3com corebuilder 10002211 Manuel D’Utilisation

The CoreBuilder system also gives you the ability to assign network 
layer information to IP VLANs. This capability allows network 
administrators to manage their VLANs by subnetwork. Flooding 
decisions are made by first matching the incoming frame using the 
protocol (IP) and then matching it with layer 3 subnetwork information. 
If received data is IP but does not match any defined IP subnetwork 
VLAN, it is flooded within all IP VLANs using the relevant switch port.

For example, two IP VLANs can be configured for ports 1-10 as follows:

IP VLAN 1 - subnet 158.101.112.0, ports 1-10

IP VLAN 2 - subnet 158.101.113.0, ports 1-10

This example shows how flooding decisions are made using overlapping IP 
VLANs (assuming a 12-port switch):

As shown in this example, when the subnet address of an IP packet does 
not match any subnet address of any defined IP VLAN in the system, it is 
flooded to all of the IP VLANs that share the source switch port, in this case, 
port 6.

1

Default

none

1 - 12

2

IP

158.103.122.0/
255.255.255.0

1 - 6

3

IP

158.103.123.0/
255.255.255.0

6 - 12

IP subnet 
158.103.122.2 
on port 6

VLAN 2

IP network layer matches layer 3 address for 
VLAN 2.

IP subnet 
158.103.123.2 
on port 6

VLAN 3

IP network layer matches layer 3 address for 
VLAN 3.

IP subnet 
158.103.124.2 
on port 6

VLAN 2 and 
VLAN 3

IP network layer does not match any layer 3 
address for IP VLANs.

IPX on port 6

VLAN 1

IPX frame does not match any defined VLAN.