Chapter 41: Port-based and Tagged VLANs
568
Section VII: Virtual LANs
Tagged VLAN Overview
The second type of VLAN is the tagged VLAN. VLAN membership in a
tagged VLAN is determined by information within the frames that are
received on a port. This differs from a port-based VLAN, where the PVIDs
assigned to the ports determine VLAN membership.
The VLAN information within an Ethernet frame is referred to as a
tag
or
tagged header
. A tag, which follows the source and destination addresses
in a frame, contains the VID of the VLAN to which the frame belongs
(IEEE 802.3ac standard). As explained earlier in this chapter in “VLAN
Identifier” on page 562, this number uniquely identifies each VLAN in a
network.
When the switch receives a frame with a VLAN tag, referred to as a
tagged frame
, the switch forwards the frame only to those ports that share
the same VID.
A port to receive or transmit tagged frames is referred to as a
tagged port
.
Any network device connected to a tagged port must be IEEE 802.1Q-
compliant. This is the standard that outlines the requirements and
standards for tagging. The device must be able to process the tagged
information on received frames and add tagged information to transmitted
frames.
The benefit of a tagged VLAN is that the tagged ports can belong to more
than one VLAN at one time. This can greatly simplify the task of adding
shared devices to the network. For example, a server can be configured to
accept and return packets from many different VLANs simultaneously.
Tagged VLANs are also useful where multiple VLANs span across
switches. You can use one port per switch to connect all VLANs on the
switch to another switch.
The IEEE 802.1Q standard describes how this tagging information is used
to forward the traffic throughout the switch. The handling of frames tagged
with VIDs coming into a port is straightforward. If the incoming frame’s VID
tag matches one of the VIDs of a VLAN of which the port is a tagged
member, the frame is accepted and forwarded to the appropriate ports. If
the frame’s VID does not match any of the VLANs that the port is a
member of, the frame is discarded.
The parts of a tagged VLAN are much the same as those for a port-based
VLAN. They are:
VLAN Name
VLAN Identifier
Tagged and Untagged Ports
Port VLAN Identifier
Summary of Contents for AT-9000/28
Page 4: ......
Page 26: ...Contents 26...
Page 30: ...Tables 30...
Page 36: ...36 Section I Getting Started...
Page 70: ...Chapter 2 Starting a Management Session 70 Section I Getting Started...
Page 96: ...96 Section II Basic Operations...
Page 142: ...Chapter 6 Basic Switch Management Commands 142 Section II Basic Operations...
Page 220: ...Chapter 9 IPv4 and IPv6 Management Addresses 220 Section II Basic Operations...
Page 244: ...Chapter 10 IPv4 and IPv6 Management Address Commands 244 Section II Basic Operations...
Page 264: ...Chapter 12 SNTP Client Commands 264 Section II Basic Operations...
Page 298: ...Chapter 15 Enhanced Stacking 298 Section II Basic Operations...
Page 312: ...Chapter 16 Enhanced Stacking Commands 312 Section II Basic Operations...
Page 318: ...Chapter 17 Port Mirror 318 Section II Basic Operations...
Page 324: ...Chapter 18 Port Mirror Commands 324 Section II Basic Operations Example awplus show mirror...
Page 350: ...Chapter 21 Multicast Commands 350 Section II Basic Operations...
Page 352: ...352 Section III File System...
Page 360: ...Chapter 22 File System 360 Section III File System...
Page 383: ...AT 9000 Switch Command Line User s Guide Section III File System 383 Example awplus show boot...
Page 386: ...Chapter 25 Boot Configuration File Commands 386 Section III File System...
Page 398: ...Chapter 26 File Transfers 398 Section III File System...
Page 406: ...Chapter 27 File Transfer Commands 406 Section III File System...
Page 408: ...408 Section IV Event Messages...
Page 430: ...Chapter 30 Syslog Client 430 Section IV Event Messages...
Page 438: ...438 Section V Port Trunks...
Page 448: ...Chapter 32 Static Port Trunks 448 Section V Port Trunks...
Page 480: ...480 Section VI Spanning Tree Protocols...
Page 520: ...Chapter 38 STP Commands 520 Section VI Spanning Tree Protocols...
Page 558: ...558 Section VII Virtual LANs...
Page 600: ...Chapter 42 Port based and Tagged VLAN Commands 600 Section VII Virtual LANs...
Page 634: ...Chapter 44 GARP VLAN Registration Protocol Commands 634 Section VII Virtual LANs...
Page 670: ...Chapter 47 Private Port VLANs 670 Section VII Virtual LANs...
Page 692: ...Chapter 50 VLAN Stacking 692 Section VII Virtual LANs...
Page 698: ...Chapter 51 VLAN Stacking Commands 698 Section VII Virtual LANs...
Page 700: ...700 Section VIII Port Security...
Page 748: ...Chapter 54 802 1x Port based Network Access Control 748 Section VIII Port Security...
Page 790: ...Chapter 55 802 1x Port based Network Access Control Commands 790 Section VIII Port Security...
Page 792: ...792 Section IX Simple Network Management Protocols...
Page 804: ...Chapter 56 SNMPv1 and SNMPv2c 804 Section X Simple Network Management Protocols...
Page 852: ...852 Section X Network Management...
Page 976: ...Chapter 63 Address Resolution Protocol ARP 976 Section X Network Management...
Page 1090: ...1090 Section XI Management Security...
Page 1114: ...Chapter 71 Telnet Server 1114 Section XI Management Security...
Page 1122: ...Chapter 73 Telnet Client 1122 Section XI Management Security...
Page 1126: ...Chapter 74 Telnet Client Commands 1126 Section XI Management Security...
Page 1138: ...Chapter 75 Secure Shell SSH Server 1138 Section XI Management Security...
Page 1158: ...Chapter 78 Non secure HTTP Web Browser Server Commands 1158 Section XI Management Security...
Page 1186: ...Chapter 80 Secure HTTPS Web Browser Server Commands 1186 Section XI Management Security...
Page 1202: ...Chapter 81 RADIUS and TACACS Clients 1202 Section XI Management Security...
Page 1230: ...Chapter 82 RADIUS and TACACS Client Commands 1230 Section XI Management Security...