Cabletron Systems 802.1Q manual Receiving Frames from Vlan Ports, Inside the Switch

Page 24

Chapter 2: VLAN Operation

Figure 2-1depicts the inside of a switch with six ports, numbered one through six. The switch has been conﬁgured to associate VLAN A and B with FID 2, VLAN C and D with FID 3, and VLAN E with FID 4. Port 6 has been classiﬁed as a 1Q Trunk Port. This classiﬁcation establishes that all VLANs are members of the Port VLAN List for Port 6 and the frames transmitted for all VLANs will contain a tag header. Also the PVID for Port 6 is set to the default VLAN with its corresponding relationship to FID 1. Although untagged frames are not usually present on a 1Q Trunk Port, any untagged frames received would need to be classiﬁed if the port has not been conﬁgured to drop all untagged frames.

Port 1 Port 2Port 3

A	B	C
FID 2	FID 2	FID 3
D	E	Default
FID 3	FID 4	FID 1
Port 4	Port 5	Port 6

2599-02

Figure 2-1 Inside the Switch

2.4.1Receiving Frames from VLAN Ports

When a switch is placed in 802.1Q Operational Mode, every frame received by the switch must belong, or be assigned, to a VLAN.

Untagged Frames

The switch receives a frame from Port 1 and examines the frame. The switch notices that this frame does not currently have a VLAN tag. The switch recognizes that Port 1 is a member of VLAN A and classiﬁes the frame as such. In this fashion, all untagged frames entering a VLAN switch assume membership in a VLAN.

NOTE

A VLAN ID is always assigned to a port. By default, it is the Default VLAN (VLAN ID = 1).

2-4	802.1Q VLAN User’s Guide

Image 24

Contents 802.1Q Vlan User’s Guide Page 802.1Q Vlan User’s Guide 802.1Q Vlan User’s Guide Contents Contents Contents Contents 802.1Q Vlan User’s Guide Figures Tables Using this Guide Structure of this GuideRelated Documents Document ConventionsChapter Virtual Local Area Networks Defining VLANsBuilding One Building Two Types of VLANs 1 802.1Q VLANsSecureFast VLANs Other Vlan StrategiesBenefits and Restrictions Vlan TermsData frame that does not have a Tag Header 1D Trunk Getting Help Your email address802.1Q Vlan User’s Guide Description Vlan ComponentsConfiguration Process 1 Deﬁning a VlanClassifying Frames to a Vlan Vlan Switch Operation Customizing the Vlan Forwarding ListInside the Switch Receiving Frames from Vlan PortsForwarding Decisions Broadcasts, Multicasts, and Unknown UnicastsKnown Unicasts Garp Switch Operation Managing the Switch Switch Without VLANsSwitch with VLANs Switch Management with VLANsManaging the Switch Summary of Vlan Local Management Preparing for Vlan Conﬁguration802.1Q Vlan Configuration Menu Screen When to UseHow to Access Menu Deﬁnitions Device Vlan Configuration Screen Device Vlan Conﬁguration ScreenField Deﬁnitions 1 Deﬁning a Vlan Changing the Vlan to FID Association Renaming a VlanDeleting a Vlan Enabling VLANsDisabling VLANs Changing the Forwarding Mode Paging Through the Vlan ListPort Assignment Configuration Screen Port Assignment Conﬁguration ScreenChanging the Port Mode Port ModeAssigning a Vlan ID Port Filtering Configuration Screen Paging Through the Port ListPort Filtering Conﬁguration Screen Displaying Vlan IDs Associated with a Port Vlan ListsSelecting the Type of Filtering for a Port Vlan Forwarding Configuration Screen Vlan Forwarding Conﬁguration ScreenViewing Current Vlan Ports Frame FormatPaging Through Vlan Forwarding List Entries Adding Forwarding List EntriesDeleting Forwarding List Entries Protocol Vlan Configuration Screen Changing the Frame FormatProtocol Vlan Conﬁguration Screen Selectable Feature Status Assigning a Protocol Family to a Vlan ID Ether typeProtocol Vlan Conﬁguration Screen Displaying the Protocol Types on Current Ports Protocol Ports Configuration Screen 10 Protocol Ports Conﬁguration ScreenDelete ALL Adding/Deleting Ports Associated with a Vlan ID Quick Vlan Walkthrough802.1Q Vlan User’s Guide Hybrid 12 Walkthrough Stage Two 13 Walkthrough Stage Three 14 Walkthrough Stage Four Quick Vlan Walkthrough 15 Final Walkthrough Stage Example 1, Single Switch Operation Chapter ExamplesSolving the Problem Switch Conﬁgured for VLANsFrame Handling Example 2, Vlans Across Multiple Switches Example 2, VLANs Across Multiple Switches Switch Example 2, VLANs Across Multiple Switches Bridge 1 Broadcasts Frames Transmitting to Switch Example 3, 1D Trunk Connection to 802.1Q Vlan Network Transmitting to BridgeExample 3, 1D Trunk Connection to 802.1Q Vlan Network Solving the Problem Frame Handling 226318 Switch 2 Forwards to 1Q Trunk Examples Example 4, Isolating Network Traffic According to Protocol 11 Example 4, Isolating Trafﬁc According to Protocol Switch Examples Example 4, Isolating Network Trafﬁc According to Protocol Examples 802.1Q Vlan User’s Guide Index NumericsIndex-2 802.1Q Vlan User’s Guide 802.1Q Vlan User’s Guide Index-3 Index Index-4 802.1Q Vlan User’s Guide