Extending VLANs into the ATM Network
You can use LAN Emulation to define and extend VLANs seamlessly through the ATM network, as shown in the example in Figure
Traffic from one Emulated LAN (ELAN) is not seen on another ELAN as they are logically separate domains. For this reason, when you plan your network, you should consider what ELANs you require, and how the VLANs will map to these ELANs.
The ATM Module has a LEC for each of the Switch’s 16 VLANS, and each VLAN/LEC can be mapped onto an Emulated LAN (ELAN). In this way, Ethernet traffic is mapped to an ELAN by a
When an Ethernet device attached to a Switch generates traffic, the Switch forwards the frames to the appropriate port.
A unicast frame is only forwarded to a port if the address of the destination device is known to be on that port and the destination port is in the same VLAN as the source port. If a unicast frame is forwarded to the ATM port, the ATM port uses the destination MAC address to identify the ATM connection to use.
A broadcast or multicast frame is forwarded to all ports in the same VLAN as the source port. If a frame is received by the ATM port, the ATM port forwards it to the BUS for the associated VLAN.
