Making Vlan Connections - SMC Networks 48-Port Installation Manual

Making VLAN Connections

VLANs can be based on port groups, or each data frame can be
explicitly tagged to identify the VLAN group it belongs to. When
using port-based VLANs, ports can either be assigned to any
number of groups. Port-based VLANs are suitable for small
networks. A single switch can be easily configured to support
several VLAN groups for various organizational entities (such as
Finance and Marketing).
When you expand port-based VLANs across several switches, you
need to make a separate connection for each VLAN group. This
approach is, however, inconsistent with the Spanning Tree
Protocol, which can easily segregate ports that belong to the same
VLAN. When VLANs cross separate switches, it is therefore better
to use VLAN tagging. This allows you to assign multiple VLAN
groups to the "trunk" ports (that is, tagged ports) connecting
different switches.
R&D
VLAN 1
VLAN 2
Testing
Figure 2-4. Making VLAN Connections
Note: When connecting to a switch that does not support IEEE
802.1Q VLAN tags, use untagged ports.
Tagged
Ports
Untagged Ports
Finance
Marketing
VLAN 3
VLAN 4
Tagged Port
VLAN
unaware
switch
Finance
VLAN 3
N P
ETWORK LANNING
VLAN
aware
switch
R&D
Testing
VLAN 1
VLAN 2
2-5