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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
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Chapter 10 Configuring VLANs
Understanding How VLANs Work
Figure 10-1 VLANs as Logically Defined Networks
VLANs are often associated with IP subnetworks. For example, all the end stations in a particular IP
subnet belong to the same VLAN. Traffic between VLANs must be routed. Port VLAN membership on
the switch is assigned manually on a port-by-port basis. Assigning switch ports to VLANs using this
method is known as port-based, or static, VLAN membership.
The in-band (sc0) interface of a switch can be assigned to any VLAN, so that you can access another
switch on the same VLAN directly without a router. Only one IP address at a time can be assigned to the
in-band interface. If you change the IP address and assign the interface to a different VLAN, the previous
IP address and VLAN assignment are overwritten.
You can set these parameters when you create a VLAN in the management domain:
•
VLAN number
•
VLAN name
•
VLAN type (Ethernet)
•
VLAN state (active or suspended)
•
Maximum transmission unit (MTU) for the VLAN
•
Security association identifier (SAID)
•
VLAN number to use when translating from one VLAN type to another
Note
When translating from one VLAN type to another, you must create a different VLAN number for each
media type.
Floor 1
Floor 2
Engineering
VLAN
Cisco router
Fast
Ethernet
Catalyst 4000
Catalyst 4000
Catalyst 4000
Floor 3
Marketing
VLAN
Accounting
VLAN
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