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Zorluk: KolayL2 Switching Concepts and MAC Table Operation

A switch receives an Ethernet frame on port FastEthernet0/1. The source MAC address is 0000.1111.1111, and the unicast destination MAC address is 0000.2222.2222. The switch checks its MAC address table and finds no entry for 0000.2222.2222. What action does the switch take to handle this frame?

  1. Floods the frame out all operational interfaces except the ingress port FastEthernet0/1.Cevap
  2. B
    Drops the frame immediately because the destination address is missing from the MAC address table.
  3. C
    Floods the frame out all active interfaces, including the ingress port FastEthernet0/1.
  4. D
    Forwards the frame directly to the default gateway interface for Layer 3 resolution.

Cevap

The switch floods the frame out all operational interfaces within the VLAN except the ingress port FastEthernet0/1.
When a Layer 2 switch receives a unicast frame whose destination MAC address is not currently in its MAC address table, it performs unknown unicast flooding. This forwards the frame out every active port belonging to the same VLAN, excluding the port on which the frame was received.

Adım Adım Çözüm

1
Examine the source MAC address processing.
The switch records MAC address 0000.1111.1111 in its MAC address table mapped to port FastEthernet0/1 if it is not already present.
Switches learn MAC addresses dynamically from incoming frames' source MAC addresses.
2
Examine the destination MAC address lookup.
The destination MAC address 0000.2222.2222 is determined to be an unknown unicast address because it is not present in the MAC address table.
Forwarding decisions are made based on looking up the destination MAC address in the switch MAC address table.
3
Determine the forwarding behavior for unknown unicast traffic.
The switch floods the frame out all active switch ports in the VLAN, except for the incoming port FastEthernet0/1.
Flooding unknown unicast traffic ensures the destination host receives the packet regardless of which port it is connected to.

Anahtar Kavram

Unknown Unicast Flooding and MAC Address Table Lookup Operations
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Konular

L2 Switching Concepts and MAC Table Operation

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