Foundry Networks Switch and Router Installation And Configuration Manual page 960

Foundry Switch and Router Installation and Configuration Guide
Configuring the Same IP Sub-Net Address on Multiple Port-Based
VLANs
For a Foundry device to route between port-based VLANs, you must add a virtual interface to each VLAN.
Generally, you also configure a unique IP sub-net address on each virtual interface. For example, if you have
three port-based VLANs, you add a virtual interface to each VLAN, then add a separate IP sub-net address to
each virtual interface. The IP address on each of the virtual interfaces must be in a separate sub-net. The
Foundry device routes Layer 3 traffic between the sub-nets using the sub-net addresses.
NOTE: This feature applies only to BigIron Layer 3 Switches.
NOTE: Before using the method described in this section, see "Configuring VLAN Groups and Virtual Interface
Groups" on page 25-43. You might be able to achieve the results you want using the methods in that section
instead.
Figure 25.17 shows an example of this type of configuration.
Figure 25.17 Multiple port-based VLANs with separate protocol addresses
As shown in this example, each VLAN has a separate IP sub-net address. If you need to conserve IP sub-net
addresses, you can configure multiple VLANs with the same IP sub-net address, as shown in Figure 25.18.
25 - 40
VLAN 2
VLAN 3
VLAN 4
BigIron
Switching Router
VLAN 2 VLAN 3
VE 1 VE 2
-IP 10.0.0.1/24 -IP 10.0.1.1/24
VLAN 4
VE 3
-IP 10.0.2.1/24
December 2000