<Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> Early network designers often configured VLANs with the aim of reducing the size of the collision domain in a large single Ethernet segment and thus improving performance . When Ethernet switches made this a non-issue (because each switch port is a collision domain), attention turned to reducing the size of the broadcast domain at the MAC layer . A VLAN can also serve to restrict access to network resources without regard to physical topology of the network, although the strength of this method remains debatable as VLAN hopping is a means of bypassing such security measures if not prevented . VLAN hopping can be mitigated with proper switchport configuration . </P> <P> VLANs operate at Layer 2 (the data link layer) of the OSI model . Administrators often configure a VLAN to map directly to an IP network, or subnet, which gives the appearance of involving Layer 3 (the network layer). In the context of VLANs, the term "trunk" denotes a network link carrying multiple VLANs, which are identified by labels (or "tags") inserted into their packets . Such trunks must run between "tagged ports" of VLAN - aware devices, so they are often switch - to - switch or switch - to - router links rather than links to hosts . (Note that the term' trunk' is also used for what Cisco calls "channels": Link Aggregation or Port Trunking). A router (Layer 3 device) serves as the backbone for network traffic going across different VLANs . </P>

Which of the following is not a reason to use vlans in a network