ZyXEL Communications IES-1248-51 - Chapter 48 IEEE 802.1 Q Tagged VLAN Commands; Introduction to Vlans; IEEE 802.1 Q Tagging Types; Filtering Databases

IES-1248-51/51A/53 User’s Guide
Chapter 48 IEEE 802.1Q Tagged VLAN Commands 313
CHAPTER 48
IEEE 802.1Q Tagged VLAN
Commands
This chapter describes the IEEE 802.1Q Tagged VLAN commands.
48.1 Introduction to VLANs
See Chapter 19 on page 157 for more background information on VLANs.
48.2 IEEE 802.1Q Tagging Types
There are two kinds of tagging:
• Explicit Tagging
A VLAN identifier is added to the frame header that identifies the source VLAN.
• Implicit Tagging
The MAC (Media Access Control) number, the port or other information is used to identify the
source of a VLAN frame.
The IEEE 802.1Q Tagged VLAN uses both explicit and implicit tagging.
It is important for the IES-1248 to determine what devices are VLAN-aware and VLAN-
unaware so that it can decide whether to forward a tagged frame (to a VLAN-aware device) or
first strip the tag from a frame and then forward it (to a VLAN-unaware device).
48.3 Filtering Databases
A filtering database stores and organizes VLAN registration information useful for switching
frames to and from the IES-1248. A filtering database consists of static entries (Static VLAN
or SVLAN table).
48.3.1 Static Entries (SVLAN Table)
Static entry registration information is added, modified and removed by administrators only.