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Cabletron Systems 802.1Q manual Chapter Vlan Operation, Description, Vlan Components

Models: 802.1Q

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CHAPTER 2

VLAN OPERATION

This chapter describes the operation of a VLAN switch and discusses the operations that a VLAN switch performs in response to both normal and VLAN-originated network trafﬁc.

2.1DESCRIPTION

The 802.1Q VLAN operation is slightly different than the operation of traditional switched networking systems. These differences are due to the importance of keeping track of each frame and its VLAN association as it passes from switch to switch or from port to port within a switch.

2.2VLAN COMPONENTS

Before describing the operation of an 802.1Q VLAN, it is important to understand the basic elements that are combined to make up an 802.1Q VLAN.

Stations

A station is any end unit that belongs to a network. In the vast majority of cases, stations are the computers through which the users access the network.

Switches

In order to conﬁgure a group of stations into a VLAN, the stations must be connected to VLAN aware switches. It is the job of the switch to classify received frames into VLAN memberships and transmit frames, according to VLAN membership, with or without a VLAN Tag Header.

802.1Q VLAN User’s Guide

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Cabletron Systems 802.1Q manual Chapter Vlan Operation, Description, Vlan Components

Contents

9032599-02 802.1Q VLAN User’s GuidePage 802.1Q VLAN User’s Guide 802.1Q VLAN User’s Guide PREFACE CONTENTSCHAPTER VIRTUAL LOCAL AREA NETWORKSVLAN CONFIGURATION ContentsCHAPTER 802.1Q VLAN User’s GuideCHAPTER ContentsEXAMPLES 802.1Q VLAN User’s Guide802.1Q VLAN User’s Guide Contents802.1Q VLAN User’s Guide FIGURES802.1Q VLAN Configuration Menu Screen Menu Items TABLES802.1Q VLAN User’s Guide viiiUSING THIS GUIDE PREFACESTRUCTURE OF THIS GUIDE DOCUMENT CONVENTIONS RELATED DOCUMENTS1.1 DEFINING VLANs CHAPTER VIRTUAL LOCAL AREA NETWORKSBuilding Two Building One1.2.1 802.1Q VLANs 1.2 TYPES OF VLANs1.2.2 SecureFast VLANs 1.2.3 Other VLAN Strategies1.4 VLAN TERMS 1.3 BENEFITS AND RESTRICTIONSA data frame that does not have a Tag Header Generic Attribute Registration Protocol GARP 1D TrunkGARP VLAN Registration Protocol GVRP GARP Multicast Registration Protocol GMRP1.5 GETTING HELP 802.1Q VLAN User’s Guide Chapter 1 Virtual Local Area NetworksCHAPTER VLAN OPERATION 2.1 DESCRIPTION2.2 VLAN COMPONENTS 2.3.1 Deﬁning a VLAN 2.3 CONFIGURATION PROCESS2.3.2 Classifying Frames to a VLAN Chapter 2 VLAN Operation2.3.3 Customizing the VLAN Forwarding List 2.4 VLAN SWITCH OPERATIONUntagged Frames 2.4.1 Receiving Frames from VLAN Ports2.4.2.1 Broadcasts, Multicasts, and Unknown Unicasts 2.4.2 Forwarding Decisions2.4.2.2 Known Unicasts Tagged Frames2.5 GARP SWITCH OPERATION 3.1 MANAGING THE SWITCH CHAPTER VLAN CONFIGURATION3.1.1 Switch Without VLANs 802.1Q Switch802.1Q Switch 3.1.2 Switch with VLANs2. Use the Port Assignment Configuration screen for the following 3.2.1 Preparing for VLAN Conﬁguration 3.2 SUMMARY OF VLAN LOCAL MANAGEMENTWhen to Use 3.3 802.1Q VLAN CONFIGURATION MENU SCREENHow to Access Screen ExampleFigure 3-4 802.1Q VLAN Conﬁguration Menu Screen 802.1Q VLAN Conﬁguration Menu Screen Menu Deﬁnitions802.1Q VLAN User’s Guide Table 3-1 802.1Q VLAN Conﬁguration Menu Screen Menu ItemsWhen to Use 3.4 DEVICE VLAN CONFIGURATION SCREENHow to Access Screen ExampleDevice VLAN Conﬁguration Screen Field Deﬁnitions802.1Q VLAN User’s Guide Table 3-2 Device VLAN Conﬁguration Screen Field Deﬁnitions3.4.1 Deﬁning a VLAN 3.4.3 Renaming a VLAN 3.4.2 Changing the VLAN to FID Association3.4.5 Enabling VLANs 3.4.4 Deleting a