3com WX3000 Manuel D’Utilisation

 

1-4 

After VLANs are configured on a switch, the MAC address learning of the switch has the following two 

modes.  

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Shared VLAN learning (SVL): the switch records all the MAC address entries learnt by ports in all 

VLANs to a shared MAC address forwarding table. Packets received on any port of any VLAN are 

forwarded according to this table. 

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Independent VLAN learning (IVL): the switch maintains an independent MAC address forwarding 

table for each VLAN. The source MAC address of a packet received on a port of a VLAN is 

recorded to the MAC address forwarding table of this VLAN only, and packets received on a port of 

a VLAN are forwarded according to the VLAN’s own MAC address forwarding table. 

Currently, the device adopts the IVL mode only. For more information about the MAC address 

forwarding table, refer to the “MAC Address Forwarding Table Management” part of the manual.  

Hosts in different VLANs cannot communicate with each other directly unless routers or Layer 3 

switches are used to do Layer 3 forwarding. The device supports VLAN interfaces configuration to 

forward packets in Layer 3.  

VLAN interface is a virtual interface in Layer 3 mode, used to realize the layer 3 communication 

between different VLANs, and does not exist on a switch as a physical entity. Each VLAN has a VLAN 

interface, which can forward packets of the local VLAN to the destination IP addresses at the network 

layer. Normally, since VLANs can isolate broadcast domains, each VLAN corresponds to an IP network 

segment. And a VLAN interface serves as the gateway of the segment to forward packets in Layer 3 

based on IP addresses.  

 

The switching engine used in the device can be configured with a maximum number of eight VLAN 

interfaces.  

 

Depending on how VLANs are established, VLANs fall into the following six categories. 

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Port-based VLANs 

z 

MAC address-based VLANs 

z 

Protocol-based VLANs 

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IP-subnet-based VLANs 

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Policy-based VLANs 

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Other types 

Port-based VLAN technology introduces the simplest way to classify VLANs. You can assign the ports 

on the device to different VLANs. Thus packets received on a port will be transmitted through the 

corresponding VLAN only, so as to isolate hosts to different broadcast domains and divide them into 

different virtual workgroups.