color MVE Created Jul 31, 2019 09:15:49 Helpful(0) Helpful(0)

thank you all for your answer
it was helpful
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