Amer Networks SS3GR24i - Manual (Page 33)

SS3GR24i/SS3GR48i Layer3 Stackable Gigabit Switch User’s Guide
VLANs must be configured on the Switch before they can be
assigned IP subnets. Furthermore, the static VLAN configuration
is specified on a per port basis. On the Switch, a VLAN can consist
of end-nodes – just like a traditional layer 2 Switch, but a VLAN
can also consist of one or more Switches – each of which is
connected to multiple end-nodes or network resources.
So, the IP subnets for a network must be determined first, and the
VLANs configured on the Switch to accommodate the IP subnets.
Finally, the IP subnets can be assigned to the VLANs.
Assigning IP Network Addresses and Subnet Masks to VLANs
The SS3GR24i/SS3GR48i allows the assignment of IP subnets to
individual VLANs. This is the fundamental advantage of VLANs in
IP Switching.
Developing an IP addressing scheme is a complex subject, but it is
sufficient here to mention that the total number of anticipated end
nodes – for each IP interface – must be assigned a unique IP
address. It should be noted that the Switch regards a VLAN with
an IP network address and corresponding subnet mask assigned as
an IP interface.
Understanding 802.1Q VLANs
This review of 802.1Q VLANs presents some basic background
about how VLANs work according to the IEEE 802.1Q standard.
VLANs operate according to the same rules regardless of whether
the Switching environment is Layer 2 or Layer 3. The difference is
primarily that in a Layer 3 Switch there is an added capability of
unique association between a VLAN and an IP interface or subnet
group.
A VLAN is a collection of end nodes grouped logically rather than
by physical location. End nodes that frequently communicate with
each other are assigned to the same VLAN, regardless of where
they are located physically on the network. Logically, a VLAN can
be equated to a broadcast domain, because broadcast packets are
forwarded only to members of the VLAN on which the broadcast
was initiated.
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