3Com 2500 manual 7 Routing in the LANplex Bridging and Routing Model

Bridging and Routing Models 3-7

In the LANplex bridging and routing model, a packet is routed as follows (see Figure 3-7):

1The packet enters the LANplex system.

2The packet’s destination address is examined by the bridging layer.

3The destination address corresponds to the address of one of the system ports configured for routing (as opposed to a learned end-station address). The packet is passed to the router interface associated with the port on which the packet was received.

4The 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.

5The bridging layer then selects a segment (port) based on the destination MAC address and forwards the packet to that segment.

	4		Router	Routing Layer
3	1	2	3	Router Interfaces
		5	Bridge
2				Bridging Layer
1
	1	2	3	Subnets

Transmitting Host

Destination Host

Figure 3-7 Routing in the LANplex Bridging and Routing Model