Static Virtual LANs (VLANs)

Port-Based Virtual LANs (Static VLANs)

General Steps for Using VLANs

1.Plan your VLAN strategy and create a map of the logical topology that will result from configuring VLANs. Include consideration for the interaction between VLANs and other features such as Spanning Tree Protocol, load balancing, and IGMP. (Refer to “Effect of VLANs on Other Switch Fea­ tures” on page 2-38.)If you plan on using dynamic VLANs, include the port configuration planning necessary to support this feature. (See chapter 3, “GVRP”)

By default, VLAN support is enabled and the switch is configured for eight VLANs.

2.Configure at least one VLAN in addition to the default VLAN.

3.Assign the desired switch ports to the new VLAN(s).

4.If you are managing VLANs with SNMP in an IP network, each VLAN must have an IP address. Refer to the chapter on IP addressing in the Manage­ ment and Configuration Guide.

VLAN Operating Notes

If you are using DHCP/Bootp to acquire the switch’s configuration, packet time-to-live, and TimeP information, you must designate the VLAN on which DHCP is configured for this purpose as the primary VLAN. (In the factory-default configuration, the DEFAULT_VLAN is the primary VLAN.)

IGMP, and some other features operate on a “per VLAN” basis. This means you must configure such features separately for each VLAN in which you want them to operate.

You can rename the default VLAN, but you cannot change its VID (1) or delete it from the switch.

Any ports not specifically assigned to another VLAN will remain assigned to the DEFAULT_VLAN.

To delete a VLAN from the switch, you must first remove from that VLAN any ports assigned to it.

Changing the number of VLANs supported on the switch requires a reboot. Other VLAN configuration changes are dynamic.

Multiple VLAN Considerations

Switches use a forwarding database to maintain awareness of which external devices are located on which VLANs. Some switches, such as those covered by this guide, have a multiple-forwarding database, which means the switch allows multiple database entries of the same MAC address, with each entry

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