Nortel Networks 24T manual Virtual Local Area Networks VLANs

Using the BayStack 410-24T 10BASE-T Switch

Virtual Local Area Networks (VLANs)

In a traditional shared-media network, traffic generated by a station is propagated to all other stations on the local segment. Therefore, for any given station on the shared Ethernet, the local segment is the collision domain because traffic on the segment has the potential to cause an Ethernet collision. The local segment is also the broadcast domain because any broadcast is sent to all stations on the local segment. Although Ethernet switches and bridges divide a network into smaller collision domains, they do not affect the broadcast domain. In simple terms, a virtual local area network provides a mechanism to fine-tune broadcast domains.

Your BayStack 410-24T switch allows you to create two types of VLANs:

•Port-based VLANs

A port-based VLAN is a VLAN in which the ports are explicitly configured to be in the VLAN. When you create a port-based VLAN, you assign a Port VLAN Identifier (PVID) and specify which ports belong to the VLAN. The PVID is used to coordinate VLANs across multiple switches.

•Protocol-based VLANs

A protocol-based VLAN is a VLAN in which you assign your switch ports as members of a broadcast domain, based on the protocol information within the packet. Protocol-based VLANs can localize broadcast traffic and assure that only the protocol-based VLAN ports are flooded with the specified protocol type packets.

Your switch ports can be members of multiple protocol-based VLANs that are not based on the same protocol. Only tagged ports can be members of multiple protocol-based VLANs that are based on the same protocol.

BayStack 410-24T switches support up to 64 port-based or protocol-based VLANs. When a switch port is configured to be a member of a VLAN, it is added to a group of ports (workgroup) that belong to one broadcast domain. You can assign different ports (and therefore the devices attached to these ports) to different broadcast domains. This feature allows network flexibility because you can reassign VLANs to accommodate network moves, additions, and changes, eliminating the need to change physical cabling.

For more information about VLANs, see “IEEE 802.1Q VLAN Workgroups” on page 1-36.

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