3Com LANPLEX 2500 EXTENDEDPLEX®2500 EXTENDED User Manual page 29

Data received on... Is flooded on...
XNS - port 1
IP - port 2
IP - port 12
Overlapped IP The LANplex system also gives you the ability to assign network layer
VLANs 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:
This example shows how flooding decisions are made using overlapping IP
VLANs (assuming a 12-port switch):
Index
1
2
3
VLAN 1
VLAN 2
VLAN 1
IP VLAN 1 - Subnet 158.101.112.0, ports 1-10
IP VLAN 2 - Subnet 158.101.113.0, ports 1-10
VLAN
Default
IP
IP
Because...
XNS data does not match any defined VLAN
in the system.
IP data received matches IP VLAN 2 for
source ports 1 - 10.
IP data received on source port 12 does not
match any defined source port for IP VLAN,
so the Default VLAN is used.
Network
Address/Mask Ports
none 1 - 12
158.103.122.0/ 1 - 6
255.255.255.0
158.103.123.0/ 6 - 12
255.255.255.0
About VLANs 2-7