HP Network Direr Software Products manual Vlan Management

544CHAPTER 13: VLAN MANAGEMENT

Figure 291 VLAN with Gaps

As well as checking for gaps such as this, 3Com Network Director also assumes that for a VLAN to be complete it should be possible for devices on this VLAN to communicate with devices on other VLANs and vice-versa. This means that the switches on which the VLAN is to be created should include at least one Layer 3 switch that is capable of performing VLAN-based IP routing. See“Communication between VLANs” on page 504. If there is no such Layer 3 switch in the selected switches, 3Com Network Director will find the nearest suitable Layer 3 switch and work out which switch ports would need to be added to the VLAN to connect this Layer 3 switch to the other switches in the VLAN.

3Com Network Director will not search beyond clouds in the map when trying to locate the nearest suitable Layer 3 switch. If you are adding a VLAN to a set of devices where there is no path in the map from the devices to a Layer 3 switch, 3Com Network Director will be unable to determine which switch ports would need to be added to the VLAN in order to connect a Layer 3 switch to the other switches in the VLAN.

For example, in the network below if the Create VLAN wizard was launched with the switch2-switch3, switch3-switch4 and the switch4-PC links selected, 3Com Network Director would spot the fact that there was no Layer 3 switch in the selection. 3Com Network Director would then find the nearest Layer 3 switch, L3switch, and determine that the ports connecting L3switch to switch1, and the ports connecting switch1 and switch2, should also be added to the new VLAN.