A Cisco Catalyst switch with an empty MAC address table receives an ingress Ethernet frame on interface GigabitEthernet1/0/24 assigned to VLAN 50. The frame contains a source MAC address of 001B.D455.A1B2 and a destination MAC address of 001B.D488.F9E0. Which processing action does the switch perform upon receiving this frame?
- It records source MAC address 001B.D455.A1B2 associated with interface GigabitEthernet1/0/24 in VLAN 50 in its MAC address table and floods the frame out all active interfaces in VLAN 50 except GigabitEthernet1/0/24.Cevap
- BIt drops the frame immediately because the destination MAC address 001B.D488.F9E0 is not present in its MAC address table.
- CIt forwards the frame directly to the default gateway router on VLAN 50 to perform Layer 3 lookup and address resolution.
- DIt floods the frame out all active interfaces in VLAN 50, including GigabitEthernet1/0/24, without updating its MAC address table.
Cevap
The switch records the source MAC address 001B.D455.A1B2 associated with interface GigabitEthernet1/0/24 in VLAN 50 in its MAC address table and floods the frame out all active interfaces in VLAN 50 except GigabitEthernet1/0/24.
When a switch receives a frame, it always performs MAC learning by binding the source MAC address to the ingress port and VLAN. If the destination MAC address is not found in the MAC address table for that VLAN, the switch performs an unknown unicast flood, transmitting the frame out all operational ports within the VLAN except the port on which the frame arrived.
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Anahtar Kavram
Layer 2 MAC Address Table Learning and Unknown Unicast Flooding Logic