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VLAN Support
The virtual LAN (VLAN) concept creates a virtual switch within a physical switch.
Frames are not forwarded between VLANs unless directed via a router or layer-3
switch.
The CrossFire 8730 provides the following VLAN functionality:
•
No frames are forwarded between ports belonging to different VLANs.
•
Each VLAN may be assigned a separate IP address.
•
Spanning Tree determination is executed independently within each VLAN.
VLANs on the Token-Ring Side
On the Token-Ring side, VLANs are set up on a per-port basis. This means that all
stations connected to a port must be part of the same VLAN. VLAN tagging is not used.
IEEE 802.1Q tagged VLANs entering the switch from the Fast Ethernet side are
translated into port-based VLANs on the Token-Ring side (and vice-versa).
Port groups on different VLANs may be assigned the same ring number, but ring
numbers must be unique within the same VLAN.
VLANs on the Fast Ethernet Side
On the Fast Ethernet side, IEEE 802.1Q VLAN tagging is applied. This enables
traffic from several Token-Ring port-based VLANs to pass over a single Fast
Ethernet link. Furthermore, Q-tagged VLAN information is able to travel further
into the network so VLAN information will be preserved by all equipment that
supports Q-tagging, regardless of the manufacturer or topology.
IEEE 802.1Q tagged VLANs entering the switch from the Fast Ethernet side are
translated into port-based VLANs on the Token-Ring side (and vice-versa).
The following figure illustrates an example of a VLAN with a CrossFire 8730
Switch.
CrossFire 8730 Switch Reference Guide, DOC-7047 v. 1.1
35
Switch Overview
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