DELL N3000 User Manual

650

Configuring VLANs

Tagging may be required when a single port supports multiple devices that are

members of different VLANs. For example, a single port might be connected

to an IP phone, a PC, and a printer (the PC and printer are connected via

ports on the IP phone). IP phones are typically configured to use a tagged

VLAN for voice traffic, while the PC and printers typically use the untagged

VLAN.
Trunk ports can receive tagged and untagged traffic. Untagged traffic is

tagged internally with the native VLAN. Native VLAN traffic received

untagged is transmitted untagged on a trunk port.
By default, trunk ports are members of all existing VLANs and will

automatically participate in any newly created VLANs. The administrator can

restrict the VLAN membership of a trunk port. VLAN membership for tagged

frames received on a trunk port is configured separately from the membership

of the native VLAN. To configure a trunk port to accept frames only for a

single VLAN, both the native VLAN and the tagged VLAN membership

settings must be configured. If the native VLAN for a trunk port is deleted,

the trunk port drops untagged packets.
Access ports accept untagged traffic and traffic tagged with the access port

PVID. Untagged ingress traffic is considered to belong to the VLAN

identified by the PVID. If the PVID for an access port is deleted, the PVID is

set to VLAN 1.

GVRP

The GARP VLAN Registration Protocol (GVRP) helps to dynamically

manage VLAN memberships on trunk ports. When GARP is enabled,

switches can dynamically register (and de-register) VLAN membership

information with other switches attached to the same segment.
Information about the active VLANs is propagated across all networking

switches in the bridged LAN that support GVRP. You can configure ports to

forbid dynamic VLAN assignment through GVRP.
The operation of GVRP relies upon the services provided by the Generic

Attribute Registration Protocol (GARP). GVRP can create up to 1024 VLANs.