Advanced Configuration and Management Guide
NOTE: If the device’s ARP table does not contain the requested host, the device forwards the ARP request on Layer 2 to the same VLAN as the one that received the ARP request. Then the device sends an ARP for the destination to the other VLANs that are using the same IP sub-net address.
•If the destination is in the same VLAN as the source, the device does not need to perform a proxy ARP. To configure multiple VLANs to use the same IP sub-net address:
•Configure each VLAN, including adding tagged or untagged ports.
•Configure a separate virtual interface for each VLAN, but do not add an IP sub-net address to more than one of the virtual interfaces.
•Configure the virtual interfaces that do not have the IP sub-net address to “follow” the virtual interface that does have the address.
USING THE CLI
To configure the VLANs shown in Figure 16.15, you could enter the following commands.
HP9300(config)# vlan 1 by port
HP9300(config-vlan-1)# untag ethernet 1/1
HP9300(config-vlan-1)# tag ethernet 1/8
HP9300(config-vlan-1)# router-interface ve 1
Syntax: ip follow ve <num>
The commands above configure port-based VLAN 1. The VLAN has one untagged port (1/1) and a tagged port (1/8). In this example, all three VLANs contain port 1/8 so the port must be tagged to allow the port to be in multiple VLANs. You can configure VLANs to share a Layer 3 protocol interface regardless of tagging. A combination of tagged and untagged ports is shown in this example to demonstrate that sharing the interface does not change other VLAN features.
Notice that each VLAN still requires a unique virtual interface.
The following commands configure port-based VLANs 2 and 3.
HP9300(config-vlan-1)# vlan 2 by port
HP9300(config-vlan-2)# untag ethernet 1/2
HP9300(config-vlan-2)# tag ethernet 1/8
HP9300(config-vlan-2)# router-interface ve 2
HP9300(config-vlan-2)# vlan 3 by port
HP9300(config-vlan-3)# untag ethernet 1/5 to 1/6
HP9300(config-vlan-3)# tag ethernet 1/8
HP9300(config-vlan-3)# router-interface ve 3
The following commands configure an IP sub-net address on virtual interface 1.
HP9300(config-vlan-3)# interface ve 1
HP9300(config-vif-1)# ip address 10.0.0.1/24
The following commands configure virtual interfaces 2 and 3 to “follow” the IP sub-net address configured on virtual interface 1.
HP9300(config-vif-1)# interface ve 2
HP9300(config-vif-2)# ip follow ve 1
HP9300(config-vif-2)# interface ve 3
