Brocade Communications Systems Brocate Ethernet Access Switch 6910 - Manual (Page 1092)

1042 Brocade 6910 Ethernet Access Switch Configuration Guide
53-1002581-01
IP Routing and Switching
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FIGURE 337 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
Unt Untagged Unt Untagged
Tagged or Untagged Tagged or Untagged Tagged or Untagged Tagged or Untagged
Intra-subnet traffic (Layer 2 switching)