DES-3326S Layer 3 Fast Ethernet Switch User’s Guide

and the destination port transmits it to its attached network segment.

If the packet is not tagged with VLAN information, the ingress port will tag the packet with its own PVID as a VID (if the port is a tagging port). The switch then determines if the destination port is a member of the same VLAN (has the same VID) as the ingress port. If it does not, the packet is dropped. If it has the same VID, the packet is forwarded and the destination port transmits it on its attached network segment.

This process is referred to as ingress filtering and is used to conserve bandwidth within the switch by dropping packets that are not on the same VLAN as the ingress port at the point of reception. This eliminates the subsequent processing of packets that will just be dropped by the destination port.

VLANs in Layer 2 Only Mode

The switch initially configures one VLAN, VID = 1, called the DEFAULT_VLAN. The factory default setting assigns all ports on the switch to the DEFAULT_VLAN.

Packets cannot cross VLANs if the switch is in Layer 2 Only mode. If a member of one VLAN wants to connect to another VLAN, the link must be through an external router.

When the switch is in Layer 2 Only mode, 802.1Q VLANs are supported.

If no VLANs are configured on the switch and the switch is in Layer 2 Only mode, then all packets will be forwarded to any destination port. Packets with unknown source addresses will be flooded to all ports. Broadcast and multicast packets will also be flooded to all ports.

Switch Management and Operating Concepts

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D-Link DES-3326S manual VLANs in Layer 2 Only Mode