Viper SC+™ IP Router for Licensed Spectrum PN 001-5008-000 Rev. C
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APPENDIX I
– VLAN INTRODUCTION
When VLAN is enabled, the Viper can perform certain actions based on the interface configuration and the content of
packets’ VLAN identifiers or “tags.” Actions the Viper can perform include adding or removing, or replacing VLAN tags,
and filtering or not filtering packets, based on their VLAN tag.
VLAN TAGGING AND UNTAGGING
Adding a VLAN header to an Ethernet packet is called “tagging,” and removing a VLAN header from an Ethernet packet
is called “untagging.”
Packets with a VLAN header can be recognized by looking at the Ethernet type field.
Some common Ethernet types:
0x0800 : Ethernet data is an IP packet.
0x0806 : Ethernet data is an ARP packet.
0x8100 : Ethernet data is preceded by a VLAN header.
VLAN TAGGING
Reception of an untagged Ethernet packet.
An untagged Ethernet packet is structured like the following.
Adding a VLAN header to an untagged Ethernet packet.
The VLAN Header is added following the Ethernet Header and before the Ethernet data, as indicated highlighted in
beige in the following figure.