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XGS4700-48F User’s Guide
119
C
H A P T E R
9
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.
9.1 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.
9.1.1 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 XGS4700 Series
Page 2: ......
Page 8: ...Safety Warnings XGS4700 48F User s Guide 8...
Page 24: ...Table of Contents XGS4700 48F User s Guide 24...
Page 25: ...25 PART I User s Guide...
Page 26: ...26...
Page 32: ...Chapter 1 Getting to Know Your Switch XGS4700 48F User s Guide 32...
Page 54: ...Chapter 3 Hardware Overview XGS4700 48F User s Guide 54...
Page 97: ...97 PART II Technical Reference...
Page 98: ...98...
Page 104: ...Chapter 7 System Status and Port Statistics XGS4700 48F User s Guide 104...
Page 118: ...Chapter 8 Basic Setting XGS4700 48F User s Guide 118...
Page 138: ...Chapter 9 VLAN XGS4700 48F User s Guide 138...
Page 142: ...Chapter 10 Static MAC Forward Setup XGS4700 48F User s Guide 142...
Page 174: ...Chapter 14 Bandwidth Control XGS4700 48F User s Guide 174...
Page 188: ...Chapter 17 Link Aggregation XGS4700 48F User s Guide 188...
Page 198: ...Chapter 18 Port Authentication XGS4700 48F User s Guide 198...
Page 216: ...Chapter 21 Policy Rule XGS4700 48F User s Guide 216...
Page 260: ...Chapter 25 AAA XGS4700 48F User s Guide 260...
Page 284: ...Chapter 26 IP Source Guard XGS4700 48F User s Guide 284...
Page 316: ...Chapter 32 Error Disable XGS4700 48F User s Guide 316...
Page 320: ...Chapter 33 Static Route XGS4700 48F User s Guide 320...
Page 328: ...Chapter 35 RIP XGS4700 48F User s Guide 328...
Page 384: ...Chapter 42 ARP Learning XGS4700 48F User s Guide 384...
Page 420: ...Chapter 45 Access Control XGS4700 48F User s Guide 420...
Page 426: ...Chapter 47 Syslog XGS4700 48F User s Guide 426...
Page 434: ...Chapter 48 Cluster Management XGS4700 48F User s Guide 434...
Page 438: ...Chapter 49 MAC Table XGS4700 48F User s Guide 438...
Page 442: ...Chapter 50 IP Table XGS4700 48F User s Guide 442...
Page 446: ...Chapter 52 Routing Table XGS4700 48F User s Guide 446...
Page 454: ...Chapter 54 Troubleshooting XGS4700 48F User s Guide 454...
Page 464: ...Chapter 55 Product Specifications XGS4700 48F User s Guide 464...
Page 473: ...Appendix B Legal Information XGS4700 48F User s Guide 473...
Page 474: ...Appendix B Legal Information XGS4700 48F User s Guide 474...