Intra-subnet traffic (Layer 2 switching)
IP Switching
IP Switching (or packet forwarding) encompasses tasks required to forward pa ckets
for both Layer 2 and Layer 3, as well as traditional routing. Thes e functions i nclude:
• Layer 2 forwarding (switching) based on the Layer 2 desti nation MAC address
• Layer 3 forwarding (routing):
- Based on the Layer 3 destination address
- Replacing destination/source MAC addresses for each hop
- Incrementing the hop count
- Decrementing the time-to-live
- Verifying and recalculating the Layer 3 checksum
If the destination node is on the same sub network as the source network, then the
packet can be transmitted directly without the help of a router. However, if the MAC
address is not yet known to the switch, an Address Resolution Protocol (AR P)
packet with the destination IP address is broadcast to get the de stination MA C
address from the destination node. The IP packet can then be sent direc tly with th e
destination MAC address.
If the destination belongs to a different subnet on t his switch , the pack et can be
routed directly to the destination node. However, if the packet belongs to a subnet

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Each VLAN represents a virtual interface to Layer 3. You just need to provide the
network address for each virtual interface, and the traffic between different
subnetworks will be routed by Layer 3 switching.
Inter-subnet traffic (Layer 3 switching)
Routing
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