About VLANs 2-7
Overlapped IP
VLANs
The LANplex system also gives you the ability to assign network layer
information to IP VLANs. This capability allows network administrators to
manage their VLANs by subnet. Flooding decisions are made by first
matching the incoming frame using the protocol (IP) and then matching it
with layer 3 subnet information. If received data is IP but does not match
any defined IP subnet 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):
Data received on... Is flooded on... Because...
XNS - port 1 VLAN 1 XNS data does not match any defined VLAN
in the system.
IP - port 2 VLAN 2 IP data received matches IP VLAN 2 for
source ports 1 - 10.
IP - port 12 VLAN 1 IP data received on source port 12 does not
match any defined source port for IP VLAN,
so the Default VLAN is used.
Index VLAN
Network
Address/Mask
Ports
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
