Layer 2 Switch Forwarding Process
Layer 2 forwarding in hardware is based on the destination MAC address. The Layer 2 switch learns the address, based on the source MAC address. The MAC address table lists MAC and VLAN pairs with associated interfaces.
How a Layer 2 Switch Forwards Packets
The table describes how a Layer 2 switch forwards packets.
|
Step |
Action |
|
1. |
The Layer 2 engine receives a frame. |
|
2. |
The Layer 2 engine performs the input ACL lookup. |
|
3. |
The Layer 2 lookup engine looks up the destination MAC address and determines if the frame is to be switched at Layer 2 or Layer 3. |
|
4. |
If the frame is to be switched at Layer 2, then the Layer 2 forwarding engine performs the outbound security ACL lookup. |
|
5. |
The Layer 2 forwarding engine performs the outbound quality of service (QoS) lookup. |
|
6. |
The Layer 2 forwarding engine forwards the packet. |
© 2006 Cisco Systems, Inc. Implementing Inter-VLAN Routing 4-15
Continue reading here: Logical Packet Flow for a Multilayer Switch
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