In a Passport network designed to carry LAN traffic, each Passport 4400 unit must designate a user core router (UCR). When a Passport 4400 receives LAN traffic destined for a remote node (outside the physically attached LAN), the traffic is directed to its designated UCR.
For a Passport 4400 in a multi-layered (hierarchical) network, it is best to designate the node at the next highest level in the hierarchy as its UCR. This will allow LAN user traffic to be efficiently directed across the Passport network, without flooding the network with traffic.
In the network illustration shown below, units D and E should designate unit B as their UCR. Unit B, in turn, should designate unit A as its UCR. In this scenario, LAN traffic from D to E will travel through unit B, offering the shortest path between the two nodes. For more information about constructing and configuring a Passport network, see Configure Connections to the Passport Network.
If your Passport network includes a third-party bridge or router, it is possible to use the third-party device to perform the bridging/routing tasks of the UCR. In this case, the third-party device should be connected to the central node of the Passport network for best performance. The procedure for connecting a third-party device to a Passport 4400 can be found in Virtual Ports.
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Inter-LAN Switching (ILS) and Passport 6400 Interworking
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