Web Management Guide-R04

Table Of Contents
Chapter 17
| General IP Routing
IP Routing and Switching
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Figure 459: Virtual Interfaces and Layer 3 Routing
IP Routing and 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 Layer 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. However, if the MAC
address is not yet known to the switch, an Address Resolution Protocol (ARP)
packet with the destination IP address is broadcast to get the destination MAC
address from the destination node. The IP packet can then be sent directly with the
destination MAC address.
VLAN 1
VLAN 2
Inter-subnet traffic (Layer 3 switching)
Routing
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Intra-subnet traffic (Layer 2 switching)