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

Forwarding rules between ports – decides filter or forward the packet

Egress rules – determines if the packet must be sent tagged or untagged.

Figure 5-6. IEEE 802.1Q Packet Forwarding

802.1Q VLAN Tags

The figure below shows the 802.1Q VLAN tag. There are four additional octets inserted after the source MAC address. Their presence is indicated by a value of 0x8100 in the EtherType field. When a packet’s EtherType field is equal to 0x8100, the packet carries the IEEE 802.1Q/802.1p tag. The tag is contained in the following two octets and consists of 3 bits or user priority, 1 bit of Canonical Format Identifier (CFI – used for encapsulating Token Ring packets so they can be carried

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Switch Management and Operating Concepts

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D-Link DES-3326S manual 802.1Q Vlan Tags, Ieee 802.1Q Packet Forwarding