VLAN3.4.6 Disabling VLANs The default VLAN cannot be deleted from the list3.4.7 Changing the Forwarding Mode 3.4.8 Paging Through the VLAN ListThe default VLAN cannot be disabled When to Use 3.5 PORT ASSIGNMENT CONFIGURATION SCREENHow to Access Screen ExampleField Deﬁnitions 3.5.1 Changing the Port Mode3.5.2 Assigning a VLAN ID 3.6 PORT FILTERING CONFIGURATION SCREEN 3.5.3 Paging Through the Port ListWhen to Use Screen Example How to AccessChapter 3 VLAN Conﬁguration 3-18Field Deﬁnitions 3.6.1 Displaying VLAN IDs Associated with a Port3.6.2 Selecting the Type of Filtering for a Port When to Use 3.7 VLAN FORWARDING CONFIGURATION SCREENHow to Access Screen Example3.7.1 Viewing Current VLAN Ports Field DeﬁnitionsSee the frame format Tagged or Untagged for the frames 3.7.2 Paging Through VLAN Forwarding List Entries 3.7.3 Adding Forwarding List Entries3.7.4 Deleting Forwarding List Entries 3.8 PROTOCOL VLAN CONFIGURATION SCREEN 3.7.5 Changing the Frame FormatWhen to Use Screen Example How to AccessProtocol VLAN Conﬁguration Screen 802.1Q VLAN User’s GuideChapter 3 VLAN Conﬁguration Field Deﬁnitions3-26 802.1Q VLAN User’s Guide802.1Q VLAN User’s Guide Protocol VLAN Conﬁguration Screen3-27 Table 3-6 Protocol VLAN Conﬁguration Screen Field Deﬁnitions Cont’d3.8.2 Assigning a Protocol Family to a VLAN ID 3.8.1 Displaying the Current Protocol, VLAN ID, and Port AssignmentsTo see if there are VLANs currently assigned to the Protocol Protocol VLAN Conﬁguration ScreenTIP displayed in the Protocol ﬁeld, press ENTER 802.1Q VLAN User’s Guide3.8.3 Displaying the Protocol Types on Current Ports When to Use 3.9 PROTOCOL PORTS CONFIGURATION SCREENHow to Access Screen ExampleChapter 3 VLAN Conﬁguration Field Deﬁnitions3-32 802.1Q VLAN User’s Guide3.10 QUICK VLAN WALKTHROUGH 3.9.1 Adding/Deleting Ports Associated with a VLAN ID6. Use the arrow keys to highlight the ADD/DEL field It is now time to assign a port to this new VLAN Figure 3-12 Walkthrough Stage Two Figure 3-13 Walkthrough Stage Three 17. Press the SPACE bar to toggle the field to display Enabled 21. Use the arrow keys to highlight the Port field 3-40 Chapter 3 VLAN Conﬁguration802.1Q VLAN User’s Guide Figure 3-15 Final Walkthrough Stage4.1 EXAMPLE 1, SINGLE SWITCH OPERATION 802.1Q SwitchCHAPTER EXAMPLES R1 R2 R34.1.1 Solving the Problem 802.1Q SwitchB3 B2 B1 4.1.2 Frame Handling 4.2 EXAMPLE 2, VLANS ACROSS MULTIPLE SWITCHES Figure 4-3 Example 2, VLANs Across Multiple Switches 4.2.1 Solving the ProblemSwitch 4 is set as follows Switch 2 is set as follows Figure 4-4 Bridge 1 Broadcasts Frames 4.2.2 Frame HandlingFigure 4-5 Transmitting to Switch Figure 4-6 Transmitting to Bridge 4.3 EXAMPLE 3, 1D TRUNK CONNECTION TO 802.1Q VLAN NETWORKFigure 4-7 Example 3, 1D Trunk Connection to 802.1Q VLAN Network User BGreen Incorporated 4.3.1 Solving the Problem 4.3.2 Frame Handling Figure 4-8 Bridge 1 Broadcasts Frames Figure 4-10 Switch 1 Forwards to 1D Trunk Figure 4-9 Switch 2 Forwards to 1Q TrunkSwitch 1 checks the Filtering Database for the MAC address of User B. User B’s MAC address is located, and Port 2 is identified as User B’s location. The frame is then checked for eligibility and frame format for Port 2. Since Port 2 is a 1Q Trunk port, it is eligible to transmit frames for all VLANs. The frame is tagged and transmitted out Port 4.4 EXAMPLE 4, ISOLATING NETWORK TRAFFIC ACCORDING TO PROTOCOL Figure 4-11 Example 4, Isolating Trafﬁc According to Protocol 4.4.1 Solving the ProblemSwitch 3 is set as follows Switch 5 is set as follows Port 2, VLAN ID 6, Protocol AppleTalk Chapter 4 Examples 4-22802.1Q VLAN User’s Guide Numerics INDEXIndex Index-2802.1Q VLAN User’s Guide Index 802.1Q VLAN User’s GuideIndex-3 Index Index-4802.1Q VLAN User’s Guide