User's Manual

506 CHAPTER 13: VLAN MANAGEMENT
Figure 261 Switches Connected by 802.1Q Tagged Links
Primary and Secondary IP interfaces
Some 3Com Layer 3 switches allow multiple IP interfaces to be created
for one VLAN. To support this, these Layer 3 switches have the concept of
primary and secondary IP interfaces. Primary and secondary IP interfaces
determine how the switch processes broadcast and multicast traffic that
arrives on a VLAN with multiple IP interfaces.
Take for example a broadcast packet arriving on VLAN 10, which has a
primary interface of 158.101.68.254/255.255.255.0 and a secondary of
158.101.69.254/255.255.255.0. If the source address of the packet was
on the 158.101.69.0 network, the agent receives the packet on the
158.101.69.254 interface. But there may be times where a packet may