GS2200-48 User’s Guide
79
C
H A P T E R
8
VLAN
The type of screen you see here depends on the VLAN Type you selected in the
Switch Setup screen. This chapter shows you how to configure 802.1Q tagged
and port-based VLANs.
8.1 Introduction to IEEE 802.1Q Tagged VLANs
A 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 for the TPID (Tag Protocol Identifier, residing within the type/
length field of the Ethernet frame) and two bytes for the TCI (Tag Control
Information, starting 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
frame with VID (VLAN Identifier) of null (0) is called a priority frame, meaning that
only the priority level is significant and the default VID of the ingress port is given
as the VID of the frame. Of the 4096 possible VIDs, a VID of 0 is used to identify
priority frames and the value 4095 (FFF) is reserved, so the maximum possible
number of VLAN configurations is 4,094.
8.1.1 Forwarding Tagged and Untagged Frames
Each port on the Switch is capable of passing tagged or untagged frames. To
forward a frame from an 802.1Q VLAN-aware switch to an 802.1Q VLAN-unaware
TPID
2 Bytes
User Priority
3 Bits
CFI
1 Bit
VLAN ID
12 bits
Summary of Contents for GS2200-48
Page 2: ......
Page 8: ...Safety Warnings GS2200 48 User s Guide 8 ...
Page 22: ...22 ...
Page 28: ...Chapter 1 Getting to Know Your Switch GS2200 48 User s Guide 28 ...
Page 32: ...Chapter 2 Hardware Installation and Connection GS2200 48 User s Guide 32 ...
Page 40: ...40 ...
Page 62: ...Chapter 6 System Status and Port Statistics GS2200 48 User s Guide 62 ...
Page 76: ...Chapter 7 Basic Setting GS2200 48 User s Guide 76 ...
Page 78: ...78 ...
Page 102: ...Chapter 9 Static MAC Forward Setup GS2200 48 User s Guide 102 ...
Page 122: ...Chapter 11 Spanning Tree Protocol GS2200 48 User s Guide 122 ...
Page 126: ...Chapter 12 Bandwidth Control GS2200 48 User s Guide 126 ...
Page 148: ...Chapter 17 Port Security GS2200 48 User s Guide 148 ...
Page 156: ...Chapter 18 Classifier GS2200 48 User s Guide 156 ...
Page 164: ...Chapter 19 Policy Rule GS2200 48 User s Guide 164 ...
Page 214: ...Chapter 24 IP Source Guard GS2200 48 User s Guide 214 Figure 98 DHCP Snooping ...
Page 236: ...236 ...
Page 270: ...270 ...
Page 278: ...Chapter 31 Maintenance GS2200 48 User s Guide 278 ...
Page 304: ...Chapter 34 Syslog GS2200 48 User s Guide 304 ...
Page 312: ...Chapter 35 Cluster Management GS2200 48 User s Guide 312 ...
Page 316: ...Chapter 36 MAC Table GS2200 48 User s Guide 316 ...
Page 320: ...Chapter 37 IP Table GS2200 48 User s Guide 320 ...
Page 324: ...Chapter 39 Routing Table GS2200 48 User s Guide 324 ...
Page 327: ...327 PART VI Product Specifications Product Specifications 329 ...
Page 328: ...328 ...
Page 336: ...Chapter 41 Product Specifications GS2200 48 User s Guide 336 ...
Page 338: ...338 ...
Page 352: ...Appendix B Legal Information GS2200 48 User s Guide 352 ...
Page 362: ...Index GS2200 48 User s Guide 362 ...