GE ML2400 Switch User Manual

A group of network users (ports) assigned to a VLAN form a broadcast domain. Packets are
forwarded only between ports that are designated for the same VLAN. Cross-domain
broadcast traffic in the switch is eliminated and bandwidth is saved by not allowing
packets to flood out on all ports. For many reasons a port may be configured to belong to
multiple VLANs.
As shown below, ports can belong to multiple VLANs. In this figure, a simplistic view is
presented where some ports belong to VLANs 1, 2 and other ports belong to VLANs 2,3.
Ports can belong to VLANs 1, 2 and 3. This is not shown in the figure.
FIGURE 10–2: Ports assigned to multiple VLANs
By default, on the MultiLink family of switches, VLAN support is enabled and all ports on
the switch belong to the default VLAN (DEFAULT-VLAN). This places all ports on the switch
into one physical broadcast domain.
If VLANs are entirely separate segments or traffic domains - how can the VLANs route
traffic (or “talk”) to each other? This can be done using routing technologies (e.g., a router
or a L3-switch). The routing function can be done internally to a L3-switch. One advantage
of an L3 switch is that the switch can also support multiple VLANs. The L3 switch can thus
route traffic across multiple VLANs easily and provides a cost effective solution if there are
may VLANs defined.
As shown below, routing between different VLANs is performed using a router or a Layer 3
switch (L3-switch)
FIGURE 10–3: VLAN routing
The MultiLink family of switches supports up to 32 VLANs per switch