Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide User Manual
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routing interface MAC address, the device switches the packet on Layer 3 to the destination host on
the VLAN.
NOTE
If the Brocade device ARP table does not contain the requested host, the Brocade 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 subnet address.
• If the destination is in the same VLAN as the source, the Brocade device does not need to perform a
proxy ARP.
To configure multiple VLANs to use the same IP subnet address:
• Configure each VLAN, including adding tagged or untagged ports.
• Configure a separate virtual routing interface for each VLAN, but do not add an IP subnet address to
more than one of the virtual routing interfaces.
• Configure the virtual routing interfaces that do not have the IP subnet address to "follow" the virtual
routing interface that does have the address.
To configure the VLANs shown in
, you could enter the following commands.
device(config)# vlan 1 by port
device(config-vlan-1)# untagged ethernet 1/1
device(config-vlan-1)# tagged ethernet 1/8
device(config-vlan-1)# router-interface ve 1
Syntax: router-interface ve number
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 routing interface.
The following commands configure port-based VLANs 2 and 3.
device(config-vlan-1)# vlan 2 by port
device(config-vlan-2)# untagged ethernet 1/2
device(config-vlan-2)# tagged ethernet 1/8
device(config-vlan-2)# router-interface ve 2
device(config-vlan-2)# vlan 3 by port
device(config-vlan-3)# untagged ethernet 1/5 to 1/6
device(config-vlan-3)# tagged ethernet 1/8
device(config-vlan-3)# router-interface ve 3
The following commands configure an IP subnet address on virtual routing interface 1.
device(config-vlan-3)# interface ve 1
device(config-vif-1)# ip address 10.0.0.1/24
The following commands configure virtual routing interfaces 2 and 3 to "follow" the IP subnet address
configured on virtual routing interface 1.
device(config-vif-1)# interface ve 2
device(config-vif-2)# ip follow ve 1
device(config-vif-2)# interface ve 3
device(config-vif-3)# ip follow ve 1
VLANs
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