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SmartSwitch ATM User Guide 2-15
IP Over ATM and LANE Creating an Emulated LAN
Figure 2-1 Single PVP connection between clients and LANE services
Physical BUS multicasting implies that the BUS performs multicasting according to physical ports. With a single PVP,
the BUS understands that all requests are coming from a particular port. Accordingly, the BUS replies over that port,
and it is up to the switch at the other end of the PVP connection to sort out which reply belongs to which client (see
Figure 2-2).
Another possible ATM WAN configuration involves multiple PVPs across the WAN, with each PVP terminated on its
own virtual port, and all virtual ports residing on the same physical port. In this configuration, LANE join requests for
the same ELAN may appear on different virtual ports of the same physical port of the switch running LANE services.
Because these requests are appearing on multiple logical entities (multiple virtual ports), this requires the BUS to be
capable of logical multicasting.
Figure 2-2 Multiple PVP connection between clients and LANE services
Logical BUS multicasting implies that the BUS of a particular ELAN can distinguish the difference between virtual
ports on the same physical port. In essence, the BUS treats each virtual port as a physical entity, and keeps track of its
point-to-multipoint connections to the clients through various PVPs.
ATM WAN
SW1
SW2
Single
PVP
Single
Virtual Port
LANE
Server
(elan1)
Single
Physical
Port
Any SmartSwitch
ATM Switch
Single
PVP
Single
Virtual Port
Single
Physical
Port
Client
Join
Requests
ATM WAN
SW1
SW2
LANE
Server
(elan1)
Must be
SmartSwitch 6500
Multiple
Virtual Ports
Multiple
Virtual Ports
Multiple
PVPs
Multiple
PVPs
Single
Physical
Port
Single
Physical
Port
Client
Join
Requests