NetXtreme II User Guide
January 2010
Broadcom Corporation
Page 64 VLAN Overview Document ENGSRVT52-CDUM100-R
Figure1 shows an example network that uses VLANs. In this example network, the physical LAN consists of a switch, two
servers, and five clients. The LAN is logically organized into three different VLANs, each representing a different IP subnet.
The features of this network are described in Table1.
NOTE: VLAN tagging is only required to be enabled on switch ports that create trunk links to other switches, or on
ports connected to tag-capable end-stations, such as servers or workstations with Broadcom adapters.
Table 1: Example VLAN Network TopologyComponent Description
VLAN #1 An IP subnet consisting of the Main Server, PC #3, and PC #5. This subnet
represents an engineering group.
VLAN #2 Includes the Main Server, PCs #1 and #2 via shared media segment, and PC #5.
This VLAN is a software development grou p.
VLAN #3 Includes the Main Server, the Accounting Server and PC #4. This VLAN is an
accounting group.
Main Server A high-use server that needs to be accessed from all VLANs and IP subnets. The
Main Server has a Broadcom adapter installed. All three IP subnets are
accessed via the single physical adapter interface. The server is attached to one
of the switch ports, which is configured for VLANs #1, #2, and #3. Both the
adapter and the connected switch port have tagging turned on. Because of the
tagging VLAN capabilities of both devices, the server is able to communicate on
all three IP subnets in this network, but continues to maintain broadcast
separation between all of them.
Accounting Server Available to VLAN #3 only. The Accounting Server is isolated from all traffic on
VLANs #1 and #2. The switch port connected to the server has tagging turned
off.
PCs #1 and #2 Attached to a shared media hub that is then connected to the switch. PCs #1 and
#2 belong to VLAN #2 only, and are logically in the same IP subnet as the Main
Server and PC #5. The switch port connected to this segment has tagging turned
off.
PC #3 A member of VLAN #1, PC #3 can communicate only with the Main Server and
PC #5. Tagging is not enabled on PC #3 switch port.
PC #4 A member of VLAN #3, PC #4 can only communicate with the servers. Tagging
is not enabled on PC #4 switch port.
PC #5 A member of both VLANs #1 and #2, PC #5 has an Broadcom adapter installed.
It is connected to switch port #10. Both the adapter and the switch port are
configured for VLANs #1 and #2 and have tagging enabled.