Intel ZT 8101 10/100 user manual IEEE 802.1Q VLANs, Gvrp, Switch Management and Operating Concepts

Switch Management and Operating Concepts

The complexity of the VLAN configuration is hidden. The switch applies the following rules when it creates the VLAN:

•Tagged frames are discarded. With port-based VLANs, frames are assumed to be untagged, so that the VLAN members do not receive frames coming from another VLAN.

•VLAN ID is assigned using an internal algorithm. The switch allocates the largest free VLAN ID that is smaller than 4095 (for example, 4094, 4093, 4092).

•The member port's PVID is assigned as the VLAN ID.

•A port can only belong to one port-based VLAN.

IEEE 802.1Q VLANs

IEEE 802.1Q VLANs have the following characteristics:

•Use filtering to assign packets to VLANs.

•Assume the presence of a single global spanning tree.

•Use an explicit tagging scheme with one-level tagging.

An IEEE 802.1Q VLAN is not as simple as a port-based VLAN, but it is also more flexible. You can configure ports to be tagged, untagged, or forbidden.

•Untagged Member Port—Designates the port as an untagged member of the VLAN. When an untagged packet is transmitted by the port, the packet header remains unchanged. When a tagged packet exits the port, the tag is stripped and the packet is changed to an untagged packet. If the port is attached to a device that is not IEEE 802.1Q VLAN compliant (VLAN- tag unaware), then the port should be set to untagged.

•Tagged Member Port—Designates the port as a tagged member of the VLAN. When an untagged packet is transmitted by the port, the packet header is changed to include the 32-bit tag associated with the PVID (Port VLAN Identifier). When a tagged packet with a different VID exits the port, the packet header is unchanged. If the port is attached to a device that is IEEE 802.1Q VLAN compliant, (VLAN-tag aware), then the port can be set to tagged.

•Forbidden Port—Designates the port as not being a member of the VLAN and prevents packets tagged with the VLAN’s VID from entering the port.

You can enable or disable the following per port for IEEE 802.1Q VLANs:

•GVRP

•Ingress Checking

GVRP

GVRP (GARP VLAN Registration Protocol) must be enabled globally on the switch before individual ports can be enabled.

A global flag controls the switch's ability to participate in dynamically configured VLANs. If the GVRP flag is enabled, ports can dynamically register to be a member of a VLAN. If the flag is disabled, only statically configured ports can be members of VLANs.

The default value is disabled.

36 Intel® NetStructure™ ZT 8101 10/100 Ethernet Switch User’s Manual