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Management Switch Card User’s Guide
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H A P T E R
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VLAN Screens
15.1 VLAN Introduction
A VLAN (Virtual Local Area Network) allows a physical network to be partitioned into multiple logical
networks. Devices on a logical network belong to one group. A device can belong to more than one
group. With VLAN, a device cannot directly talk to or hear from devices that are not in the same
group(s); the traffic must first go through a router.
In MTU (Multi-Tenant Unit) applications, VLAN is vital in providing isolation and security among the
subscribers. When properly configured, VLAN prevents one subscriber from accessing the network
resources of another on the same LAN, thus a user will not see the printers and hard disks of
another user in the same building. If you have enabled port isolation in the
Switch Setup
screen,
you do not need to configure the VLAN to isolate subscribers.
VLAN also increases network performance by limiting broadcasts to a smaller and more
manageable logical broadcast domain. In traditional switched environments, all broadcast packets
go to each and every individual port. With VLAN, all broadcasts are confined to a specific broadcast
domain.
15.2 IEEE 802.1Q Tagged VLAN
The IEEE 802.1Q Tagged VLAN uses both explicit and implicit tagging.
1
Explicit Tagging
A VLAN identifier is added to the frame header that identifies the source VLAN.
2
Implicit Tagging
The MAC (Media Access Control) number, the port or other information is used to identify the source
of a VLAN frame.
Tagged VLAN uses an explicit tag (VLAN ID) in the MAC header to identify the VLAN membership of
a frame across bridges - they are not confined to the switch on which they were created. The VLANs
can be created statically by hand or dynamically through GVRP. The VLAN ID associates a frame
with a specific VLAN and provides the information that switches need to process the frame across
the network. A tagged frame is four bytes longer than an untagged frame and contains two bytes of
TPID (Tag Protocol Identifier, residing within the type/length field of the Ethernet frame) and two
bytes of TCI (Tag Control Information, starts after the source address field of the Ethernet frame).
The CFI (Canonical Format Indicator) is a single-bit flag, always set to zero for Ethernet switches. If
a frame received at an Ethernet port has a CFI set to 1, then that frame should not be forwarded as
it is to an untagged port. The remaining twelve bits define the VLAN ID, giving a possible maximum
number of 4,096 VLANs. Note that user priority and VLAN ID are independent of each other. A
Summary of Contents for MSC1000G Series
Page 38: ...Table of Contents Management Switch Card User s Guide 38...
Page 39: ...39 PART I Introduction...
Page 40: ...40...
Page 54: ...Chapter 1 Getting to Know Your MSC Management Switch Card User s Guide 54...
Page 61: ...61 PART II Web Configurator...
Page 62: ...62...
Page 80: ...Chapter 3 The Web Configurator Management Switch Card User s Guide 80...
Page 162: ...Chapter 5 Alarm Screens Management Switch Card User s Guide 162...
Page 178: ...Chapter 6 Diagnostic Screens Management Switch Card User s Guide 178...
Page 184: ...Chapter 7 Maintenance Screens Management Switch Card User s Guide 184...
Page 204: ...Chapter 8 Multicast Screens Management Switch Card User s Guide 204...
Page 226: ...Chapter 9 Subscriber Port Setup Screens Management Switch Card User s Guide 226...
Page 227: ...Chapter 9 Subscriber Port Setup Screens Management Switch Card User s Guide 227...
Page 330: ...Chapter 10 IMA Screens Management Switch Card User s Guide 330...
Page 412: ...Chapter 11 Profile Screens Management Switch Card User s Guide 412...
Page 512: ...Chapter 12 Statistics Screens Management Switch Card User s Guide 512...
Page 560: ...Chapter 13 Switch Screens Management Switch Card User s Guide 560...
Page 598: ...Chapter 15 VLAN Screens Management Switch Card User s Guide 598...
Page 636: ...Chapter 16 VoIP Management Switch Card User s Guide 636...
Page 638: ...Chapter 17 Config Save Management Switch Card User s Guide 638...
Page 639: ...639 PART III Commands...
Page 640: ...640...
Page 646: ...Chapter 18 Commands Management Switch Card User s Guide 646...
Page 682: ...Chapter 19 acl Commands Management Switch Card User s Guide 682...
Page 690: ...Chapter 20 alarm Commands Management Switch Card User s Guide 690...
Page 696: ...Chapter 22 config Commands Management Switch Card User s Guide 696...
Page 754: ...Chapter 28 multicast Commands Management Switch Card User s Guide 754...
Page 840: ...Chapter 29 port Commands Management Switch Card User s Guide 840...
Page 924: ...Chapter 30 profile Commands Management Switch Card User s Guide 924...
Page 926: ...Chapter 31 redundant Commands Management Switch Card User s Guide 926...
Page 1062: ...Chapter 35 vlan Commands Management Switch Card User s Guide 1062...
Page 1103: ...1103 PART IV Troubleshooting Specifications Appendices and Index...
Page 1104: ...1104...
Page 1134: ...Chapter 39 Product Specifications Management Switch Card User s Guide 1134...
Page 1146: ...Appendix B Legal Information Management Switch Card User s Guide 1146...