IP R
OUTING
3-247IP Switching
IP Switching (or packet forwarding) encompasses tasks required to
forward packets for both Layer 2 and Layer 3, as well as traditional routing.
These functions include:
Layer 2 forwarding (switching) based on the Lay er 2 destination 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 subnetwork as the source network,
then the packet can be transmitted directly without the help of a router.
VLAN1 VLAN2
Inter-subnettraffic (Layer 3 switching)
Routing
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Intra-subnettraffic (Layer 2 switching)