3Com CoreBuilder 2500 User Manual - page 51
Bridging and Routing Models
3-7
Figure 3-7 illustrates CoreBuilder 2500 routing:
1
The packet enters the CoreBuilder system.
2
The bridging layer examines the packet’s destination address. The
destination address corresponds to the address of one of the system ports
configured for routing (as opposed to a learned end station address).
3
The packet is passed to the router interface that is associated with the
port where the packet was received.
4
The routing layer:
a
Selects a destination interface based on the destination network
address
b
Determines the MAC address of the next hop (either the destination
host or another gateway)
c
Passes the packet back to the bridging layer
5
The bridging layer then selects a segment (port) based on the destination
MAC address and forwards the packet to that segment.
Figure 3-7
CoreBuilder 2500 Routing
1
Transmitting host
3
Destination host
5
2
1
2
3
Router interfaces
Bridging layer
Routing layer
Subnetworks
4
1
2
3
Router
Bridge