Mac-address in L2 switches

[pradeepkum]

Why do L2 switch ports themselves have MAC addresses? When/how are they used?

[dnyan.gujar]

Hi,

There is inbuilt allocated MAC address for the swithch. Which the L2 switch using it as per it's requirement. According to me those MAC address are used by L2 switch to assign to ports.

As per the rule when the frame is forwarded it is using the MAC address of exit interface or next hop interface MAC Address for communication.

for Deciding the Port ID the Port's MAC address are used, though you can use this to tune the STP decisions.

Please do correct me if it is wrong.

Thanks.

[Giuseppe Larosa]

Hello Dnyan,

MAC addresses are allocated to lan switches because they need to talk STP and to be able to detect when two ports of the same switch are connected together.

so each port needs ist own MAC address to be used as source for STP, VTP, CDP and other L2 protocols.

internal forwarding is based on the CAM table and each port should be addressed there with its SNMP ifindex or STP port index.

Hope to help

Giuseppe