11-2
Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
78-13315-02
Chapter 11 Configuring VLANs
Understanding How VLANs Work
Figure 11-1 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. When you assign switch ports to VLANs using
this method, it is known as port-based, or static, VLAN membership.
The in-band (sc0) interface of a switch can be assigned to any VLAN, so 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.
VLAN Ranges
Catalyst 6000 family switches support 4096 VLANs in accordance with the IEEE 802.1Q standard.
These VLANs are organized into several ranges; you use each range slightly differently. Some of these
VLANs are propagated to other switches in the network when you use a management protocol, such as
the VLAN Trunking Protocol (VTP). Other VLANs are not propagated and you must configure them on
each applicable switch.
There are three ranges of VLANs:
•
Normal-range VLANs: 1–1000
•
Extended-range VLANs: 1025–4094
•
Reserved-range VLANs: 0, 1002–1024, 4095
Floor 1
Floor 2
Engineering
VLAN
Cisco router
Fast
Ethernet
Floor 3
Marketing
VLAN
Accounting
VLAN
16751